What is the difference between orthodromic and antidromic conduction?

Conduction during NCS In an orthodromic study, the recording electrodes measure the action potential traveling in the physiologic direction. In an antidromic study, the recording electrodes measure the action potential traveling opposite the physiologic direction.

When performing an orthodromic sensory nerve conduction velocity test the recording electrode should be positioned on or directly over which of the following Stuctures?

Orthodromic technique. Stimulating electrodes are usually ring electrodes placed around the proximal and middle phalanxes of the 2nd or 3rd digits and the recording electrodes are placed on the ventral aspect of the wrist, over the median nerve, usually at about 1–2 cm proximal to the proximal wrist crease.

What is antidromic conduction?

the conduction of a nerve impulse in a reversed direction (i.e., from axon to cell body), produced for experimental purposes. Also called antidromic activation; antidromic phenomenon.

What is sensory nerve conduction velocity?

A nerve conduction velocity (NCV) test — also called a nerve conduction study (NCS) — measures how fast an electrical impulse moves through your nerve. NCV can identify nerve damage. During the test, your nerve is stimulated, usually with electrode patches attached to your skin.

What affects nerve conduction velocity?

Conduction velocities are affected by a wide array of factors, which include; age, sex, and various medical conditions. Studies allow for better diagnoses of various neuropathies, especially demyelinating diseases as these conditions result in reduced or non-existent conduction velocities.

What determines orthodromic conduction?

Orthodromic denotes the propagation of an impulse along a conduction system (for example, nerve fiber) in the direction it normally travels. In the heart, orthodromic refers to an impulse going in the correct direction from the atria to the ventricles, in contrast to some impulses in re-entry.

What does a normal nerve conduction test rule out?

NCV tests can measure the speed and strength of nerve signals. Nerve conduction velocity between 50 to 60 meters per second is considered normal. A damaged nerve may send a slower and weaker signal than a healthy one. It is possible to have normal results even if a person has nerve damage.

What causes Antidromic conduction?

Antidromic activation is often induced experimentally by direct electrical stimulation of a presumed target structure. Antidromic (cell theory) activation is often used in a laboratory setting to confirm that a neuron being recorded from projects to the structure of interest.

How do you fail a nerve conduction test?

You must stay at a normal body temperature. Being too cold or too warm alters nerve conduction and can give false results. Tell your doctor if you have a cardiac defibrillator or pacemaker. Special steps will need to be taken before the test if you have one of these devices.

Why was my EMG so painful?

Pain is commonly associated with EMG, because the procedure involves the use of needles and electric shock. Not only friends and relatives who have had a previous EMG experience, but also physicians can sometimes discourage patients from undergoing EMG, believing that the test is very painful and of little benefit (1).

Which nerve has the slowest conduction velocity?

Sural nerve
Sural nerve conduction amplitude is significantly smaller in females than males, and the latency of impulses is longer in females, thus a slower conduction velocity.

What has the slowest conduction velocity?

atrioventricular node
The region between atrium and atrioventricular node has the slowest conduction velocity (. 05 M./see.)

When was antidromic nerve conduction testing first used?

Antidromic testing was first described by Sears in 1959, as quoted in papers in which the authors used the antidromic technique to examine a large number of patients with suspected carpal tunnel syndrome ( Campbell, 1962) or a single patient with polyneuritis ( Bannister and Sears, 1962 ).

What’s the difference between antidromic and near-nerve recording?

The two techniques differ on how physical and physiological changes affect the action potential. Near-nerve recording is better suited for the orthodromic than for the antidromic technique, while studies of nerve excitability are better suited for the antidromic than for the orthodromic technique.

Which is the most commonly performed sensory nerve conduction test?

Research studies may specifically demand one or the other technique. Median sensory nerve conduction studies are arguably the most often performed electrodiagnostic tests worldwide.

How are nerve conduction studies used in myopathy?

Nerve conduction studies are commonly used to evaluate for specific nerve injury or entrapment, but can also help with the diagnosis of polyneuropathies, myopathy or NMJ disorders. Lesions of the motor or sensory axon typically result in loss of CMAP and SNAP amplitudes.