Correlation between clinical and electrophysiological findings of carpal tunnel syndrome

Abstract

Background: Carpal tunnel syndrome (CTS) is the commonest condition referred for neurophysiological assessment. Some believe that neurophysiological confirmation is not required prior to decompression if the diagnosis seems definite on clinical grounds alone. Aim: To objectively assess correlation between the clinical and neurophysiological diagnosis in CTS. Method: Two hundred and three patients with suspected CTS were studied. A clinical score based on the sensory symptoms, ranging from +3 to 2 (higher the score, carpal tunnel syndrome is more likely) and presence or absence of Tinel’s and Phalen’ sign was completed prior to electrodiagnostic tests. For reasons including simplicity and ease of performance motor signs were not included. Electrodiagnostic grading (Normal, Mild, Moderate or Severe) was then compared with the clinical score. Results: Clinical scores of 0, 1, 2, and 3 were obtained in 34.9%, 42.1%, 19.0% and 4.0% hands, respectively. The frequency of electrophysiological severity grading obtained is as follows: (N, Normal; Mi, Mild; Mod, Moderate; S, Severe); Score 0: N (63%), Mi (16%), Mod (14%) and S (6%); Score 1: N (42%), Mi (16%), Mod (21%) and S (21%); Score 2: N (23%), Mi (13%), Mod (36%) and S (27%); Score 3: N (19%), Mi (06%) Mod (38%) and S (38%). Tinel’s was false-positive in 18/40 (45%) ‘‘Normal’’ hands, and false-negative in 8/15 (53%) hands with proven CTS. Phalen’s was false positive in 16/46 (33%) and false negative in 3/7 (43%). Discussion: Although a clear trend is observed with objective sensory scoring the findings show 36% false positives with score ‘‘0’’ and 19% false negatives with score 3. The degree of false positives and false negatives for Tinel’s and Phalen’s testing are also unacceptably high. Conclusion: Sensory symptoms and clinical diagnostic tests alone are unreliable predictors in the diagnosis of CTS and should not lead to unnecessary surgical decompressions or unjustified preclusion for those who deserve surgery.