Juvenile myoclonic epilepsy · Grey Matter

Juvenile myoclonic epilepsy is a common generalised epilepsy that starts in adolescence, recognised by sudden muscle jerks shortly after waking, and it is the clearest example of an epilepsy whose seizures follow sleep, light and fatigue.

Juvenile myoclonic epilepsy. Juvenile myoclonic epilepsy is a common generalised epilepsy that starts in adolescence, recognised by sudden muscle jerks shortly after waking, and it is the clearest example of an epilepsy whose seizures follow sleep, light and fatigue.

The signature seizure is myoclonic: a jerk lasting a fraction of a second, mostly in the arms and shoulders, with awareness kept, so a cup or a toothbrush flies out of the hand in the first hour after getting up. Most people with it also have tonic-clonic seizures, often preceded by a cluster of jerks, and about a third have absences too. Between seizures the EEG shows generalised polyspike-and-wave discharges at about 4 to 6 per second, often brought out by flashing lights or by hyperventilation.

Sleep loss is the main trigger, together with waking itself; alcohol and stress add to it, and 30 to 40 % of people with it are photosensitive.

It is often missed. Morning jerks are put down to clumsiness, and the diagnosis is made only after a tonic-clonic seizure, when the history of jerks is asked for.

Drug choice matters. Valproate is the most effective, with lamotrigine and levetiracetam used especially for women who may become pregnant (valproate carries a high risk for the fetus), and carbamazepine and other sodium channel blockers can make the jerks worse.

It is usually lifelong. Most people need treatment for years, and stopping medication often brings seizures back, although about a third eventually do well with little or none.

Questions: Why do sleep loss and the first hour after waking matter so much in juvenile myoclonic epilepsy? In juvenile myoclonic epilepsy the thalamocortical networks that switch the brain between sleep and waking are prone to generalised discharges, and the transition after waking, especially after too little sleep, is when they fire most easily. That is why the typical jerks come shortly after getting up and why sleep deprivation, together with alcohol, is the strongest trigger. The link between sleep, waking and these networks is described well and explained only in part, and it is why clinicians treat regular sleep as part of managing this epilepsy.