Can J Anaesth. 2013 Oct;60(10):1003-12. doi: 10.1007/s12630-013-0009-5. Epub 2013 Jul 27.

Brief review: piriformis syndrome: etiology, diagnosis, and management.

Jankovic D1, Peng P, van Zundert A.

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Abstract

In this narrative review, we aim to provide the pathophysiology and diagnostic criteria of thepiriformis syndrome (PS), an underdiagnosed cause of buttock and leg pain that can be difficult to treat. Based on existing evidence, frequencies of clinical features are estimated in patients reported to have PS. In view of the increasing popularity of ultrasound for intervention, the ultrasound-guided technique in the treatment of PS is described in detail.

A literature search of the MEDLINE® database was performed from January 1980 to December 2012 using the search terms e.g., " piriformis injection", " ultrasound guided piriformis injection", " botulinum toxin", "pain management", and different structures relevant in this review. There was no restriction on language.

A review of the medical literature pertaining to PS revealed that the existence of this entity remains controversial. There is no definitive proof of its existence despite reported series with large numbers of patients.

Piriformis syndrome continues to be a controversial diagnosis for sciatic pain. Electrophysiological testing and nerve blocks play important roles when the diagnosis is uncertain. Injection of local anesthetics, steroids, and botulinum toxin into the piriformis muscle can serve both diagnostic and therapeutic purposes. An ultrasound-guided injection technique offers improved accuracy in locating thepiriformis muscle. Optimizing the therapeutic approach requires an interdisciplinary evaluation of treatment.

梨状筋症状群250名を対象にした治療の縦断研究として貴重。

Ann Phys Rehabil Med. 2013 Jul;56(5):371-83. doi: 10.1016/j.rehab.2013.04.003. Epub 2013 Apr 25.

Piriformis muscle syndrome: diagnostic criteria and treatment of a monocentric series of 250 patients.

Michel F1, Decavel P, Toussirot E, Tatu L, Aleton E, Monnier G, Garbuio P, Parratte B.

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Abstract

Piriformis Muscle Syndrome (PMS) is caused by sciatic nerve compression in the infrapiriformis canal. However, the pathology is poorly understood and difficult to diagnose. This study aimed to devise a clinical assessment score for PMS diagnosis and to develop a treatment strategy.

Two hundred and fifty patients versus 30 control patients with disco-radicular conflict, plus 30 healthy control subjects were enrolled. A range of tests was used to produce a diagnostic score for PMS and an optimum treatment strategy was proposed.

A 12-point clinical scoring system was devised and a diagnosis of PMS was considered 'probable' when greater or equal to 8. Sensitivity and specificity of the score were 96.4% and 100%, respectively, while the positive predictive value was 100% and negative predictive value was 86.9%. Combined medication and rehabilitation treatments had a cure rate of 51.2%. Hundred and twenty-two patients (48.8%) were unresponsive to treatment and received OnabotulinumtoxinA. Visual Analogue Scale (VAS) results were 'Very good/Good' in 77%, 'Average' in 7.4% and 'Poor' in 15.6%. Fifteen of 19 patients unresponsive to treatment underwent surgery with 'Very good/Good' results in 12 cases.

The proposed evaluation score may facilitate PMS diagnosis and treatment standardisation. Rehabilitation has a major role associated in half of the cases with botulinum toxin injections.

Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Diagnosis; Nerf ischiatique; OnabotulinumtoxinA (BoNTA); Piriformis Muscle Syndrome; Sciatic nerve;Syndrome du muscle piriforme; Évaluation clinique

Ann Phys Rehabil Med. 2013 May;56(4):300-11. doi: 10.1016/j.rehab.2013.03.006. Epub 2013 Apr 30.

The piriformis muscle syndrome: an exploration of anatomical context, pathophysiological hypotheses and diagnostic criteria.

Michel F1, Decavel P, Toussirot E, Tatu L, Aleton E, Monnier G, Garbuio P, Parratte B.

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Abstract

The piriformis muscle syndrome (PMS) has remained an ill-defined entity. It is a form of entrapment neuropathy involving compression of the sciatic nerve by the piriformis muscle. Bearing this in mind, a medical examination is likely to be suggestive, as a classical range of symptoms corresponds to truncal sciatica with frequently fluctuating pain, initially in the muscles of the buttocks.

The piriformis muscle is biarticular, constituting a bridge in front of and below the sacroiliac joint and behind and above the coxo-femoral joint. It is essentially a lateral rotator but also a hip extensor, and assumes a secondary role as an abductor. Its action is nonetheless conditioned by the position of the homolateral coxo-femoral joint, and it can also function as a hip medial rotator, with the hip being flexed at more than 90°. The main clinical manoeuvres are derived from these types of biomechanical considerations. For instance, as it is close to the hip extensors, the piriformis muscle is tested in medial rotation stretching, in resisted contraction in lateral rotation. On the other hand, when hip flexion surpasses 90°, the piriformis muscle is stretched in lateral rotation, and we have consequently laid emphasis on the manoeuvre we have termed Heel Contra-Lateral Knee (HCLK), which must be prolonged several tens of seconds in order to successfully reproduce the buttocks-centred and frequently associated sciatic symptoms.

A PMS diagnosis is exclusively clinical, and the only objective of paraclinical evaluation is to eliminate differential diagnoses. The entity under discussion is real, and we favour the FAIR, HCLK and Freiberg stretching manoeuvres and Beatty's resisted contraction manoeuvre.

Can J Neurol Sci. 2012 Sep;39(5):577-83.

The diagnosis and management of Piriformis Syndrome: myths and facts.

Miller TA1, White KP, Ross DC.

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Abstract

Piriformis Syndrome (PS) is an uncommon, controversial neuromuscular disorder that is presumed to be a compression neuropathy of the sciatic nerve at the level of the piriformis muscle (PM). The diagnosis is hampered by a lack of agreed upon clinical criteria and a lack of definitive investigations such as imaging or electrodiagnostic testing. Treatment has focused on stretching, physical therapies, local injections, including botulinum toxin, and surgical management. This article explores the various sources of controversy surrounding piriformis syndrome including diagnosis, investigation and management. We conclude with a proposal for diagnostic criteria which include signs and symptoms, imaging, and response to therapeutic injections.