AAET DEF Questions & Answers

AAET DEF Questions & Answers A-waves or Axon reflex Seen when using sub- maximal stimulation during the F-wave recording. Consistent in latency and amplitude and usually occurring before the F-wave. Thought to be a result of reinnervation of the nerve. Abduct Move away from the median plane Abductor digiti minimi (ADM or ADQ) Ulnar innervated muscle on the medial side of the little finger alongside the 5th metacarpal. The most superficial muscle in the hypothenar eminence. Commonly used when recording ulnar motor studies. Abductor digiti quinti pedis (ADQp) Medial plantar, thus tibial nerve, innervated muscle on the medial side of the foot below the navicular bone. Commonly used when recording tibial motor studies. Abductor pollicis brevis (APB) Median innervated muscle just medial to the 1st metacarpal bone. The most superficial muscle of the thenar eminence. Commonly used when recording median motor studies. Accessory peroneal nerve A branch of the superficial peroneal nerve that partly supplies the extensor digitorum brevis (EDB) in 18-22% of people. The EDB is normally innervated by the deep peroneal. The accessory peroneal nerve is seen when the peroneal amplitude, recording from the EDB, is larger when stimulating at the fibular head than when stimulating at the ankle. It can be confirmed by stimulating behind the lateral malleous, adding that amplitude to the ankle amplitude. The sum of which should closely equal the amplitude when stimulating at the fibular head. Acetylcholine The chemical transmitter in a neuromuscular junction Action potential Whenever a stimulus reached or exceeds threshold an action potential is generated propagating along a single axon. Active electrode Synonymous with recording electrode, G1, E1 or cathode. To complete the circuit a differential amplifier requires the Active electrode and a Reference electrode. Acute Inflammatory Demyelinating Polyneuropathy (AIDP) Guillain-Barré Syndrome. An acute areflexic ascending sensory-motor polyneuropathy where deficit is maximum in 4 weeks. Characterized by absent or prolonged F-waves, slowed conduction velocities, prolonged latencies and conduction block (especially proximally) Sensory NCS may be normal in early cases, but as the disease advances low amplitudes and slowed conductions may be seen. Adduct Move toward the median plane Afferent Otherwise known as sensory neurons - carry nerve impulses from receptors or sense organs toward the central nervous system. Age Affects time and amplitude so normative values reflect different age groups. All or none response When depolarization occurs it either causes an all response it reaches threshold, or no response if the depolarization is insufficient to reach threshold. Alternating Current Current that is forced rapidly back and forth along a circuit, repeatedly reversing its direction. Ampere A measure of current, designated by the letter A. Amplifier The hardware component used to increase the size of the small physiological signal. Amyotrophic lateral sclerosis (ALS) Often referred to, as "Lou Gehrig's disease." Motor neurons go from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. Anodal block Hyperpolarization occurring under the anode prevents the depolarization, that occurs under the cathode, from passing thus, causing a reduction in the resulting potential. Anode The positive terminal of the stimulating electrode Anomalous Innervation Anomalous pathways that can cause erroneous results in some people. Common anomalies include Martin-Gruber anastomosis and Accessory peroneal nerve. Antecubital fossa The triangular area on the anterior view of the elbow joint of the arm. A common stimulation site for the median and radial nerves. Anterior In the front or in the forward part, ventral surface Anterior horn cells Motor unit cell bodies in the ventral gray matter of the spinal cord. Eventually become the motor nerves. Anterior interosseous nerve A branch the median nerve originating several centimeters distal to the elbow. Innervates several muscles in the forearm including the flexor digitorum profundus and the flexor pollicis longus muscles. Antidromic conduction Nerve conduction propagation in a direction other that the normal physiological direction. Area The area under a curve; represents duration and amplitude. Measured in mVms (for MNC, its most useful place) and helps differentiate between a conduction block and simple dispersion. Artifact Unwanted electrical or physiological signals that obscure the desired response. Atoms Make up the elements found in all matter Axillary nerve Originates from the posterior cord of the brachial plexus via the upper trunk and the C5/6 nerve roots. Innervates the deltoid and teres minor muscles. Axolemma A semipermeable membrane that covers the axoplasm Axon Nerve fibers that transmit impulses to and from the periphery. Axons are in effect the primary transmission lines of the nervous system and as bundles they help make up nerves.