Mitochondria are components of cells that are involved in metabolism and enzyme production. They are the energy factories of our cells. They also contain genetic material. Particular abnormalities in the mitochondrial genes are often associated with epileptic disorders. The metabolic disorders involving the mitochondria affect different parts of the body, including muscle and brain.

Mitochondria are inherited through the mother. Two mitochondrial disorders are often associated with epileptic seizures:

MELAS

One is MELAS: mitochondrial myopathy, encephalopathy, lactic acidosis (meaning too much lactic acid in the blood), and strokelike episodes. MELAS can lead to strokelike episodes at a young age (usually before 40), seizures, dementia, headaches, vomiting, unsteadiness, and ill effects from exercise. Persons with MELAS can have both generalized seizures (including myoclonic and tonic-clonic) and partial seizures.

MERRF

The other mitochondrial disorder with epileptic seizures is MERRF: myoclonic epilepsy with ragged red muscle fibers). MERRF is one of the progressive myoclonic epilepsies. It can also be associated with hearing loss, unsteadiness, dementia, and ill effects from exercise. In addition to myoclonic seizures, patients with MERRF often have generalized tonic-clonic seizures that can be controlled with standard medications.

There are other mitochondrial disorders that do not fit clearly into the MELAS or MERRF syndromes but which can cause epilepsy and additional neurologic problems.

Topic Editor: Steven C. Schachter, M.D.
Last Reviewed:12/15/06