Brainstem auditory evoked potentials and somatosensory evoked potentials in cerebral malaria--a prognostic significance.

ABSTRACT

OBJECTIVE: To study the changes in brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SSEPs) in cerebral malaria and to see their prognostic significance. METHODS: BAEPs and right median nerve SSEPs were performed in 25 adult patients of strictly defined cerebral malaria in acute stage in a semi-dark, sound proof chamber on four channel computerized multi-basis OTE-Biomedica machine in department of neurology, SP Medical College, Bikaner. RESULTS: The abnormalities of BAEPs were delayed peak latency of wave III in 13/25 (52%) and wave V in 20/25 (80%) patients and delayed interpeak latencies (IPLs) of wave I-III in 9/25 (36%), wave I-V in 15/25 (60%) and wave III-V in 12/25 (48%) patients. In SSEPs delayed N20 was seen in 11/25 (44%); delayed IPLs of N13-N20 (central conduction time; CCT) in 12/25 (48%) patients. Distorted N20 was recorded in 12/25 (48%) patients. Both N13-N20 IPLs in SSEPs and wave III-V IPLs in BAEPs were delayed in five patients and all of them expired. Delayed N13-N20 with normal III-V IPLs was present in seven patients and two of them died, whereas delayed III-V IPLs with normal N13-N20 was present in seven patients, and one of them expired. In remaining six patients both the parameters were normal and one of them died. CONCLUSIONS: The values of BAEPs and SSEPs were abnormal in patients of cerebral malaria and it was observed that BAEPs/SSEPs alone was not useful for predicting the outcome of coma, whereas abnormalities in both was predictive of worst prognosis. The changes in evoked potentials (BAEPs and SSEPs) could be due to either interruption of conduction in central pathways because of structural changes due to petechial hemorrhages and malarial granuloma at multiple levels in the brain including brainstem or due to metabolic abnormalities.