Which clinical history findings are characteristic of epilepsy partialis continua (EPC)?

Updated: Feb 13, 2018
  • Author: Julie L Roth, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Answer

Focal SE of the motor cortex, known as epilepsy partialis continua, may occur in various contexts. Some authors subdivide epilepsy partialis continua into type I (nonprogressive) and type II (progressive).

Type I epilepsy partialis continua features intermittent, semirhythmic, and involuntary twitching involving a discrete subset of muscles. Although any group of muscles may exhibit these features, it is observed most commonly in the face and ipsilateral distal hand musculature. Myoclonus of this variety may evolve into a partial or generalized convulsion.

Many other attendant historical symptoms may be present, depending on the nature of the focal insult. These symptoms heavily influence the ultimate clinical outcome in this setting.

Type I classically occurs after acute insults to the sensorimotor cortex. These insults may be infectious (eg, Russian spring-summer encephalitis), neoplastic, immune mediated, structural, traumatic, metabolic, or vascular.

Nonketotic hyperglycemic diabetes, particularly in association with hyponatremia, occasionally causes epilepsy partialis continua, often in patients with a preexisting focal CNS lesion (eg, stroke). Epilepsy partialis continua may be a feature of mitochondrial disorders such as mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) and myoclonic epilepsy with ragged-red fiber disease (MERRF). [51]

The syndrome of childhood epilepsy with rolandic spikes (ie, benign rolandic epilepsy) may occasionally involve epilepsy partialis continua. Patients have prolonged speech arrest, facial twitching, and sialorrhea, in episodes that are clinically similar to those of the syndrome, though more prolonged than usual.

Type II epilepsy partialis continua, the progressive form, is usually linked with Rasmussen encephalitis, a unique and rare epilepsy syndrome that predominantly affects children. Children with Rasmussen encephalitis historically had a variety of seizures, including simple and complex partial seizures with occasional secondary generalization; epilepsy partialis continua is yet another seizure type these patients have.

In addition to seizures, patients have gradual loss of unilateral function, and in parallel, imaging studies show focal or unilateral hemispheric atrophy. The typical age of onset is 5-10 years, though the range is broad, and rare cases are reported in adults.

Intellectual skills may become impaired to various degrees, and language skills may be affected, depending on the age of onset and the laterality of the process. Pathologic findings include cortical atrophy, reactive gliosis including microglial nodules, and some perivascular lymphocytosis, occasionally with necrotic features.

Although the subject of intense scrutiny, the etiology of Rasmussen encephalitis remains unknown. Numerous attempts to identify a consistent viral pathogen have failed. An autoimmune hypothesis based on a glutamate receptor subtype has been suggested, but this remains unproven in humans.


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