EMG has anyone had this kind of testing?

[Guest guest]

or gotten through this testing? I remember now, he first stuck it in my thigh, I

was told to move my foot and flex the muscle but I couldn't move it. it hurt

really bad there but not even close to what it felt like in my lower back.

http://en.wikipedia.org/wiki/Electromyography

There are two kinds of EMG in widespread use: surface EMG and intramuscular

(needle and fine-wire) EMG. To perform intramuscular EMG, a needle electrode or

a needle containing two fine-wire electrodes is inserted through the skin into

the muscle tissue. A trained professional (most often a physiatrist or

neurologist) observes the electrical activity while inserting the electrode. The

insertional activity provides valuable information about the state of the muscle

and its innervating nerve. Normal muscles at rest make certain, normal

electrical sounds when the needle is inserted into them. Then the electrical

activity when the muscle is at rest is studied. Abnormal spontaneous activity

might indicate some nerve and/or muscle damage. Then the patient is asked to

contract the muscle smoothly. The shape, size, and frequency of the resulting

motor unit potentials are judged. Then the electrode is retracted a few

millimeters, and again the activity is analyzed until at least 10–20 units have

been collected. Each electrode track gives only a very local picture of the

activity of the whole muscle. Because skeletal muscles differ in the inner

structure, the electrode has to be placed at various locations to obtain an

accurate study.

Intramuscular EMG may be considered too invasive or unnecessary in some cases.

Instead, a surface electrode may be used to monitor the general picture of

muscle activation, as opposed to the activity of only a few fibres as observed

using a intramuscular EMG. This technique is used in a number of settings; for

example, in the physiotherapy clinic, muscle activation is monitored using

surface EMG and patients have an auditory or visual stimulus to help them know

when they are activating the muscle (biofeedback).

A motor unit is defined as one motor neuron and all of the muscle fibers it

innervates. When a motor unit fires, the impulse (called an action potential) is

carried down the motor neuron to the muscle. The area where the nerve contacts

the muscle is called the neuromuscular junction, or the motor end plate. After

the action potential is transmitted across the neuromuscular junction, an action

potential is elicited in all of the innervated muscle fibers of that particular

motor unit. The sum of all this electrical activity is known as a motor unit

action potential (MUAP). This electrophysiologic activity from multiple motor

units is the signal typically evaluated during an EMG. The composition of the

motor unit, the number of muscle fibres per motor unit, the metabolic type of

muscle fibres and many other factors affect the shape of the motor unit

potentials in the myogram.

Nerve conduction testing is also often done at the same time as an EMG to

diagnose neurological diseases.