Weakness is not one of the more common symptoms of a cervical spine disorder, but when it is present it indicates a relatively more severe case of nerve compression and it does require in-depth investigation. Patients may suffer from an inability to balance their head, weakness in their arm(s), inability to work with arms over the head, grip weakness, dropping things from one or both hands, breaking dishes, or difficulty eating or writing. If several or all of the nerves for one muscle are involved, muscle atrophy can be extreme. The symptom of weakness can be caused by either pain in the muscles that are trying to move or by damage to the nerve, that supplies the muscle, to the point where it is no longer able to contract.
"Weakness can be assessed in six grades:
|0||_||no evidence of any contractility|
|1||trace only||evidence of slight contractility but with no joint motion|
|2||poor||complete range of motion with gravity eliminated|
|3||fair||complete range of motion against gravity only|
|4||good||complete range of motion against gravity with some resistance|
|5||normal||complete range of motion against gravity with full resistance"3|
A common cause for weakness in the arms associated with neck pain is a herniated disc that "pinches" a nerve where it exits the spinal column. When the outer lining (annulus) of a disc "tears," its center (the nucleus) may rupture and press a spinal nerve(s) against the bony surface of a vertebra. Another cause of weakness is degenerative disc disease (DDD). DDD can cause bone spurs to form around the nerve roots. This usually occurs inside the foramen - the opening in the cervical spine where the nerve root leaves the spine to travel into the arm. If these bone spurs get large enough, they may begin to rub on the nerve root causing irritation. This causes the same symptoms as a herniated disc. The irritation causes: pain to run down the arm, weakness to occur in the areas to which the nerve provides sensation, and weakness in the muscles that the nerve supplies.
Spinal stenosis, or the narrowing of the spinal canal is another disorder that can cause the symptom of weakness. In the late stages of spinal degeneration, bone spurs and arthritic changes make the space available for the spinal cord, within the spinal canal, much smaller. The bone spurs may begin to press on the spinal cord or the nerve roots, and that pressure on the nerves in the spinal cord can cause weakness.
Difficulty walking due to generalized weakness or problems with balance and coordination can be caused by several different cervical spine problems. One of the more worrisome reasons that someone has trouble walking or problems with gait and balance is that the spinal cord is being squeezed by bone spurs and other degenerative changes in the cervical spine. This condition, called myelopathy, affects the entire spinal cord and is very different from isolated points of pressure on the individual nerve roots. Myelopathy can be difficult to detect, because it usually develops gradually and also occurs at a time in life when people are beginning to slow down a bit anyway. Many people who have myelopathy will begin to have difficulty with things that require a fair amount of coordination, like walking up and down stairs or fastening the buttons on clothing.
Changes in coordination, recent weakness, and difficulty doing tasks that used to be easier because your body seemed more responsive in the past, are definite warnings signs that you should see a doctor. Diagnosis of walking difficulties can sometimes pose a problem for the physician. There are many reasons why elderly people have difficulty walking, and not everyone has a problem with their cervical spine. However, this is a symptom that is taken very seriously by doctors, and every attempt will be made to find the cause of the weakness and disability. Often this requires further tests, like MRI's or CT scans, and often consultation with other doctors who are specialists in areas of medicine such as neurology.
3 John H. Bland, Disorders of the Cervical Spine (Philadelphia: W.B. Saunders Company, 1987) 83.