Median nerve somatosensory evoked potentials in patients with lacunar and other small subcortical strokes.

We recorded median nerve somatosensory evoked potentials (SSEPs) in 42 patients with small subcortical strokes associated with lacunar syndromes. Seventeen patients had abnormal SSEPs. The P22 component was most often affected; changes in N20 and N18 were less common. Four patients with pure motor strokes (PMS) had abnormal SSEPs. Abnormalities of P22 correlated best with motor findings; those of N20 with sensory signs and symptoms. Similar SSEP abnormalities were produced by lesions in various locations. P22 and N20 abnormalities occurred independently and together. We conclude: (1) abnormal SSEPs are common in patients with small subcortical strokes associated with lacunar syndromes, including pure motor stroke; (2) P22 and N20 have separate cortical generators; and (3) P22 may be generated within sensory pathways which are adjacent to or influenced by motor pathways.