LAUSR

Electrodiagnosis of entrapment neuropathy at the upper limb is important to determine the treatment procedure. The median sensory nerve conduction studies and median nerve motor nerve distal latency have conventionally been performed for the diagnosis of carpal tunnel syndrome (CTS), but their sensitivities are not always sufficient. As a result of our research in 104 hands with CTS symptoms, both the ring finger test and second lumbrical–interossei comparison test had especially high sensitivity (92%), and this result supports the practice parameters recommended by the Japanese Society of Neurological Therapeutics. Exact localization of the lesion by electrodiagnosis in patients with ulnar neuropathy at the elbow (UNE) is often difficult because other disorders may mimic its symptoms (e.g., cervical lesion, brachial plexopathy, and Guyon’s canal syndrome). In one of our studies, sensitivity of the ulnar nerve motor nerve conduction velocity across the elbow lacked accuracy (54%). Meanwhile, the short-segment incremental study had the highest sensitivity (82%), maintaining high specificity (95%). In extreme UNEs, the combination of sensory nerve conduction studies evoked from the dorsal ulnar cutaneous branch and the medial antebrachial cutaneous nerve may be helpful in the exclusion of other disorders.