The author responds to The Continuing Challenge of Evaluating Carpal Tunnel Syndrome Impairment in the March/April 2000 issue of The Guides Newsletter. Carpal Tunnel Syndrome (CTS) is a clinical diagnosis based on the patient's history and objective findings on examination. Patients present with dull, aching discomfort of the hand, forearm, or upper arm; paresthesias and tingling of the hand; subjective weakness or numbness; and, occasionally, autonomic changes. Nerve conduction velocity studies are highly accurate in documenting median nerve entrapment at the level of the wrists, but this is an anatomic finding and does not mean that the entrapment produces any symptoms. An electrophysiologic study does not predict if or when the median nerve entrapment will become symptomatic, which is based on the patient's history. Electromyography (EMG) and nerve conduction velocity (NCV) studies do not help distinguish among the many etiologies of CTS. EMG/NCV testing can provide significant, highly accurate information regarding the physiologic function of the median nerve at the level of the wrist, but physicians must know how to interpret this information in the clinical setting. [The Editor responds: Several traditional findings of CTS have little or no diagnostic value, and electrodiagnosis is the diagnostic test of choice, although reported sensitivities range from 49% to 84% with specificities of 95% to 97%.]

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