STUDY OF MEDIAN MOTOR VERSUS SENSORY CONDUCTION STUDIES IN THE DIAGNOSIS OF CARPAL TUNNEL SYNDROME

Dr.Ch.Ramakrishna Rao; Dr.W.Maruthi

Volume : V, Issue : X, October - 2015

STUDY OF MEDIAN MOTOR VERSUS SENSORY CONDUCTION STUDIES IN THE DIAGNOSIS OF CARPAL TUNNEL SYNDROME

Dr. Ch. Ramakrishna Rao, Dr. W. Maruthi

Abstract :

Introduction. Carpal Tunnel Syndrome is defined as a constellation of symptoms and signs due to median nerve compression in the carpal canal. The clinical presentations of Carpal Tunnel Syndrome are varied and the most common are acroparesthesias of median innervated fingers followed by thenar atrophy without sensory symptoms, acute carpal tunnel syndrome, and atypical descriptions of nerve compression symptoms. As histopathological proof of local median nerve disease is unavailable as a diagnostic source, the diagnosis of Carpal Tunnel Syndrome is essentially clinical, supported by electrodiagnosis.Aim. To study the sensitivity of motor versus sensory conduction studies in the diagnosis of carpal tunnel syndrome. Methods. The study included 55 consecutive patients with symptoms suggestive of carpal tunnel syndrome (83 symptomatic hands) who attended the Neurology outpatient department. Electrodiagnostic studies were carried out by surface recording and stimulation. Recording electrodes were disk electrodes made of silver for motor nerve studies and orthodromic sensory studies and Velcro ring electrodes for the antidromic sensory studies. Electro diagnosis is performed with motor nerve conduction studies and sensory nerve conduction studies and their relative sensitivities are studied. The parameters studied are 1. Median Motor Distal Latency (Median DML), 2. Wrist–Palm Median Motor Conduction Velocity (W–P Median MCV), 4. Median Antidromic Sensory Distal Latency (Median DSL) and 4. Median P–W (80 mm segment) orthodromic SCV .Results. The test results were compared with normative data. Among the 83 symptomatic hands, 76 (91.56%) were found to have at least one abnormal electrophysiologic study and 7 (8.43%) were found to have normal electrophysiologic results for all parameters tested. The parameter of Wrist–Palm median motor conduction velocity has emerged as the most sensitive test among other electro diagnostic parameters.Conclusions.The motor conduction studies can be equally sensitive including the DML and W–P MNCV. The study of W–P MNCV is no more difficult as made out in earlier studies, with improvement in technique. Even in the presence of dominant sensory symptoms and signs and minimal motor findings, the abnorrmalities of the motor conduction studies can be significant and diagnostic. In the patient with suspected carpal tunnel syndrome, in whom the DML and DSL were within normal limits, the study of W–P motor conductions will increase the diagnostic yield.