Is It Safe to Treat Massive Disc Herniations Nonoperatively?

Introduction

Should the presence of a massive disc herniation be an automatic indication for disc surgery? Not according to researchers from southern California.

"Disc size alone should not be a major determining factor in the decision for or against surgical intervention," according to Michael S. Sinel, MD, and colleagues. "We believe the majority of clinically significant massive lumbar disc herniations can safely undergo a trial of conservative therapy, provided there is no absolute indication for surgery, such as cauda equina syndrome." (See Sinel et al., 1999.)

"The size of a disc herniation alone is clearly not predictive [of outcome]," said co-author Ted Goldstein, MD. "You treat the patient and not the MRI," he added.

Gunnar B. J. Andersson, MD, PhD, who attended the study presentation at the recent annual meeting of the American Academy of Orthopaedic Surgeons, says that he agrees that the presence of a massive disc extrusion or sequestration is not an absolute indication for surgery. However, his clinical experience suggests that many patients with massive disc herniations will opt for surgery, because of persistent, severe pain. If they can wait out their symptoms, he says, he is confident that the fragment will eventually diminish in size. He says he is less confident about the ability of the body to resorb a massive contained disc herniation.

What Constitutes a Surgical Emergency?

There is universal agreement in the spine world that cauda equina syndrome -- the neurologic emergency marked by bowel and bladder dysfunction -- is an absolute indication for surgery. 

What About Giant Herniations?

But what about gigantic disc herniations? The mere sight of a massive disc herniation on an MRI scan often worries clinicians and patients, and pushes them toward surgery. However, there is no scientific evidence that large disc herniations have poor outcomes.

Sinel and colleagues recently performed an MRI study of 20 patients (9 male, 11 female; aged 30-68) with massive disc herniations (AP diameter greater than seven millimeters). All the disc herniations were symptomatic, with some of the patients suffering motor and/or sensory deficits. None of the subjects had any hint of cauda equina syndrome or gross motor weakness.

"All patients were treated conservatively. All patients underwent baseline and follow-up MRI scans, with a minimum elapsed time of six months between scans. The scans were read in a blinded fashion by two musculoskeletal radiologists.

The average size of the disc extrusion measured in the AP dimension was 8.95 mm at baseline and 3.35 mm (ranging from 0-10 mm) at follow-up. "This represents a reduction of 62.6% in the disc herniation size between initial and follow-up studies," according to Sinel et al. Average size in the ML dimension decreased 40%. There was a 48.6% reduction in the average size of the disc herniation in the CC dimension.

The authors also measured the fragment to canal ratio. The average canal size among the patients was 18.15 mm in the AP dimension and 28.5 in the IP dimension. The average disc fragment to canal ratio in the AP dimension declined from .493 at the initial MRI to .185 at follow-up. "This represents a 62.5% reduction in the disc fragment:canal ratio between the initial and follow-up exam."

Goldstein noted that several of the patients in the study were very worried by the size of their disc herniations. "They were ready to go to surgery because they were frightened." He suggests that clinicians offer reassurance as well as pain control as the patient with a giant disc herniation embarks on a course of conservative care.

"Our results show that the majority of large disc extrusions might decrease in size," Sinel et al. conclude. "Therefore disc size alone should not be one of the primary factors determining which patients should undergo surgery."

 So even with a clear-cut, large disc herniation and nerve root compromise, clinical decisions should be based on the patient and not on the appearance of the disc herniation on imaging scans.

References

         Schade V et al., The impact of clinical, morphological, psychosocial, and work-related factors on the outcome of lumbar discectomy, Pain, 1999; 80:239-49.

       Sinel T et al., Conservative management of larger lumbar disc extrusions treated conservatively: An MRI Study, presented at the annual meeting of the American Academy of Orthopaedic Surgeons, Anaheim, 1999