Study Title: The clinical features of piriformis syndrome: A systematic review
Authors: Hopayian K, Song F, Riera R and Sambandan S
Publication Information: European Spine Journal, 2010; 19: 2095-2109.
Study Title: The clinical features of piriformis syndrome: A systematic review
Authors: Hopayian K, Song F, Riera R and Sambandan S
Publication Information: European Spine Journal, 2010; 19: 2095-2109.
Background Information
Piriformis syndrome (PS) is classically referred to as sciatica resulting from compression of the sciatic nerve by the pirformis muscle. This clinical entity was described more than 70 years ago and is frequently discussed and diagnosed, despite a paucity of scientific literature to help us specifically define, identify and treat it. There is controversy surrounding the existence of this condition1, as well as whether it is over-diagnosed2 or under-diagnosed.3 In addition to sciatica, patients with piriformis syndrome can present with associated intolerance to sitting, painful hip motion, dyspareunia or painful bowel movements.
Proposed pathoanatomical mechanisms for piriformis syndrome include:
- contracture or spasm in the piriformis muscle (after some sort of trauma?);
- prolonged external pressure;
- predisposition to nerve compression due to congenital variations in the sciatic nerve, its course (e.g., piercing the muscle) or the piriformis itself (e.g., bifid piriformis muscle creating compression of the sciatic nerve between the two bellies);
- overuse or hypertrophy of the piriformis;
- the authors did not include but I will add – changes in the fascia of the posterior hip musculature resulting in fibrosis or adhesions that could frictionally irritate the sciatic nerve
Conclusions and practical applications
The authors appropriately mention that the research on piriformis syndrome is at an impasse. High-quality clinical trials are unlikely to be performed on this syndrome until two conditions are met: a high enough prevalence of the condition itself, and a reliable and valid method of diagnosing it, are arrived at. We currently have no diagnostic “gold standard” for this condition.
For now, the take-home message is that four features appear to be the most common in piriformis syndrome:
- buttock pain
- aggravation of sciatica with sitting
- external tenderness over the greater sciatic notch
- augmentation of pain with manoeuvres that place the piriformis under tension.
Even if the research on certain conditions we treat is not complete, it is important to maintain our awareness of the state of the literature. The authors suggest that future research is required to elucidate whether the features listed above occur more frequently in patients without a spinal cause of sciatica (this would help us further distinguish PS from other forms of sciatica), as well as whether these findings are consistently accompanied by any deficiencies on objective measures of nerve trunk compression (such as imaging or nerve conduction).
Dr. Shawn Thistle is the founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners to integrate current, relevant scientific evidence into their practice. Shawn graduated from CMCC and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider. For more information about the Research Review Service, visit www.researchreviewservice.com.
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