Epilepsia partialis continua

Epilepsia partialis continua is a rare type of brain disorder in which a patient experiences recurrent motor epileptic seizures that are focal (hands and face), and recur every few seconds or minutes for extended periods (days or years).

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Presentation

During these seizures, there is repetitive focal myoclonus or Jacksonian march. After a seizure has subsided, Todd's phenomenon may be observed, which includes transient unilateral weakness.

Causes

There are numerous causes for this kind of seizure and they differ depending somewhat on the age at which the seizures begin. Epilepsy most often occurs at the extremes of life – in childhood or in very old age – but can develop at any time throughout one's life. Epilepsy really begins at conception or the completion of one's genome, because from then on all the things that affect the brain may have the potential to cause seizure to begin.

Although these seizures are usually due to large, acute brain lesions resulting from strokes in adults and focal cortical inflammatory processes in children (Rasmussen's encephalitis), possibly caused by chronic viral infections or autoimmune processes. They are very therapy-resistant, and the primary therapeutic goal is to stop secondary generalization. There are also many other reasons why these seizures occur. For example, they could be due to genetics, infections, problems with brain development. Commonly the cause is unknown.

Genetic background determines such features as height, eye color, and potential to develop certain diseases like diabetes, but it also determines all the chemicals and structures that make up the brain, therefore playing a role in epilepsia partialis continua. The chemicals and structures that make up the brain have similarities across different people, but they vary in certain enzymes and receptors. These variations are not usually enough to cause a problem, but occasionally they do. For example, if a person has a mutation in a gene that creates the sodium channel (a part of the neuron required for firing) it makes it easier for neuronal firing to get out of control.

An infection of the brain (encephalitis) can also be a contributing factor. Although this sort of infection is uncommon it can be due to a virus, bacterium, or (very rarely) fungus. If a seizure happens during the infection itself, the person most likely doesn't have epilepsy, but has "symptomatic seizures" or seizures occurring because of a known injury to the brain. Once the infection is stopped the seizures will stop. Another more common infection is "meningitis", infection of the membranes surrounding the brain. Since this infection does not directly involve the brain it might not appear as a possible cause of epilepsy, but has been shown that meningitis can cause epilepsy, which would give rise to the possibility of developing epilepsy partialis continua. These infections are most likely to result in epilepsy when they occur at an early age.

Problems with brain development can also be a factor. The brain undergoes a complicated process during development in which neurons are born and must travel to the surface of the brain. Here they wind up carefully placed in six distinct layers of the cerebral cortex. Throughout the brain the placement of these neurons are normally quite precise. If this system doesn't work exactly right, neurons can develop outside their appropriate areas. If this happens then the firing or circuitry of the brain is not right, and an abnormal, epileptic circuit can result.