Progressive myoclonic epilepsy

The progressive myoclonic epilepsies form a disparate group of rare severe conditions that are characterized by deteriorating action myoclonus, although other CNS symptoms and signs are often present.

Epidemiology

Most commonly they clinically manifest in late childhood or teens, although they may present at any age .

Clinical presentation

The archetypal feature of the conditions is an action myoclonus, which demonstrates persistent worsening, but is also found at rest, and is precipitated by certain stimuli, including touch, loud sounds or light.

Concurrent CNS features that are often - but not invariably - present, include:

  • other forms of seizures: especially generalized tonic-clonic
  • progressive ataxia
  • dementia

Treatment and prognosis

The progressive myoclonic epilepsies are usually relatively refractory to anticonvulsant therapy. Most patients eventually require wheelchairs with a decreased lifespan .