Newer electrodiagnostic techniques in peripheral nerve injuries

Careful attention to technique is essential for the accurate evaluation of peripheral nerve function using conventional EMG and nerve conduction studies. Numerous technical, anatomic, and physiologic pitfalls must be avoided. The amplitudes of the M wave and SNAP contain useful diagnostic information and should be evaluated carefully in addition to conduction velocity and distal latency. Newer techniques using the F wave, H reflex, SEP, dermatomal SEP, and quantitative EMG may be helpful in evaluation of selected peripheral nerve problems. Comparative nerve conductiion studies using 'inching' technique permit evaluation of short nerve segments. Comparisons with parallel nerves improve diagnostic sensitivity.