What is the placebo effect on burning mouth syndrome? A review

This summary is based on the article published in Oral Diseases: Placebo effect in burning mouth syndrome: a systematic review (April 2014)

M Kuten-Shorrer, JM Kelley, ST Sonis, NS Treister

Context

• Burning mouth syndrome (BMS), also referred to as stomatodynia, is a chronic pain condition that manifests as a burning dysesthesia in the oral cavity, generally localized to the tongue, but that also frequently affects the inner aspect of the lips and the anterior hard palate. ¹
• BMS is defined by the absence of any local or systemic causes such as candidiasis, hyposalivation, nutritional deficiencies, or uncontrolled diabetes. Additional associated features include xerostomia, dysgeusia, and other oral dysesthesias. ²
• The pathophysiology of BMS is poorly understood and likely involves interactions between local, systemic, and/or psychogenic factors. ³
• Given the subjective nature of BMS symptoms and the subsequent reliance on patient-reported outcomes, a better understanding of the placebo effect in BMS is critical in the assessment of treatment response and future study design.

Purpose of the study

The objective of this study was to evaluate the placebo effect in published randomized controlled clinical trials of therapies for BMS.

Key Findings

• Recent advances from behavioral, psychophysiological, and neuroimaging methods demonstrate that the placebo effect is a ‘real’ neurobiological phenomenon and that the altered pain experience during placebo analgesia results from active inhibition of nociceptive activity. ⁴ Specifically, placebo analgesia is thought to be regulated, at least in part, by endogenous opioid mechanisms.
• In this systematic review of twelve RCTs evaluating different treatments for BMS, the calculated mean placebo response as a fraction of drug response was 72%. In other words, on average, treatment with placebos produced a response that was 72% as large as the response to active drugs.
• In most cases, the placebo used was cellulose in the form of oral pills, and in all six studies reporting a positive placebo response, the therapy evaluated, as well as the placebo, was administered systemically.
• Despite limitations in the studies reviewed, the magnitude of the placebo response in BMS appears to be quite robust.

References

1. Grushka M (1987). Clinical features of burning mouth syndrome. Oral Surg Oral Med Oral Pathol 63: 30–36.
2. Scala A, Checchi L, Montevecchi M, Marini I, Giamberardino MA (2003). Update on burning mouth syndrome: overview and patient management. Crit Rev Oral Biol Med 14: 275–291.
3. Patton LL, Siegel MA, Benoliel R, De Laat A (2007). Management of burning mouth syndrome: systematic review and management recommendations. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 103(Suppl: S39): e1–e13.
4. Meissner K, Bingel U, Colloca L, Wager TD, Watson A, Flaten MA (2011). The placebo effect: advances from different methodological approaches. J Neurosci 31: 16117–16124.