Somatosensory evoked potential studies in internal capsule and corona radiata infarction

To document the somatosensory evoked potential (SEP) changes in capsular and corona radiata infarction and correlate these with clinical and radiological findings, 15 patients with corona radiata and 16 with internal capsular infarction were studied. The mean age of the patients was 55 years (range 26-80), and 6 of them were female. In the patients with corona radiata infarction, median N9-N20 conduction time was abnormal in 4 cases, which correlated with sensory abnormalities in 1. In 3 of these patients, infarction was located in the anterior two-thirds and in 1 there was total corona radiata infarction. The amplitude of N20 potential on the affected side was reduced in 1 patient. In the capsular infarction group, N9-N20 conduction time was abnormal in 1 patient only who had total involvement of the posterior limb of the internal capsule. The amplitude of N20 was reduced in another patient. There were 4 patients who had abnormal sensory findings, but their SEPs were normal. At 3 months, the SEP changes remained stable in all of the patients who were followed up. The SEP changes did not correlate with changes in sensation or 3-month outcome as assessed by the Barthel index score. The lack of clinicoradiological and SEP correlation may be owing to variation on the organisation of sensory pathways in the corona radiata and internal capsule.