Electrophysiological Phalen’s provocation test in carpal tunnel syndrome

Abstract

Objective Routine nerve conduction studies (NCS) are considered the golden standard for the objective diagnosis of clinically detectable carpal tunnel syndrome (CTS); however, fallacies can still befall. Clinically, phalen’s provocation test has proven reliability for screening CTS, yet, its use during NCS is still to be assessed. Thus, we aim to evaluate the role of our newly proposed electrophysiological Phalen’s provocation test (EPPT) in the diagnostic work-up of CTS. Patients and Methods One-hundred clinically suspected CTS hands and forty healthy hands were included in this study. Routine median motor and sensory NCSs were performed twice; once before and secondly, after provocation with wrist in 90 degrees flexion for 60 seconds (EPPT). Results All patients showed significantly delayed median distal motor and sensory latencies than controls (P<0.001). After EPPT, the percentage of change in median nerve distal sensory latency (MDSL) only was significantly higher in patients compared to controls (P<0.05). Moreover, the increased MDSL after provocation was more significant among clinically phalen’s positive hands (P=0.001). In addition, a cut off value of 3.2 msec could detect median sensory neuropathy at the thumb after provocation and it showed better performance than distal sensory recording before provocation. Conclusion EPPT might be promising for early detection of sensory neuropathic changes in CTS.

Keywords

• carpal tunnel
• electrodiagnosis
• Phalen’s test
• provocative tests