The Relation of Somatosensory Evoked potentials to central Post-stroke Pain

Objective: To find out the clinical features of central post stroke pain (CPSP) and how somatosensory evoked potentials (SEPs) are affected in patients with CPSP. Method: One hundred and one patients with stroke who showed normal results in nerve conduction study, were enrolled. SEPs were evoked by electrical stimulation of the median and tibial nerves. The results of the SEPs in the CPSP group were compared with those in the non-CPSP group. Brain SPECT (single photon emission computed tomography) was examined and thalamic involvement in SPECT was compared between the groups. Results: Seventeen patients met the diagnostic criteria of CPSP. Nine patients showed normal findings in SEP. Abnormal findings in SEP were not related to the development of CPSP, but those who showed no response in SEP had significantly higher chance of developing CPSP. Thalamic involvement in SPECT was found in thirteen patients with CPSP, but was not related to the development of CPSP. Conclusion: Stroke patients who showed severe abnormality in SEP seem to be more likely to have CPSP. Therefore, SEP is thought to be helpful in the prediction of CPSP.