EMG/NCS Guide

What is EMG/NCS testing?

Electromyography (EMG) and nerve conduction testing (NCS) are forms of electrodiagnostic testing that are used to study nerve and muscle function. Commonly performed by a neurologist trained in this procedure, EMG/NCS testing can provide your doctor with specific information about the extent of nerve and/or muscle injury and can also determine the exact location of injury and give some indication whether the damage is reversible.

What should you expect?

There may be two parts to and EMG/NCS testing: a nerve conduction study (NCS and a needle exam (EMG) for muscle testing. Both may result in some discomfort, but are usually well tolerated without the need for medication beforehand. The nerve conduction study entails stimulating the nerves at different points with small electric shocks artificially activating them to their function can be measured. The needle exam involves inserting very fine needles into several muscles. The needle has a microscopic electrode that picks up both the normal and abnormal electrical signs given off by a muscle. Routinely, your doctor will perform both parts of the procedure, but there are situations where only the nerve conduction or muscle testing is performed.

EMG/NCS testing usually takes anywhere from 30 to 90 minutes, depending on the condition being tested and findings of the study. A report that includes the results and an interpretation will be sent to your referring doctor.

What you should know before the exam?

EMG/NCS testing is extremely safe. EMG needles are used for only one patient, are not recycled, and are immediately disposed of following use. Side effects may include some muscle soreness, which rarely lasts more than an hour or two after the exam. Patients on anticoagulation or blood thinners and those with pacemakers or implated defibrillators should notify the physician performing the test, but generally this is not a contradiction. Patients with joint replacements or other artificial components in their body do not need to take antibiotics specifically for the EMG. Patients on medication should take their usual medication on the day of the test. No special preparation is necessary; however please refrain from using body lotion from the night before your exam.

Why has the test been ordered?

If you have numbness, decreased sensation, tingling, radiating pain or burning, your doctor may refer you for an EMG/NCS. Symptoms such as muscle spasms, weakness and difficulty butting clothes, handling objects or walking may also indicate the need for an EMG/NCS. Conditions that EMG/NCS tests help diagnoise include carpal tunnel syndrome, a pinched nerve, radiculopathy, sciatica, neuropathies, muscle disease, muscular dystrophy, Lou Gehrig’s disease and myasthenia graivs.