Increased Diagnostic Yield of Early and Mild Carpal Tunnel Syndrome by Using Median-to-Ulnar Comparative Study

Background: Carpal Tunnel Syndrome (CTS) is the most common focal entrapment neuropathy caused by median nerve compression in the carpal tunnel. Clinically there is pain and paresthesia in the distribution of median nerve. Electrodiagnostic (EDX) studies are gold standard means of confirming the diagnosis. Early and mild CTS cause discomfort for patients but remains undiagnosed during routine motor and sensory nerve conduction studies. Objective: To evaluate the most sensitive electro diagnostic method i.e. comparative Median-to-Ulnar motor and sensory study, for diagnosis of early and mild CTS. Methods: Comparative analytical cross sectional study was done in Department of Neurology, Mayo hospital Lahore, from June to November 2022. We included 50 clinically symptomatic CTS patients of both genders of age between 20 and 55 years in our study and comparison was done with healthy control. Patients were symptomatic with normal conventional EMG/NCS. Patients having moderate to severe or incidental CTS and patients with underlying polyneuropathy and radiculopathy were excluded. For comparative analysis student’s t test (two tailed) was used. EDX findings were noted in the predesigned proforma along with history & demographic variables. Results: Out of 50 patients, females were 35 and males were 15, so female: male was 7:3. Mean age of the patient group was 37.24 ± 2.27 years. Sensitivity was highest for the median-versus-ulnar palmar mixed study (80.0%), followed by median-versus-ulnar digit 4 sensory latency (32.0%) and median distal sensory latency (14.0%). Median distal motor latency had the lowest sensitivity (10.0%). Conclusion: Conventional nerve conduction study methods i.e. median distal motor latency and median distal sensory latency tests are less sensitive in diagnosing early and mild CTS. Highly sensitive electrophysiological tests including median-versus-ulnar palmar mixed study and median-versus-ulnar digit 4 sensory study should be incorporated in the evaluation of patients with early and mild CTS to increase the diagnostic yield of CTS.