Progressive Myoclonic Epilepsies (PME) are a rare group of inherited neurodegenerative diseases characterized by myoclonus, resistance to treatment, and neurological deterioration.
There is no current cure for PME and treatment focuses on managing myoclonus and seizures through antiepileptic medication (AED).
[2] Symptoms often include action or stimuli induced myoclonus, seizures, neuropathy, cognitive decline, and spike and wave or no cerebral discharges.
[2] The myoclonus can be fragmented or multifocal and can be triggered by posture, actions, and external stimuli such as light, sound, and touch.
[4][5] As PME progresses neurological ability decreases and can lead to myopathy, neuropathy, cognitive decline, cerebellar ataxia, and dementia.
[4][2][3] Diagnosis of PME is based on the individual's signs and symptoms as well as failure to respond to antiepileptic drugs and therapy.
[2] Therefore, diagnosis is best made using a combination of different tools like signs and symptoms, age of onset, EEG, gene testing, enzyme measurements, and biopsy of skin and muscle.
[4] The main component setting PME apart from other forms of epilepsy is progressive deterioration and resistance to treatment.
Some antiepileptic drugs used in treatment are valproic acid, benzodiazepines, phehobarbital, piracetam, zonisamide, clonazepam, and levetiracetam.
In Lafora body disease the neurological deterioration progresses until resulting in a vegetative state and death within 10 years of diagnosis.
The wide range of symptoms including the differing EEG makes studying the effects of the AEDs difficult.
[7] Lundborg was the first to name progressive myoclonus epilepsy in 1903 due to his study of several Swedish families as well as research done by Heinrich Unverricht in 1891.
It has autosomal recessive inheritance, and is caused by a mutation in the cystatin B (EPM1) gene on chromosome 21q22.3, which was discovered in 1996.
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.
The first symptoms may include ataxia and myoclonus (unsteadiness and difficulty coordinating movements), along with generalized tonic-clonic ("grand mal") seizures.
The symptoms are progressive, and individuals with MEAK often need to use a wheelchair by their late teenage years because of movement difficulties and myoclonus.
Seizures may become less frequent in adulthood, but other neurological complications, including myoclonus, ataxia and tremor, may worsen.
[citation needed] The incidence and prevalence of PME is unknown, but there are considerable geography and ethnic variations amongst the specific genetic disorders.