By David Fiore, MD
Professor of Family Medicine, University of Nevada, Reno
Dr. Fiore reports no financial relationships relevant to this field of study.
SYNOPSIS: An Australian study of 207 patients suffering from acute and chronic clinically diagnosed sciatica did not find that treatment with pregabalin for eight weeks reduced pain at eight or 52 weeks.
SOURCE: Mathieson S, Maher CG, McLachlan AJ, et al. Trial of pregabalin for acute and chronic sciatica. N Engl J Med 2017;376:1111-1120.
Sciatica, pain radiating down the leg (usually) associated with low back pain, is a common ailment, with a prevalence of 2-14%.1 It is caused most commonly by nerve root irritation from protruding disk material, causing a combination of pain, paresthesias, and weakness down the affected leg.2 Acute sciatica can be debilitating but often resolves without treatment, making it challenging to assess the efficacy of treatment for acute sciatica. Chronic sciatica is less common but more challenging to manage, with few proven successful treatment options. A Cochrane Review of nonsteroidal anti-inflammatory drugs (NSAIDs) found 10 studies with low to very low quality evidence that NSAIDs provided better “global improvement” than placebo, but did not provide more pain relief, at the cost of more side effects. A meta-analysis of only five studies on exercise found some evidence for benefit of varying kinds of exercise in limiting the duration of sciatica.3
Pregabalin has been established as a modestly effective medication for neuropathic pain.4 Since the pain from sciatica likely is a combination of both nociceptive (due to tissue damage or direct irritation of nociceptors) and neuropathic (nervous system injury or irritation), it is possible that pregabalin can relieve the neuropathic component of sciatic pain. As the authors of this paper noted, one prior study on pregabalin for sciatica had significant methodological flaws limiting the interpretation of their (moderately positive) results.5 The current study evaluated pain relief using multiple measures on 207 patients with acute or chronic sciatica. The study was well-designed, with patient randomization and adequate blinding. Patients had their medication (or placebo) dose increased from 75 mg twice a day to 300 mg twice a day over four weeks. Leg pain was evaluated at eight weeks (primary outcome) and 52 weeks (secondary time point for the primary outcome). Disability, absenteeism, quality of life, and healthcare use were measured as secondary endpoints. The authors found no benefit of treatment with pregabalin compared to placebo for any of the measured outcomes at either eight weeks or 52 weeks.
COMMENTARY
Although it’s disappointing that this study did not find that pregabalin is effective for sciatica, the results are not surprising. Pregabalin is only moderately effective for conditions such as diabetic neuropathy and fibromyalgia, which are considered classic neuropathic pain syndromes. Sciatica is, at best, only partially neuropathic, and it’s likely that acute sciatica primarily is due to injury resulting in nociceptive pain. Although this study was well-designed, it contains a major flaw: combining acute and chronic sciatica. As we should now be aware, given all the attention to pain management and the “opioid crisis,” acute and chronic pain are two very different beasts and must be treated differently. Since most of the patients in this study presented with acute sciatica (80%) and only 21% (placebo) to 34% (pregabalin) experienced neuropathic pain (as determined by the painDETECT questionnaire), it is not surprising that pregabalin was not effective. However, buried in the study, is good news: The pain and disability scores in both groups improved quickly (most improvement in the first four to six weeks). Unfortunately, the authors did not provide the data to assess the degree or significance of this improvement.
The bottom line from this study seems to be that there is no role for pregabalin in the management of acute sciatica and that we just don’t know if it’s helpful for patients with chronic sciatica. Given that pregabalin is not without significant side effects, and that exercise has been validated as effective for low back pain and sciatica, I will continue to push exercise as the primary treatment for sciatica with or without low back pain. For acute sciatica, it is reasonable to give a short course of medication for pain relief along with physical therapy and a “tincture of time.”
REFERENCES
- Pinto RZ, Maher CG, Ferreira ML, et al. Drugs for relief of pain in patients with sciatica: Systematic review and meta-analysis. BMJ 2012;344:e497.
- Ropper AH, Zafonte RD. Sciatica. N Engl J Med 2015;372:1240-1248.
- Rasmussen-Barr E, Held U, Grooten WJ, et al. Non-steroidal anti-inflammatory drugs for sciatica. An updated Cochrane review. Spine 2017. doi: 10.1097/BRS.0000000000002092. [Epub ahead of print].
- Moore RA, Straube S, Wiffen PJ, et al. Pregabalin for acute and chronic pain in adults. Cochrane Database Syst Rev 2009 Jul 8;(3):CD007076. doi: 10.1002/14651858.CD007076.pub2.5.
- Baron R, Freynhagen R, Tölle TR, et al. The efficacy and safety of pregabalin in the treatment of neuropathic pain associated with chronic lumbosacral radiculopathy. Pain 2010;150:420-427.
An Australian study of 207 patients suffering from acute and chronic clinically diagnosed sciatica did not find that treatment with pregabalin for eight weeks reduced pain at eight or 52 weeks.
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