The relationship between electrodiagnostic findings and patient symptoms and function in carpal tunnel syndrome

OBJECTIVE: To examine whether, in patients with carpal tunnel syndrome (CTS), electrodiagnostic study findings were associated with patient symptom severity and functional limitations after controlling for potentially confounding variables including depression, somatization, and pain-related catastrophizing. DESIGN: Cross-sectional design including data from 2 ongoing CTS studies. SETTING: Patients enrolled from hospitals and clinics in Washington State between October 2002 and February 2006. PARTICIPANTS: Adults with CTS (N=215) (based on symptoms and abnormal electrodiagnostic findings) were analyzed. Exclusion criteria were any mass, tumor, severe trauma, or deformity in the hand or wrist, radiculopathy, polyneuropathy, pregnancy, lactation, or severe CTS. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Carpal Tunnel Syndrome Assessment Questionnaire (CTSAQ) functional status scale assessed the ability to perform 9 common hand-related tasks. The CTSAQ symptom severity scale included 11 items that assess pain, numbness, and weakness. Patients also rated their average hand and wrist pain in the last month. RESULTS: With and without controlling for patient characteristics, including age, sex, body mass index, symptom duration, depression, somatization, and pain-related catastrophizing, there were no statistically significant relationships between the electrodiagnostic findings and patient functional status and symptom severity. CONCLUSIONS: Electrodiagnostic findings and patient CTS-related symptoms and function appear to be independent measures. Clinicians and researchers interested in CTS outcomes need to assess both.