Advanced Carpal Tunnel Syndrome is Almost Always Bilateral: Implications for Electrodiagnostic Practice

Background and/or Objectives: To determine whether more advanced Carpal Tunnel Syndrome (CTS) in the more involved wrist predicts an increased probability of CTS in the contralateral wrist.

Design: Retrospective review of nerve conduction study database.

Setting : Academic Physical Medicine and Rehabilitation Department Electrodiagnostic laboratory.

Participants : 226 patients with complete bilateral upper extremity nerve conduction testing with unilateral or bilateral CTS.

Interventions: N/A

Main Outcome Measures: Percentage of patients with bilateral CTS with mild to average CTS on the more affected side, compared to those with those with greater than average severity.

Results: Among 104 patients with Median sensory latency (MSL)≤4.5 msecs (the median value), 68.3% (95% CI: 59-76%) had CTs on the contralateral side. In contrast, among 92 patients with MSL>4.5 msecs, 95.7% (CI: 89-98%) had CTS on the contralateral side. Similarly, among 115 patients with Median motor distal latency (MMDL) ≤5.0 msecs (the median), 68.7% had contralateral CTS (CI: 60-76%). In comparison, among 105 patients with MMDL>5.0 msecs, 97.1% had contralateral CTS (CI: 92-99%). The differences in contralateral CTS prevalence between those with mild to average and greater than average Median sensory latency were quite significant for both sensory and motor testing (both p<.001).

Conclusions: Patients with greater than average CTS severity on one side have an extremely high incidence of CTS on the contralateral side. All CTS patients with MSL>4.5 msecs or MMLD>5.0 msecs should undergo bilateral testing.