Focal epilepsy
The content of the article:
- General information
- Causes and pathogenesis
- Classification
- Symptoms
- Diagnostics
- Treatment
- Forecast
- Video
Focal epilepsy (FE) is one of the forms of the disease in which the occurrence of epileptic seizures is caused by the presence of a clearly localized and limited focus of paroxysmal activity in the brain. Usually it is of a secondary nature, that is, it develops against the background of some other pathology.
The disease is characterized by the periodic appearance in the patient of simple or complex epiparoxisms, the clinical picture of which is determined by the area of the lesion.
Focal (focal) epilepsy is talked about 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 then spread through the cerebral cortex, which leads to a secondary generalized seizure in the patient. This distinguishes them from paroxysms with primary generalization, in which the focus of excitation is initially diffuse.
In the general structure of epilepsy morbidity, FE accounts for 82%. The debut of the disease in 75% of cases occurs in childhood. Most often, it develops against the background of infectious, ischemic or traumatic brain damage, 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 FZ:
- volumetric neoplasms of the brain (benign and malignant);
- metabolic disorders;
- disorders of cerebral circulation;
- traumatic brain injury;
- infectious brain lesions (neurosyphilis, meningitis, encephalitis, arachnoiditis, cysticercosis);
- congenital anomalies in 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 disorders of metabolic processes in the nerve cells of a certain area of the cerebral cortex.
The causes of focal epilepsy in children are most often various prenatal lesions of the central nervous system:
- intrauterine infection;
- fetal hypoxia;
- asphyxia of the newborn;
- intracranial birth injury.
Disruption of the maturation process of the cerebral cortex can also lead to the development 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 steadily 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 | It is a section of the cortex, the cells of which potentiate epi-discharges. |
| Symptomatic | It includes that part of the cortex, the excitation of neurons in 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 deficits |
An area of the cortex, the damage of which leads to the formation of neurological and mental disorders characteristic of PE. |
Classification
Currently, specialists in the field of neurology distinguish several forms of focal epilepsy:
| Disease form | Description |
| Symptomatic FE | It occurs against the background of any damage to the brain, accompanied by morphological changes in its tissue. In most cases, when carrying out tomographic research methods, the foci of changes can be visualized. |
| Cryptogenic PE (probably symptomatic) | The disease is secondary, but morphological changes in cerebral tissue cannot be detected using modern imaging methods. |
| 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 disorders of the maturation process of the cerebral cortex, as well as hereditary membranopathies. Idiopathic focal epilepsy is characterized by a benign course. It includes: · Benign infantile 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 (no loss of consciousness occurs) 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 start out the same way as simple ones and then the patient loses consciousness. Automatisms may appear. After an attack, confusion persists for some time.
In some patients with FE, secondary generalized partial seizures may occur. They begin as a complex or simple seizure, and then, as the diffuse spread of excitation along the cerebral cortex, they turn into classic epileptic tonic-clonic seizures.
Seizures in patients with focal epilepsy of symptomatic genesis are combined with a gradual decrease in intelligence, delayed mental development of the child and the development of cognitive impairments. In addition, in the clinical picture of the disease there are also symptoms characteristic of the main brain damage.
Features of the clinical picture, depending on the localization of the epichage, 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 occurs most often. It is characterized by the presence of automatisms and auras, sensorimotor seizures, and loss of consciousness. The attack lasts 45-60 seconds on average. In adults, automatisms of the type of gestures prevail, and in children, oral automatisms. Secondary generalized seizures are noted in about 50% of patients. If the epiocenter is located in the dominant hemisphere, then at the end of the attack, patients experience post-attack aphasia. |
| Frontal |
For this form of the disease, the aura is not characteristic. The clinical picture consists of short-term stereotypical paroxysms prone to seriality. Patients often have: · Emotional symptoms (increased agitation, crying out, aggression); · Motor phenomena (pedaling with feet, automatic complex gestures); · Turns of the head and eyes. Often attacks occur during sleep. If the focus is located in the area of the precentral gyrus, then the patient has seizures of motor paroxysms of Jacksonian epilepsy. |
| Occipital |
Attacks often occur with various types of visual impairment: · Ictal blinking; • visual illusions; · Narrowing of the visual fields; · Transient amovroz. Most often, with this form of the disease, bouts 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 dysplasias, 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. With the localization of the focus in the postcentral gyrus, patients have Jacksonian sensory seizures. |
Diagnostics
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;
- volumetric 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.
Electroencelography (EEG) is performed to confirm the diagnosis. In most cases, this method of instrumental diagnostics makes it possible to reveal the epiativity of the brain even in the interictal period. In case of insufficient information content, an EEG is recorded with provocative tests or daily EEG monitoring is performed.
Electroencephalography is one of the methods for diagnosing focal epilepsy
The most accurate determination of the localization of the epileptogenic focus allows subdural corticography - an EEG recording, in which the electrodes are placed under the dura mater. 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 carry out the study with a section thickness not exceeding 1-2 mm. In the symptomatic form of the disease, the 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 localization of the epichage, the zone of hypometabolism of the medulla is determined.
- Single-photon emission computed tomography (SPECT). At the site of localization of the focus during an attack, hyperperfusion of cerebral tissue is determined, and outside the attack, hypoperfusion.
Treatment
Disease therapy is performed by a neurologist or epileptologist. Conservative treatment is based on the systematic long-term use of anticonvulsants (anticonvulsants). The drugs of choice include:
- derivatives of valproic acid;
- carbamazepine;
- phenobarbital;
- levetiracetam;
- topiramate.
In the symptomatic form of focal epilepsy, treatment of the underlying disease is mandatory.
Drug therapy is most effective for parietal and occipital epilepsy. Patients with focal temporal lobe epilepsy often develop resistance (resistance) to treatment with anticonvulsants after 1-3 years.
Focal epilepsy can be treated with valproic acid medications
If conservative anticonvulsant therapy does not allow achieving a pronounced effect, the question of the expediency of surgical intervention is considered.
During the operation, the neurosurgeon removes the focal neoplasm (vascular malformation, tumor, cyst) and / or excises the epileptogenic area. Surgical intervention is most effective with a clearly localized focus of epileptic activity.
Forecast
The prognosis for focal epilepsy is determined by the type of disease. It is most favorable for idiopathic FE. This form of the disease is characterized by a benign course, cognitive impairment does not develop with it. Often, after the child reaches adolescence, paroxysms spontaneously stop.
In symptomatic epilepsy, the prognosis is largely determined by the severity of the underlying cerebral pathology. It is most serious in severe malformations of the brain, tumor neoplasms. Symptomatic PE in children is often associated with mental retardation.
Video
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
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