مرکز منطقه ای اطلاع رساني علوم و فناوري - Short-distance sensory stimulation technique in the early diagnosis of carpal tunnel syndrome

Abstract :

Aim. Normal results obtained from nerve conduction studies do not exclude the diagnosis of carpal tunnel syndrome (CTS). We intended to increase diagnostic sensitivity of nerve conduction studies in the early stage CTS by stimulating shorter palm-wrist segment, and excluding distal region outside the entrapment site of the median nerve which is unaffected from pathologic changes. Methods. In this prospective study, 41 patients (66 hands) with clinically diagnosed CTS with normal conventional electrophysiologic examinations were stimulated with electrodes placed at 8, 7, 6, 5, 4 cm from the distal wrist crease (DWC) on the palm-wrist segment, and the conduction velocities, latencies, and the differential latencies (conduction delay) were compared with those of 34 patients (68 hands) in the control group. Results. Conduction delay recorded between 4-5, 5-6, 6-7, 7-8 cm. away from DWC of both groups was statistically insignificant (p 0.1), while the conduction velocities and the latencies obtained from the electrodes placed on 4, 5, 6, 7, and 8 cm away from DWC differed statistically significantly between two groups (p 0.001). Conclusion. In electrophysiologic examinations performed to confirm the diagnosis of CTS, assessment of shorter palm-wrist segment, and stimulation of a predetermined location 4 or 5 cm distal to DWC are sufficient to detect a slight and localized conduction delay in the carpal tunnel. This method eliminated slowing-down effect of distal segment on normal nerve conduction velocities yielding higher degrees of (up to 92.4 %) sensitivity.