Sixteen patients exhibited pseudoperiodic lateralized paroxysmal discharges (PLPDs). Typically, PLPDs repeated every one to two seconds and consisted of moderate- to high-amplitude, sharp, biphasic or triphasic discharges over a large area of one cerebral hemisphere. Although for a short interval the periodicity was constant, some variation in the repetition rate was the rule rather than the exception. In the intervals between PLPDs, background activity consisted of low-voltage, irregular theta activity mixed with fast rhythms but little or no alpha rhythms. In a repeat study after a few days, PLPDs tended to disappear or be succeeded by random focal spike or sharp-wave discharges. Fifteen of the 16 patients had varying degrees of altered consciousness at the time the EEG showed PLPDs. Thirteen patients had seizures, usually of a focal motor type. About two-thirds of the patients also had focal neurological deficits. An acute cerebral lesion seemingly accounted for the development of focal seizures and PLPDs. Six patients had acute thrombotic or embolic infarctions, and 2 had sickle cell disease with multiple cerebral infarctions due to intravascular sickling. One patient suffered from neurosyphilis and another had acute necrotizing encephalitis. In the remaining 6 patients, clinical findings suggested a recent cerebrovascular accident of the ischemic type. Most patients recovered with cessation of seizures after a few days to a week or two.
ASJC Scopus subject areas
- Clinical Neurology