Somatosensory evoked potentials in patients with thalamic lesions.

Somatosensory evoked potentials (SEPs) were recorded in 20 patients with thalamic lesions confirmed by CT (10 with infarction, 10 with haemorrhage). The changes in SEP configuration are discussed in their relationship to clinical symptoms. Four types of SEP abnormality produced by thalamic lesion are distinguished: (1) "FF" type, (2) "N20/P23 dissociation" type, (3) "N18/N20 false shift" type, and (4) "reduced early component" type. It was shown that clinically similar lesions might produce different SEP patterns.