The prevalence of lumbar paraspinal spontaneous activity in asymptomatic subjects.

Electrodiagnostic findings of fibrillations and positive sharp waves in the lumbosacral paraspinals in patients without previous back surgery has been generally considered to be abnormal, consistent with posterior rami denervation. In some cases, it is the only abnormality on the electromyographic examination. This study was undertaken to determine the prevalence of abnormal spontaneous activity in lumbosacral paraspinals in asymptomatic individuals. Nine (14.5%) of 62 subjects studied had positive sharp waves or fibrillations noted on the needle examination of bilateral lumbosacral paraspinal muscles. There was a significant increase in the prevalence of abnormal activity with increasing age. This suggests that caution should be taken in attributing radiculopathy as the etiology of low back pain when electromyographic lumbosacral paraspinal abnormalities are the only positive findings in the middle-aged or older individual.