Morphological and electrophysiological evaluation of median and ulnar nerve in complex regional pain syndrome type 1.

OBJECTIVE

Complex regional pain syndrome (CRPS) can be distinguished as type I without and type II with electrophysiological evidence of major nerve lesion. The pathophysiology of both subgroups is still under investigation. The aim of this research is to demonstrate the nerve morphology and electrophysiology in CRPS type I patients.

MATERIALS AND METHODS

Bilateral median and ulnar nerve cross-sectional areas were evaluated with ultrasound and also median and ulnar nerve conduction studies of both hands were performed. Cross-sectional areas of median and ulnar nerves and nerve conduction studies in healthy controls were also obtained and compared with the patients.

RESULTS

Twenty-five male patients and 11 healthy male controls were enrolled in the study. The mean age of the patients was 24.08 ± 5.50 years and controls was 23.18 ± 5.09 (p > 0.05). Compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes of the diseased side were found significantly lower than the healthy side (p < 0.05). Both median and ulnar nerve distal motor latency values were significantly higher in the patient group (p < 0.05). There was no significant difference in the median and ulnar nerve cross-sectional area when compared with the opposite extremity and healthy volunteers.

CONCLUSION

The lower SNAP and CMAP amplitudes of the median and ulnar nerves compared to the healthy side and the prolongation of the affected side median and ulnar nerve distal motor latencies of the affected individuals may indicate axonal involvement in patients with CRPS type 1. Decreased CMAP amplitudes may also indicate muscle atrophy due to a decrease in the number of functional motor units.