Piriformis syndrome: diagnosis, treatment, and outcome--a 10-year study

Treatment of an individual with piriformis syndrome focusing on hip muscle strengthening and movement reeducation: a case report

STUDY DESIGN

Case report.

OBJECTIVE

To describe an alternative treatment approach for piriformis syndrome using a hip muscle strengthening program with movement reeducation.

BACKGROUND

Interventions for piriformis syndrome typically consist of stretching and/or soft tissue massage to the piriformis muscle. The premise underlying this approach is that a shortening or "spasm" of the piriformis is responsible for the compression placed upon the sciatic nerve.

CASE DESCRIPTION

The patient was a 30-year-old male with right buttock and posterior thigh pain for 2 years. Clinical findings upon examination included reproduction of symptoms with palpation and stretching of the piriformis. Movement analysis during a single-limb step-down revealed excessive hip adduction and internal rotation, which reproduced his symptoms. Strength assessment revealed weakness of the right hip abductor and external rotator muscles. The patient's treatment was limited to hip-strengthening exercises and movement reeducation to correct the excessive hip adduction and internal rotation during functional tasks.

OUTCOMES

Following the intervention, the patient reported 0/10 pain with all activities. The initial Lower Extremity Functional Scale questionnaire score of 65/80 improved to 80/80. Lower extremity kinematics for peak hip adduction and internal rotation improved from 15.9 degrees and 12.8 degrees to 5.8 degrees and 5.9 degrees, respectively, during a step-down task.

DISCUSSION

This case highlights an alternative view of the pathomechanics of piriformis syndrome (overstretching as opposed to overshortening) and illustrates the need for functional movement analysis as part of the examination of these patients.

LEVEL OF EVIDENCE

Therapy, level 4.

[The main tunnel syndromes]

Several tunnel syndromes are responsible for substantial functional impairment. The diagnosis has to be made and treatment is most often very simple--nerve decompression--with excellent results. Of these syndromes, the most common are median and ulnar tunnel syndromes of the wrist and ulnar tunnel syndrome of the elbow, but other syndromes must be identified at the risk of therapy failure due to poorly adapted treatment. Finally, good knowledge of this pathology must lead to prevention of the iatrogenic forms (sequelae of inguinal hernia treatment, ileac crest graft harvesting) by educating all surgeons interested in peripheral nerve surgery.

PIRIFORMIS SYNDROME

OBJECTIVE

Herein, we provide an unbiased review of piriformis syndrome (PS), a highly controversial syndrome for which no consensus exists regarding diagnostic criteria or pathophysiology.

METHODS

A review of the literature in the English language.

RESULTS

A nonpartisan 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.

CONCLUSION

PS remains a controversial diagnosis for sciatic pain. The debate regarding the clinical significance of PS remains active. Nonetheless, there may be a subset of patients in whom the piriformis muscle is a source of pain. The syndrome should be considered in the differential diagnosis of patients with unilateral lower extremity pain.

[Buttocks sciatic pain]

Confusion between radicular and nerve trunk syndrome is not rare. With sciatic pain, any nerve trunk pain or an atypical nerve course should suggest nerve trunk pain of the sciatic nerve in the buttocks. The usual reflex with sciatic pain is vertebral-radicular conflict. The absence of spinal symptoms and the beginning of pain in the buttocks and not in the lumbar region should reorient the etiologic search. Once a tumor of the nerve trunk has been ruled out (rarely responsible for pain other than that caused by tumor pressure), a myofascial syndrome should be explored searching for clinical, electrophysiological, and radiological evidence of compression of the sciatic trunk by the piriform muscle but also the obturator internus muscle. Hamstring syndrome may be confused with this syndrome. Treatment is first and foremost physical therapy. Failures can be treated with classical CT-guided infiltrations with botulinum toxin. Surgery should only be entertained when all these solutions have failed.

Piriformis syndrome, diagnosis and treatment

Piriformis syndrome (PS) is an uncommon cause of sciatica that involves buttock pain referred to the leg. Diagnosis is often difficult, and it is one of exclusion due to few validated and standardized diagnostic tests. Treatment for PS has historically focused on stretching and physical therapy modalities, with refractory patients also receiving anesthetic and corticosteroid injections into the piriformis muscle origin, belly, muscle sheath, or sciatic nerve sheath. Recently, the use of botulinum toxin (BTX) to treat PS has gained popularity. Its use is aimed at relieving sciatic nerve compression and inherent muscle pain from a tight piriformis. BTX is being used increasingly for myofascial pain syndromes, and some studies have demonstrated superior efficacy to corticosteroid injection. The success of BTX in treating PS supports the prevailing pathoanatomic etiology of the condition and suggests a promising future for BTX in the treatment of other myofascial pain syndromes.

Piriformis and related entrapment syndromes: diagnosis & management

Highly reliable evidence for piriformis syndrome and other pelvic sciatic syndromes arises from three major categories of data: magnetic resonance neurography diagnostic imaging, open magnetic resonance-guided injection studies, and patient treatment outcome studies. This article reviews the evidence in each category. This is part of a Point-Counterpoint discussion with Dr. Robert Tiel's presentation of "Myth and Fallacy".

Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria)

AIMS

The diagnosis of pudendal neuralgia by pudendal nerve entrapment syndrome is essentially clinical. There are no pathognomonic criteria, but various clinical features can be suggestive of the diagnosis. We defined criteria that can help to the diagnosis.

MATERIALS AND METHODS

A working party has validated a set of simple diagnostic criteria (Nantes criteria).

RESULTS

The five essentials diagnostic criteria are: (1) Pain in the anatomical territory of the pudendal nerve. (2) Worsened by sitting. (3) The patient is not woken at night by the pain. (4) No objective sensory loss on clinical examination. (5) Positive anesthetic pudendal nerve block. Other clinical criteria can provide additional arguments in favor of the diagnosis of pudendal neuralgia. Exclusion criteria are also proposed: purely coccygeal, gluteal, or hypogastric pain, exclusively paroxysmal pain, exclusive pruritus, presence of imaging abnormalities able to explain the symptoms.

CONCLUSION

The diagnosis of pudendal neuralgia by pudendal nerve entrapment syndrome is essentially clinical. There are no specific clinical signs or complementary test results of this disease. However, a combination of criteria can be suggestive of the diagnosis.

Accuracy of ultrasound-guided versus fluoroscopically guided contrast-controlled piriformis injections: a cadaveric study

OBJECTIVE

The purpose of this study was to compare the accuracy of ultrasound-guided piriformis injections with fluoroscopically guided contrast-controlled piriformis injections in a cadaveric model.

METHODS

Twenty piriformis muscles in 10 unembalmed cadavers were injected with liquid latex using both fluoroscopically guided contrast-controlled and US-guided injection techniques. All injections were performed by the same experienced individual. Two different colors of liquid latex were used to differentiate injection placement for each procedure, and the injection order was randomized. The gluteal regions were subsequently dissected by an individual blinded to the injection technique. Colored latex seen within the piriformis muscle, sheath, or both was considered an accurate injection.

RESULTS

Nineteen of 20 ultrasound-guided injections (95%) correctly placed the liquid latex within the piriformis muscle, whereas only 6 of the 20 fluoroscopically guided contrast-controlled injections (30%) were accurate (P = .001). The liquid latex in 13 of the 14 missed fluoroscopically guided contrast-controlled piriformis injections and the single missed ultrasound-guided injection was found within the gluteus maximus muscle. In the single remaining missed fluoroscopically guided contrast-controlled piriformis injection, the liquid latex was found within the sciatic nerve.

CONCLUSIONS

In this cadaveric model, ultrasound-guided piriformis injections were significantly more accurate than fluoroscopically guided contrast-controlled injections. Despite the use of bony landmarks and contrast, most of the fluoroscopically attempted piriformis injections were placed superficially within the gluteus maximus. Clinicians performing piriformis injections should be aware of the potential pitfalls of fluoroscopically guided contrast-controlled piriformis injections and consider using ultrasound guidance to ensure correct needle placement.

Low-Dose Botulinum Toxin Type A for the Treatment of Refractory Piriformis Syndrome

STUDY OBJECTIVES

To evaluate the efficacy of a single, low-dose injection of botulinum toxin type A in relieving pain in Korean patients with piriformis syndrome resistant to conventional therapy, and to assess the drug's influence on these patients' quality of life.

DESIGN

Prospective, single-site, open-label trial.

SETTING

Rehabilitation medicine clinic in Seoul, Korea.

PATIENTS

Twenty-nine patients with a confirmed diagnosis of chronic piriformis syndrome and 82 age- and sex-matched healthy subjects were enrolled from April 1, 2003-February 28, 2004. Intervention. In 20 of the patients, botulinum toxin type A 150 U was injected using computed tomographic guidance into the affected unilateral piriformis muscle. The other nine patients served as active controls and received an injection of dexamethasone 5 mg and 1% lidocaine. The healthy subjects did not receive any injection.

MEASUREMENTS AND MAIN RESULTS

The patients' pain at baseline and at 4, 8, and 12 weeks after treatment was rated by using a numeric rating scale. Health-related quality of life was assessed by using the validated Korean version of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) at baseline and at 4 weeks of treatment. Healthy subjects also completed the SF-36 at baseline. Pain intensity scores were significantly lower at 4, 8, and 12 weeks after treatment than at baseline (p<0.0001). Baseline scores from the SF-36 subscales, including those for physical functioning (p<0.0001), role physical (p<0.0001), bodily pain (p<0.0001), general health (p<0.0001), vitality (p<0.0001), and social functioning (p<0.002), were significantly lower in the patients than in the healthy subjects. Four weeks after treatment, physical functioning (p=0.003), role physical (p=0.021), bodily pain (p=0.016), general health (p=0.013), vitality (p=0.031) and social functioning (p=0.035) improved significantly from baseline in the patients. However, at 4 weeks, patients in the active control group were withdrawn from the study because their pain did not improve, and continuation without further medical care was considered unethical.

CONCLUSION

A low dose of botulinum toxin type A relieved pain and improved quality of life in patients with refractory piriformis syndrome.

Ultrasound-Guided Piriformis Injection: Technique Description and Verification

Piriformis injections are commonly used in the evaluation and treatment of patients presenting with buttock pain syndromes. Because of its small size, deep location, and relation to adjacent neurovascular structures, the piriformis is traditionally injected by using electromyographic, fluoroscopic, computed tomographic, or magnetic resonance imaging guidance. This report describes and verifies a technique for performing ultrasound-guided piriformis injections. Ultrasound offers several advantages over traditional imaging approaches, including accessibility, compact size, lack of ionizing radiation exposure, and direct visualization of neurovascular structures. With appropriate training and experience, interested physiatrists can consider implementing ultrasound-guided piriformis injections into their clinical practices.

Measurement of Motor Nerve Conduction Velocity of the Sciatic Nerve in Patients With Piriformis Syndrome: A Magnetic Stimulation Study

OBJECTIVE

To assess the motor nerve conduction of the sciatic nerve by a magnetic stimulation method in patients with piriformis syndrome.

DESIGN

Prospective study.

SETTING

An electrodiagnostic laboratory in a university hospital.

PARTICIPANTS

Twenty-three patients with piriformis syndrome and 15 healthy persons for control.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Motor nerve conduction velocity (MNCV) of the sciatic nerve was measured at the gluteal segment by magnetic stimulation proximally at L5 and S1 roots and distally at sciatic nerve at gluteal fold and recording at the corresponding muscles. Diagnostic sensitivities were measured in the magnetic stimulation method and the conventional nerve conduction, long latency reflex, and needle electromyography studies.

RESULTS

The mean MNCV of the sciatic nerve +/- standard deviation at the gluteal segment in L5 component was 55.4+/-7.8 m/s in patients with piriformis syndrome, which was slower than the mean value of 68.1+/-10.3 m/s obtained in healthy controls (P=.014). The MNCV of the sciatic nerve in S1 component showed no significant difference between the patients and controls (P=.062). A negative relation was found between the disease duration and the MNCV values of sciatic nerves in patients with piriformis syndrome (r=-.68, P<.01). The diagnostic sensitivity by magnetic stimulation is .467.

CONCLUSIONS

Magnetic nerve stimulation provides a painless, noninvasive, and objective method for evaluation of sciatic nerve function in patients with piriformis syndrome.

Possible generators of retrotrochanteric gluteal and thigh pain: the gemelli-obturator internus complex

OBJECTIVE

To investigate and correlate the anatomy of the gluteal region with the clinical findings of retrotrochanteric and posterior thigh pain, as seen in clinical chiropractic practice, and describe potential treatment options.

METHODS

A descriptive gross anatomic study is correlated to a case presentation of a patient with deep persistent aching pain in the retrotrochanteric region of the left hip and upper posterolateral thigh.

RESULTS

The structures that are located in the same location as the retrotrochanteric pain described by the patient are the gemelli-obturator internus muscle complex and associated bursae.

CONCLUSIONS

In patients with persistent gluteal and sciatica-like pain, especially when centered in the retrotrochanteric region, the gemelli-obturator internus muscle complex and associated bursae should be considered as a possible source of the pain.

Musculoskeletal Causes of Chronic Pelvic Pain: A Systematic Review of Diagnosis: Part I*

Chronic pelvic pain in women has multifactorial etiology, but pelvic musculoskeletal dysfunction is not routinely evaluated as a cause by gynecologists. Whether diagnostic tests can reliably identify women with such conditions is unclear. The objective of this study was to determine the level of support in the literature for diagnostic tests of pelvic musculoskeletal problems. We used a set of key words pertaining to pain and the pelvic musculoskeletal structures to initially review the PUBMED database. Study inclusion was restricted to English-language publications that reported a patient-related chronic pelvic pain diagnostic test. Relevant bibliographies were also searched, and outside consultation with a pain researcher was sought to identify additional needed studies. For each selected article, 2 investigators separately summarized relevant data on study characteristics, patient profiles, and test efficacy. Discrepancies were resolved by discussion. Six diagnostic studies were identified that met entry criteria. No gold standard diagnostic tests exist for pelvic musculoskeletal problems, and the methodologic quality of available studies is low. Studies defining such clinically useful tests are needed to further refine a rational approach to chronic pelvic pain management.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe the paucity of evidence-based literature and valid consensus of diagnostic criteria and modalities in defining the musculoskeletal causes of chronic pelvic pain in women, to recall that there is no gold standard diagnostic test for pelvic musculoskeletal problems, and to recall that the statistical evaluation of the methods described were wanting.

Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance neurography and interventional magnetic resonance imaging with outcome study of resulting treatment

Object. Because lumbar magnetic resonance (MR) imaging fails to identify a treatable cause of chronic sciatica in nearly 1 million patients annually, the authors conducted MR neurography and interventional MR imaging in 239 consecutive patients with sciatica in whom standard diagnosis and treatment failed to effect improvement.

Methods. After performing MR neurography and interventional MR imaging, the final rediagnoses included the following: piriformis syndrome (67.8%), distal foraminal nerve root entrapment (6%), ischial tunnel syndrome (4.7%), discogenic pain with referred leg pain (3.4%), pudendal nerve entrapment with referred pain (3%), distal sciatic entrapment (2.1%), sciatic tumor (1.7%), lumbosacral plexus entrapment (1.3%), unappreciated lateral disc herniation (1.3%), nerve root injury due to spinal surgery (1.3%), inadequate spinal nerve root decompression (0.8%), lumbar stenosis (0.8%), sacroiliac joint inflammation (0.8%), lumbosacral plexus tumor (0.4%), sacral fracture (0.4%), and no diagnosis (4.2%).

Open MR—guided Marcaine injection into the piriformis muscle produced the following results: no response (15.7%), relief of greater than 8 months (14.9%), relief lasting 2 to 4 months with continuing relief after second injection (7.5%), relief for 2 to 4 months with subsequent recurrence (36.6%), and relief for 1 to 14 days with full recurrence (25.4%). Piriformis surgery (62 operations; 3-cm incision, transgluteal approach, 55% outpatient; 40% with local or epidural anesthesia) resulted in excellent outcome in 58.5%, good outcome in 22.6%, limited benefit in 13.2%, no benefit in 3.8%, and worsened symptoms in 1.9%.

Conclusions. This Class A quality evaluation of MR neurography's diagnostic efficacy revealed that piriformis muscle asymmetry and sciatic nerve hyperintensity at the sciatic notch exhibited a 93% specificity and 64% sensitivity in distinguishing patients with piriformis syndrome from those without who had similar symptoms (p < 0.01).

Evaluation of the nerve beyond the proximal foramen provided eight additional diagnostic categories affecting 96% of these patients. More than 80% of the population good or excellent functional outcome was achieved.

Piriformis syndrome: Correlation of muscle morphology with symptoms and signs

OBJECTIVE

To determine the relation of symptoms and pain provocation tests to abnormal piriformis morphology among people with chronic buttock pain.

DESIGN

Each of 2 clinical symptoms and 2 clinical signs were compared with the abnormal morphology found on ultrasound. The pain-free side was used as an internal control.

SETTING

A tertiary referral center.

PARTICIPANTS

A series of 27 consecutive patients (26 women, 1 man; average age, 48 y) with chronic low lumbosacral or buttock pain, who presented to a musculoskeletal clinic over a 12-month period, underwent ultrasound assessment of piriformis muscle morphology. Four patients were excluded because their body mass index was in excess of 30 kg/m 2 .

INTERVENTION

The symptomatic piriformis muscle was injected with bupivacaine after pain was assessed on a visual analog scale (VAS), using the resisted abduction test.

MAIN OUTCOME MEASURE

A 70% reduction of pain on the VAS was considered positive for pain in the piriformis muscle.

RESULTS

Odds ratios (ORs) and 95% confidence intervals were calculated comparing each of the signs and symptoms with normal morphology. The highest ORs were found for pain on walking up inclines (10.8), referred pain (5.3), and pain on needling the piriformis muscle (6.0).

CONCLUSIONS

This study did not provide a criterion standard for the diagnosis of piriformis syndrome, but it did support the syndrome as a contributing factor in chronic buttock pain and very low back pain.

The level of the sciatic nerve division and its relations to the piriform muscle

Background. The sciatic nerve, as the terminal branch of the sacral plexus, leaves the pelvis through the greater sciatic foramen beneath the piriform muscle. Afterwards, it separates into the tibial and the common peroneal nerve, most frequently at the level of the upper angle of the popliteal fossa. Higher level of the sciatic nerve division is a relatively frequent phenomenom and it may be the cause of an incomplete block of the sciatic nerve during the popliteal block anesthesia. There is a possibility of different anatomic relations between the sciatic nerve or its terminal branches and the piriform muscle (piriformis syndrome). The aim of this research was to investigate the level of the sciatic nerve division and its relations to the piriform muscle. It was performed on 100 human fetuses (200 lower extremities) which were in various gestational periods and of various sex, using microdissection method. Characteristic cases were photographed. Results. Sciatic nerve separated into the tibial and common peroneal nerve in popliteal fossa in 72.5% of the cases (bilaterally in the 66% of the cases). In the remainder of the cases the sciatic nerve division was high (27.5% of the cases) in the posteror femoral or in the gluteal region. Sciatic nerve left the pelvis through the infrapiriform foramen in 192 lower extremities (96% of the cases), while in 8 lower extremities (4% of the cases) the variable relations between sciatic nerve and piriform muscle were detected. The common peroneal nerve penetrated the piriform muscle and left the pelvis in 5 lower extremities (2.5% of the cases) and the tibial nerve in those cases left the pelvis through the infrapiriform foramen. In 3 lower extremities (1.5% of the cases) common peroneal nerve left the pelvis through suprapiriform, and the tibial nerve through the infrapiriform foramen. The high terminal division of sciatic nerve (detected in 1/3 of the cases), must be kept in mind during the performing of popliteal block anesthesia. Conclusion. Although very rare, anatomical abnormalities of common peroneal nerve in regard to piriform muscle are still possible.

Sports and performing arts medicine. 3. Lower-limb injuries in endurance sports

This self-directed learning module highlights new advances in this topic area. It is part of the study guide on sports medicine and performing arts in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article uses case vignettes as a vehicle to elaborate on (1) ankle pain in a runner, (2) heel pain in an adolescent, (3) anterior knee pain in a runner, (4) lateral knee pain in a cyclist, (5) shin splints in a runner, (6) buttock pain in a hiker, and (7) collapse of a marathoner from hyponatremia.

OVERALL ARTICLE OBJECTIVE

To summarize lower-limb injuries commonly seen in endurance sports.

Botulinum Neurotoxin Type B and Physical Therapy in the Treatment of Piriformis Syndrome

OBJECTIVE

To measure dosage effects of botulinum neurotoxin type B with physical therapy in piriformis syndrome.

DESIGN

Prospective study of consecutive patients complaining of buttock pain and sciatica, measuring serial H-reflex tests in flexion, adduction, and internal rotation; visual analog scale; and adverse effects at 0, 2, 4, 8, and 12 wks. We used an electrophysiologic criterion for piriformis syndrome: a 1.86-msec prolongation of the H-reflex with the flexion, adduction, and internal rotation test. Four piriformis syndrome groups were identified. Serial groups were injected once with either 5000, 7500, 10,000, or 12,500 units of botulinum neurotoxin type B in successive months under electromyographic guidance in four separate locations of the affected piriformis muscle, with a 1-mo safety observation period between groups. Patients received physical therapy twice weekly for 3 mos.

RESULTS

The flexion, adduction, and internal rotation test and visual analog scale declined significantly, correlating at 72% sensitivity and 77% specificity. A total of 24 of 27 study patients had >/=50% pain relief. Mean visual analog scale score declined from 6.7 to 2.3. A volume of 12,500 units of botulinum neurotoxin type B was superior to 10,000 units at 2 wks postinjection. The most severe adverse effects were dry mouth and dysphagia, approaching 50% of patients at 2 and 4 wks.

CONCLUSION

Physical therapy and 12,500 units of botulinum neurotoxin type B seem to be safe and effective treatment for piriformis syndrome. In addition, the flexion, adduction, and internal rotation test seems to be an effective means of diagnosing piriformis syndrome and assessing its clinical improvement. Injection may benefit patients for >3 mos.

BOTOX and physical therapy in the treatment of piriformis syndrome

OBJECTIVE

This study evaluates the efficacy of botulinum toxin A injections used in conjunction with physical therapy for the treatment of piriformis syndrome.

DESIGN

This a double-blind, placebo controlled clinical trial using electrophysiologic criteria for patient selection and a visual analog scale to assess treatment efficacy in relieving pain.

RESULTS

As measured on the visual analog scale, patients injected with botulinum toxin A experienced more relief from pain than patients receiving lidocaine with steroid (P < 0.05) and more relief than patients receiving placebo (P = 0.001).

CONCLUSIONS

Injection with botulinum toxin A is an effective adjunct to physical therapy in the treatment of piriformis syndrome. H-reflex prolongation by flexion, adduction, and internal rotation (FAIR test) beyond 1.86 msec (3 SD) of the mean is a clinical indication of piriformis syndrome.