Pain-Related and Electrically Stimulated Somatosensory Evoked Potentials in Patients With Stroke

Background and Purpose Pain-related somatosensory evoked potentials (SEPs) were applied to study abnormality of pain sensation in stroke, together with electrically stimulated SEPs for deep sensation. Methods We recorded pain-related SEPs after CO2 laser stimulation to the dorsum of the hand and electrically stimulated SEPs after median nerve stimulation at the wrist in 12 patients with stroke. We analyzed P340 in pain-related and parietal N20 in electrically stimulated SEPs. Results In 5 patients with a putaminal lesion, P340 was absent or its latency was delayed, and N20 was absent or reduced in amplitude. In 3 patients with a thalamic lesion, P340 and N20 showed various patterns according to the involved sites. In 4 patients with a lesion in the corona radiata, P340 and N20 were normal. Conclusions Abnormalities of P340 and N20 in the stroke location were related to impairment of the pain and vibration senses, respectively. Thus, pain-related and electrically stimulated SEPs were useful to investigate the sensory function of each structure in the central nervous system in patients with stroke.