Juvenile absence epilepsy is an idiopathic variant of epilepsy that manifests in adolescence. The basis of symptoms are generalized epileptic seizures in the form of absences and episodes of tonic-clonic seizures. Intellectual decline and gross mental disorders are atypical. Diagnostics includes assessment of neurological status and psyche, electroencephalography, MRI of the brain. Monotherapy or combined treatment with anticonvulsants is carried out. Therapy has been carried out for years, with its cancellation, relapses are possible.
G40.3 Generalized idiopathic epilepsy and epileptic syndromes
Juvenile absence epilepsy (JAE) is a form of generalized epilepsy, the basis of which is transient short—term paroxysms of disconnection of consciousness (absences). The disease occurs in adolescence, therefore, in the middle of the XX century, it was isolated from childhood epilepsy abscess (CEA) as a separate nosology. The share of JAE accounts for 2-3% of all epilepsies. Among people over 20 years of age suffering from idiopathic generalized epilepsy, about 10% have a diagnosis of JAE. The youth form can manifest in the range from 5 years to 21 years. The typical age of onset of seizures is 9-13 years. Gender differences in morbidity are not pronounced, unlike CEA, which girls are more likely to suffer from.
Juvenile absence epilepsy is an idiopathic disease because it has no established causes of occurrence. The genetic nature of the pathology is most likely. In 35% of cases, cases of epilepsy are detected among relatives. The exact localization of genetic aberrations has not been determined, presumably these are chromosomes 5, 8, 18 and 21. There is a connection between the juvenile and child forms of absentee epilepsy, juvenile myoclonic epilepsy and awakening epilepsy. These forms are often found within the same family.
Factors provoking the development of an epileptic seizure in JAE include:
- insufficient amount of sleep (sleep deprivation),
- excessive psychological or mental activity,
- alcohol intake.
More often, paroxysm occurs when these triggers are combined. Atypical is the development of an attack as a result of photo-provocation (bright light, flickering, flashes).
The mechanism of development of JAE is not fully known in modern neurology. The study of absences in animals showed the presence of hypersynchronous discharges going from the thalamus to the cerebral cortex. A detailed study of the neurons of the cerebral cortex of cats during an artificially provoked abscess revealed a violation of membrane depolarization. As a result, it was concluded that the basis of idiopathic absentee epilepsy is a genetically determined defect in the functioning of K-Na channels of neurons of the cerebral cortex. The consequence of paroxysmal depolarization of neurons is diffuse excitation of the cortex with the development of generalized epileptic seizure. The difference in clinical forms of epilepsy is probably due to the variability of defects in potassium-sodium channels.
In about 70% of cases, the disease begins with absences. Short-term attacks of turning off consciousness are usually not accompanied by motor activity, they last for 4 to 30 seconds. A distinctive feature is their sporadic nature: paroxysms do not occur daily, with varying frequency. In some cases, abscess occurs with a myoclonic component: twitching of the eyelids, corners of the mouth.
Patients subjectively experience an attack as a sudden concentration disorder, an eclipse in the head, trance or lethargy. Some people note a sense of detachment from reality, a kind of strange feeling. For others, a person in a state of absenteeism looks frozen in place with a frozen facial expression and open eyes. Short paroxysms occur unnoticed by the patient’s relatives and acquaintances, have a latent course for a long time.
In 30% of cases, the juvenile form of absentee epilepsy debuts with generalized epileptic paroxysm with clonic-tonic convulsions covering the entire body. The episode proceeds with complete loss of consciousness, falling, biting the tongue. Similar generalized tonic-clonic seizures (GTCS) are observed in 75-80% of patients. If the disease begins with absences, GTCS occurs after 1-10 years and can cause the detection of epilepsy. Generalized paroxysms are rare, usually 1 time per month. They develop in the evening, upon awakening, under the influence of provoking triggers, sometimes in a dream.
Usually absentee epilepsy of adolescence is characterized by a benign course without other neurological abnormalities against the background of preserved mental abilities. However, the disease lasts a lifetime and requires constant antiepileptic therapy.
Resistance of epilepsy to ongoing drug therapy is noted in 20% of patients. These are mainly cases of late diagnosis and belatedly initiated antiepileptic treatment. Lack of therapy or resistance leads to an increase in the number of paroxysms, which significantly affects the quality of life of the patient and his relatives. In such a situation, there is a gradual development of mental changes: isolation, depression, aggressiveness. There may be an epileptic status of absences. A complication of the GTCS is injury in a fall (bruise, fracture, TBI).
Diagnostically difficult are cases when juvenile absence epilepsy begins with short-term absences. The difficulties of diagnosis are complemented by various subjective interpretation of seizures by patients, the peculiarities of the adolescent age of patients. The examination is aimed at identifying paroxysmal activity and confirming the idiopathic nature of epilepsy. It includes:
- Neurological examination. The study of the neurological status does not diagnose pathological abnormalities. Assessment of the mental status with a sufficiently long course of the disease reveals some features of the patient’s psyche.
- Consultation of an epileptologist. It is carried out to confirm the diagnosis, and subsequently – again to correct the treatment.
- Consultation of a geneticist. At the reception, the doctor together with the patient make up a family tree, identify cases of epilepsy in relatives.
- Electroencephalography (EEG). Allows you to confirm the presence of epileptic brain activity, determine its nature. The ictal EEG typical for the South Caucasus registers generalized spikes with a frequency of 3.5-4.5 Hz or polyspikes alternating with slow-wave activity. To carry out the study, they often resort to EEG with provocative samples or daily EEG monitoring. The interictal EEG registers the normal basic bioelectric activity of the brain, against which focal epileptiform discharges occur.
- MRI of the brain. It is carried out to exclude organic pathology and the secondary nature of the absence of epilepsy. There are no morphological intracranial changes. Signs of a TBI suffered as a result of a fall may be detected.
Differential diagnosis is necessary with CEA, juvenile myoclonic epilepsy, awakening epilepsy with GTCS. The latter proceeds mainly with generalized convulsive seizures that occur during the transition from sleep to wakefulness. Childhood absentee epilepsy is characterized by an earlier onset, daily frequent absences, rare occurrence of GTCS, persistent remission at the age of 12. Juvenile myoclonus epilepsy is characterized by the predominance of bilateral myoclonic paroxysms.
The basis of therapy is the regular intake of anticonvulsants. The basic means are derivatives of valproic acid and succinimides (for example, ethosuximide). If necessary, they are assigned in combination. Monotherapy with valproates is indicated in the presence of GTCS.
Relatively new antiepileptic drugs have proven themselves well in the therapy of JAE: lamotrigine, levetiracetam. They are used as monotherapy and in combination with valproates. Lamotrigine treatment is a good alternative for women of childbearing age, since valproates have a teratogenic effect.
The selection of the pharmaceutical product, its dosage, frequency of administration is carried out individually in the process of regular observation of the patient by a neurologist with repeated EEG monitoring and consultation of a neurophysiologist. In the absence of paroxysms during the year, you can think about reducing the dosage of the anticonvulsant. Patients should be aware of the factors provoking seizures and try to avoid them.
Prognosis and prevention
Juvenile absence epilepsy is known for its good response to anticonvulsant therapy. In 80% of patients, it is possible to achieve persistent pharmacological remission, i.e. the absence of absences and GTCS against the background of basic antiepileptic pharmacotherapy. Early initiation of treatment in patients with absences can prevent the appearance of GTCS. The difficulty is usually presented by cases of late initiation of treatment. Specific prevention has not been developed. Secondary prevention is reduced to observing a normal daily routine with a sufficient amount of sleep, excluding physical and mental overload, abstaining from alcohol, etc.