Use of nerve conduction studies and the pressure-specified sensory device in the diagnosis of carpal tunnel syndrome.

Sixty-nine patients with signs of carpal tunnel syndrome (CTS) underwent nerve conduction studies (NCS) and testing with the Pressure-Specified Sensory Device (PSSD). A total of 102 tests were performed (28 bilateral). Twenty patients underwent a carpal tunnel release and were retested after 4 to 6 months. The Symptom Severity Score (SSS) was calculated before and after surgery. A control group of 20 hands in 10 asymptomatic volunteers underwent identical testing. The NCS sensitivity was 87% with a specificity of 90% whereas the PSSD sensitivity was 81% with a specificity of 65%. The combined sensitivity of the two tests was 93%. In the operative group the SSS improved from a mean of 3.34 pre-operatively to 1.95 postoperatively. The NCS improved in 19/21 hands whereas the PSSD improved in 16/19 hands. The non-invasive SSS and PSSD can increase the diagnostic yield in CTS, especially when the NCS are normal.