An electomyelogram or EMG is a test to identify the strength of a muscle contraction following nerve stimulation. The nerve is stimulated, and the time it takes to produce a muscle contraction is measured. The strength of the impulse and contraction is also measured.

Following critical illness, nerves can stop working properly. Motor nerves are the nerves that carry messages to make muscles contract. If the motor nerves lose their ability to conduct or carry information to the muscles, extreme muscle weakness can develop. This is called "Polyneuropathy of Critical Illness". "Poly" means many, "neuropathy" means nerves that are not working normally.

The diaghram is the large muscle located between the lungs and abdominal cavity. It is the main muscle of breathing. While patients who develop Polyneuropathy of Critical Illness will experience extreme weakness in their arms and legs, they also develop weaknes in the diaphragm. If this happens, they will be unable to breathe without a ventilator until the nerves recover.

Although Polyneuropathy of Critical Illness can signficantly prolong the recovery time for the patient, most patients do eventually recover muscle strength and the ability to breathe without the ventilator. The treatment for this condition is generally rest, nutrition and ongoing support until the patient recovers. The biggest concern when this condition develops is the risk for developing another complication before the neuropathy recovers.


Image 1: EMG







Last Reviewed: October 23, 2014