Background: The most common entrapment neuropathy seen in electrodiagnostic (EDX) laboratories is carpal tunnel syndrome (CTS). The diagnostic value of EDX with regard to CTS is well-established, but EDX's predictive value is unclear. To date, only one study has attempted to establish a relationship between EDX findings and a patient's clinical status pre-and post-treatment, and there was no significant relationship found.

To correlate electrodiagnostic (EDX) variables and clinical severity assessment with Disabilities of Arm, Shoulder & Hand (DASH) scores and to measure change over time with corresponding change in DASH scores. Design: Prospective Single Group Cohort, Pre-Post Design. Setting: Hospital-based electrodiagnostic clinic. Participants: 41 consecutive patients consented to participate and were invited to return for repeat study. Interventions: All subjects underwent EDX study and completed DASH. Data included: median sensory, mixed and motor latencies, amplitudes, conduction velocities and needle EMG. Main Outcome Measures: Paired samples t test was performed for change in DASH score over time. Results or Clinical Course: 41 subjects (6 female) enrolled. 6 rated as severe, 23 moderate and 12 mild CTS (NS). Mean DASH score [95 % C.I.] at start: 36.4 [30.5, 42.2]; final DASH score: 35.3 [27.1, 43.5], thus no significant change (t ¼ .293, df ¼ 27, p¼ .772). 26 subjects returned for their repeat study. Initial DASH score showed significant negative correlation with age: r ¼ -0.379, p < .05), but no significant correlation with time interval between measurements: r ¼ -0.047, p ¼ .82). Principal components analysis was used to reduce the large number of EDX variables which explained 73.5% of the cumulative variance. None of the EDX variables alone or in combination gave statistically significant correlation with the change in DASH score over time. Conclusions: This prospective cohort study attempted to examine influence of electrodiagnostic parameters on the self-reported disability and outcome using the DASH instrument. Significant drop-out (2nd visit) reduced the power to detect a meaningful difference. Our results showed no significant avg. change in DASH score over the time interval between visits. DASH showed a significant negative correlation with age of subject. Individual EDX did not predict change in DASH score over time.