Evoked potential studies in thalamic hemorrhage.

Due to paucity of a comprehensive study on somatosensory and motor evoked potentials in thalamic hemorrhage, the present study has been undertaken. Clinical examination, motor evoked potential (MEP) and median somatosensory evoked potential (SEP) studies were performed on 22 consecutive patients with CT-proven thalamic hemorrhage. The clinical and evoked potential studies were carried out on admission and repeated at the end of 3 months. The hematomas were classified as type A (with posterolateral extension) and type B (without posterolateral extension). The hematomas were of type A and type B in 11 patients each. The patients with type A hematomas had persistent inexcitability of motor pathways and SEPs were unrecordable. In type B, MEP was not recordable in three, prolonged in five and normal in three patients; in all these patients, MEP returned to normal in the follow-up study. The cortical potentials of median SEP were normal in four and unrecordable in five patients with type B hematoma. In the follow-up study, SEPs became recordable in all, although central sensory conduction time (CSCT) was prolonged in three patients. MEP and SEPs were related to the respective motor and sensory dysfunction and to posterolateral extension of hematoma. Patients with type A hemorrhage had worse prognosis compared to type B, emphasising the importance of posterolateral extension. A persistently unrecordable MEP and SEP in thalamic hemorrhage suggests a posterolateral extension which predicts a poor outcome.