Personal experience in treating phyto hippocampal sclerosis. Temporal Epilepsy - Hippocampal Sclerosis

Research Institute of Ambulance named after N.V. Sklifosovsky participates in the "Program for the comprehensive treatment of patients with epilepsy" in conjunction with the Russian National Research Medical University. N.I. Pirogov, Moscow State Medical and Dental University. A.I. Evdokimov, Institute of Higher Nervous Activity and Neurophysiology RAS, Scientific and Practical Psychoneurological Center. Z.P. Solovyov, Interdistrict Department of Paroxysmal Condition No. 2, City Clinical Hospital No. 12, which includes a comprehensive examination of patients with epilepsy, selection and correction of conservative therapy, specialist advice, observation, surgical treatment of patients suffering from epilepsy.

Epilepsy is one of the most common neurological diseases, its prevalence in the population according to data on the Russian Federation is 0.34%.

Currently, there are more than 50 million patients with epilepsy in the world. Among diseases of the nervous system, epilepsy is one of the most common causes of disability. Despite the success of pharmacotherapy, the frequency of "uncontrolled" epilepsy in industrialized countries adhering to modern treatment standards is from 30 to 40%. Patients with epilepsy with removable lesions are the most likely candidates for surgical treatment.

Mortality among patients with persistent seizures is 4 to 4.5 times higher than in patients without seizures.

The main causes of symptomatic epilepsy are:

• brain tumors;
• brain malformations;
• cortical malformations (focal cortical dysplasias, heterotopies, etc.);
• hippocampal sclerosis;
• post-traumatic cicatricial-atrophic changes.

Diagnostics.

To solve the question of the possibility of surgical treatment of epilepsy, a comprehensive “pre-surgical” examination, which includes:

1. A clinical study of the semiology of seizures;
2. Neuropsychological studies;
3. Neuroimaging research methods (high-resolution magnetic resonance imaging on an apparatus with a capacity of 3.0 Tesla according to the special program "epilepsy", positron emission tomography).
4. Neurophysiological studies, including both invasive methods (recording the bioelectric activity of the brain using intracranial electrodes) and non-invasive methods (EEG, video-EEG monitoring, magnetoencephalography).

Fig. 1. MRI of the brain (coronary sections), arrows indicate focal cortical dysplasia of the left temporal lobe with left hippocampal hyperplasia.

Fig. 2. Electrodes for invasive registration of bioelectrical activity of the brain (the electrode on the left for installation in the hippocampus, on the right - the cortical subdural electrode).

The main objective of the treatment of epilepsy, both medical and surgical, is to control seizures. In patients with persistent seizures resistant to anticonvulsant therapy, the cessation of seizures after surgical treatment significantly improves the quality of life - professional and social adaptation and leads to a decrease in mortality.

With continued anticonvulsant therapy, seizure control can be achieved in no more than 8% of cases. At the same time, during surgical treatment seizure control is achieved in 58% of patients, and in the group of patients with temporal lobe epilepsy - in 67%.

Only after a thorough thorough examination is it possible to resolve the issue of surgical treatment.

The main method of surgical treatment of epilepsy is the removal of the epileptogenic zone of the brain under neurophysiological control, using a high-resolution microscope, as well as stereotactic navigation methods.

At the Research Institute of Emergency Care named after N.V. Sklifosovsky conducted a full examination, as well as all types of surgical treatment of patients with pharmacologically resistant forms of epilepsy.

Surgical Treatment Examples

Patient N., 40 years old.

Diagnosis: Symptomatic pharmacoresistant epilepsy. Sclerosis of the right hippocampus. Focal cortical dysplasia of the right frontotemporal region. (PKD IIId).

Medical history: a convulsive attack first occurred at 2 months after suffering meningoencephalitis. At the age of 8 years, a generalized epileptic seizure with loss of consciousness first developed, the frequency of seizures at that time was 1 time per year. It was observed by a neurologist, received conservative therapy - without effect, the number of seizures increased every year. From the age of 17, the frequency of seizures reached 1 seizure per week. At the age of 30, the number of seizures reached 4-5 per day. 2 years ago, the patient noted the appearance of an aura in the form of visual and tactile hallucinations, preceding seizures. It was observed by a neurologist, the dose of anticonvulsants continued to increase, however, despite this, the frequency of seizures increased.

Fig. 3. MRI of the brain (coronary sections). Arrows indicate signs of sclerosis of the right hippocampus in the form of a decrease in the size of the structure with expansion of the lower horn of the right lateral ventricle, an increase in the signal from the white matter of the brain

  The first stage of the operation was the patient - an intracranial installation of subdural and intracerebral electrodes with invasive EEG monitoring using the BrainLab frameless neuronavigation system and the Vario Guide system.

Fig. 4 (left). The stage of planning the operation is the installation of intracranial electrodes using the BrainLab and VarioGuide neuronavigation devices.

Fig. 5 (right). The operation step is to install the electrode in the right hippocampus using the BrainLab and VarioGuide navigation system.

  With five daily video-EEG monitoring in the interictal period, the patient recorded paroxysmal activity, most pronounced on the basal surface of the temporal lobe on the right. The onset of seizures was localized in the right hippocampus and the basal surface of the right temporal lobe.

Fig. 6 (left). Carrying out video EEG monitoring

Fig. 7 (right). Single room for video-EEG monitoring (an infrared camera is installed allowing video-EEG monitoring around the clock).

  The patient underwent surgery - pterion-infratemporal craniotomy, resection of the anterior-medial sections of the right temporal lobe with hippocampectomy. The operation was performed using intraoperative ECoG (electrocortography) - it is performed for intraoperative monitoring of the bioelectrical activity of the brain, allows confirming the epileptogenic focus, as well as increasing the effectiveness of surgical treatment.

The patient was discharged on the 12th day in a satisfactory condition, with control EEG - data for the presence of paroxysmal activity was not received.

The histological conclusion of the resected sections of the right temporal lobe and the right hippocampus): morphological picture of PCD (focal cortical dysplasia) III d type (ILAE). A clear picture of sclerosis of the right hippocampus.

In the patient (follow-up history of 12 months), no epileptic seizures were observed after surgical treatment.

Patient N., 25 years old.

Diagnosis: Focal cortical dysplasia (PKD IIIa). Sclerosis of the left hippocampus. Symptomatic pharmacoresistant post-traumatic epilepsy. SHKG-15 points.

Complaints: for epileptic seizures with a frequency of 1-2 times a month with loss of consciousness and seizures 1 time per week, without loss of consciousness.

Medical history:  at 8 months, he suffered a severe head injury with a prolonged coma, later weakness in the right extremities developed. From the age of 6, the patient developed seizures - local convulsions of the facial muscles. From the age of 15, generalized seizures appeared. He took carbamazepine, topamax doses were increased to subtoxic, but no significant effect was achieved.
  Currently, the patient has epileptic seizures with loss of consciousness with a frequency of 1-2 times a month for up to 1 minute and seizures 1 time per week, without loss of consciousness, lasting up to 15 seconds.

Fig. 8 (left). MRI of the brain (coronary section). Post-traumatic cicatricial-atrophic changes in the left parietal lobe of the brain are determined (marked with a red circle).

Fig. 9 (right). MRI of the brain (axial section). Arrow 1 marks the right hippocampus and arrow 2 marks the left hippocampus. Attention is drawn to the asymmetric arrangement and reduction of the size of the left hippocampus (arrow 2).

  The patient underwent daily video-EEG monitoring - where paroxysmal activity was detected in the left frontal and temporal areas. Irritative changes are expressed in the right central region. In a dream, epileptiform activity in the left parietal and temporal regions increases significantly, manifests itself in prolonged periods, in most cases accompanied by twitching of the right arm or leg.

The first stage of the operation was the patient - an intracranial installation of subdural and intracerebral electrodes with invasive EEG monitoring using the BrainLab frameless neuronavigation system and the Vario Guide system.

The patient underwent invasive EEG monitoring for 7 days. During the observation, the patient registered three clinical epileptic seizures.

Against the background of complete well-being and the absence of seizures, the patient constantly registers paroxysmal activity in the left hippocampus and in the scar zone.

During one of the epileptic seizures, the onset of the seizure is localized in the area of \u200b\u200bthe post-traumatic scar with the involvement of the left hippocampus and the basal parts of the left temporal lobe.

During two other epileptic seizures, the patient registered the onset of the seizure in the projection of the left hippocampus with subsequent spread to the area of \u200b\u200bthe left temporal lobe.

Fig. 10 (left). Conducting round-the-clock invasive video-EEG monitoring (using a high-resolution infrared video camera). The red arrow indicates the zone of the beginning of the registration of paroxysmal activity on the electrode located in the projection of the post-traumatic scar of the left parietal lobe.

Fig. 11 (right). Conducting round-the-clock invasive video-EEG monitoring (using a high-resolution infrared video camera). The red arrow indicates the zone of the beginning of the registration of paroxysmal activity on the electrode located in the left hippocampus.

  Thus, it was revealed that the patient has two zones of the onset of epileptic seizures - the post-traumatic scar of the left parietal lobe and the left hippocampus.

Surgical intervention for the patient - osteoplastic trepanation of the skull in the left frontoparietal - temporal region, selective resection of the left temporal lobe, hippocampectomy on the left, removal of the cerebral scar of the left parietal and temporal lobes, using intraoperative ECOG (electrocortography).

Fig. 12. Planning for surgery. A three-dimensional model of the brain with tractography (built on the BrainLab neuronavigation system using high-resolution MR 3.0 Tesla with MR tractography).

Fig. 13. Planning of surgical intervention, areas of operative access using the BrainLab neuronavigation system.

Fig. 14. Intraoperative corticography after removal of the post-traumatic scar. The red arrow marks the subdural electrode. The black arrow marks the corticogram from the subdural electrode.

The patient was discharged on the 12th day in satisfactory condition, with control EEG - rare rare paroxysms were recorded in the right hemisphere of the brain, a clear positive dynamics was observed in the left hemisphere of the brain in the form of a decrease in paroxysmal activity.

Fig. 15. Conducting video-EEG monitoring after surgery. A distinct positive dynamics of the EEG is noted in the form of a decrease in paroxysmal activity in the left hemisphere of the brain, rare rare paroxysms in the right hemisphere of the brain are preserved.

  Histological conclusion: focal cortical dysplasia (PKD IIIa). Sclerosis of the left hippocampus. Gliomesodermal scar with traces of hemorrhage.

In a patient (follow-up history of 8 months), no epileptic seizures were observed after surgical treatment.

In this case, it is noteworthy that with MRI of the brain there were no clear signs of focal cortical dysplasia of the left temporal lobe and hippocampal sclerosis, and only the installation of intracranial electrodes with subsequent video EEG monitoring revealed two areas of the onset of epileptic seizures.

This once again confirms the need for a comprehensive comprehensive examination of patients with epilepsy.

& copy 2009-2020 department of Emergency Neurosurgery Research Institute of Ambulance them. N.V. Sklifosovsky

3 minutes to read

Temporal epilepsy is a type of chronic neurological ailment characterized by recurring unprovoked seizures. In this case, the focus of epileptic activity is located in the medial or lateral part of the temporal lobe of the brain. The temporal form of epilepsy is manifested in simple, partial epiprides, when the preservation of consciousness is noted, and complex partial epipripsies, when the patient loses consciousness. With a further escalation of the symptoms of the disease, secondary-generalized seizures occur and mental disorders are observed. This type of epilepsy is considered the most common form of the disease.

Temporal epilepsy can give rise to a whole range of factors. In some cases, a pathological discharge is not localized in the temporal part of the brain, but radiates there from a focus located in other areas of the brain.

Causes of temporal lobe epilepsy

The disease in question refers to pathologies of the nervous system. In addition, it also affects processes related to metabolism.

Temporal epilepsy is so named because of the location of the epileptogenic focus, causing the appearance of repeated attacks. A pathological discharge can also be generated not in the temporal regions of the brain, but can get there from other areas of the brain, provoking appropriate reactions.

Temporal epilepsy has many different causes that contribute to its formation. They can be conditionally divided into two groups: perinatal, including factors that affect the period of intrauterine maturation and during the birth process, and postnatal, that is, those that arise during life.

The first group includes cortical dysplasia, prematurity, asphyxia of the newborn, intrauterine infection, birth injury, lack of oxygen (hypoxia). The temporal region is subjected to extreme impact during the birth process due to its location. During the configuration of the head (compensatory-adaptive process, which ensures the adaptation of the shape and size of the baby’s head when passing through the birth canal to the forces acting on it), the hippocampus is compressed in the birth canal. As a result, sclerosis, ischemia occurs in the restrained tissues, and subsequently transforms into a source of pathological electrical activity.

The second group includes severe intoxications, traumatic brain injuries, infections, tumor or inflammatory processes localized in the brain, various allergic reactions, excessive consumption of alcoholic beverages, high fever, metabolic and circulatory disorders, hypoglycemia, and vitamin deficiency.

Temporal epilepsy can often occur due to hippocampal sclerosis, which is a congenital deformity of the temporal lobe hippocampus.

Often the reasons for the development of this ailment cannot be established even with a detailed diagnosis and a thorough examination.

The likelihood of transmitting temporal lobe epilepsy from parents to their offspring is rather low. More often, children can inherit only a predisposition to the occurrence of the pathology under consideration when exposed to a number of factors.

Today, frontotemporal epilepsy is detected in more people. This is due to factors such as steadily growing toxic environmental pollution, high levels of toxins in food products, and increased stressful living conditions. In addition, often in patients suffering from this form of the disease, there are a number of concomitant pathologies that disappear after adequate basic treatment.

Symptoms of temporal lobe epilepsy

The etiological factor determines the clinical picture, its severity and debut, therefore, symptomatic temporal lobe epilepsy can begin at any age period. In patients with the occurrence of this form of the disease simultaneously with medial temporal sclerosis, this pathology begins with atypical febrile convulsions that occur at an early age (usually up to 6 years). After that, spontaneous remission of the disease can occur over two to five years, after which psychomotor afebrile seizures appear.

Since the diagnosis of the disease in question is rather complicated due to the late treatment of patients with epilepsy for medical help, when seizures are already extensive, it is necessary to know the main manifestations of temporal lobe epilepsy. Often, signs of temporal lobe epilepsy, often manifested in simple partial seizures, are left without due attention to the patient.

Examining the form of the disease is characterized by three variations in the course of seizures, namely partial simple convulsions, complex partial seizures and secondary-generalized seizures. In most cases, symptomatic temporal lobe epilepsy is manifested by the mixed nature of the attacks.

Simple convulsions are conserved. They often precede complex partial seizures or secondary-generalized seizures in the form of an aura. You can determine the localization of the focus of this form of pathology by the nature of its seizures. Motor simple seizures are found in a fixed installation of the hand, turning the eyes and head toward the location of the epileptogenic focus, less often appear in the form of a turn of the foot. Sensory simple seizures can appear like olfactory or taste paroxysms, in the form of attacks of systemic dizziness, visual or auditory.

So, simple partial seizures of temporal lobe epilepsy have the following symptoms:

Lack of loss of consciousness;

The appearance of a distortion of smell and taste, for example, patients complain of unpleasant odors around, an unpleasant sensation in the mouth, complain of pain in the stomach and speak of a sensation of a dropping unpleasant taste to the throat;

Preoperative examination includes various types of neuroimaging, such as video EEG monitoring and an electrocorticogram, as well as passing tests to detect the dominance of the cerebral hemisphere.

The task of neurosurgeons is to eliminate the pathogenic focus and prevent movement, and expand the range of epileptic impulses. Surgery itself consists in performing a lobectomy and removal of the mediobasal departments and the anterior zones of the temporal region of the brain.

After neurosurgical intervention, in almost 70 cases out of 100, the frequency of epiprots decreases significantly and disappears completely in about 30% of cases.

In addition, surgical treatment has a positive effect on the intellectual activity of patients and their memory. The state of remission with the use of anticonvulsant drugs is achieved on average in approximately 30% of patients.

Prevention of the considered form of the disease consists in timely medical examination of risk groups (children and pregnant women), in the adequate treatment of identified concomitant diseases, vascular pathologies of the brain, as well as in the prevention of the development of neuroinfections.

If patients are absent, then they can work in any field, excluding high-altitude work, manipulation of fire (due to oxygen deficiency), or work with moving mechanisms, as well as occupations associated with night shifts and increased concentration of attention.

Thus, the considered form of the disease requires not only the correct, but also timely therapeutic effect, which will return the full life activity to the patient with epilepsy.

Doctor of the Psycho-Med Medical Psychological Center

The information presented in this article is intended for informational purposes only and is not a substitute for professional advice and qualified medical assistance. At the slightest suspicion of the presence of temporal lobe epilepsy, be sure to consult your doctor!

The hippocampus is located in the medial sections of the temporal lobe and represents two bent strips of nervous tissue nested in one another: the dentate gyrus and the hippocampus itself (Ammonov horn - cornu Ammonis - CA). The internal structure of the hippocampus is normally shown in Fig. 1. Histologically, the hippocampal cortex belongs to the archicortex, represented by three layers of neurons. The outermost layer of the hippocampus, which forms the medial wall of the temporal horn of the lateral ventricle, is called the alveus (tray) and is formed by axons emerging from the hippocampus. Followed by stratum oriens  (represented by axons and interneurons), then a layer of pyramidal cells, which are the main cellular elements of the hippocampus and, finally, the deepest layer - stratum lacunosum and molecularerepresented by dendrites, axons and interneurons (see Fig. 1). The division of the pyramidal layer into 4 sectors (CA1, CA2, CA3 and CA4) proposed by Lorente de No is important for understanding the various types of lesions of the Ammon horn during its sclerosis. The most pronounced layer of pyramidal cells is located in the CA1 sector, which continues into the part of the para-hippocampal gyrus, called the subiculum (backup). The CA4 segment is adjacent to the concave part of the dentate gyrus. The dentate gyrus is a C-shaped structure having three layers of cells: the outer molecular, middle granular and inner layer of polymorphic cells that merge with the CA4 sector (see Fig. 1).

Fig. 1. The internal structure of the hippocampus is normal (own histological studies, right side). Subiculum (subiculum) - part of the para-hippocampal gyrus, passing into the CA1 sector. The dentate gyrus (highlighted in blue) covers the CA4 sector (highlighted in green). a - alveus: 1 - stratum oriens of the hippocampus, 2 - pyramidal layer, 3 - molecular zone of the hippocampus, 4 - molecular layer of the dentate gyrus, 5 - granular layer, 6 - polymorphic layer.

The bottom picture shows the same hippocampus. A layer of pyramidal cells of sectors S.A. The dentate gyrus (indicated by arrows) covers the CA4 sector, a layer of granular cells is visible. Triangular arrows indicate the deep part of the hippocampal groove, which separates the CA sectors and the dentate gyrus (own histological studies).

Structural changes in hippocampal sclerosis can vary from minimal, limited to one sector of CA to gross, extending beyond the medial temporal lobe. The description of pathological changes in the structure of the brain tissue in hippocampal sclerosis is distinguished by an exceptional variety of terms and the presence of several classifications with different concepts that describe the same histological substrate.

The histological structure of the sclerosed hippocampus

Macroscopically sclerosed hippocampus is reduced in volume and has a dense texture. Among the main microscopic characteristics, a decrease in the number of pyramidal cells in various CA layers and a variable degree of gliosis stand out. In the granular layer of the dentate gyrus, a different degree of decrease in the density of neurons can be noted, although in general its structure is more preserved in comparison with S.A. sectors A distinctive histological feature is that the loss of neurons does not extend beyond the CA sectors, which distinguishes hippocampal sclerosis from its atrophy in ischemic injuries and neurodegenerative diseases. It was noted that the loss of neurons in the pyramidal layer of the hippocampus can occur in several ways, which was the basis for the formation of the classification of this pathology. The most common classification of hippocampal sclerosis, created by the commission of ILAE. When S.G. Type 1 (pronounced or classic) neuronal prolapse is observed in all layers of the hippocampus (Fig. 2). The second type is characterized by the loss of neurons mainly in the CA1 sector, and with the 3rd type of SG only the CA4 sector is affected in the area of \u200b\u200btransition into the dentate gyrus (the so-called end folium sclerosis). In the literature, along with the term “hippocampal sclerosis”, a number of definitions are often used that emphasize that the histological signs of a disturbed structure of the brain tissue can extend beyond the hippocampus.

   Fig. 2. Sclerosed hippocampus (right side): the absence of the pyramidal layer in all segments of the CA is determined (type 1 sclerosis according to the ILAE classification). The granular layer of the dentate gyrus is preserved (marked by arrows).

So, the term “mesial temporal sclerosis” reflects the fact that along with the hippocampus, atrophic and gliotic changes are observed in the amygdala and hook. When analyzing the histological material obtained during surgery of temporal lobe epilepsy, it became apparent that hippocampal sclerosis is accompanied by histopathological changes in the lateral neocortex of the temporal lobe. M. Thom proposed the term "temporal sclerosis", which defines the loss of neurons and gliosis in the 2nd and 3rd layers of the temporal cortex. Quite often, heterotopic neurons in the 1st layer of the cortex and white matter are detected in the neocortex, which is referred to as the term “microdisgenesis”. In 2011, the ILAE Commission introduced a new classification of focal cortical dysplasias, where a group of type 3 PKD was distinguished, when hippocampal sclerosis can be combined with temporal lobe dysplasia in the form of a violation of its laminar structure, which, in turn, is classified as PKD of the 1st type. Microdisgenesis, the role of which in epileptogenesis is not yet known, is attributed to the so-called small malformations of the cerebral cortex, and when they are detected with hippocampal sclerosis, the diagnosis is defined as type 3 PKD. Just like type 3 PKD, a combination of temporal sclerosis and hippocampal sclerosis is considered. The concept of “dual pathology” is often found in the literature when hippocampal sclerosis is combined with a potentially epileptogenic lesion of the neocortex, including outside the temporal lobe, for example, a tumor, vascular malformation, type 2 PCD, Rasmussen encephalitis, gliotic scar . Moreover, the concept of "double pathology" does not include PKD type 3a. The terminology becomes even more complex, since the presence of two epileptogenic brain lesions, but without sclerosis of the hippocampus, is designated as double pathology.

To understand the connections between the various parts of the hippocampus and the pathogenesis of its sclerosis, it is necessary to have an idea of \u200b\u200bthe structure of the polysynaptic intragippocampal pathway, which begins from neurons of the 2nd layer of the entorhinal cortex (located in the front of the parahippocampal gyrus and in the hook region). The processes of these neurons form a perforating path that goes through the subiculum of the para-hippocampal gyrus into the dentate gyrus and contacts the dendrites of the cells of the granular layer. Neurons of the granular layer form mossy fibers innervating the pyramidal neurons CA3 and CA4, which in turn through the lateral axons, the so-called Schaffer collaterals, are in contact with the CA1 sector. The abnormal germination of mossy fibers into the dentate gyrus instead of CA sectors with the formation of excitatory synapses is considered one of the pathogenetic links in S.G. Of the above segments of CA, axons enter the alveus and then into the arch of the brain through the hippocampus fimbria. Given the anatomical and functional relationship between the Ammon horn, the dentate gyrus, the subiculum, a number of authors have designated them with the term “hippocampal formation” (Fig. 3).

   Fig. 3. The internal connections of the hippocampal formation are normal. The pyramidal neurons of the CA sector (indicated by a red triangle) with their dendrites come into contact with the dendrites of the granular cells of the dentate gyrus. 1 - the perforating path (indicated by the red line) goes through the subiculum into the molecular layer of the dentate gyrus, where it contacts the dendrites of granular cells (indicated by a circle); 2 - mossy fibers (indicated by a purple arrow) go to the dendrites of the pyramidal cells CA3 and CA4 sectors of the hippocampus. 3 - Schaffer collaterals (marked in green) innervate the apical dendrites of the CA1 pyramidal cells.

Causes of hippocampal sclerosis, pathogenesis

The central question of the etiology of hypertension is to determine what occurs primarily: the structural pathology of the hippocampus, which triggers chronic pharmacoresistant epilepsy, or vice versa - prolonged pathological electrical activity leads to sclerosis over time. It is important to note that a significant part of patients with pharmacologically resistant epilepsy associated with hypertension suffer early status of febrile seizures or other acute CNS pathology (trauma, anoxia, neuroinfection), which has been designated in the literature as initial precipitating damage. In favor of the acquired nature of hypertension are those rare observations when pathology occurs only in one of the monozygotic twins, and, therefore, the genetic factor is not paramount. Nevertheless, the presence of hereditary familial forms of temporal lobe epilepsy (for example, a group of epilepsies associated with mutations of the SCN1a and SCN1b genes encoding sodium channel proteins) indicates that the genetic factor also plays a role, causing hippocampal sclerosis without febrile seizures in some of these patients. . Speaking about the acquired nature of the disease, it should also be taken into account that not every type of seizure is associated with the development of hypertension: autopsy data indicate that long-term uncontrolled epilepsy with frequent generalized seizures does not lead to neuronal prolapse in the hippocampus, as well as afebrile epileptic status. On the other hand, febrile status epilepticus is accompanied by MRI signs of hippocampal edema.

The answer to the question of how often the status of febrile seizures in a child is realized in hypertension and pharmacoresistant epilepsy may be given by a prospective study of FEBSTAT. It has already been established that out of 226 children after the status of febrile seizures, 22 showed MRI signs of hippocampal edema, most pronounced in the Sommer sector (CA1). Of these 22 patients, repeated MRI at various times was performed in 14, while in 10 cases signs of hippocampal sclerosis were detected. However, out of 226 children, epilepsy was diagnosed in only 16 patients and in most cases was not temporal. Thus, febrile status does not always lead to epilepsy with hippocampal sclerosis, although the time interval between precipitating brain injury and the appearance of temporal lobe epilepsy can be more than 10 years, and the history of this duration has not yet been studied. Genetic studies also suggest that the etiology of hypertension is heterogeneous. The study of genome-wide associations showed that febrile seizures with hippocampal sclerosis can be a genetic syndrome, since they are associated with the presence of a specific allele of a single nucleotide sequence located next to the sodium channel gene SCN1a. Such an association was not detected for cases of epilepsy with hypertension without febrile seizures. The consensus opinion of epileptologists is the idea that there is a certain initial genetic predisposition that is realized in hippocampal sclerosis in the presence of a certain damaging factor (double-hit hypothesis).

Hippocampal sclerosis has two fundamental pathological characteristics: the first is a sharp decrease in the number of neurons, the second is the hyper excitability of the remaining nervous tissue. One of the key roles in epileptogenesis in hypertension is played by the sprouting of mossy fibers: abnormal axons of granular cells, instead of innervating the CA, reinnervate the molecular neurons of the dentate gyrus through excitatory synapses, thus creating local electrical circuits capable of synchronizing and generating the epiprute. An increase in the number of astrocytes and gliosis can also play a role in epileptogenesis, since altered astrocytes cannot sufficiently re-capture glutamate and potassium. Proinflammatory cytokines such as IL-1β, IL-1, TNFα can also act through a mechanism to increase glutamate release and reduce reuptake, inhibition of gamma-aminobutyric acid. In this regard, the role of herpes simplex virus type 6, whose DNA is found in the brain tissue in patients with temporal lobe epilepsy, is discussed in the pathogenesis of hypertension.

Clinic and Diagnostics

The case history of hippocampal sclerosis epilepsy is described mainly on the basis of numerous studies evaluating the effectiveness of surgical treatment of temporal lobe epilepsy. Often in the history there is an indication of an acute CNS pathology suffered in childhood (usually up to 5 years): the status of febrile seizures, neuroinfection, traumatic brain injury. Stereotypic seizures begin in the period from 6 to 16 years, and there may be a so-called latent period, which falls on the time between the initial precipitating damage and the development of the first epileptic seizure. Situations are also not uncommon when the so-called “silent” period lasts between the first attack and the development of pharmacoresistance. This feature of the course of the disease indicates its progressive nature. A characteristic cognitive deficit in hypertension may be a decrease in memory, especially with uncontrolled seizures.

The diagnosis of hippocampal sclerosis is based on three basic principles. The first is a detailed analysis of the sequence of symptoms in an epileptic seizure, or semiology, which depends on which parts of the brain spread epileptic activity. The second is the analysis of EEG data and comparing them with the semiology of the attack. And the third is the identification of epileptogenic lesions in MRI. Speaking about the semiology of the attack in temporal lobe epilepsy associated with hypertension, it must be remembered that, firstly, each of the symptoms individually is not specific, although there is a typical pattern of the course of the attack. Secondly, symptoms during an attack appear when epileptic activity spreads to the parts of the brain associated with the hippocampus, which in itself does not produce clinical manifestations. A characteristic beginning of a temporal lobe is an aura in the form of an ascending sensation in the abdomen. Fear or anxiety is also possible when amygdala is involved at the beginning of an attack. At the beginning of the attack, a sensation of “already seen” (déjà vu) may be noted. The aura in the form of dizziness or noise is alarming in terms of diagnosis, which may indicate an extra-hippocampal onset of the attack. The intact ability to name objects and speak during an attack is an important lateralizing sign of damage to the non-dominant hemisphere. A change in consciousness is accompanied by a halt in action, while the patient has a frozen look with eyes wide open (staring - starring). The aura and the cessation of action are followed by the organoalimentary automatisms with chewing, smacking of lips. Also, dystonia of the contralateral side of the sclerosed hippocampus of the hand often occurs (which is associated with the spread of epiactivity in the basal ganglia) and manual automatisms appearing in the form of fingering the ipsilateral fingers. Among the lateralizing symptoms, postictal paresis is important, which indicates the involvement of the contralateral hemisphere, and postictal aphasia in lesions of the dominant hemisphere. These symptoms should be considered in the context of EEG data.

The basis of the electroclinical diagnosis of hippocampal sclerosis is video EEG monitoring, which consists in the simultaneous video recording of an epileptic attack and electrical activity of the brain.

Video EEG monitoring solves several problems:

1. Allows to exclude pseudo-attacks and non-epileptic paroxysms, including when combined with truly existing epilepsy.

2. It makes it possible to evaluate in detail the semiology of the attack and compare it with the dynamics of its epiactivity: its lateralization and regional localization.

3. Long recording allows you to find out the lateralization and localization of interictal activity. The most successful option in terms of a favorable outcome of epilepsy surgery is the coincidence of lateralizing and localizing symptoms in the attack with the data of the ictal and interictal EEG and MRI picture. In a pre-surgical examination, the question of the duration of video EEG monitoring is essential. It is known that the probability of registering paroxysm on a 30-minute EEG with a seizure frequency of 1 time per week is about 1%, and long-term video EEG monitoring with an average duration of 7 days does not reveal interictal activity in 19% of patients. The question of the necessary duration of video EEG monitoring is important from the point of view of the mandatory fixation of ictal events on the EEG when determining indications for surgery. A number of epileptologists believe that with a characteristic clinical picture and history of the disease, a picture of hippocampal sclerosis on MRI, recording of an ictal event is not necessary with more than 90% lateralization of interictal epiactivity in the temporal region on the affected side. In most cases, the resolution of the scalp EEG is sufficient to properly lateralize the onset of the attack in temporal lobe epilepsy and, in the context of consistent attack semitology and MRI data, determine the strategy for surgical treatment.

MRI diagnosis of hypertension is the next fundamental stage of pre-surgical examination. It should be performed according to the epileptological protocol, among the main characteristics of which one can distinguish a small thickness of sections and a high magnetic field strength. The optimal condition for performing MRI is the interaction between the epileptologist and the radiologist, when the study is planned taking into account the alleged localization of the epileptogenic zone. Hippocampal sclerosis on MRI has characteristic signs: a decrease in the volume of the hippocampus and a violation of the structure of the SA layers, a hyperintense signal in T2 and FLAIR mode (Fig. 4). Atrophic changes in the ipsilateral amygdala, temporal lobe pole, fornix, and mamillary body are often detected. The tasks of high-resolution MRI also include the detection of another epileptogenic pathology of the brain located outside the hippocampus, i.e., a double pathology, such as focal cortical dysplasia. Without this task, an MRI scan will not be sufficient to make a decision about the operation, even if it shows signs of hippocampal sclerosis.

   Fig. 4. MRI anatomy of the normal and sclerotic hippocampus. a - T2, coronary section. Sclerosis of the right hippocampus: determined by a decrease in its volume, the absence of an internal structure compared with the left hippocampus; b - the same section with explanations. The hippocampus is surrounded by a red line (a decrease in the volume of the right hippocampus is visible), the blue line is the subiculum on the left. The yellow line in the center of the hippocampus is drawn along the deep part of the hippocampal sulcus (in Fig. “A” this sulcus is not defined in the right hippocampus). FG - fusiform gyrus, ITG - lower temporal gyrus; c - coronary section in the FLAIR mode, a decrease in volume and a hyperintensive signal from the right hippocampus are visible.

A fundamental point in understanding the electrophysiology of medial temporal temporal epilepsy is the fact that the scalp EEG alone does not reveal epi-activity in the hippocampus, which has been demonstrated in numerous studies using intracerebral electrodes. For the appearance of epiactivity in the temporal region on the scalp EEG, its distribution from the hippocampus to the adjacent cortex of the temporal lobe is required. In this case, the main clinical manifestations of an attack in medial temporal lobe epilepsy are associated with the spread of epi-activity to certain parts of the brain associated with the hippocampus: déjà vu is associated with excitation of the entorhinal cortex, a sense of fear with the amygdala, an abdominal aura with the islet, oroalimentary automatisms with the islet and frontal operculum, dystonia in the contralateral arm - with the spread of excitation to the ipsilateral basal ganglia. These anatomical and electrophysiological features can cause the patient to have seizures that are very similar to temporal paroxysms, but which actually have extra-hippocampal and extra-temporal onset.

As experience gained in surgical treatment of temporal lobe epilepsy, it became apparent that removal of the medial structures of the temporal lobe completely eliminated seizures in 50-90% of patients, but in some cases the frequency of seizures did not change. Research data on the electrical activity of the brain using intracerebral electrodes and analysis of unsuccessful outcomes of operations have shown that in some cases the reason for the persistence of seizures after removal of hypertension is the presence of a more extensive epileptogenic zone that extends beyond the hippocampus. Parts of the brain that are anatomically and functionally associated with the hippocampus, such as the islet, orbitofrontal cortex, parietal operculum, butt joint of the parietal, temporal and occipital lobes, can generate seizures similar in clinical and EEG picture to temporal paroxysms. The concept of “temporal lobe epilepsy plus” has been proposed to describe situations in which hippocampal sclerosis exists along with the extra temporal zone of attack initiation. In this regard, it is important to determine the indications for an invasive EEG study in temporal lobe epilepsy due to S.G. Alarming symptoms are taste aura, aura in the form of vertigo, noise. Interictal epiactivity is more often localized bilaterally in the temporal regions or in the precentral region. Ictally, epi-activity in “temporal plus” forms is more often observed in the anteropulmonary, temporoparietal, and precentral regions. Differential diagnosis of temporal lobe epilepsy from "temporal lobe epilepsy plus", conducted by a qualified epileptologist, is key in planning surgical intervention and predicting the outcome of treatment.

Treatment of hippocampal sclerosis-associated epilepsy

The standard of care for patients with pharmacoresistant medial temporal lobe epilepsy is referral to a specialized center for pre-surgical examination and surgical treatment. Among the enormous number of publications confirming the effectiveness of surgery for temporal lobe epilepsy, it is worth noting two key studies with the highest level of evidence. S. Wiebe et al. in 2001, they conducted a randomized controlled trial, which showed that surgery of temporal lobe epilepsy in hippocampal sclerosis eliminates seizures in 58% of cases, and only 8% in case of drug therapy. The basis for another study was the fact that the average duration of the disease in patients who received surgical treatment is 22 years, and 10 years or more elapse between the diagnosis of pharmacoresistant epilepsy and surgical treatment. J. Engel et al. in a multicenter randomized controlled trial showed that continued pharmacotherapy with the ineffectiveness of the two drugs with medial temporal lobe epilepsy is not accompanied by remission of seizures, while surgical treatment in such situations can be effective (in 11 out of 15 patients, seizures cease).

Surgery for temporal lobe epilepsy has two obvious goals: 1) rid the patient of attacks; 2) cancellation of drug therapy or dose reduction. According to the literature, about 20% of patients after surgery stop taking anticonvulsants, 50% remain on monotherapy and 30% receive polytherapy. The third goal, less obvious, but of fundamental importance, is to reduce the risk of sudden unexplained death in epilepsy (SUDEP - sudden unexplained death in epilepsy), which is associated with a sharp reflex inhibition of cardiorespiratory function in patients with pharmacoresistant epiprises.

The task of surgical treatment of temporal lobe epilepsy is the complete removal of the epileptogenic cerebral cortex with maximum preservation of the functional areas of the brain and minimization of neuropsychological deficit. In this regard, there are two surgical approaches: temporal lobectomy and selective amygdalogippocampectomy. Both operations include removal of the hook, amygdala and hippocampus. Selective access to the medial temple can be done through several different accesses. Temporal lobectomy also involves the removal of the lateral neocortex of the temporal lobe (from 3 to 5 cm, depending on the dominance of the hemisphere). Proponents of the selective approach assume that the preservation of the lateral neocortex minimizes neuropsychological deficits, in particular, a decrease in verbal memory. On the other hand, as already noted, pathological changes can extend beyond the hippocampus into the amygdala, the pole of the temporal lobe and the lateral neocortex. Invasive EEG studies using deep electrodes have shown that in 35% of cases of hippocampal sclerosis, epi-activity occurs in the pole of the temporal lobe earlier than in the hippocampus. Also, based on the analysis of data from deep electrodes, several types of temporal lobe epilepsy were identified: medial, medial-lateral, temporal polar and the already mentioned “temporal lobe epilepsy plus". Thus, when choosing the tactics of surgical treatment, one should take into account the likelihood of a more extensive epileptogenic zone that extends beyond the sclerotic hippocampus, which may lead to a greater effectiveness of lobectomy. Nevertheless, at the moment there is no evidence of the 1st class of evidence confirming the advantage of any technique that provides control of seizures, neuropsychological outcome, or the need for postoperative antiepileptic drugs, so the choice of operation depends on the preferences of the surgeon.

Surgery of temporal lobe epilepsy in hippocampal sclerosis with sufficient experience of the surgeon has minimal risks of neurological deficiency (persistent hemiparesis - less than 1%, complete hemianopsia - 0.4%). An unresolved problem remains the prediction of the risk of memory impairment after surgery. It is known that after resection of the hippocampus of the hemisphere dominant in speech, about 35% of patients show the worst performance with a neuropsychological assessment of verbal memory. The risk of a decrease in verbal memory is increased in the case of a late onset of the disease, high preoperative performance during testing, dominant hemisphere hypertension, minimal changes in the hippocampus on MRI - these circumstances indicate that the epileptogenic hippocampus can maintain functional activity. Nevertheless, it is difficult to determine how much a decrease in verbal memory affects postoperative quality of life. To a greater extent, the quality of life of a patient after surgery depends on careful control of seizures and the elimination of concomitant depressive and anxiety disorders. Definition of indications for surgery in high-risk patients should be carried out with particular care, because if the epileptological outcome is unsuccessful, the patient will also experience cognitive deficit, which sharply reduces the quality of life. In this regard, it should be emphasized that the necessary condition for organizing surgical care for patients with epilepsy is the formation of a team approach to each clinical case, close interaction between the epileptologist, surgeon, neuro-radiologist and neuropsychologist.

There is no conflict of interest.

Mesial temporal sclerosis and its role in the development of paleocortical temporal epilepsy (review of literature)

MESIAL TEMPORAL SCLEROSIS AND ITS ROLE IN DEVELOPMENT OF PALEOCORTICAL TEMPORAL LOBE EPILEPSY (A REVIEW)

S.H. Gataullina, K.Yu. Mukhin, A.S. Petrukhin

Department of Neurology and Neurosurgery, Department of Pediatrics, GOU VPO RSMU Roszdrav, Moscow

A review of the literature on the problem of mesial temporal sclerosis is presented. Hippocampal sclerosis was first described by Bouchet and Cazauvieilh in 1825 and is now considered as a multifactorial, classic epileptogenic lesion of the brain, which underlies limbic or mediobasal paleocortical temporal epilepsy, which manifests itself as resistant epileptic seizures. The article highlights the historical aspects of studying the issue, the anatomy and pathophysiology of hippocampal sclerosis, its role in the development of paleocortical temporal lobe epilepsy.

Key words: epilepsy, mesial temporal sclerosis, etiology, pathogenesis, anatomy, pathophysiology.

The articles gives a review of works on mesial temporal sclerosis. Hippocampal sclerosis was first described by Bouchet and Cazauvieilh in 1825, and is presently classified as a multifactor, classical epileptogenic cerebral affection, underlying limbic or mediobasal paleocortical temporal lobe epilepsy manifested by resistant epileptic seizures. The article highlights historical issues of the subject, anatomy and pathophysiology of hippocampal sclerosis and its role in development of paleocortical temporal lobe epilepsy.

Key words: epilepsy, mesial temporal sclerosis, etiology, pathogenesis, anatomy, pathophisiology.

Definition

Mesial temporal sclerosis (synonyms: hippocampal sclerosis, sclerosis of the Ammon horn, incisural sclerosis, mesial temporal sclerosis) is a multifactorial, classic epileptogenic lesion of the brain, which is the basis of limbic or mediobasal epileptic incisive paleocorticemia. The term "mesial temporal sclerosis" (MVS) is most often used in the literature, although German authors consider the notion of "sclerosis of the Ammon horn" to be more correct. The prevalence and clinical picture of mesial temporal sclerosis in children is currently not well understood.

Study history

The Italian anatomist Giulio Cesare Aranzi in 1564 first applied the term hippocampus to describe the structure of the brain, which looks like a sea horse. Initially, this organ was known only as a center of smell. Later neurophysiologist V.M. Bekhterev, based on examinations of patients with severe memory impairments, established the role of the hippocampus in maintaining the human memory function. Attacks of a psychomotor nature (complex partial, automotor), which according to modern concepts constitute the “core” of the clinical picture of amygdala-hippocampal temporal lobe epilepsy, were described by Hippocrates as well. There is a legend that the legendary

S.Kh. Gataullina, K.Yu. Mukhin, A.S. Petrukhin

Mesial temporal sclerosis and its role in the development of paleocortical temporal lobe epilepsy (literature review). Rus zhur. children neur .: vol. III, no. 3, 2008.

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Hercules during the "attack of epileptic madness" killed his wife and children.

Hippocampal sclerosis was first described by Bouchet and Cazauvieilh in 1825 during an anatomical examination of the brain of patients suffering from frequent epileptic seizures. A little later, in 1880, Sommer revealed by microscopy the presence of a characteristic histological pattern in the hippocampus: the death of pyramidal neurons at the base of the temporal horn (Sommer sector or CAI subfield). Since microscopy created a visual resemblance to the helmet of the Egyptian pharaoh Ammon, which consisted of columns of gold coins, this pathology was called "sclerosis of the ammonian horn." But at that time, this discovery did not arouse much interest, possibly because epilepsy was considered a mental (and not morphologically determined) disease. Only at the end of the 19th century Chaslin (1889) in France and Bratz (1889) in Germany expressed the opinion that the revealed changes may play a role in the genesis of epilepsy. A little earlier, in 1880, the great English neurologist John Hughlings Jackson suggested that neurons in damaged areas of the brain have abnormally increased excitability. This further defined the concept of "epileptic focus." In 1899, Bratz, studying autopsy materials, discovered that epileptic seizures at an early age could be one of the causes of hippocampal sclerosis. He showed that sclerosis of the Sommer sector of the hippocampus can be observed not only with epilepsy, but also with other neurological disorders. According to Bratz, the detected changes in the hippocampus were congenital.

Until now, the sclerosis of the ammonian horn and its relation to epilepsy (cause or effect?) Has caused heated debate. The morphology and topography of changes in hippocampal sclerosis were studied in detail by Spielmayer (1927) and Scholz (1951, 1954), who attributed the detected changes to the consequence of frequent convulsive attacks. Gastaut and Roger (1955), as well as Norman (1956, 1957), showed increased sensitivity to hypoxia in various parts of the hippocampus and amygdala. According to Gastaut, damage to the mediobasal

departments of the temporal lobe were the result of cerebral edema and subsequent compression of the cerebral vessels. According to Gastaut, Sano, and Malamud (1953), febrile status epilepticus played an important role in the formation of hippocampal sclerosis. Margerson and Corselli (1966) also hypothesized the importance of epileptic seizures in the genesis of hippocampal sclerosis. In subsequent publications, Falconer (1970) and Oxbury (1987) confirmed the relationship of prolonged febrile seizures and sclerosis of the Ammon horn through clinical and pathological studies.

In 1822, Prichard cited epileptic seizures that were ambulatory. Jackson made a great contribution to the history of temporal lobe epilepsy, who in 1889 first described olfactory hallucinations as an epileptic phenomenon, and proved their appearance when the hippocampus hook is irritated (uncus). Until now, this type of seizure has retained its historical name, Jackson's Unusual Attacks.

In 1937, Gibbs F.A. and Gibbs E.L. with Lennox W.G. proposed the term "psychomotor seizures." And 10 years later, Gibbs and Furster (1948) revealed that with the localization of the epileptic focus in the anterior temporal region, attacks with automatisms are predominantly observed. Therefore, to describe this type of seizure, they used the term "automatic", thereby separating them from other "psychomotor" seizures. Gibbs F.A. and Gibbs E.L. in 1938, they presented a description of specific EEG patterns for temporal lobe epilepsy, and later, in 1951, together with Bailey, they came close to resolving the issue of surgical treatment of temporal lobe epilepsy. EEG recording during “psychomotor” seizures showed that rhythmic slow theta activity quickly spreads outside the temporal region to the entire hemisphere of the same name with the possible capture of the opposite. This feature prompted Gastaut in 1958 to designate this type of seizure as "partial seizures with diffuse EEG patterns." Other authors, reflecting the localization of the epileptic focus, used the terms “temporal-frontal attacks”, “rinencephalic attacks”. Later

studies using video-EEG monitoring and special patient testing methods have shown that with temporal seizures, impaired consciousness is often observed. Therefore, the term “complex partial seizures” was introduced, which was constantly subjected to fierce criticism and was eventually removed from the 2001 Project for Classification of Epileptic Seizures.

The term "temporal lobe epilepsy" was proposed in 1941 by Canadian neurologists Penfíeld and Erickson to describe the epileptic syndrome, which manifests itself in attacks with impaired consciousness and automatisms in combination with temporal ligaments on the EEG. For the first time, Roger & Roger (1954) became interested in the electroclinical features of temporal lobe epilepsy in children. According to their research, simpler automatisms in the structure of the attack were observed in children and pronounced autonomic symptoms prevailed. However, all the works of that time equated complex partial seizures with temporal seizures, while modern studies have established that some of them are frontal or parietal-occipital, in which the epileptic discharge extends to the mediobasal parts of the temporal lobe.

Despite numerous ongoing studies in the field of temporal lobe epilepsy, there are still no definitive answers to the questions: what is the cause of sclerosis of the ammonian horn? When is it formed? What is the evolution of this pathology?

Anatomical and histological features of the hippocampus

In 1878, Pierce Paul Broca described a region of the central nervous system located in the medial part of both hemispheres of the cerebrum and called it “limbic lobe” (from Latin “lim-bus” - edge). Later this structure was called “rinencephalon”, which indicated its important role in the sense of smell. In 1937, James Papez proposed another term - the "limbic system" - and emphasized the key role of this anatomical substrate in the formation of memory, emotions and behavior (Peipec circle). Currently, the term "limbic system"

indicates only the anatomical unity of the structures that form it. The central structure of the limbic system is the hippocampus (Ammon horn). Besides

Fig. 1. Hippocampus and corpus callosum, top view.

moreover, the limbic system includes the dentate and cingulate gyrus, entorhinal and septal regions, gray shirt (indusium griseum), amygdala (corpus amig-daloideum), thalamus, mastoid bodies (corpus mammillare). In the hippocampus, the head, body, tail, edge, arch leg and base are distinguished (Fig. 1, 2, 3). Histologically, the following layers are distinguished in the hippocampus (Bogolepova, 1970; Villani et al., 2001):

1. Alveus, contains efferent hippocampal and subicular axons.

2. Stratum oriens, contains basket cells.

3. Stratum piramidale, contains pyramidal cells, stellate cells, and intercalary neurons.

4. Stratum radiatum, consists of apical dendrites of pyramidal cells.

5. Stratum lacunosum, contains perforating fibers.

6. Stratum moleculare, includes a small number of intercalated neurons and a wide branching of apical dendrites of pyramidal cells.

According to Lorente de No (1934), depending on the location and shape of the pyramidal cells, the hippocampus is divided into 4 subfields: CAI (Sommer's sector) - triangular-shaped neurons, multi-layered, of different sizes; CA2 - densely spaced, large pyramidal cells; SAZ - pyramidal cells located

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laid less dense and mossy fibers (thin, non-myelinated fibers coming from granular cells of the dentate gyrus); CA4 - large pyramids -

Fig. 2. Hippocampus and corpus callosum, side view.

cells, triangular in shape, scattered between mossy fibers (Fig. 4).

In the dentate gyrus (dentate gyrus) there are 3 layers: the molecular layer (long dendrites), the granular layer (granular cells), the polymorphic or sub-granular layer, which contains inhibitory neurons of various sizes.

Pathanatomy and pathophysiology

Fig. 3. Intraventricular part of the hippocampus: 1. body of the hippocampus, 2. head of the hippocampus, 3. tail of the hippocampus, 4. free edge of the hippocampus, 5. pedicle of the hippocampus, 6. base of the hippocampus (subiculum), 7. corpus callosum (splenium), 8. bird spur (calcar avis), 9-collateral triangle, 10. collateral elevation, 11. hook-shaped pocket (recess) of the temporal horn of the lateral ventricle.

Pathognomonic for hippocampal sclerosis, according to many authors, is the selective death of neurons with secondary astroglial proliferation in the CAI zones (Sommer sector), SAZ, CA4, dentate gyrus granular cells and relative safety of the CA2 zone pyramidal cells (Bruton, 1987; Gloor, 1991; Babb, 1997). The anatomical manifestation of cellular damage consists in the death of inserted neurons in the gates of the hippocampus and pyramidal cells in the Sommer zone, with subsequent processes of scarring and atrophy. It is assumed that the death of neurons in the hippocampus leads to a reorganization of the synaptic connections between the remaining neurons and thereby to the dysfunction of the inhibitory and exciting neurotransmitter systems of the hippocampus. The death of neurons, gliosis, axonal and synaptic reorganization are the main pathological links in the formation of MVS. Plots of gliosis in MVS, like neurons, are able to generate action potentials as a result of the content of pathologically altered astrocytes with a high density of sodium channels. The severity and prevalence of pyramidal cell death can vary from slight to deep, but the CA2 subfield always remains intact. In many cases, even in the absence of apparent death of the pyramidal cells in the epileptogenic hippocampus, one can observe the selective defeat of insertion neurons containing somatostatin, substance P and neuropeptide Y.

Often, pathological changes in the hippocampus are bilateral in nature. In some cases, neuronal damage extends to other structures of the limbic system (amygdala, islet, mastoid bodies, thalamus), sometimes involving the lateral cortex and the pole of the temporal lobe.

It is known that the metabolic state of the thalamus is closely dependent on the state of the hippocampal neurons in the same hemisphere. Studies by spectroscopic measurement of excitatory amino acids in the hippocampus with frequent repeated attacks show involvement in the pathological process through the neural networks of contralat

Bulb of posterior cornu Calcar avia

Collateral eminence hippocampi

the hippocampus and both thalamuses. Damage to the functional connections of the hippocampus as a result of its sclerosis can affect the maturation processes

Fig. 4. Fields of the hippocampus.

brain in children.

In the process of studying the hippocampus in children with resistant temporal lobe epilepsy, the following features were identified (Tikh1yugp et al., 1997):

1. In the postnatal period, the increase in the number of granular cells, the formation of neurons and axons, continues in the hippo-campus.

2. Epileptic seizures generated outside the hippocampus (cortical dysplasia, postencephalitic changes, etc.) can help reduce the number of granular cells and neurons of the ammonian horn.

3. Long-term epileptic seizures in children, unlike adults, do not always lead to severe damage to nerve cells.

It is known that during an epileptic seizure, an excess amount of an exciting neurotransmitter, glutamate, is released into the synaptic cleft. The hippocampus is the structure most susceptible to glutamate-induced damage due to the high density of glutamate receptors, especially in the Sommer zone. In the hippocampus, in comparison with other parts of the brain, the GAM-Kergic reverse inhibition system is relatively poorly developed, but the system of the return excitation of pyramidal neurons is maximally represented. Significant influx occurs during epileptic seizure

calcium ions into the postsynaptic membrane of pyramidal neurons. An increase in the intracellular content of calcium ions triggers a cascade of reactions that trigger the activation of proteases, phospholipases, and endonucleases, which, in turn, leads to the release of active and potentially toxic metabolites. Deficiency of the main inhibitory neurotransmitter - GABA - is one of the most important factors leading to cytotoxicity.

The limbic system is characterized by the so-called “kindling” process, in which the normal brain structures gradually become epileptogenic. In the process of “ignition”, mossy fibers (efferent paths from granular cells of the dentate gyrus) undergo axonal and synaptic reorganization - sprouting. As a result of this, return excitatory bonds are formed that are involved in the progressive development of hypersynchronous discharges. Such synaptic reorganizations are accompanied by the death of pyramidal cells in the hippocampus. Along with damage to neurons, the growth of axons to new target cells begins. So, there is an increase in the axons of the granular cells of the dentate gyrus (mossy fibers) in the direction of the inner molecular layer of the dentate gyrus. Since mossy fibers contain glutamate, violation of the conditions for the formation of synapses can contribute to a state of hyper-excitability, which provokes the appearance of excessive discharges. Sloviter (1994) found that insertion neurons (mossy fibers), which form synapses with GABA-containing basket cells, are most sensitive to excitation. As the mossy fibers die, basket cells become functionally inactive (“dormant”). Deficiency of the functional activity of the inhibitory system contributes to hyper-excitability and the occurrence of epileptic seizures. Normally, mossy fibers (synonyms are intercalary neurons, efferent paths of granular cells of the dentate gyrus) perform the function of limiting and protecting against excessive activation of their own targets - pyramidal cells of the SAZ zone of the hippocampus. The abundance of return

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of excitatory synaptic connections in pyramidal cells of the SAZ zone of the hippocampus and the ability of individual pyramidal cells of the SAZ zone to trigger an active potential as an explosive pattern, explains their role in epileptogenesis. Afferents of SAZ pyramidal cells - mossy fibers, perform the so-called “gatekeeper” function, limiting the excessive activation of SAZ pyramidal cells and preventing the onset of attack activity. Using autoradiography, it was proved that the granular cells of the dentate gyrus actually serve as a barrier that protects the hippocampus from excessive activation. Violation of the barrier function of granular cells leads to excessive activation of the SAZ of the pyramidal cells and the hyper-excitability of the hippocampus.

Despite the large number of works devoted to the study and description of pathological changes in hippocampal sclerosis, its etiology remains a subject of debate.

Etiology

Currently, MVS is considered a multifactorial pathology. The main reasons for the development of hippocampal sclerosis according to modern concepts are: atypical febrile convulsions with a high duration of seizures, perinatal ischemia (after the 28th week of gestation), intracranial infections. There is an opinion that the genetic predisposition is important in the genesis of hippocampal sclerosis, as shown by the example of studying family cases of mesial temporal lobe epilepsy. Of the etiological factors, we can separately note the effect of various metabolic disorders (congenital hyperinsulinism, anomalies of beta oxidation, etc.), which, causing energy deficiency in the brain tissue, can lead to damage to the structure of the brain most sensitive to hypoxia - the hippocampus.

BaL (1997) indicates that the epileptic focus forms when new pathological recurrent, excitatory synapses form in the hippocampus

instead of the dead normal. Although the epileptogenic potential of hippocampal sclerosis is sufficient for the formation of epilepsy, epilepsy and hippocampal sclerosis may be different symptoms of the same pathology underlying them, respectively, the development of temporal lobe epilepsy may not depend on cell death and hippocampal plasticity.

There are at least 2 types of MVS, which basically mean different etiological factors. The first type always includes a unilateral lesion of the hippocampus with a predominant lesion of the CAI zone, the second type - bilateral, with the spread of pathological changes in the SAZ field and other parts of the temporal lobe.

If before the attitude of MVS to mesial temporal lobe epilepsy (cause or effect?) Caused great controversy, now modern studies prove the post-attack etiology of hippocampal sclerosis. It is believed that prolonged atypical febrile convulsions, epileptic status, and even a single short generalized tonic-clonic seizure, can lead to the formation of MVS. Experimentally provoked prolonged febrile convulsions cause axonal reorganization in the immature hippocampus, which leads to its hyper-excitability. Probably, the frequency of seizures does not play a significant role in the formation of hippocampal sclerosis. So, in many patients with a very high frequency of seizures, requiring even surgical functional separation of the hemispheres, hippocampal sclerosis is not detected. On the other hand, prolonged seizures and status epilepticus can contribute to the formation of structural changes ranging from hippocampal sclerosis to hemisphere atrophy. However, only a long duration of seizures is insufficient for the formation of MVS. So, benign occipital epilepsy with an early debut is often accompanied by prolonged seizures ("ictal syncopes", "comatose-like seizures"), but without any structural damage to the brain. Obviously, there are other factors that contribute to the formation of structural changes that are still

not fully identified.

Some authors hypothesize the role of angiogenesis in the etiology of hippocampal sclerosis. According to this theory, a process of neovascularization or angiogenesis takes place in the hippocampus, which is accompanied by neuronal-glial reorganization of the epileptogenic focus. It is possible that angiogenesis is stimulated by frequent repeated attacks. The proliferating capillaries in the epileptogenic hippocampus express erythropoietin receptors that are highly immunoreactive. Angiogenesis is most pronounced in the region of the greatest death of neurons and reactive gliosis - in the CAI, CAP zones and the gates (chylus) of the dentate gyrus. It is possible that erythropoietin penetrates the brain through receptor-mediated endocytosis. The high content of erythropoietin receptors in the hippocampus with mesial temporal lobe epilepsy suggests a possible role for this cytokine in epileptogenesis.

With mediobasal temporal lobe epilepsy with hippocampal sclerosis, a high history of neonatal seizures and perinatal brain lesions has been established. It is suggested that, most likely, prolonged febrile seizures cause damage to the hippocampus in the brain with existing changes. However, it is possible that febrile seizures are preceded by genetically determined structural disorders in the hippocampus, which facilitate the manifestation of febrile seizures and contribute to the formation of hippocampal sclerosis.

Neuroimaging, implemented on the first day after febrile seizures, reveals hippocampal edema, which decreases after a few days, and in some cases passes into hippocampal atrophy. At the same time, not all children with prolonged atypical febrile convulsions subsequently develop temporal lobe epilepsy, which indicates the possibility of joint or isolated influence of genetic, vascular, metabolic and immunological factors.

It has been experimentally shown that in animals the induction of epileptiform activity in the hippocampus is possible.

temperature, and also that febrile seizures themselves can come from the hippocampus or amygdala. Febrile seizures, mainly with a long duration of seizures, cause hypoxic-ischemic, metabolic changes in the brain and lead to the formation of MVS with the subsequent development of temporal lobe epilepsy. It should be noted that only prolonged atypical febrile convulsions play a role in the genesis of MVS and the formation of subsequent temporal lobe epilepsy. Whereas, epilepsy that develops after typical febrile seizures is more often idiopathic. According to various authors, atypical febrile seizures have a history of 20-38% of patients with temporal lobe epilepsy. A time interval of three years or more is required (on average 8–9 years) from the onset of atypical febrile seizures to the formation of temporal lobe epilepsy. Such a long latent period does not yet find sufficient explanation, but most likely that this period of time is necessary for the "maturation" of the hippocampal scar and epileptogenesis.

Previously, some authors proposed the perinatal hypothesis of the occurrence of MVS, which to date has not found any confirmation. According to this theory, mesial temporal sclerosis can be a consequence of pathological birth with impairment of the copper-obese sections of the temporal lobe in the Bichat fissure. It was also assumed that hippocampal sclerosis occurs as a result of neuroinfections, chronic intoxications, closed craniocerebral trauma, injuries of the cervical vertebrae in the neonatal period ™. The listed pathological conditions in the acute period could cause venous stasis, thrombophlebitis, local diapedetic hemorrhages with subsequent destructive and scar adhesions in the brain tissue. Vascular disorders could contribute to chronic cerebral ischemia, causing hypoxia, sclerosis, wrinkling, and atrophy of the mediobasal temporal lobes.

It is interesting to note that children with MVS often have a “dual pathology” - a combination of hippocampal sclerosis with another intra- or extra-hippocampus

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mapal pathology, mainly cortical dysplasia or less commonly, neuronal heterotopies, microdisgesias, gangliogliomas, which suggests a violation of the processes of antenatal brain development in the etiology of MVS. It is possible that the concomitant presence of brain dysgenesis predisposes to the more rapid formation of MVS. Clinically, MVS in the structure of “double pathology” manifests earlier (up to 6 years) than MVS in its “pure form” (the beginning of the puberty), and epileptic seizures are more “evil” and resistant to therapy.

It was noted that during the first 5 years of life, the number of granular cells in the dentate gyrus of the hippocampus continues to increase. The forming granular cells express a special embryonic form of neuronal adhesion protein and the number of cells expressing this protein increases during the first 5 years of life. This protein indicates the immaturity of granular cells and their postnatal development, proliferation and migration. Since the mitosis and migration process continues in the granular cells of the hippocampus in the postnatal period, it is possible that sclerosis of the ammonian horn is the result of a violation of neuronal migration. This statement is confirmed by the fact that in the studied groups of patients with neuronal heterotopia of the temporal region and hippocampal sclerosis in isolation, identical patterns of cell death in the hippocampus are found. Animals with experimentally induced impairment of neuronal migration were found to be more susceptible to damage to the hippocampus.

In recent years, the literature describes the so-called "devastating epileptic encephalopathy in school-age children" or "pseudoencephalitis". This pathology makes its debut with severe prolonged epileptic status, fever of unknown etiology and leads to bilateral hippocampal atrophy with the development of severe pharmacoresistant epilepsy with cognitive impairment. In such epileptic syndromes as severe myoclonic epilepsy of infancy and syndrome of hemiconvulsive seizures, hemiparesis and epilepsy (HHE - syndrome), manifested by prolonged febrile seizures and status, ammonium sclerosis (Nabbout et al., In press) is also noted.

It should be noted interesting observations, according to which, in the etiology of MVS, persistence of herpetic infection (herpes simplex virus type 6) in the mediobasal parts of the temporal lobe may be of importance. It is noted that a herpetic virus in brain tissue is detected, even in the absence of inflammatory changes. In some cases, the herpes virus causes encephalitis with a characteristic lesion of the temporal lobe and limbic structures. Herpes simplex virus type 1 predominantly underlies herpes encephalitis in children older than 6 months, while herpes simplex virus type 2 is more often a congenital or perinatal infection. As is known, herpetic encephalitis is common in children, and it must be remembered as one of the causes of hippocampal sclerosis.

RUSSIAN JOURNAL OF CHILDREN NEUROLOGY

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Hippocampal sclerosis  [SG] and mesial temporal sclerosis  (MTS) are the most common histopathological abnormalities found in adult patients with a pharmacoresistant form of temporal lobe epilepsy (mesial temporal lobe epilepsy is the most difficult to treat form of epilepsy in adults and in children over 12 years of age).

SG - loss of more than 30% of cells in the CA1 and CA3 regions of the hippocampus with a relative thickening of the CA2 region. The term “MTS” reflects the fact that along with the hippocampus, atrophic and gliotic changes are observed in the amygdala and hook (see figure).

SG has two fundamental pathological characteristics: [ 1 ] a sharp decrease in the number of neurons, [ 2   ] hyper excitability of the remaining nervous tissue. One of the key roles in epileptogenesis in hypertension is played by the sprouting of mossy fibers: abnormal axons of granular cells, instead of innervating the hippocampus (Ammon horn - cornu Ammonis), reinner the molecular neurons of the dentate gyrus through exciting synapses, thus creating local electrical circuits capable of epiphys. An increase in the number of astrocytes and gliosis can also play a role in epileptogenesis, since altered astrocytes cannot sufficiently re-capture glutamate and potassium.

Patients with temporal lobe epilepsy (due to SG / MTS) often have a history of acute CNS pathology (precipitating lesions) in their childhood (usually up to 5 years): the status of febrile seizures, neuroinfection, and traumatic brain injury. Stereotypic seizures begin in the period from 6 to 16 years, and there may be a so-called latent period, which falls on the time between the initial precipitating damage and the development of the first epileptic seizure. There are also frequent situations when the so-called “silent” period lasts between the first attack and the development of pharmaco-resistance. This feature of the course of the disease indicates its progressive nature. Also, hypertension can lead to: acute circulatory disorders in the pool of the terminal and lateral branches of the posterior cerebral artery (which cause basal temporal ischemia, neuronal death, gliosis and atrophy) and impaired development of the temporal lobe during embryogenesis. No less urgent problem, called the double pathology, which was first described by M.L. Levesque et al. (1991) - a combination of extra-hippocampal lesions (both temporal and extra temporal) with hypertension. The frequency of occurrence of this pathology is high: from 8% for tumors to 70% for cortical dysplasias.

Hypertension is often determined in patients with complex partial seizures (other options are secondary generalized seizures). Speaking about the clinical picture of an attack in temporal lobe epilepsy associated with hypertension, it is necessary to remember that [ 1   ] each of the symptoms individually is not specific, although there is a typical pattern of the course of the attack; [ 2 ] symptoms during an attack appear when epileptic activity spreads to the parts of the brain associated with the hippocampus, which in itself does not give clinical manifestations (the scalp EEG alone does not reveal epi-activity in the hippocampus, which has been demonstrated in numerous studies using intracerebral electrodes; for the appearance of epiactivity in the temporal region on the scalp EEG requires its distribution from the hippocampus to the adjacent cortex of the temporal lobe).

Mesial temporal lobe epilepsy has 3 peaks of age debut - at 6, 15 and, less commonly, at 27 years of age. A characteristic beginning of a temporal attack is an aura in the form of an ascending sensation in the abdomen (associated with the excitation of the islet). Fear or anxiety is also possible when amygdala is involved at the beginning of an attack. At the beginning of the attack, there may be a sensation of “already seen” (déjà vu, associated with excitation of the entorhinal cortex). The aura in the form of dizziness or noise is alarming in terms of diagnosis, which may indicate an extra-hippocampal onset of the attack. The intact ability to name objects and speak during an attack is an important lateralizing sign of damage to the non-dominant hemisphere. A change in consciousness is accompanied by a halt in action, while the patient has a frozen look with eyes wide open (staring - starring). The aura and the cessation of action are followed by the organoalimentary automatisms with chewing, smacking of the lips (associated with excitation of the islet and frontal operculum). Also, dystonia of the contralateral side of the sclerosed hippocampus of the hand often occurs (which is associated with the spread of epiactivity in the basal ganglia) and manual automatisms appearing in the form of sorting objects with the fingers of the ipsilateral hand. Among the lateralizing symptoms, postictal paresis is important, which indicates the involvement of the contralateral hemisphere, and postictal aphasia in lesions of the dominant hemisphere. These symptoms should be considered in the context of EEG data. A characteristic cognitive deficit in hypertension may be a decrease in memory, especially with uncontrolled seizures.

Diagnosis of epilepsy due to hypertension is based on three basic principles:

[1   ] a detailed analysis of the sequence of symptoms in an epileptic seizure, or semiology, which depends on which parts of the brain the epileptic activity spreads (see above);

[2 ] analysis of EEG data and comparing them with the semiology of the attack; EEG epileptic activity in mesial temporal lobe epilepsy (MVE) may be absent or only indirect conditional epileptiform elements (rhythmic slow-wave [delta-theta] activity) may be recorded; a study of the bioelectric activity of the brain during EEG monitoring of sleep significantly increases the likelihood of diagnosing pathological epileptiform activity (regional spike-wave activity); however, for the correct interpretation of the sleep EEG in MVE, a highly qualified neurologist-epileptologist is needed who can assess the complex of clinical and EEG symptoms and establish the correct diagnosis; accurate diagnosis of MVE is possible with the use of intracerebral, subdural and intracisternal (implantable through the oval hole) electrodes.

[3   ] detection of epileptogenic lesions in MRI (should be performed according to the epileptological protocol, the main characteristics of which can be distinguished by a small thickness of sections and a high magnetic field strength): a decrease in the volume of the hippocampus and violation of the structure of its layers, a hyperintense signal in T2 and FLAIR mode; atrophic changes in the ipsilateral amygdala, temporal lobe pole, fornix, and mamillary body are often detected.

The standard of medical care for patients with pharmacoresistant MVE is to refer the patient to a specialized center for pre-surgical examination and surgical treatment. Surgery for temporal lobe epilepsy has two obvious goals: [ 1   ] getting rid of the patient from attacks; [ 2   ] withdrawal of drug therapy or reduction of the dose of the drug. The task of surgical treatment of temporal lobe epilepsy is the complete removal of the epileptogenic cerebral cortex with maximum preservation of the functional areas of the brain and minimization of neuropsychological deficit. In this regard, there are two surgical approaches: temporal lobectomy and selective amygdalogippocampectomy. removal of hook, amygdala and hippocampus. Surgery of temporal lobe epilepsy in hypertension with sufficient experience of the surgeon has minimal risks of neurological deficiency (persistent hemiparesis, complete hemianopsia).

Literature:

article "Hippocampal sclerosis: pathogenesis, clinical features, diagnosis, treatment" D.N. Kopachev, L.V. Shishkina, V.G. Bychenko, A.M. Shkatova, A.L. Golovteev, A.A. Troitsky, O.A. Grinenko; FSAI “Research Institute of Neurosurgery named after Acad. N.N. Burdenko »Ministry of Health of Russia, Moscow, Russia; FSBI Scientific Center of Obstetrics, Gynecology and Perinatology named after Acad. IN AND. Kulakova "of the Ministry of Health of Russia, Moscow, Russia (journal" Issues of Neurosurgery "No. 4, 2016) [read];

article “Mesial temporal sclerosis. The current state of the problem ”Fedin AI, Alikhanov AA, Generalov V.O .; Russian State Medical University, Moscow (journal "Almanac of Clinical Medicine" No. 13, 2006) [read];

article "Histological classification of mesial temporal sclerosis" Dmitrenko D.V., Stroganova M.A., Schneider N.A., Martynova G.P., Gazenkampf K.A., Dyuzhakova A.V., Panina Yu.S.; GBOU VPO Krasnoyarsk State Medical University named after prof. V.F. Voyno-Yasenetsky ”of the Ministry of Health of Russia, Krasnoyarsk (journal“ Neurology, Neuropsychiatry, Psychosomatics ”No. 8 (2), 2016) [read];

article “Febrile seizures as a trigger of mesial temporal sclerosis: a clinical case” N.A. Schneider, G.P. Martynova, M.A. Stroganova, A.V. Dyuzhakova, D.V. Dmitrenko, E.A. Shapovalova, Yu.S. Panin; GBOU VPO Krasnoyarsk State Medical University named after prof. V.F. Voyno-Yasenetsky Ministry of Health of the Russian Federation, University Clinic (Journal of Women's Health Problems No. 1, 2015 [read];

article “Possibilities of magnetic resonance imaging in assessing structural changes in the brain in patients with temporal lobe epilepsy” Anna A. Totolyan, T.N. Trofimova; LLC “NMC-Tomography” Russian-Finnish clinic “Scandinavia”, St. Petersburg (journal “Russian electronic journal of radiation diagnostics” No. 1, 2011) [read];

article "Surgical treatment of symptomatic temporal lobe epilepsy" A.Yu. Stepanenko, Department of Neurology and Neurosurgery, Russian State Medical University, City Clinical Hospital No. 12 of the Moscow Department of Health (journal "Neurosurgery" No. 2, 2012) [read]

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