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.
- Unverricht–Lundborg disease (EPM1)
- Lafora body disease (EPM2)
- action myoclonus renal failure (AMRF) syndrome (EPM4)
- PRICKLE1-gene-related progressive myoclonic epilepsy with ataxia (EPM5)
- 'North Sea’ progressive myoclonus epilepsy (EPM6)
- myoclonic epilepsy with ragged-red fibers (MERRF)
- neuronal ceroid lipofuscinoses
- dentatorubral-pallidoluysian atrophy (DRPLA)
- sialidosis type 1 (cherry-red spot myoclonus syndrome)
- GM2 gangliosidoses
- Tay–Sachs disease and variants
- Sandhoff disease and variants
- AB variant of GM2 gangliosidosis
- Gaucher disease: type 3 disease
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:
Treatment and prognosis
The progressive myoclonic epilepsies are usually relatively refractory to anticonvulsant therapy. Most patients eventually require wheelchairs with a decreased lifespan .