Improved diagnosis of Carpal tunnel syndrome using amplitude difference between m. Abductor pollicis brevis and m. Pronator quadratus?

Sammanfattning: The purpose of this study was to investigate the difference in amplitude between M-response from m. Abductor pollicis brevis/m. Pronator quadratus and m. Abductor pollicis brevis/m. Abductor digiti minimi on patients with carpal tunnel syndrome, compared with control subjects. We wanted to see if m. Pronator quadratus is a better alternative than m. Abductor digiti minimi as comparison with m. Abductor pollicis brevis on patients with carpal tunnel syndrome. Nerve conduction studies were performed on 20 patients with carpal tunnel syndrome and on 31 healthy subjects. The test-retest result shows that this method was reproducible. The amplitude difference of m. Abductor pollicis brevis-m. Abductor digiti minimi, for the patients, was 1,5mV lower and the amplitude for m. Abductor pollicis brevis-m. Pronator quadratus was 2mV lower than for healthy subjects. Two of the patients were outside the 2SD for the m. Abductor pollicis brevis-m. Pronator quadratus difference but not on the m. Abductor pollicis brevis-m. Abductor digiti minimi. This may indicate that m. Pronator quadratus was better than m. Abductor digiti minimi in the comparison with the m. Abductor pollicis brevis amplitude.