Juvenile myoclonic epilepsy (UME) (Egg syndrome).

Juvenile myoclonic epilepsy is a form of idiopathic generalized epilepsy of adolescence with an identified genetic defect, which is characterized by massive bilateral myoclonic seizures that occur predominantly in the hands during the period after awakening patients. This disease often combines the entire triad of primary generalized seizures: myoclonic, generalized convulsive and abscesses.

For the first time Herpin in 1867 described patients with “myoclonic impulsive paroxysms”, in whom “the body shook as if with electric shock.” A detailed classic description of the UME is given by Janz and Christian in 1957.

Frequency. UME accounts for about a third of epilepsy in adolescents. The frequency of UME among all forms of epilepsy is 11-12% (K.Yu. Mukhin, 2000). There is a prevalence of female 3: 1.
Genetics. At present, the localization of the gene determining the development of UME is established on the short arm of chromosome 6 (21 cm from the telomere). The question of the nature of inheritance remains unclear.

A two-locus model is assumed: dominant-recurrent, and it is the dominant gene located on the short arm of chromosome 6. According to Greenberg (1995), the risk of epilepsy in a family where one parent has YME, the highest among all forms of epilepsy, is 7%. The risk is significantly higher if UME suffers from a mother.

Clinic. YME characterizes age-dependent debut. The onset of the disease varies from 2 to 22 years (an average of 11 years). Despite a fairly vivid clinical picture, this form of pathology is little known to practical neurologists and is rarely diagnosed by them.
Usually, the disease is manifested by a combination of all primary-generalized seizures: myoclonic with generalized convulsive and / or absans. The most characteristic sign of UME are myoclonic seizures, it is from this type of paroxysm that one third of patients debut. During a seizure, unexpected, very short, violent twitches of various muscle groups occur with a sound mind.

There are two types of myoclonic attacks: as massive with symmetric synchronous twitching of the limbs, and asymmetric asynchronous single or multiple, varying in amplitude. The frequency and intensity of attacks may be different. Myoclonic seizures always involve the muscles of the arms (mainly the extensors) and the shoulder girdle.
Therefore, patients complain of “awkwardness”: they drop or drop objects, pour tea, etc. The attacks, as a rule, are massive, in some patients the intensity of attacks resembles a motor storm during chorea, which significantly disrupts the patient’s daily activities. When myoclonias occur in the legs, patients feel a sudden blow under their knees, squatting involuntarily. Perhaps the sudden fall of the sick as knocked out.
Consciousness is saved, patients immediately rise (myoclonic astatic seizures).
In myoclonic seizures, fulminant involvement is possible.
axial muscles, while there is a shudder, shoulders are raised, arms are thrown forward and up.

The frequency of myoclonus varies from multiple during the day to 1 time per month. Myoclonic seizures last a fraction of a second, sometimes there can be a series of twitches with a total duration of 3-5 seconds. The most important feature of these attacks is a clear dependence on circadian rhythms. Most often, seizures occur in the period immediately after awakening, in 75-80% of patients only in the morning hours, within 30-60 minutes after awakening.

Generalized convulsive seizures are recorded in the UME structure in 65-95% of cases. These attacks are characterized by nico-clonic or predominantly clonic convulsions and have their own clinical features: first, myoclonic paroxysms develop, which increase in frequency, amplitude, become more rhythmic, generalized, they transform into tonic-clonic ones. To denote this type of seizure, the term “clonic-tonic paroxysms” is proposed. Usually there are rare generalized convulsive seizures from 1 per month to a single for the entire period of the disease. As with myoclonias, generalized convulsive bouts of arousal dominate.

Absansy – the third most frequent type of seizures in UME. In nearly one third of patients, UME begins with absences, which may present diagnostic difficulties for the doctor. In UME, absences are relatively rare, often complex, with a myoclonic component. The duration of absences is usually very short, especially in female patients (about 3 seconds). Unlike myoclonic seizures and generalized convulsive seizures, there is no clear circadian rhythm with absences; however, a slight increase in the frequency of absences is possible within an hour after awakening.
Among the provoking factors, the most significant are sleep deprivation and violent sudden waking up.

Sometimes seizures occur only when there is not enough sleep or when there is a sudden nightly awakening and they do not occur spontaneously.

Neurological status, as a rule, without features. Intellectual-mnestic violations are not characteristic and are the criterion for the exclusion of the syndrome. Sometimes, microfocal neurological symptoms can be observed: minor pyramidal symptoms, vegetative lability, mild focal disorders; these symptoms have no significant diagnostic value.

local_offerevent_note March 5, 2019

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