Nerve Conduction Velocity (NCV) Study

Nerve Conduction Velocity (NCV) Study nerve conduction velocity test - ANS - NCV tests the speed of conduction of AP along a nerve - NCV is a test commonly used to evaluate the function of the motor and sensory nerves of human body uses of NCV - ANS - NCV studies are used mainly for evaluation of paresthesias (numbeness, tingling, burning) and/or weakness of arms and legs Some indicators of NCV are - ANS - symptoms of nerve damage as numbness, weakness - differentiation between local or diffuse disease process - get prognostic information on the type and extent of nerve injury peripheral neuropathy - ANS - mononeuropathy - mononeuritis multiple - polyneuropathy myopathy - ANS - muscular dystrophies - myotonia - congenital myopathies - metabolic myopathies radiculopathy - ANS problem in which on or more never are affected emphasis on the nerve root - nerve damage from herniated discs procedure - ANS - electrodes - place them - stimulus- small stimulus - current - measure current important points of NCV study - ANS - not invasive - no contraindication to the procedure, but if there is an artificial pacemaker, appropriate precautions should be taken - anesthesia is not used for this procedure - no special post procedure precautions - the test is sometimes contended with electromyography What does the motor NCV study represent? - ANS the conduction of an impulse along peripheral motor nerve fibers what is recorded and measured? - ANS it is recorded as a compound evokes potential from a motor point within the muscle the time that it takes or electrical impulse to travel from the stimulation to the recording site is measure? median nerve conduction sites and muscle - ANS - wrist and elbow - abductor pollicis brevis ulnar nerve conduction sites and muscles - ANS - wrist and elbow - first dorsal interosseous and abductor digiti minimi peroneal nerve conduction site and muscles - ANS - ankle and head of fibular - extensor digitorum brevis - tibialis anterior tibial nerve conduction side and muscles - ANS - ankle - abductor hallucis - abductor digiti quinti pedis Sensory nerve conduction study - ANS - this NCS represents the conduction of an impulse along the sensory nerve fibers - it is performed by electrical stimulation of a peripheral nerve and recording from a purely sensory portion of the nerve, such as a finger - the recording electrode is placed proximal to the stimulating electrode Are sensory amplitude smaller or larger than motor amplitudes? - ANS musch smaller, usually in the microvolt range median nerve - sensory nerve conduction sites - ANS index finger thumb ulnar nerve - sensory nerve conduction sites - ANS little finger ring finger sural nerve - sensory nerve conduction sites - ANS behind the lateral malleolus saphenous nerve - sensory nerve conduction sites - ANS anterior to the medial malleolus axonal neuropathy - ANS normal velocity, low amplitude demyelinating neuropathy - ANS low velocity MN degeneration - ANS normal velocity and amplitude myopathy- disorder - ANS normal velocity and low amplitude NM synaptic problem - ANS low amplitude h- reflex - ANS evokes by electrically stimulating Ia sensory fibers from the muscle spindles in mixed nerve m- wave - ANS evokes by electrically stimulating alpha motor neruon low intensity and H-reflex - ANS Low intensity stimulation only an H reflex is produced because only the spindle adherents are excited high intensity and M-wave - ANS at very high intensity of stimulation only a M-wave is evokes