Stem cell injections for axial back pain: a systematic review of associated risks and complications with a case illustration of diffuse hyperplastic gliosis resulting in cauda equina syndrome.

Axial low-back pain is a disease of epidemic proportions that exerts a heavy global toll on the active workforce and results in more than half a trillion dollars in annual costs. Stem cell injections are being increasingly advertised as a restorative solution for various degenerative diseases and are becoming more affordable and attainable by the public. There have been multiple reports in the media of these injections being easily available abroad outside of clinical trials, but scientific evidence supporting them remains scarce. The authors present a case of a serious complication after a stem cell injection for back pain and provide a systematic review of the literature of the efficacy of this treatment as well as the associated risks and complications. A systematic review of the literature was performed using the PubMed, Google Scholar, and Scopus online electronic databases to identify articles reporting stem cell injections for axial back pain in accordance with the PRISMA guidelines. The primary focus was on outcomes and complications. A case of glial hyperplasia of the roots of the cauda equina directly related to stem cell injections performed abroad is also reported. The authors identified 14 publications (including a total of 147 patients) that met the search criteria. Three of the articles presented data for the same patient population with different durations of follow-up and were thus analyzed as a single study, reducing the total number of studies to 12. In these 12 studies, follow-up periods ranged from 6 months to 6 years, with 50% having a follow-up period of 1 year or less. Most studies reported favorable outcomes, although 36% used subjective measures. There was a tendency for pain relief to wane after 6 months to 2 years, with patients seeking a surgical solution. Only 1 study was a randomized controlled trial (RCT). There are still insufficient data to support stem cell injections for back pain. Additional RCTs with long-term follow-up are necessary before statements can be made regarding the efficacy and safety.