International Journal of Editorial Clinical Rheumatology Piriformis syndrome: Still unsolved issues

Piriformis Syndrome (PS) is an example What is the cause of piriformis syndrome? of extra-spinal due to compressive It is very difficult to make conclusive remarks neuropathy and can also be named as ‘deep about PS causation, as few publications are gluteal syndrome’, ‘pelvic outlet syndrome’ or addressing the question what may cause PS to ‘pseudo-sciatica’. Its prevalence among Low develop. Based on previous LoE articles, overuse (LBP) sufferers ranged between 0.3% of PM may be one of the most important reasons, and 36%; though the condition is prevalent in though most of the published works didn’t women, men also get the disorder [1]. In PS, precisely define PM overuse, rather hypothesized resultant localized gluteal and radiating LBP Md Abu Bakar Siddiq*1 & how it could be [1]. In our previous research, 2 is due to a spasmodic (PM) Johannes Jacobus Rasker we explained how the PM could get overused; 1 and compressed, irritated and stretched Sciatic Department of Physical Medicine and however the way of overusing PM was not Rheumatology, Brahmanbaria Medical Nerve (SN) behind the PM, respectively [1]. the same in all PS cases. So it is important to College, Bangladesh In clinical practice, sometimes regional gluteal define exactly the PM overuse pathophysiology 2Department of Rheumatology, Faculty of pain predominates in PS, whereas in some Behavioral Sciences, University of Twente, causing PS. Anomalous and / or The Netherlands patients, pain alike sciatica can be the presenting PM could contribute to PS features, though complaint confusing treating physician, leading *Author for correspondence: this idea is not confirmed by a recent large- [email protected] to incorrect treatment of the patients. There are scale collaborative radiologic study by Bertret two types of PS – primary and secondary; in and colleagues who didn’t find significant PS case of primary PS, the pathology is intrinsic prevalence in anomalous sciatic nerves compared to PM and or SN, however; in secondary PS, to normal [6]. Primary PS features could be due clinical features of associated disorders, like to spreading of myofascial trigger points within Lumbar (LSS), Leg-Length the PM. Direct gluteal trauma and a previous fall Discrepancy (LLD), fibromyalgia (FMS), fatty also may contribute to PS induction [1]. wallet, etc., may complicate the clinical picture [2]. Although 70 years have elapsed after the 1st Sometimes PS is synonymously, though clinical description of PS, we are yet to define incorrectly used with wallet ; in the precisely the PS pathophysiology, etiology, latter condition patients usually complain unique clinical features, confirmed diagnostic about sciatica-like pain upon persistent gluteal tests, best treatment modality, natural history compression due to an external fatty wallet and they rarely have deep seated regional gluteal of the disease, etc. [3]. Published studies with pain and in most cases they are negative for PS Lower level of Evidence (LoE) address various maneuvers and most importantly they improve aspects of PS and most of the study outcomes dramatically following radical ‘walletectomy’ are inconclusive. So, we take the privilege of [2]. However, both PS and wallet neuritis may addressing areas of PS that might interest both simultaneously be present in a single patient [7]. clinicians and researchers in the field. Leg-Length Discrepancy (LLD) may be associated Who is prone to get PS? with PS. In LLD, the resultant asymmetry of poses lower lumbosacral segment, pelvis Piriformis syndrome may affect people and deep gluteal structures including the PM irrespective of age, sex and occupation [1]. under intense stretch contributing to PS features. However, the disorder is apparently more According to the ACR 1990 classification common in women than in men because of criteria for Fibromyalgia syndrome (FMS), one the wider pelvis and Q-angle [4]. It appears the of the 18 tender areas resides at the insertion condition affects young people less frequently of PM tendon to the posterior aspect of greater [1]. Since the piriformis muscle is a deep seated trochanter of the femur that could get irritated structure, overuse of the lower back could pose depending on the risk factors causing more deep gluteal musculatures including PM under gluteal pain or persistent regional gluteal pain. sustained strain evoking clinical manifestations Because of inappropriately treated PS could suggestive for PS. In our previous studies, we induce the development of central sensitization reported higher PS frequency among Bangladeshi which may result in generalized body ache, for housewives; however day laborers, drivers and example FMS [8,9]. bankers also had the disorder [1]. PS may cause problems in dancers [5]. Despite these studies The double crush hypothesis postulates that still little is known about the prevalence of PS in axons compressed at one site could also get men and women and more research is required. compressed at another site and first came into

Int. J. Clin. Rheumatol. (2018) 13(6), 338-340 ISSN 1758-4272 338 Editorial Siddiq and Rasker

light by Upton and McComas in 1973. Based infective piriformis myositis fever is one of the on this hypothesis higher prevalence of cervical most common presenting feature and unique for is observed in patients with this purulent PS [11]. However, in finding more (CTS) than that of accurate diagnostic features we need to do more non-CTS [10]. Piriformis syndrome especially prospective, multicenter, longitudinal studies. in association with LSS could be an example of ‘double crush syndrome’, as SN nerve roots and What are confirmed diagnostic tests for PS? SN get compressed at lumbar spine and extra- There is no single confirmatory test for PS spinal levels (behind PM), respectively; however diagnosis. It’s a disorder of exclusion of other requires further exploration. clinical mimicries, namely LSS, cyclical sciatica, Piriformis pyomyositis due to an invading FMS, deep seated gluteal abscess, wallet neuritis, infectious agent, such as Staphylococcus aureus, pelvis tumor, Pott’s disease, hip arthritis, superior group A. Streptococcus, B. melitensis could cluneal nerve disorder, osteitis condensans illii, cause severe gluteal pain with fever and require sacroiliitis, etc. [2,11-12,14]. Clinical maneuvers different treatment approach than usual for PS with variable sensitivity and specificity may [11,12]. As of today, published papers regarding identify whether PM is involved in the presenting etiology and association of PS are scarce and gluteal pain; examples of these maneuvers are mostly based on poor study samples, warranting the Piriformis sign, Pace sign, FAIR (Flexion, more research. Adduction, Internal Rotation) test, Freiberg test, and Beatty test. Digital per-rectal examination What are the common diagnostic features revealing pain, especially when the index finger of PS? glides over the affected side of the pelvic wall is Regional and or radiating gluteal pain according suggestive of PS [1]. The positive Straight Leg to the sciatic nerve distribution is the mostly Raising (SLR) test signifies lumbar nerve roots seen pattern in PS, often mimicking true lumbar pathology and usually is negative in PS, however spinal sciatica. In PS, gluteal pain may aggravate in acute PS, SLR could be positive, though based during longstanding sitting, especially on hard on lower LoE. Besides this clinical information, surface and is associated with tingling, numbness MRI/CT scanning of pelvis could approximate or burning sensations on the outer aspect of the PM pathology and its extension. MRI also ipsilateral leg. Pain also aggravates with walking, could exclude associated pelvis and lumbar spine lying on the affected side, during attempted pathology. Moreover, nerve conduction velocity standing from sitting position or squatting, and electromyogram of the affected gluteal however, in chronic cases ambulation may region and ipsilateral lower limb can differentiate provide some pain relief [1]. The most important between myopathy and neuropathy - true peculiarity of PS diagnosis are its ‘inconsistent spinal sciatica from extra-spinal sciatica [1,7]. clinical manifestations’ and one of the most Taheri et al. describe that the musculoskeletal important reasons of why PS is underdiagnosed ultrasonography has higher sensitivity in and remains undiagnosed for a long time; In diagnosing hypoechoeic myofascial trigger some cases PS features are completely inseparable points and appears to be useful in diagnosing from those of spinal sciatica, especially during piriformis myofascial pain syndrome, however an acute attack, a reason why PS can be over- its reliability should be tested in a longitudinal diagnosed [1]. In an excellent literature review study with large number study participants [15]. regarding PS clinical manifestations, Hopayian So in terms of confirmed diagnostic test for PS and colleagues mentioned the following four we are yet to have the most appropriate one. features that are common in PS – Is PS life threatening? • Buttock pain, It is very difficult to provide a straightforward • External tenderness over the greater sciatic answer of this question as studies addressing the notch, fact are lacking. Most published works did not • Aggravation of the pain through sitting and highlight this part of PS and rather mentioned it as a benign neuromuscular condition without • Augmentation of the pain with maneuvers any significant comorbid consequences, although that increase PM tension [3]. it may be very painful and incapacitating. As of Gluteal atrophy can be a complication in chronic now, no published report document mortality cases [1]. Even though SN gets compressed issues associated with PS. However, recently, behind PM, SN deficit is not common in the piriformis pyomyositis is being considered as a disorder, but lower limbs weakness because of life threatening cause of PS and may be fatal when SN neuropathy could be seen in bilateral PS as proper attention has not been given in terms of reported in a case report by Moon et al. [13]. In timely diagnosis and treatment [11,12]. In a

339 Int. J. Clin. Rheumatol. (2018) 13(6) Piriformis syndrome: Still unsolved issues Editorial published case report Gaughan and colleagues Europ. J. Orthop. Surg. Traumatol. 27(2), 193–203 hypothesized that transient intravenous cannula (2016). induced septicemia could complicate piriformis 2. Siddiq AB. Piriformis syndrome and wallet neuritis: pyomyositis due to seeding of the infectious Are They the same?Cureus. 10(5), e2606 (2018). agent into the PM and generated gluteal pain 3. Hopayian K, Song F, Riera R et al. The clinical with fever, treated successfully with antibiotics features of the piriformis syndrome: a systemic [11]. Jeon et al. documented PS features, gluteal review. Eur. Spine. J. 19(12), 2095–2101 (2010). atrophy and ipsilateral lower limb weakness due to radiotherapy induced scarring of the respective 4. Boyajian-O’Neil LA, McClain RL, Coleman MK PM compressing SN vicinity in cervical cancer et al. Diagnosis and management of piriformis J. Am. [16]. Lower limb weakness is reportedly possible syndrome: an osteopathic approach. Osteopath. Assoc. 108(11), 657–664 (2008). in cases of bilateral PS [13]. However, all these study outcomes based on lower LoE and further 5. Martinez N, Mandel S, Peterson JR. Neurologic research with large number of PS could provide causes of in dancers. J. Dance. Med. Sci. further valuable information. 15,157–159 (2011). What are the most effective treatments for 6. Bartret AL, Beaulieu CF, Lutz AM. Is it painful to be different? Sciatic nerve anatomical variants on PS? MRI and their relationship to piriformis syndrome. Before treating PS, it is of paramount importance Eur. Radiol. 28(11), 4681 (2018). to classify it. In case of primary PS, treatment 7. Siddiq AB, Jahan I, Alpha M. Wallet neuritis – An should focus on intrinsic PM pathology only, example of peripheral sensitization. Curr. Rheum. however secondary PS deserves treatment Rev. 13, 999 (2017). for associated conditions. Commonly used 8. Wolfe F, Smythe HA, Yunus MB et al. The pharmacological and non-pharmacological American College of Rheumatology 1990 criteria modalities that are found to be useful in PS: Non- for the classification of fibromyalgia. Report of the Steroidal Anti-Inflammatory Drugs (NSAIDs), Multicenter Criteria Committee. Arthritis. Rheum. analgesics (including adjuvants), piriformis 33, 160–172 (1990). exercise, activities of daily living 9. Siddiq MA, Khasru MR, Rasker JJ. Piriformis modification; however, intra-lesional steroid- syndrome in fibromyalgia- clinical diagnosis and combination and -A successful treatment. Case Rep. Rheumatol. 2014, injections are reportedly most effective in the 893836 (2014). disorder, but we are yet in the dark to know exactly how frequent and how long patients with 10. Schmid AB, Coppieters MW. The double crush PM should receive these sort of interventions, syndrome revisited - A Delphi study to reveal current expert views on mechanisms underlying in order to experience complete pain relief [1]. dual nerve disorders. Manual. Therapy. 16, 557–562 PS secondary to PM infection doesn’t suit above (2011). modalities, judicial selection of antibiotics is indicated a [11,12]. Sometimes exploration of 11. Gaughan E, Eogan M, Holohan M. Pyomyositis PM for surgical drainage, PM tendon resection after vaginal delivery. BMJ. Case Rep. 2011, or sciatic nerve neurolysis appears appropriate. bcr0420114109 (2011). So, best treatment approach for PS depends on 12. Kraniotis P, Marangos M, Lekkou A et al. Brucellosis myriad factors and there is no rule of thumb, for presenting as piriformis myositis: a case report. J. each individual a personal approach should be Med. Case. Rep. 5(1), 125 (2011). applied [1]. 13. Moon HB, Nam KY, Kwon BS et al. Leg weakness In conclusion, piriformis syndrome is an caused by bilateral piriformis syndrome: a case report. example of pseudo-sciatica with varying clinical Ann. Rehabil. Med. 39(6), 1042–1046 (2015). manifestations. Our current knowledge about its 14. Siddiq AB. Superior cluneal nerve disorder: how pathophysiology, epidemiology, causation, risks often do we consider? J. Recent. Adv. Pain. 2, 4–5 association, clinical presentations, diagnosis, (2016). treatment, and consequences is insufficient and 15. Taheri N, Okhovatian F, Rezasoltani A et al. most importantly they are based on inconclusive Ultrasonography in diagnosis of myofascial pain study outcomes. So, future researchers could syndrome and reliability of novel ultrasonic indexes explore them and could provide more consistent of upper trapezius muscle. Ortopedia. Traumatologia. information concerning piriformis syndrome. Rehabilitacja. 18(2), 149–154 (2016). References 16. Jeon SY, Moon HS, Jung Han YJ et al. Post- radiation piriformis syndrome in a cervical cancer 1. Siddiq AB, Hossain S, Khasru MR et al. Piriformis patient -a case report. Korean. J. Pain. 23(1), 88–91 syndrome: a case series of 31 Bangladeshi people. (2010).

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