Electrophysiologic Characteristics of Chronic Complex Regional Pain Syndrome in Post-stroke Patients

J Korean Assoc EMG Electrodiagn Med 2004;6(2):170-176.
Published online May 10, 2004.

Abstract

Objective: A criticism about the cause related to the central and peripheral nervous system are persisting in the complex regional pain syndrome (CRPS) which occurred after stroke. The purpose of this study is to find out the possible factors leading to serious complications such as profound atrophy and persistent pain in post-stroke patient with chronic CRPS through electrophysiologic evaluation. Method: Ten patients who reached the chronic state after development of CRPS and 12 patient who did not experience CRPS (non-CRPS) were included in this study. All subjects underwent nerve conduction and electromyographic examination in both upper limbs. None of them had peripheral nerve disorders including carpal tunnel syndrome and brachial plexus damage and they had no definite difference in duration of illness, muscle power, Brunnstrom stage, and the degree of spasticity between both groups. The ratio of difference in amplitude and area of compound muscle action potentials (CMAP) of median and ulnar nerve in both hands and amplitude of median sensory nerve action potentials (SNAP) were examined on nerve conduction study. Abnormal spontaneous activity (ASA) in abductor pollicis brevis, abductor digiti quinti, extensor carpi radialis, biceps brachii, and paraspinal muscles were also examined. Results: Amplitude of CMAP in hemiplegic hand in CRPS was markedly decreased (47.3±17.8% of unaffected hand) compared to decrease of non-CRPS group (72.8±14.2% of unaffected hand). The similar findings were detected in area of CMAP. ASAs obtained at hand muscles of CRPS groups were significantly more than those of non-CRPS group. However, there was no definite difference in SNAP amplitude of CRPS group at both sides. Conclusion: Remarkable decrease of the CMAP in chronic, atrophic CRPS is considered as a result from neurogenic change besides a non-neurogenic muscle atrophy like disuse. Our results support that the main change depends on motoneuron cell level considering the electrophysiologic characteristics.

Key Words: Stroke, Complex regional pain syndrome, Electromyography