Focal epilepsy (FE) is one of the forms of the disease in which the occurrence of epileptic seizures is due to the presence in the brain of a clearly localized and limited focus of paroxysmal activity.. Usually it is secondary, that is, it develops against the background of some other pathology.

The disease is characterized by the periodic appearance of simple or complex epiparoxysms in the patient, the clinical picture of which is determined by the location of the lesion.

They speak of focal (focal) epilepsy when it is possible to identify a clear focus of epiactivity General information Focal epilepsy includes all types of epileptic seizures, the development of which is associated with the presence of a local zone of pathological electrical activity of neurons in cerebral structures.

Epileptic activity, starting focally, can later spread throughout the cerebral cortex, which leads to the occurrence of a secondary generalized seizure in the patient.. This distinguishes them from paroxysms with primary generalizations, in which the focus of excitation has an initially diffuse character..

Separately, multifocal epilepsy is distinguished, characterized by the presence in the brain of not one, but several epileptogenic foci at once..

In the overall structure of the incidence of epilepsy, FE accounts for 82%. The debut of the disease in 75% of cases occurs in childhood. Most often, it develops against the background of an infectious, ischemic or traumatic brain injury, as well as congenital anomalies of its development.. Secondary (symptomatic) focal epilepsy accounts for 71% of cases.

Causes and pathogenesis The following diseases can lead to the development of FD:.

volumetric neoplasms of the brain (benign and malignant);

metabolic disorders;

cerebral circulatory disorders;

traumatic brain injury;

infectious lesions of the brain (neurosyphilis, meningitis, encephalitis, arachnoiditis, cysticercosis);

congenital anomalies of the structure of the brain (congenital cerebral cysts, arteriovenous malformations, focal cortical dysplasia).

Also, the cause of the development of the disease can be genetically determined or acquired metabolic disorders in the nerve cells of a certain area of \u200b\u200bthe cerebral cortex..

The most common causes of focal epilepsy in children are various prenatal lesions of the central nervous system:.

intrauterine infection;

fetal hypoxia;

neonatal asphyxia;

intracranial birth injury.

Violation of the process of maturation of the cerebral cortex can also lead to the occurrence of PE in a child.. In this case, there is a high probability that in the future, as it grows and develops, its clinical manifestations will permanently disappear..

In the pathological mechanism of the development of seizures, the main role belongs to the epileptogenic focus.. Experts distinguish several zones in it:.

Zone.

Description.

epileptogenic damage.

Covers an area with obvious morphological changes in cerebral tissue. In most cases, it is well visualized during magnetic resonance imaging..

Primary.

Represents a section of the cortex, the cells of which potentiate epi-discharges.

symptomatic.

It includes that part of the cortex, the excitation of neurons of which leads to the development of an epileptic seizure..

irritative.

It is a source of epi-signals recorded in the interictal period on the electroencephalogram.

functional deficit.

Area of \u200b\u200bthe cortex, damage to which leads to the formation of neurological and mental disorders characteristic of PE.

Classification Currently, experts in the field of neurology distinguish several forms of focal epilepsy:.

Form of the disease.

Description.

Symptomatic FE.

Occurs against the background of any damage to the brain, accompanied by morphological changes in its tissue. In most cases, when conducting tomographic research methods, it is possible to visualize the foci of changes..

Cryptogenic FE (probably symptomatic).

The disease is of a secondary nature, however, with the help of modern imaging methods, it is not possible to detect morphological changes in cerebral tissue..

idiopathic.

The patient does not have any pathologies of the central nervous system that could provoke the development of epilepsy. The most common causes of the disease are violations of the process of maturation of the cerebral cortex, as well as hereditary membranopathies.. Idiopathic focal epilepsy is characterized by a benign course. It includes:.

benign infant episyndromes;

Pediatric occipital epilepsy Gastaut;

benign ronaldic epilepsy.

Symptoms Focal epilepsy in children and adults is manifested by recurrent focal (partial) paroxysms. They are divided into simple (loss of consciousness does not occur) and complex.

Simple seizures, depending on the characteristics of the manifestation, are divided into several types:.

sensory (sensitive);

motor (motor);

somatosensory;

with mental disorders;

with hallucinations (gustatory, olfactory, visual, auditory).

Complex focal seizures begin in the same way as simple ones, and then the patient loses consciousness. Automatisms may appear. After an attack, confusion persists for some time..

Some patients with PE may experience secondary generalized partial seizures.. They begin as a complex or simple seizure, and then, as the excitation spreads diffusely through the cerebral cortex, they turn into classic epileptic tonic-clonic convulsions..

Seizures in patients with symptomatic focal epilepsy are combined with a gradual decrease in intelligence, mental retardation of the child and the development of cognitive impairment.. In addition, in the clinical picture of the disease there are also symptoms characteristic of the main brain lesion..

Focal idiopathic epilepsy is characterized by a benign course, the absence of disorders in the intellectual and mental spheres, neurological deficit.

Features of the clinical picture depending on the localization of the epicenter are presented in the table.

Type of epilepsy.

Description.

temporal.

The epileptogenic focus is localized in the temporal lobe of the brain. This form of the disease is observed most often. It is characterized by the presence of automatisms and aura, sensorimotor seizures, loss of consciousness. An attack lasts an average of 45-60 seconds. In adults, automatisms by the type of gestures predominate, and in children, oral automatisms. Approximately 50% of patients have secondary generalized seizures.. If the epicenter is located in the dominant hemisphere, then at the end of the attack, patients experience post-seizure aphasia..

Frontal.

Aura is not typical for this form of the disease.. The clinical picture consists of short-term stereotypical paroxysms prone to serialization.. Patients often experience:.

Emotional symptoms (increased arousal, screaming, aggression);

motor phenomena (foot pedaling, automatic complex gestures);

head and eye movements.

Seizures often occur during sleep. If the focus is located in the region of the precentral gyrus, then the patient has attacks of motor paroxysms of Jacksonian epilepsy.

Occipital.

Seizures often occur with various types of visual impairment:.

ictal blinking;

visual illusions;

Narrowing of visual fields;

transient amorrhosis.

Most often, with this form of the disease, attacks of visual hallucinations are observed, lasting up to 10-15 minutes..

Parietal.

The most rare form of focal epilepsy. Various structural disorders of the brain (cortical dysplasia, tumors) lead to its development.. The main symptom of the disease is recurrent somatosensory simple paroxysms.. After the end of the attack, the patient may develop Todd's paralysis or short-term aphasia.. When the focus is localized in the region of the postcentral gyrus, patients experience Jacksonian sensory seizures..

Diagnosis If a person has a partial paroxysm, then he should definitely consult a doctor for an examination, since their development can cause various serious pathologies:.

cortical dysplasia;

vascular malformation;

massive neoplasms of the brain.

When interviewing a patient, a neurologist specifies the sequence, duration, frequency and nature of epileptic seizures.. The data obtained allow the specialist to establish the approximate location of the pathological focus.

To confirm the diagnosis, the patient undergoes electroencelography (EEG). This method of instrumental diagnostics in most cases makes it possible to detect the epiactivity of the brain even in the interictal period.. In case of insufficient information content, an EEG recording with provocative tests is performed or daily EEG monitoring is performed..

Electroencephalography - one of the methods for diagnosing focal epilepsy. However, the technical complexity of the technique somewhat limits its application in wide clinical practice..

To identify morphological changes in the brain that underlie the pathological mechanism of development of focal epilepsy, the following types of studies are performed:.

Magnetic resonance imaging (MRI). It is advisable to perform the study with a slice thickness not exceeding 1-2 mm. In the symptomatic form of the disease, tomograms reveal signs of the underlying disease (dysplastic or atrophic changes, focal lesions). If the study does not reveal any abnormalities, the patient is diagnosed with cryptogenic or idiopathic focal epilepsy.

Positron emission tomography. In the area of \u200b\u200blocalization of the epicenter, the zone of hypometabolism of the medulla is determined.

Single photon emission computed tomography (SPECT). Hyperperfusion of the cerebral tissue is determined at the site of the focus during an attack, and hypoperfusion is determined outside the attack..

TreatmentTreatment of the disease is carried out by a neurologist or epileptologist. Conservative treatment is based on the systematic long-term use of anticonvulsants (anticonvulsants). Drugs of choice include:.

valproic acid derivatives;

carbamazepine;

phenobarbital;

levetiracetam;

topiramate.

With a symptomatic form of focal epilepsy, treatment of the underlying disease is mandatory..

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