Degenerative Disc Information

Electromyogram (EMG)

An electromyogram (EMG) is a test that is used to record the electrical activity of muscles. When muscles are active, they produce an electrical current. This current is usually proportional to the level of the muscle activity. An EMG is also referred to as a myogram. 

Surface EMG (SEMG) involves placing the electrodes on (not into) the skin overlying the muscle to detect the electrical activity of the muscle

 Intramuscular EMG (the most commonly used type) involves inserting a needle electrode through the skin into the muscle whose electrical activity is to be measured.

A needle is inserted through the skin into the muscle. The electrical activity is detected by this needle (which serves as an electrode). The activity is displayed visually on an oscilloscope and may also be displayed audibly through a microphone.

Since skeletal muscles are often large, several needle electrodes may need to be placed at various locations to obtain an informative EMG.

After placement of the electrode(s), the patient may be asked to contract the muscle (for example, to bend the leg).

The presence, size, and shape of the wave form (the action potential) produced on the oscilloscope provide information about the ability of the muscle to respond to nervous stimulation. Each muscle fiber that contracts produces an action potential. The size of the muscle fiber affects the rate (how frequently an action potential occurs) and the size (the amplitude) of the action potential.

There is some undeniable discomfort at the time the needle electrodes are inserted. They feel like shots (intramuscular injection), although nothing is injected during an EMG. Afterwards, the muscle may feel a little sore for up to a few days.

Nerve Conduction Velocity (NCV)

A nerve conduction velocity (NCV) test is often done at the same time as an EMG. In this test, the nerve is electrically stimulated while a second electrode detects the electrical impulse ‘down stream’ from the first. This is usually done with surface patch electrodes (they are similar to those used for an electrocardiogram) that are placed on the skin over the nerve at various locations. One electrode stimulates the nerve with a very mild electrical impulse. The resulting electrical activity is recorded by the other electrodes. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the speed of impulse transmission (nerve conduction velocity). A decreased speed of transmission indicates nerve disease.

Anterior Cervical Dysectomy and Fusion

Anterior cervical discectomy is an operation performed on the upper spine to relieve pressure on one or more nerve roots, or on the spinal cord. The procedure is explained by the words anterior (front), cervical (neck), and discectomy (cutting out the disc).

Why is it done?

Neck and arm pain, among other symptoms, may occur when an intervertebral disc herniates. This happens, either suddenly with injury or slowly over time, when some of the disc's jelly-like center (the nucleus pulposus) bulges or ruptures through its tough, fibrous outer ring (the annulus fibrosus) and presses on a nerve.

When a disc ruptures in the cervical spine, it puts pressure on one or more nerve roots (often called nerve root compression) or on the spinal cord. This pressure causes symptoms in the neck, arms, and even legs. Further pressure may be caused by rough edges of bone, called bone spurs, that naturally build up around some herniated discs.

In this operation, the cervical spine is reached through a small incision in the front of your neck. After the soft tissues of the neck are separated, the intervertebral disc and bone spurs are removed. The space left between the vertebrae may be left open or filled with a small piece of bone. In time the vertebrae may fuse, or join together.

If used, the pre-formed bone graft may be obtained from a bone bank. It will not be rejected by your body, because it is avascular (contains no blood cells). In some circumstances, or if your surgeon prefers, the bone graft might instead be removed from your own hip through a second incision.

What happens afterwards?

Successful recovery from anterior cervical discectomy requires that you approach the operation and recovery with confidence based on a thorough understanding of each process. Your surgeon has the training and expertise to correct physical defects by performing the operation; he and the rest of the health care team will support your body's efforts to heal its damaged tissues. Full recovery will also depend on you having a strong, positive attitude, setting small, realistic goals for improvement, and working steadily to accomplish each goal.
source:  http://www.espine.com/

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