Diagnostic Testing Alternatives Effective in Evaluating Spinal Stenosis

Newswise — Patients with symptoms consistent with spinal stenosis may benefit from having both a needle electromyography (EMG) examination, and magnetic resonance imaging (MRI). In new research conducted at the University of Michigan by Dr. Henry Tong, needle EMG and MRI were compared to determine whether the tests provided the physician with the same or different diagnostic information.

MRI is commonly used to provide physicians with a clear image of the patient's spinal structure, and to determine possible degenerative changes or abnormalities, but does not evaluate nerve functioning. Needle EMG is complementary since it assesses muscle and nerve function.

From a larger study, thirty-eight individuals, ages 55-79--a group that most frequently experiences degenerative changes in the spine—were felt on clinical evaluation to have symptomatic spinal stenosis. In conjunction with the MRI studies, the study group also underwent standard needle EMG studies. The MRI examinations were classified as positive either using the bony canal diameter or thecal sac diameter using a 95% specificity cutoff. The results of the two different MRI methods were then compared to the needle EMG findings. The findings revealed disagreements in 16-18 of the 38 subjects, when comparing the two MRI criteria to the two EMG criteria. This indicates that needle EMG is a complementary test for patients with spinal stenosis, providing different diagnostic information to the physician than the MRI alone.

According to Dr. Tong, "Clinical diagnosis should always be done using a combination of the patient's clinical presentation, the patient's clinical evaluation, and results of the diagnostic tests. If the patient's symptoms are not classic in nature, or if the findings of either the MRI or needle EMG are uncertain, then the physician and the patient may benefit from proceeding with the other test."

The full research results will be reported at the 52nd annual meeting of the American Association of Neuromuscular and Electrodiagnostic Medicine in Monterey, California, September 21-24.