Somatosensory evoked potentials over the unaffected hemisphere in patients with unilateral intracerebral hematoma

: Somatosensory evoked potentials (SEPs) recorded from the unaffected hemispheres were studied in patients of less than one month after the onset of unilateral intracerebral hematoma. We examined 66 SEPs obtained from 49 patients with putaminal hemorrhage (midline shift 0-15 mm), 38 SEPs from 25 patients with thalamic hemorrhage (midline shift 0-8 mm), and 14 SEPs from 10 patients with subcortical hemorrhage (midline shift 0-12 mm). These examinations were made after electrical stimulation of the median nerve at the wrist by using square waves of 0.2 msec in duration delivered at a rate of 3 Hz. We analyzed the first cortical potential N 20 recorded from the contralateral scalp over the unaffected hemisphere with reference on Fpz. N 20 peak latency was compared with the maximum shift of the midline structure such as in foramen of Monro or third ventricle in computed tomogram. Also with the site of the hematoma and the disturbance of consciousness. N 20 peak latency was not correlated with the degree of the midline shift in all the patients. There was abnormal prolongation of N 20 peak latency in one SEP of one patient, and disappearance of N 20 in two SEPs of two patients with putaminal hemorrhage. Abnormal prolongation of N 20 peak latency was found in 3 SEPs of 3 patients with thalamic hemorrhage. There was no disappearance of N 20 in patients with thalamic hemorrhage. There was no abnormal prolongation or disappearance of N 20 peak latency in patients with subcortical hemorrhage. In two of five patients showing stuporous state, disappearance of N 20 was found.(ABSTRACT TRUNCATED AT 250 WORDS)