Peripheral neuropathy is nerve damage or dysfunction that is present in the hands or feet. Is is generally suspected by a medical provider when deficits in temperature, pain, and vibratory sensation exist. Nerve conduction studies and electromyography studies are used to diagnose neuropathy.
Nerve conduction studies measure the speed of conduction of an electrical impulse through a nerve. This procedure may be performed by a trained medical technician or medical provider. NCS involves the placement of electrodes on the extremity to be tested, then a small amount of electricity is applied to detect nerve conductivity. This is typically not painful.
Electromyography measures muscle response or electrical activity in response to a nerve’s stimulation of the muscle. This procedure is usually performed by a medical provider. EMG involves the insertion of fine needles into at least one muscle in the extremity to be tested. This may cause mild pain during needle insertion, but is generally not a painful procedure.
Generally, both procedures are done in sequence for comprehensive nerve conduction testing. If nerve conduction tests demonstrate slowed conduction or nerve dysfunction, then investigation is necessary to determine the underlying cause of damage. Generally, it is necessary to perform blood tests, and a complete history and physical examination to ascertain the etiology.
Some information obtained from http://www.hopkinsmedicine.org/healthlibrary/test_procedures/neurological/electromyography_emg_92,p07656/.