Objective: A prospective, observational study assessed median and ulnar nerve conduction during pregnancy, to identify the optimum test for differentiating physiological effects of pregnancy from pathological carpal tunnel syndrome (CTS).
Methods: Pregnant women (n=18) and age- and parity-matched non-pregnant controls (n=13) were recruited. Symptomatic and neurophysiological evaluations were performed. Median and ulnar nerve latencies and intrapalmar latency (difference between median and ulnar nerve latencies) were computed.
Results: Median nerve distal latency is more prolonged in pregnant women compared with non-pregnant controls. Median nerve latency is more prolonged in pregnant women with symptoms of CTS than in asymptomatic women. The difference between median and ulnar nerve conduction (normal <0.2 ms) discriminates well between symptomatic and asymptomatic pregnant women.
Conclusions: Intrapalmar latency is proposed as a useful diagnostic test for classification of carpal tunnel syndrome during pregnancy.