— But Canadian study may have important limitations

by Judy George, Senior Staff Writer, MedPage Today March 18, 2020

Microdiscectomy produced better pain relief than standard nonsurgical care (see below) for patients with chronic sciatica caused by lumbar disk herniation, a single-center trial showed.

Six months after surgery, leg-pain intensity scores were 2.8 in the surgical group and 5.2 in the nonsurgical group on a 1-to-10 scale with higher scores indicating more severe pain, reported Chris Bailey, MD, at Western University in London, Canada, and colleagues, in the New England Journal of Medicine.

Earlier research has focused largely on treating acute or sub-acute disc herniation, Bailey noted. “We studied patients with chronic sciatica and found a significant and lasting advantage in surgery. I believe that primary care physicians may now be more supportive of surgery for this cohort of patients,” he told MedPage Today.

“Certainly, surgeons have good evidence to support what they already knew anecdotally: that although surgery is not the only option, it appears to be the best for many in this chronic sciatica population,” he added.

For patients with persistent sciatica and disk herniation, “it has been our practice to provide information about the association between symptom duration and outcomes and to offer a decision regarding surgical or nonsurgical treatment on the basis of the patient’s preference,” noted Andrew Schoenfeld, MD, and James Kang, MD, both of Brigham and Women’s Hospital and Harvard Medical School in Boston. “If the patient has no benefit from an appropriate course of non-operative care, we make a stronger recommendation for surgery.”

“Viewed in this light, it is encouraging that the trial reported by Bailey et al. shows that surgical intervention still results in clinically meaningful improvement in patients with persistent sciatica,” Schoenfeld and Kang wrote in an accompanying editorial. “However, the trial does not help clinicians determine which patients are most likely to benefit from immediate surgical intervention or the duration of non-operative care that is acceptable before surgery is recommended.”

In their trial, Bailey and his group randomly assigned 128 patients with sciatica that had lasted for 4 to 12 months and lumbar disk herniation at the L4-L5 or L5-S1 level to microdiscectomy or 6 months of standardized non-operative care followed by surgery if needed. Each group had 64 patients.

The primary outcome was leg pain intensity on the 1-to-10 visual analogue scale (higher scores indicated more severe pain) at 6 months after enrollment. Surgery was performed by spine surgeons using conventional microdiscectomy techniques. Nonsurgical treatment was standardized and included educating patients about day-to-day functioning, activity and exercise, and use of oral analgesics and active physiotherapy. In addition, patients in the nonsurgical group could receive epidural glucocorticoid injections as needed.

Patients were recruited from 2010 to 2016. Their average age was 38; 41% were women, and disk herniation occurred most commonly at L5-S1. The only significant between-group difference was a higher rate of antidepressant use in the surgical group.

Mean baseline score for leg-pain intensity was 7.7±2.0 in the surgical group and 8.0±1.8 in the nonsurgical group. At 6 months, leg-pain intensity scores were 2.8±0.4 in the surgical group and 5.2±0.4 in the nonsurgical group (difference 2.4, 95% CI 1.4 to 3.4, P<0.001).

Secondary outcomes — Oswestry Disability Index scores, back and leg pain, and quality of life scores at 6 weeks, 3 months, 6 months, and 1 year — were generally in the same direction as the primary outcome, though the study design prevented clinical inferences from being drawn about secondary outcome data. Nine patients had adverse events associated with surgery, and one patient underwent repeat surgery for recurrent disk herniation.

Pain scores may have improved because surgical intervention allowed the compressed nerve root to be decompressed more quickly, Schoenfeld and Kang observed. “Patients in the current trial who were assigned to undergo surgery received the intervention relatively quickly, at a median of 3 weeks, and it is reasonable to conclude that expeditious removal of the nerve compression minimized the potential for long-term persistence of pain,” they wrote.

Several trial limitations need to be kept in mind, they added. Patients who had symptoms for 4 to 12 months were in the trial, but researchers “did not account specifically for the effect of symptom duration in this window or other clinical factors known to influence outcome after diskectomy, such as the size of the disk herniation or the extent of nerve-root compression,” they pointed out.

The study also took place in Canada and results “may also not be generalizable to health systems such as the one in which we practice, which allows (if not encourages) patients to influence the timing of surgery, with some preferring to be relieved of sciatic pain immediately with surgery and others who prefer to avoid surgery and wait for spontaneous improvement,” the editorialists wrote. In addition, this was a single-center trial with potential for selection bias, the researchers noted.