Proximal neuromuscular impairment in lumbar disc herniation: a prospective controlled study.

STUDY

DESIGN

A prospective and controlled study investigated the relation of muscle dysfunction to residual pain and disability in patients with lumbar disc herniation.

OBJECTIVES

To determine the incidence of lower limb muscle dysfunction in lumbar disc herniation and its evolution over time after surgery, and to ascertain whether neuromuscular dysfunction has a prognostic value regarding pain and disability.

SUMMARY OF BACKGROUND DATA: Residual sciatica, low back pain, and disability are common after lumbar discectomy. Preoperative motor dysfunction corresponding to the afflicted nerve root is often seen.

METHODS

The participants in this study were 71 patients, ages 15 to 50 years, with disc prolapse at L4-L5 or L5-S1. Before surgery, then 6 weeks, 4 months, and 12 months after surgery, low back pain and leg pain were estimated on a visual analog scale, and disability was determined according to the Roland-Morris Questionnaire and a designed functional muscle test.

RESULTS

Motor function of the sciatic leg frequently was impaired. Inferior outcome of proximal motor tests 6 weeks after surgery predicted pain and disability 1 year after surgery. The mean leg pain was 59 mm before surgery and 15 mm at 6 weeks, remaining at that level during the follow-up period. The mean disability score was 14.4 before surgery, 8.8 at 6 weeks, and 4.7 at 4 and 12 months, whereas muscle function improved gradually through 1 year of follow-up evaluation.

CONCLUSIONS

Neuromuscular dysfunction frequently is present in patients with lumbar disc herniation. Sciatica resolves quickly after surgery, whereas disability improves gradually up to 4 months and muscular performance improves throughout the first year. Proximal muscular dysfunction in lumbar disc herniation has a prognostic value concerning residual pain and disability.