Juvenile myoclonic epilepsy

Despite its name, juvenile myoclonic epilepsy is probably the most common form of genetic (idiopathic) generalised epilepsy in adults. Onset is usually in late adolescence. Typically, the patient presents with a single tonic-clonic seizure and often has a history of myoclonic jerks (especially when waking in the morning, and after sleep deprivation). Childhood or juvenile absence epilepsy may precede juvenile myoclonic epilepsy. Occasionally, patients present with myoclonus without tonic-clonic seizures.

Myoclonic and generalised tonic-clonic seizures usually respond to sodium valproate. To prevent seizures, the patient may need to avoid sleep deprivation and excessive alcohol intake. Other antiepileptic drugs are not as effective as sodium valproate, and some (eg carbamazepine, oxcarbazepine, phenytoin) can aggravate juvenile myoclonic epilepsy. Long-term treatment is usually needed, even when seizures are fully controlled, because the epileptic disorder lasts for many years.

If possible, avoid sodium valproate in females of childbearing potential who do not have reliable contraception. Levetiracetam and lamotrigine are alternative drugs. If sodium valproate is needed, have an informed discussion with the patient (and parents of younger patients) about its harms and benefits before starting therapy; see Planning for pregnancy in patients with epilepsy and Teratogenic and neurodevelopmental effects of antiepileptic drugs.

If considering starting sodium valproate in males of reproductive potential, see Sodium valproate use in males of reproductive potential; a discussion about the potential risk of neurodevelopmental disorders in children born to males taking sodium valproate may be appropriate.

For sodium valproate monotherapy in females of childbearing potential who do not have reliable contraception, use:

For adult females who have reliable contraception or cannot have children, or for adult males, use:

If the maximum dose of sodium valproate is not effective or adverse effects are intolerable, refer for expert advice—other antiepileptic drugs (eg levetiracetam, lamotrigine) may need to be added or substituted.