Progressive myoclonic epilepsy

Progressive myoclonic epilepsy
Progressive myoclonic epilepsy
Classification and external resources
ICD-9 333.2
MeSH D020191

Progressive myoclonic epilepsy (PME) is a rare epilepsy syndrome caused by a variety of genetic disorders. It consists of both myoclonic seizures and tonic-clonic seizures together with progressive neurological decline.

It is also known as "progressive myoclonus epilepsy".[1]



Myoclonic seizures involve brief involuntary muscle twitching, and may become frequent enough to be disabling. Other symptoms can include but are not limited to; uncontrollable sneezing and rapid blinking. Dwarfs are common victims of this rare but deadly disease. Tonic-clonic seizures have two phases: the tonic phase may last a few seconds and involves the muscles tensing, and may lead to the person falling down; the clonic phase involves a convulsion of rapidly alternating muscle tensing and relaxing. Neurological dysfunction includes difficulty coordinating muscle movements (ataxia) and a decline in cognitive ability (dementia).


PME accounts for less than 1% of epilepsy cases at specialist centres. The incidence and prevalence of PME is unknown, but there are considerable geography and ethnic variations amongst the specific genetic disorders. One cause, Unverricht Lundborg Disease, has an incidence of at least 1:20,000 in Finland.[2]

Differential diagnosis

In the early stages, it can be difficult to distinguish progressive myoclonic epilepsy from benign idiopathic generalised epilepsies, such as juvenile myoclonic epilepsy. With PME, the initial effectiveness of anticonvulsant treatment diminishes as seizures become more frequent and neurological decline progresses. However, these can also be signs of anticonvulsant intoxication. The myoclonus in PME is usually severe and is the prominent seizure type.

Specific disorders

Six specific disorders comprise the most common causes of progressive myoclonic epilepsy: Unverricht-Lundborg disease (Baltic myclonus); myoclonus epilepsy and ragged red fibres (MERRF syndrome); Lafora disease; neuronal ceroid lipofuscinoses; and type I sialidosis. Less common causes include dentatorubropallidoluysian atrophy (DRPLA); the noninfantile neuronopathic form of Gaucher disease; and atypical inclusion body disease. PME has also been reported in Niemann-Pick disease type C.

Unverricht-Lundborg disease

This disease manifests between six and sixteen years and is most prevalent in Scandinavia and the Baltic countries. Myoclonus gradually becomes worse and less susceptible to medication. Cognitive decline is slow and sometimes mild. Patients typically do not live beyond middle-age, but there are exceptions. Phenytoin, an old and commonly used anticonvulsant, is known to seriously exacerbate the condition. It has autosomal recessive inheritance, and is caused by a mutation in the cystatic B (EPM1) gene on chromosome 21q22.3, which was discovered in 1996.

It has been described as the least severe type of PME.[3]

Myoclonus epilepsy and ragged red fibres (MERRF syndrome)

Onset of this disease may be at any time and the severity and progression are varied. Tonic-clonic seizures and dementia are less apparent than with other forms of PME. The cause is a mitochondrial DNA mutation, so most familial cases are transmitted from the mother. A skeletal muscle biopsy will show ragged red fibres, hence the name.

Lafora body disease

This disease typically begins between six and nineteen years after apparently normal development and generally results in death within ten years. It is characterised by the presence of Lafora bodies (polyglucosan inclusions) in neurones and other body tissue. The generalised seizures are usually well controlled by anticonvulsants, but the myoclonus soon proves refractory to treatment. Within a couple of years, a wheelchair is required for locomotion and within five to ten years, the person is confined to bed and is often tube fed. Valproic acid and zonisamide are first choice anticonvulsants, and the ketogenic diet may be helpful. An autosomal-recessive genetic defect is responsible, which has been tracked down to two genes. The EPM2A gene on chromosome 6q24 was discovered in 1998 and encodes for the protein laforin. It is responsible for 80% of cases. The EPM2B gene on chromosome 6p22.3 was discovered in 2003 and encodes for the protein malin. There may be a third gene of unknown locus.

Neuronal ceroid lipofuscinoses

There are various forms of these disorders, each with their own genetic cause and geographical variation, which lead to accumulation of lipopigments (lipofuscin) in the body's tissues and are inherited in an autosomal-recessive fashion. Onset and symptoms vary with the particular form, but death usually occurs within five to fifteen years.

Type I sialidosis

This is an autosomal recessive disorder in which the body is deficient in α-neuraminidase.

External links


  1. ^ edited by (2005). Electroencephalography: basic principles, clinical applications, and related fields. Hagerstwon, MD: Lippincott Williams & Wilkins. pp. 389. ISBN 0-7817-5126-8. 
  2. ^ "Unverricht-Lundborg Disease". Retrieved 2008-01-26. 
  3. ^ Genton P (2006). "[Unverricht-Lundborg disease (PME1)"] (in French). Rev. Neurol. (Paris) 162 (8–9): 819–26. PMID 17028542. 

Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • progressive myoclonic epilepsy — (EPM) any of the group of disorders causing progressive forms of myoclonic epilepsy (q.v.); Unverricht Lundborg disease is progressive myoclonic epilepsy type 1 (EMP1), and Lafora disease is progressive myoclonic epilepsy type 2 (EMP2) …   Medical dictionary

  • Myoclonic epilepsy — Classification and external resources MeSH D004831 Myoclonic epilepsy refers to a family of epilepsies which present with myoclonus. They are divided into two main families: progressive myoclonic epilepsy juvenil …   Wikipedia

  • myoclonic epilepsy — n : epilepsy marked by myoclonic seizures: as a) juvenile myoclonic epilepsy b) lafora disease * * * myoclonus epilepsy any of a group of disorders, of varying etiologies, in which seizures (epilepsy) are accompanied by muscle contractions… …   Medical dictionary

  • Juvenile myoclonic epilepsy — Classification and external resources ICD 10 G40.3 ICD 9 345.1 …   Wikipedia

  • Myoclonic astatic epilepsy — Myoclonic astatic epilepsy, also known as Doose syndrome, is a generalized idiopathic epilepsy. Generalized means that it affects both hemispheres of the brain. Idiopathic means the reason for the seizures is unknown and is most likely hereditary …   Wikipedia

  • Epilepsy Society — The Epilepsy Society (formerly known as the National Society for Epilepsy) is the largest medical charity in the field of epilepsy in the United Kingdom, providing services for people with epilepsy for over 100 years. Based in Chalfont St Peter,… …   Wikipedia

  • Epilepsy — Epileptic redirects here. For the graphic novel, see Epileptic (graphic novel). Epilepsia redirects here. For the journal, see Epilepsia (journal). Epilepsy Classification and external resources Generalized 3 Hz spike and wave discharges in EEG …   Wikipedia

  • Progressive muscular atrophy — Classification and external resources ICD 9 335.21 DiseasesDB 29149 …   Wikipedia

  • Epilepsy — (seizure disorder): When nerve cells in the brain fire electrical impulses at a rate of up to four times higher than normal, this causes a sort of electrical storm in the brain, known as a seizure. A pattern of repeated seizures is referred to as …   Medical dictionary

  • Temporal lobe epilepsy — Classification and external resources Lobe of the brain ICD 10 G40 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”