At least half of herniated discs spontaneously de-herniate
PainSci summary of Zhong 2017
Once a spinal disc has “slipped,” it seems like it’s in a biomechanically awkward situation and can’t recover any more than a broken window can reassemble itself. And yet several studies — like Kjaer 2016, which followed dozens of patients for eight years — have suggested that herniated discs spontaneously de-herniate!
This paper (Zhong et al) is the first meta-analysis of those studies. The pooled data from eleven of them shows an extremely high overall incidence of disk resorption: a whopping 66% in patients who received conservative therapy (anything but surgery). This adds to the already large pile of evidence that back pain’s bark is usually much worse than its bite, and MRI and x-ray are almost useless for most low back pain.
More study is needed — of course, as always — because none of these studies were randomized controlled trials, and there was barely enough data for meta-analysis. However, the final number is so high that it’s safe to assume that approximately “lots” of herniations resolve on their own.
As if this wasn’t counter-intuitive enough already, the worst herniations are actually the most likely to regress (see Chiu et al). The temptation to assume the opposite is hard to resist, but “common sense” is useless in musculoskeletal medicine, a field where there seem to be no safe assumptions.
Does this data show that “conservative therapy” is the key to resorption? Unfortunately not: “conservative therapy” is vague to the point of being meaningless here. All it does mean is that these patients were treated with anything but surgery (or injections). We already suspect that resorption occurs whether people receive any treatment or not (Kjaer again), and we know that there are no clearly effective therapies for back pain at all (Machado). The only thing we can tell from this paper is that many herniations resolve without surgery, not that therapy fixes herniations.
BACKGROUND: Lumbar disc herniation (LDH), a common disease, is often treated conservatively, frequently resulting in spontaneous resorption of the herniated disc. The incidence of this phenomenon, however, remains unknown.
OBJECTIVE: To analyze the incidence of spontaneous resorption after conservative treatment of LDH using computed tomography and magnetic resonance imaging.
STUDY DESIGN: Meta-analysis and systematic review of cohort studies.
SETTING: The work was performed at The Suzhou Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine.
METHODS: We initiated a search for the period from January 1990 to December 2015 using PubMed, Embase, and the Cochrane Library. Two independent reviewers examined the relevant reports. The references from these reports were also searched for additional trials using the criteria established in the PRISMA statement.
RESULTS: Our results represent the pooled results from 11 cohort studies. The overall incidence of spontaneous resorption after LDH was 66.66% (95% CI 51% – 69%). The incidence in the United Kingdom was 82.94% (95% CI 63.77% – 102.11%). The incidence in Japan was 62.58% (95% CI 55.71% – 69.46%).
LIMITATIONS: Our study was limited because there were few sources from which to extract data, either in abstracts or published studies. There were no randomized, controlled trials that met our criteria.
CONCLUSIONS: The phenomenon of LDH reabsorption is well recognized. Because its overall incidence is now 66.66% according to our results, conservative treatment may become the first choice of treatment for LDH. More large-scale, double-blinded, randomized, controlled trials are necessary to study the phenomenon of spontaneous resorption of LDH.