Sensory nerve conduction study

Recording of the sensory action potential is helpful in determining the site of nerve injury particularly in those with lesions resulting in sensory symptoms. This illustration depicts a sensory nerve conduction study of the ulnar nerve. Normal latency is seen with lesions of the central nervous system or those that are proximal to the dorsal root ganglion (arrowhead number 1). A more distal lesion (arrowhead number 2) results in a decreased amplitude but normal conduction velocity. Either a compressive mononeuropathy (arrowhead number 3) or generalized demyelinating peripheral neuropathy results in a decrease in both amplitude and conduction velocity.