Vrms/T quantitation in patients with lumbar spinal stenosis

Thirty consecutive patients with clinical and radiographic findings consistent with lumbosacral root injury were evaluated. Electrodiagnostic examinations included determination of root mean square (Vrms)/turns (T) values. Vrms/T values > or =1 are consistent with chronic neurogenic injury and have been correlated with increase in fiber density. Radiographic studies were independently classified as having severe (group I; n= 8), mild (group II; n=11), or no lumbar spinal stenosis (group III; n=11). Abnormal Vrms/T values were present in all 8 patients in group I in comparison to 0/11 in group II and 2/11 in group III (p<0.0001 and 0.0007 respectively in comparison to group I). In 5/8 patients in group I, Vrms/T values provided unique information. Large amplitude motor units were also present more frequently in group I in comparison to the other groups (p<0.02). This study indicates Vrms/T values can be helpful in the electrodiagnostic evaluation of patients with lumbosacral radiculopathies, particularly where chronic multilevel radicular injury might be expected such as in lumbar spinal stenosis.