Nerve root pressure in lumbar disc herniation

Study Design. The contact pressure between the nerve root and lumbar disc h erniation was measured and compared with clinical features. Objective. To assess levels of actual compression to the nerve root in clin ical cases. Summary of Background Data. Actual levels of pressure to the nerve root of lumbar disc herniation in clinical cases is unknown. Methods. The study was performed on 34 patients who had lumbar disc herniat ion. All of them had been treated by open discectomy. After laminotomy, ner ve root pressure was measured by inserting a transducer between the nerve r oot and the disc herniation. The magnitude of pressure was compared with cl inical features. Results. Nerve root pressures before discectomy were varied from 7 mm Hg to 256 mm Hg (mean, 53 mm Hg). After discectomy, the contact pressure was 0 m m Hg in all cases. There were no significant correlations between the magni tude of nerve root pressure and limits to the degree of straight leg raisin g, duration of symptoms, and age of the patients. However, the magnitude of the pressure in patients with neurologic deficits and trunk list was signi ficantly higher than in the absence of these findings. Conclusions. The contact pressure exerted by lumbar disc herniation on the nerve roots was recorded during surgical intervention, and the mean pressur e was 53 mm Hg. The magnitude of nerve root pressure was not correlated wit h the degree of straight leg raising, but with the severity of neurologic d eficits.