Physicians often must evaluate patients who present with symptoms in a median nerve distribution and typically diagnose carpal tunnel syndrome (CTS), but an accurate diagnosis is critical to determine causation and to define possible impairment. CTS is a constellation of symptoms and signs that result from mononeuropathy of the median nerve in the carpal tunnel; symptoms typically include tingling and/or numbness, dysesthesias, and/or pain in the radial palm and palmar aspect of the thumb, index, middle, and perhaps ring fingers. The American Academy of Orthopaedic Surgeons suggests use of the CTS-6 scoring aid (shown in a table) as a clinical aid for diagnosing CTS. Electrodiagnostic testing, nerve conduction studies in particular, are considered the gold standard for diagnosis of CTS, but research suggests that the definitions of relevant sensory and assignment of CTS are sensitive to threshold changes from a latency of, eg, >4.4 msec vs >4.5 msec. Other factors to consider include whether there are effects from the known association between wrist ratio and CTS and assessing the benefits of neuromuscular ultrasound to diagnose CTS. Nocturnal paresthesias and paresthesias while holding onto an object were sensitive indicators of the presence of CTS but use of the Phalen and Hoffmann-Tinel signs has significant potential to be unreliable.