Sonation of lumbar nerve roots as a diagnostic procedure in patients with sciatica

It has been suggested that sonation of the lumbar nerve roots in patients with sciatica will precipitate their symptoms and therefore may be a useful diagnostic tool in the evaluation of disc protrusions. Thirty healthy subjects (Group 1), mean age 36 (+/- 6) years, were evaluated to establish a baseline response. None had a positive test. A second group of 35 individuals, mean age 38 (+/- 12) years, all had histories of sciatica and sufficient signs to warrant consideration of a myelogram. Subsequently, all had positive myelograms and positive disc protrusions documented at surgery. Only three of the second group had positive responses to the ultrasound test. The ultrasound was 870 kHz continuous at 2watts/cm2 for two minutes, administered at the lumbar paravertebral muscle mass. The ultrasound test had a high specificity and very low sensitivity (.09), indicating that sonation of the lumbar nerve roots in people with sciatica is not a useful preliminary screening test of low lumbar disc disease.