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Nerve Root Pressure in Lumbar Disc Herniation

Takahashi, Keisuke, MD*; Shima, Iwao, MD; Porter, Richard W., MD

Clinical Study

Study Design. The contact pressure between the nerve root and lumbar disc herniation was measured and compared with clinical features.

Objective. To assess levels of actual compression to the nerve root in clinical 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 herniation. All of them had been treated by open discectomy. After laminotomy, nerve root pressure was measured by inserting a transducer between the nerve root and the disc herniation. The magnitude of pressure was compared with clinical 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 mm Hg in all cases. There were no significant correlations between the magnitude of nerve root pressure and limits to the degree of straight leg raising, duration of symptoms, and age of the patients. However, the magnitude of the pressure in patients with neurologic deficits and trunk list was significantly 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 pressure was 53 mm Hg. The magnitude of nerve root pressure was not correlated with the degree of straight leg raising, but with the severity of neurologic deficits.

From the *Department of Orthopaedic Surgery, Saitama Medical School, Saitama, Japan, †Department of Orthopaedic Surgery, Ishikawa Prefectural Central Hospital, Ishikawa, Japan, and ‡Royal College of Surgeons of Edinburgh, Edinburgh, United Kingdom.

Acknowledgment date: September 16, 1998.

First revision date: December 23, 1998.

Acceptance date: January 21, 1999.

Address reprint requests to

Keisuke Takahashi, MD

Department of Orthopaedic Surgery

Saitama Medical School


Saitama, 350-0451


Device status category: 1.

© 1999 by Lippincott Williams & Wilkins