Waking electroencephalograms in the blood-lymph and encephalitic stages of gambian trypanosomiasis.

Waking electroencephalograms (EEG) were recorded from 48 patients infected with Trypanosoma gambiense. The EEG of the 10 patients with blood-lymph involvement were indistinguishable from those of healthy controls but recordings from the 38 patients with the encephalitic phase of the disease showed three unusual profiles. One profile type, apparently indicative of early cerebral impairment, had a sustained low-voltage background similar to that seen during light sleep. A second profile type, seen in cases with acute cerebral involvement but without focal seizures, showed paroxystic waves. The third unusual EEG pattern was of various types of delta wave (similar to those seen in demyelinating encephalitis) and rapid, intermittent high-voltage delta bursts between periods of lower-voltage delta activity (as often seen in meningo-encephalitis); all types of delta wave were of higher voltage than the spike and wave complexes. Although no definite correlation has been established between the severity of the disease, the results of clinical tests, and waking EEG patterns, it appears that the three types of EEG profile are indicative of the degree of cerebral involvement.