Absent median somatosensory evoked potential is a predictor of type I complex regional pain syndrome after stroke.

PURPOSE: The objective was to determine whether the abnormal finding of somatosensory evoked potentials (SEPs) associated with the development of type I complex regional pain syndrome (CRPS) after stroke.

METHODS: This was a retrospective study conducted from January, 2003, to December, 2007. Seventy patients were confirmed as CRPS type I, and one hundred and eighty-two patients were assigned to the control group. The initial clinical data were reviewed including age, gender, main type of stroke, lateralization and location of the lesion, presence of glenohumeral subluxation, and the development of CRPS. Somatosensory evoked potentials tests (SEP) in median nerve (N20) and posterior tibial nerve (P37) were performed.

RESULTS: CRPS groups revealed significantly higher incidence of the absent and abnormal hemiplegic median SEP, hemorrhagic stroke, and glenohumeral subluxation (GHS). Binary logistic regression analysis indicated that GHS (exp.(B)=4.083, p<0.01) with the absent median SEP (exp.(B)=3.246, p<0.01) were significant independent predictors of CRPS onset.

CONCLUSIONS: In conclusion, GHS and the absent median SEP at sub-acute phase of stroke were primary predictors of the onset of post-stoke CRPS. Implications for Rehabilitation Recent investigations have suggested that autonomic, motor and somatosensory abnormalities of CRPS are impairments involving the central nervous system (CNS) as well as the peripheral neurogenic inflammatory process. However, the understanding of the pathophysiology of CRPS is still far from complete. The absence of SEP at the sub-acute stage of stroke correlated with the onset of post-stroke CRPS type I. The SEP evaluation at the sub-acute period after stroke might be generally used for predicting the concomitant development of post-stroke CRPS type I as well as functional recovery after stroke.