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

MR Imaging of Entrapment Neuropathies of the Hip

Entrapment neuropathies of the hip (ENH) can occur due to a variety of causes with clinical symptoms that may mimic musculoskeletal disorders. Etiologies include entrapment in a fibromuscular canal, tethering due to posttraumatic fibrosis and extrinsic compression from muscle hypertrophy or a mass. Magnetic resonance (MR) imaging enables detection and characterization of peripheral nerve pathology. In addition, MR imaging can impact both diagnostic judgment as well as therapeutic management (nonoperative and operative management) of patients with ENH. This review article will summarize the role of MR imaging in detection, characterization, and management of nerve entrapments around the hip joint.

Testing the Safety of Piriformis Dry Needling Interventions: An Observational Study Evaluating the Predictive Value of Anthropometric and Demographic Factors

Objectives: The dry needling of the piriformis muscle (especially in the medial region) is a challenging procedure since there is a high risk of accidentally puncturing the sciatic nerve. This study aimed to explain the variance of the deep limit of the piriformis based on anthropometric and demographic predictors potentially associated with it by exploring if clinicians can select the optimal needle length needed accurately to avoid accidental punctures of the sciatic nerve during palpation-guided dry needling interventions. Methods: An observational study was conducted that included fifty-six patients with piriformis muscle syndrome. We recorded the skin-to-sciatic nerve distance at the location with greatest risk of accidental sciatic puncture (assessed with ultrasound imaging) and demographic (e.g., age, gender, height, weight and body mass index-BMI) and anthropometric (hip circumference) variables. Results: Thirty-four males (n = 34) and twenty-two females (n = 22) were analyzed. Although men presented a significantly greater hip circumference than women (p = 0.007), no skin-to-sciatic nerve distance differences were observed (p > 0.05). Correlation analyses revealed that the sciatic nerve's depth is associated with weight, BMI and hip perimeter (all, p < 0.01) but not with age or height (p > 0.05). Due to shared variance and multicollinearity, the hip circumference was the only predictor included in the regression model, explaining 37.9% of the piriformis muscle's deeper fascia depth variance (R2 Adjusted = 0.379). Conclusions: Although the use of landmarks and measuring the hip perimeter may result in greater dry needling accuracy and a lower risk of adverse events derived from accidental sciatic nerve puncture, ultrasound guidance is encouraged as is the safest method for avoiding serious adverse events.

Effects of Radial Extracorporeal Shockwave Therapy on Piriformis Syndrome: A Single-Case Experimental Design

The effects of radial extracorporeal shockwave therapy (rESWT) on piriformis syndrome were investigated using a single-case study design. This study used an AB single case with a follow-up phase design. The baseline phase consisted of general physical therapy, including piriformis stretching, while the experimental phase consisted of rESWT in addition to general physical therapy. A man in his 70s diagnosed with piriformis syndrome participated in the study. The Numerical Rating Scale (NRS) score, piriformis hardness, and cross-sectional area of the sciatic nerve were measured to determine the effectiveness of the intervention. The baseline and experimental phases were compared using a binomial distribution based on the celeration line. The NRS score, piriformis hardness, and cross-sectional area of the sciatic nerve were significantly decreased in the experimental phase compared to the baseline phase (NRS, p<0.001; piriformis hardness, p<0.001; cross-sectional area of the sciatic nerve, p<0.001). This effect was carried over to the follow-up phase for all variables. rESWT for piriformis syndrome improved the clinical symptoms, piriformis hardness, and cross-sectional area of the sciatic nerve. However, these results are exploratory and require further validation in future clinical trials.

Provocative changes in nerve conductions: Fact or fiction?

At times electrodiagnostic medical consultants (EMCs) are asked to perform studies in both a neutral position, and then again after the patient is in a provocative position that exacerbates symptoms, to assess for measurable electrophysiologic changes. While this approach might seem initially appealing, particularly when standard studies are not effective at diagnosis, empiric studies in several conditions have been unimpressive. Studies in median neuropathy at the wrist, thoracic outlet syndrome, piriformis syndrome, and radial tunnel syndrome have failed to demonstrate reproducible changes in nerve conduction studies in positions that exacerbate symptoms. Furthermore, there is lack of a plausible pathophysiologic mechanism for producing both measurable and rapidly reversible electrophysiologic changes after just a few minutes, or less, of compression. Axon loss and demyelination would not be rapidly reversible, and positional changes of 2 min or less (the durations generally studied) would be insufficient to produce measurable nerve ischemia. Last, we have gained a greater appreciation for how much nerves move within limbs with changes in joint position; this movement can lead to misleading changes in nerve conduction studies. It is thus appropriate to conclude that testing nerve conduction in provocative or symptomatic positions adds no value to electrodiagnostic testing.

Piriformis syndrome

Piriformis syndrome is a condition that is proposed to result from compression of the sciatic nerve, either in whole or in part, in the deep gluteal space by the piriformis muscle. The prevalence of piriformis syndrome depends upon the diagnostic criteria being used and the population studied but is estimated by some to be 5%-6% in all cases of low back, buttock, and leg pain and up to 17% of patients with chronic low back pain. While the sciatic nerve may pierce the piriformis muscle in about 16% of healthy individuals, this frequency is no different in those with the syndrome; thus, the relationship to this anatomic finding is unclear. The most common symptoms are buttock pain, external tenderness over the greater sciatic notch, and aggravation of the pain through sitting. Many clinical signs are reported for piriformis syndrome, but the sensitivity and specificity are unclear, in part because of the lack of a uniformly accepted case definition. In the majority of cases in the literature, it appears that the diagnosis is more ascribed to a myofascial condition rather than a focal neuropathy. Electrodiagnostic studies can be useful to exclude other causes of symptoms, but there is no well-accepted test to confirm the presence of piriformis syndrome. Ultrasound imaging may show thickening of the piriformis muscle, but further research is required to confirm that this is correlated with the clinical diagnosis. Magnetic resonance imaging and neurography may hold promise in the future, but there are not yet sufficient data to support adopting these methods as a standard diagnostic tool. The initial treatment of piriformis syndrome is typically conservative management with the general rehabilitation principles similar to other soft tissue musculoskeletal conditions. Local anesthetic, botulinum toxin, and/or corticosteroid injections have been reported by some to be beneficial for diagnostic or treatment purposes. Surgical interventions have also been used with variable success.

Neurovascular structures to avoid during musculoskeletal ultrasound-guided intervention in the extremities

Ultrasound is a useful modality for guiding injections and other procedures in the extremities. Its portability and the ability to adjust the probe and needle in real time, as well as lack of radiation exposure make it preferable for many routine procedures. However, ultrasound is highly operator dependent and a firm understanding of regional anatomy is important, including neurovascular structures that are in close proximity during many of these procedures. Knowledge of the characteristic location and appearance of neurovascular structures in the extremities allows safe needle advancement and prevention of iatrogenic complications.

Diagnostic Approach to Lower Limb Entrapment Neuropathies: A Narrative Literature Review

Entrapment neuropathies of the lower limb are a misunderstood and underdiagnosed group of disorders, characterized by pain and dysesthesia, muscular weakness, and specific provoking movements on physical examination. The most frequent of these syndromes encountered in clinical practice are fibular nerve entrapment, proximal tibial neuropathy, sural nerve neuropathy, deep gluteal syndrome or sciatic nerve entrapment, and lateral femoral cutaneous nerve entrapment, also known as meralgia paresthetica. These are commonly mistaken for lumbar plexopathies, radiculopathies, and musculotendinous diseases, which appear even more frequently and have overlapping clinical presentations. A comprehensive anamnesis, physical examination, and electrodiagnostic studies should help clarify the diagnosis. If the diagnosis is still unclear or a secondary cause of entrapment is suspected, magnetic resonance neurography, MRI, or ultrasonography should be conducted to clarify the etiology, rule out other diseases, and confirm the diagnosis. The aim of this narrative review was to help clinicians gain familiarity with this disease, with an increase in diagnostic confidence, leading to early diagnosis of nerve damage and prevention of muscle atrophy. We reviewed the epidemiology, anatomy, pathophysiology, etiology, clinical presentation, and EDX technique and interpretation of the entrapment neuropathies of the lower limb, using articles published from 1970 to 2022 included in the Pubmed, MEDLINE, Cochrane Library, Google Scholar, EMBASE, Web of Science, and Scopus databases.

A systematic review of conservative and surgical treatments for deep gluteal syndrome

BACKGROUND AND OBJECTIVE

Conservative and surgical treatments, are recommended as the primary treatment in the management of patients diagnosed with deep gluteal syndrome; but evidence supporting superiority of one treatment over another is lacking. The aim of this review is to systematically review the effectiveness of treatments.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, Web of Science, Scopus, AMED, Cochrane Library (Central Register of Controlled Trials), and PEDro were screened (to 24 July 2019). Risk of bias of trials and surgical case series were assessed using the Cochrane risk of bias tool and Joanna Briggs Institute Critical appraisal checklists, respectively. Outcomes were reductions in pain or disability. For each outcome, the minimum clinically important difference (MCID) was calculated. A narrative synthesis was performed.

RESULTS

Out of 909 records, thirteen studies with 508 patients were included, eight RCTs with 336 patients and 5 case series with 172 patients. Conservative modalities were: infiltration into muscle of steroid, botulinum toxin, thiochilcoside and colchicine. There was one RCT and five case series of surgery. Only three trials reached an MCID in pain reduction for the intervention. The five surgical studies reached a before and after MCID. Only one study showed an MCID reduction in disability. The overall quality of evidence was low.

CONCLUSION

Given the low quality of evidence, no single conservative treatment can be recommended over another. Clinicians should follow general guidelines on the management of back pain and sciatica for first line treatment, namely physiotherapy. Surgery may have a place for chronic cases.

Efficacy of Ultrasound-Guided Injection of Botulinum Toxin, Ozone, and Lidocaine in Piriformis Syndrome

Background: Piriformis syndrome (PS) is a painful musculoskeletal condition characterized by a deep gluteal pain that may radiate to the posterior thigh and leg. This study was designed to compare the effectiveness of ozone and BTX to lidocaine injection in treating piriformis syndrome that was resistant to medication and/or physical therapy. Study design: Between November 2018 and August 2019, we involved eighty-four subjects diagnosed with piriformis syndrome in a double-blinded, prospective, randomized comparative study to receive an ultrasound-guided injection of lidocaine (control group), botulinum toxin A, or local ozone (28 patients each group) in the belly of the piriformis muscle. Pain condition evaluated by the visual analog score (VAS) was used as a primary outcome, and the Oswestry Disability Index (ODI) as a secondary outcome, before, at one month, two months, three months, and six months following the injection. Results: The majority (58.3%) of patients were male, while (41.7%) were female. At one month, a highly significant decrease occurred in VAS and ODI in the lidocaine and ozone groups compared to the botulinum toxin group (p < 0.001). At six months, there was a highly significant decrease in VAS and ODI in the botulinum toxin group compared to the lidocaine and ozone groups (p < 0.001). Conclusion: Botulinum toxin may assist in the medium- and long-term management of piriformis syndrome, while lidocaine injection and ozone therapy may help short-term treatment in patients not responding to conservative treatment and physiotherapy.

Physiotherapy for Piriformis Syndrome Using Sciatic Nerve Mobilization and Piriformis Release

Piriformis syndrome is also synonymous with sciatica or buttock pain. This is a condition where the muscle irritates the sciatic nerve. This nerve passes above, below, or in between the piriformis muscle piercing it. The muscle tightens or shortens, thus compressing the nerve and disturbing the impulses passing from it. The sciatic nerve is a combination of nerve roots from L4 to S3. Piriformis works as a lateral rotator and is a synergistic muscle of the flexor and abductor group. Females most commonly present with piriformis syndrome than males. Many causative factors are responsible for the compression or impingement of the sciatic nerve, one of which is piriformis syndrome. Tingling, numbness, and pain are most often felt by patients when they have compression of any of the nerves. Many physiotherapy techniques have been found to be effective in managing this problem. Techniques like nerve mobilization, stretching, myofascial release, deep friction massage, and many more have been studied by authors describing their effects in the treatment of piriformis syndrome. Neural mobilization consists of two techniques, nerve gliding and nerve tensioning. Studies have found that the gliding technique produces less strain on the nerve than the tensioning technique. Piriformis stretch reduces the tightening, which has caused the impingement. Two techniques have been used for this stretch, stretching with hip flexion over 90 degrees and hip flexion under 90 degrees. This review focuses on the different advances in treating piriformis syndrome.

Novel Use of Botulinum Toxin in Long-Standing Adductor-Related Groin Pain: A Case Series

BACKGROUND

Adductor-related groin pain (ARGP) is the most common groin injury in athletes. If conservative treatment fails, then adductor tenotomy to relieve tension can be considered. The use of botulinum toxin A (BoNT-A) has shown good results in other musculoskeletal pathologies.

OBJECTIVE

Assess the effectiveness of BoNT-A injections in ARGP in cases where usual treatment has failed.

DESIGN

Retrospective cohort study.

SETTING

Orthopedic Medicine and Rehabilitation Unit, University of Bordeaux.

PARTICIPANTS

Fifty patients treated by BoNT-A injection in ARGP after failure of medical and/or surgical treatment were included in this study.

INTERVENTIONS

One or several adductor muscles were injected with BoNT-A, according to clinical evaluation using ultrasound and electrical stimulation guidance. Patients were followed up at 1, 3, 6, and 12 months.

MAIN OUTCOME MEASURES

The primary assessment criterion was the improvement of Hip and Groin Outcome Score subscales at day 30. Secondary outcomes included pain intensity and impact on sport, work, and quality of life (QoL), the Blazina scale, and side effects.

RESULTS

All the first 50 injected patients (45 male and 5 female patients) were included. A significant improvement was noted regarding the majority of Hip and Groin Outcome Score subscales at day 30 ( P < 0.05). Pain intensity and its impacts were both significantly reduced ( P < 0.001): less sport and professional disability and lower impact on QoL. Severity of symptoms assessed by the Blazina scale was significantly reduced ( P < 0.001). The improvements remained significant until 1-year postinjection.

CONCLUSIONS

BoNT-A is promising as a new treatment for ARGP but should be fully assessed in a randomized controlled trial.

Botulinum toxin injection strategy of intractable and relapsed piriformis syndrome: A case report

RATIONALE

Piriformis syndrome (PS) is neuromuscular disorder caused by sciatic nerve compression by piriformis muscle and related to sciatic-type pain. When the conservative care fails, local injection or surgery can be also performed into piriformis. In recent years, botulinum toxin (BoNT) has also been considered as a new therapeutic option of piriformis syndrome.

PATIENT CONCERNS

A man in his late 40s came to pain clinic for left low back pain. The symptom was aggravated with sitting position.

DIAGNOSIS

Piriformis syndrome.

INTERVENTIONS

The patient underwent BoNT injection with 100 IU with 2 mL into piriformis muscle for piriformis syndrome treatment, and his pain was relieved. However, it recurred 8 months later. BoNT injection was repeated with 100 IU with 5 mL.

OUTCOMES

At the time of this writing, his pain was reduced for 2 years without any medication.

LESSONS

We report a case of treating relapsed piriformis syndrome with BoNT injection of different dilution volume, suggesting that the higher the dilution volume, the more effective for therapeutic effect of BoNT.

Visualizing Anatomic Variants of the Sciatic Nerve Using Diagnostic Ultrasound During Piriformis Muscle Injection: An Example of 4 Cases

Objective

The aim of this article is to present examples of patients in whom piriformis muscle (PM) and sciatic nerve (SN) variations were detected by a diagnostic ultrasound (US)-guided examination and were successfully diagnosed and treated for piriformis syndrome (PS) by US-guided injections.

Clinical Features

This series includes 4 cases. In case 1, a 30-year-old woman with a 7 numeric rating scale (NRS) score for pain (on a 0-10 scale) was evaluated for complaints of left gluteal pain radiating to the thigh for 5 years and right gluteal pain for 2 years. Case 2 involves a 32-year-old man with a 7 NRS score presenting with left gluteal pain radiating to his leg for 1 year. The third case presents a 37-year-old man who had pain (6 NRS score), numbness, and discomfort radiating from the right hip to the leg that lasted for 7 years. Finally, in case 4, a 23-year-old male patient was examined with deep gluteal paresthesia and discomfort on the left side for 1 year.

Intervention and Outcome

Diagnostic US evaluation of the gluteal region for each patient revealed anatomical variations of the SN. In 3 of the cases, corresponding contralateral US images demonstrated similar anatomic variations. Diagnosis of PS in each patient was made by US-guided injection. After the injection of 4 cm³ of lidocaine 2% into the PM, the patients' complaints resolved almost fully.

Conclusion

The anatomical variations of the SN and PM might be a facilitating factor for myofascial pain syndrome in PS. These cases demonstrate that SN variations could be visualized with the help of diagnostic US.

Effects of ultrasound-guided platelet rich plasma injection in patients with piriformis syndrome

BACKGROUND

Piriformis syndrome (PS) is the common entrapment neuropathy causing buttock pain. Patients are conventionally treated with lifestyle modification, exercise, non-steroidal anti-inflammatory drugs, corticosteroid or botulinum toxin injections. However, some patients may not respond to these conventional treatment methods. Platelet rich plasma (PRP) injection has been shown to be beneficial in various muscular injuries, but its effects have not yet been investigated in PS.

OBJECTIVE

The aim of this study was to explore the effect of PRP on pain and functional status in patients with PS, and to identify any correlations between clinical changes and demographic features.

METHODS

A total of 60 patients with PS were randomly separated into two groups (PRP and control groups). All patients received one session of either PRP or saline injection performed under ultrasound guidance. The pain was measured with a visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were noted at three intervals in both groups: before treatment, 1 week after treatment and 1 month after treatment.

RESULTS

The VAS and ODI scores were improved in both groups. The improvement was more obvious in the PRP group in the first week, and the results were similar for both groups when measured 1 month after the treatment.

CONCLUSION

Ultrasound-guided PRP injection provided greater improvements in both pain and functional status in patients with PS, starting in the early period after treatment. A repeat injection might be needed for a long-term effect.

Trigger Point Injections

Myofascial pain and myofascial pain syndromes are among some of the most common acute and chronic pain conditions. Many interventional procedures can be performed in both an acute and chronic pain setting to address myofascial pain syndromes. Trigger point injections can be performed with or without imaging guidance such as fluoroscopy and ultrasound; however, the use of imaging in years past has been recommended to improve patient outcome and safety. Injections can be performed using no injectate (dry needling), or can involve the administration of local anesthetics, botulinum toxin, or corticosteroids.

Ultrasound-Guided Musculoskeletal Injections

Musculoskeletal injections serve a variety of diagnostic and therapeutic purposes, with ultrasonography (US) guidance having many advantages: no ionizing radiation, real-time guidance, high spatial resolution, excellent soft tissue contrast, and the ability to identify and avoid critical structures. Sonography can be cost effective and afford flexibility in resource-constrained settings. This article describes US-guided musculoskeletal injections relevant to many radiology practices and provides experience-based suggestions. Structures covered include multiple joints (shoulder, hip), bursae (iliopsoas, subacromial-subdeltoid, greater trochanteric), peripheral nerves (sciatic, radial), and tendon sheaths (posterior tibial, peroneal, flexor hallucis longus, Achilles, long head of the biceps). Trigger point and similar targeted steroid injections, as well as calcific tendinopathy barbotage, are also described.

Piriformis Syndrome Masquerading as an Ischiofemoral Impingement

Hip pain can have a number of different etiologies. Ischiofemoral impingement (IFI), an etiology causing extra-articular hip pain, shares many of the same symptoms as other causes of gluteal or inguinal pain, making its diagnosis difficult. We present a case of a young female with persistent deep gluteal pain who was diagnosed with IFI based on radiographic findings; however, a diagnostic injection into the quadratus femoris did not confirm IFI as the primary pain generator. The patient subsequently failed several trials of physical therapy designed to address this diagnosis. The diagnosis was expanded to include piriformis syndrome and the modified treatment approach resulted in complete resolution of her pain. The similarities of these pathologies resulted in a delay of definitive treatment and would have potentially required unnecessary surgery. This case study highlights the diagnostic conundrum clinicians face in the evaluation of gluteal hip pain and provides an algorithm for considering alternate diagnoses when conservative management fails to achieve expected results.

Does piriformis muscle syndrome impair postural balance? A case control study

BACKGROUND AND PURPOSE

While patients with musculoskeletal disorders reported postural balance impairments, it is unknown whether patients with piriformis muscle syndrome (PMS) may exhibit postural balance disorders compared to controls. The aim was to compare postural balance in patients with PMS to controls in static and dynamic conditions.

MATERIAL AND METHODS

Twelve patients with PMS and twelve controls were enrolled. Static postural balance was assessed by calculating the symmetry index (SI) in the unipedal posture. To measure vision contribution, the Romberg index (RI) was computed. Dynamic postural balance was evaluated with the Timed up and go test (TUGT). Besides, inter-limb strength asymmetry (SA), pain and the short form-36 (SF-36) were assessed.

RESULTS

The PMS group (PMSG) exhibited significant (p < 0.001) higher SI in eyes opened (EO) and eyes closed (EC) conditions compared to the control group (CG). Besides, PMSG had significant higher RI (p < 0.05), TUGT scores (p < 0.001), SA values (p < 0.05), pain intensity (p < 0.001), and worse SF-36 scores on all physical health (p < 0.05) and psychological health (only in vitality and mental health [p < 0.05]), compared to CG.

CONCLUSION

Our data revealed impaired static and dynamic postural balance, and reduced quality of life in PMSG compared to CG. Postural balance impairments could explain the poor quality of life, which are likely due to the higher SA and higher pain intensity. Clinicians and physiotherapists should consider postural balance disorders while designing rehabilitation programs in these patients.

Laparoscopic surgical approach for the treatment of piriformis syndrome: Intrapelvic decompression technique

Introduction:

Piriformis syndrome is an uncommon disease resulting from the piriformis muscle’s compression of the sciatic nerve. Pain and numbness in the buttocks and down the leg are the most common symptoms. This study analyzes the laparoscopic surgical treatment of piriformis syndrome.

Methods:

We report three cases of piriformis syndrome diagnosed in our hospital. The first case was a 40 years old woman with a 7-year history of intermittent low back pain and sciatica on her right side. Hyperesthesia and cutaneous allodynia were observed in the right sciatic nerve dermatome. The second case was a 30 years old woman with a 2-year history of sciatica on her left side. The third case was a 30 years old woman with a 2-year history of sciatica on her right side. All the patients underwent laparoscopic decompression surgery, which was performed to release the sciatic nerve or sacral nerve roots.

Results:

The patients were reexamined at the postoperative 3rd and 6th months. Their visual analog scale (VAS) scores were found to be decreased from 10/10, 9/10, and 7/10 to 0/10, 1/10, and 0/10, respectively.

Conclusion:

Due to the very few cases in the literature, pelvic piriformis syndrome is an exclusively clinical diagnosis. If the sciatica is refractory to conservative treatments, laparoscopic exploration and decompression surgery of the pelvic nerves and piriformis muscle could be an option.

A clinical approach of neuropathic pain in piriformis syndrome: case presentation and rehabilitation particularities

Piriformis syndrome is a rare cause of sciatica and buttock pain and is usually considered as a diagnosis of exclusion for patients with a history of trauma. It usually presents without abnormalities regarding sensory and motor functions and tends to have a favorable evolution with pharmacological treatment. We present the case of a patient with posttraumatic piriformis syndrome who came to our department with significant pain and muscle weakness. The diagnosis was confirmed using clinical tests, imaging techniques and electroneurography. The patient did not respond to pharmacologic treatment alone and therefore surgery was performed. Surgery along with pharmacological treatment, complementary pain treatment and physical rehabilitation provided a favorable outcome. Keywords: neurology, rehabilitation, piriformis syndrome, deep gluteal syndrome, traumatic neuropathy, neuropathic pain,

‘Hand on hip’ sign: A novel screening test and diagnostic tool in piriformis syndrome

Introduction:

Currently there is no gold standard clinical test or investigation available to diagnose piriformis syndrome. We have found a pose used by the patients to describe the pain in the gluteal region in cases of suspected piriformis syndrome. This pose in our study has been described as ‘hand on hip sign’ (HHS). In this study, we aim to assess the significance of this sign in screening of patients with piriformis syndrome.

Materials and methods:

Seventy patients presenting with pain in the gluteal region with radiculopathy between the age group of 18 years and 60 years were included. All patients were asked to locate the site of the pain in the gluteal region. The demonstration of pain by the patients was noted. If the description matched the description of HHS, it was considered to be positive, else it was considered negative. All patients were subjected to four piriformis-specific confirmatory clinical tests. Considering that there is no single confirmatory test, any patient in whom any two piriformis-specific signs were elicited was considered as a case of piriformis syndrome. Using the data, sensitivity, specificity and positive and negative likelihood ratio of the HHS in the diagnosis of piriformis syndrome were calculated. Inter-test comparison was also made using Cohen’s kappa statistic.

Results:

HHS was found to have a sensitivity of 86% and a specificity of 75%. It also has a high positive predictive value of 94% and a positive likelihood ratio of 3.44. Inter-test reliability comparison showed that there was a fair to moderate agreement between HHS and other confirmatory piriformis-specific tests.

Conclusion:

HHS serves as an effective screening test in the identification of piriformis syndrome.

Ultrasound-guided trigger point injection for piriformis syndrome in the emergency department

Piriformis syndrome, a myofascial pain disorder characterized by deep gluteal pain that radiates to the ipsilateral lower back and/or posterior thigh, is an underreported cause of low back pain frequently misdiagnosed in the emergency department (ED). Often refractory to oral pain medications, this syndrome can be debilitating. Ultrasound-guided trigger point injection of the piriformis muscle can treat piriformis syndrome, but no previous reports exist in the emergency medicine literature. This case series describes 2 patients who presented to our emergency department with low back pain and were diagnosed with piriformis syndrome. Both patients received an ultrasound-guided trigger point injection of the affected piriformis muscle with a significant reduction of pain at 15 minutes and 48 hours after the procedure.

Lower extremity entrapment neuropathies

Entrapment neuropathies are frequently encountered by rheumatologists, not only because they are common but also because of their association with certain rheumatological and systemic disorders. Recognizing entrapment neuropathy early can help avoid progressive neurological deficits, as well as facilitate appropriate treatment measures, which can effectively minimize a patient's symptoms. Entrapment neuropathies may be distinguished from other musculoskeletal causes of lower extremity pain by identifying characteristic patterns of weakness and/or sensory loss, so a focused bedside neurological examination is key for diagnosis. In this chapter, we review the most common entrapment neuropathies that occur in the lower extremities, review the relevant neuroanatomy, outline a diagnostic approach to distinguish them from other mimics, and highlight appropriate management options.

Deep gluteal syndrome as a cause of posterior hip pain and sciatica-like pain

Deep gluteal syndrome is an increasingly recognized disease entity, caused by compression of the sciatic or pudendal nerve due to non-discogenic pelvic lesions. It includes the piriformis syndrome, the gemelli-obturator internus syndrome, the ischiofemoral impingement syndrome, and the proximal hamstring syndrome. The concept of the deep gluteal syndrome extends our understanding of posterior hip pain due to nerve entrapment beyond the traditional model of the piriformis syndrome. Nevertheless, there has been terminological confusion and the deep gluteal syndrome has often been undiagnosed or mistaken for other conditions. Careful history-taking, a physical examination including provocation tests, an electrodiagnostic study, and imaging are necessary for an accurate diagnosis. After excluding spinal lesions, MRI scans of the pelvis are helpful in diagnosing deep gluteal syndrome and identifying pathological conditions entrapping the nerves. It can be conservatively treated with multidisciplinary treatment including rest, the avoidance of provoking activities, medication, injections, and physiotherapy. Endoscopic or open surgical decompression is recommended in patients with persistent or recurrent symptoms after conservative treatment or in those who may have masses compressing the sciatic nerve. Many physicians remain unfamiliar with this syndrome and there is a lack of relevant literature. This comprehensive review aims to provide the latest information about the epidemiology, aetiology, pathology, clinical features, diagnosis, and treatment. Cite this article: Bone Joint J 2020;102-B(5):556-567.

Feasibility and Reliability of an Ultrasound Examination to Diagnose Piriformis Syndrome

OBJECTIVE

We explored the diagnostic performance of ultrasound examinations in the diagnosis of piriformis syndrome (PS).

METHODS

In our single-center retrospective study, 52 patients with a diagnosis of PS and 50 healthy volunteers were enrolled to undergo ultrasound examination of the piriformis and sciatic nerve. The thicknesses of the piriformis and the diameter of the sciatic nerve were measured to compare the differences between the patients with PS and healthy volunteers. The diagnostic performance of ultrasound examinations was assessed by constructing a receiver operating characteristic curve and calculating the area under the curve.

RESULTS

In patients with PS, the piriformis and sciatic nerve were enlarged on the abnormal side compared with the asymptomatic side, accompanied by a decreased echo intensity and an unclear perineurium. In addition, the piriformis thickness and sciatic nerve diameter of those with PS were significantly greater than were those of the healthy volunteers. The diagnostic performance of ultrasonography was significant. The area under the receiver operating characteristic curve for piriformis thickness and sciatic nerve diameter to discriminate between the abnormal and asymptomatic sides was 0.778 and 0.871, respectively.

CONCLUSION

Ultrasound examinations can assist in the clinical diagnosis of PS and have the potential to be an alternative method for the diagnosis of PS for most musculoskeletal clinicians.

Piriformis Syndrome: A Narrative Review of the Anatomy, Diagnosis, and Treatment

Piriformis syndrome is a form of sciatica caused by compression of the sciatic nerve by the piriformis muscle. It is a relatively uncommon, but not insignificant, cause of sciatica. The diagnosis of piriformis syndrome is complicated by the large differential diagnosis of low back and buttock pain with many diagnoses having overlapping symptoms. This narrative review highlights the relevant anatomy, history, physical exam maneuvers, electrodiagnostic findings, and imaging findings that are used to diagnose piriformis syndrome. Also discussed are posterior gluteal myofascial pain syndromes that mimic piriformis syndrome. The review then outlines the different treatment options for piriformis syndrome including conservative treatment, injections, and surgical treatment. In addition, it provides the reader with a clinical framework to better understand and treat the complex, and often misunderstood, diagnosis of piriformis syndrome.

Effect of Mannitol plus Vitamins B in the management of patients with piriformis syndrome

BACKGROUND

Piriformis syndrome (PS) is an entrapment of the sciatic nerve by the piriformis muscle, or myofascial pain from the piriformis muscle.

OBJECTIVE

The aim of this study was to investigate the effectiveness of Mannitol plus Vitamins B regime in the management of PS.

METHODS

Twenty two patients were included in this study and received 250 ml of mannitol 20% intravenous infusion for 5 days + Vitamins B (vitamin B1 10 mg + vitamin B2 10 mg + vitamin B12 50 μg PO) for 6 weeks. Clinical outcomes were assessed systematically by clinical tests (tenderness, FAIR test, Beatty's, Freiberg's and Pace's maneuver), Numeric Rating Scale (NRS), Likert Analogue Scale (LAS), and MR examination.

RESULTS

The clinical evaluations showed a significant reduction (p< 0.05) of tenderness, FAIR test, Beatty's maneuver, Freiberg's maneuver and Pace's maneuver when compared with baseline evaluation during the 3rd and 6th month follow-ups. A statistically significant improvement of pain was measured by NRS at resting (p< 0.001), at night (p< 0.001) and during activities (p< 0.001) and LAS with prolonged sitting (p< 0.001), standing (p< 0.001) and lying (p< 0.001). Concomitantly, swelling of SN revealed a significant reduction (p= 0.003) from 86.4% to 18.2%.

CONCLUSIONS

Mannitol plus Vitamins B is effective in the management of piriformis syndrome and it could be an alternative regime in treating PS.

Ultrasound appears to be a reliable technique for the diagnosis of piriformis syndrome

INTRODUCTION

Piriformis muscle syndrome (PS) is a disorder encompassing a constellation of symptoms, including buttock and hip pain. In this study we aimed to assess the value of ultrasound (US) in the diagnosis of PS.

METHODS

Thirty-three clinically diagnosed PS patients and 26 healthy volunteers underwent a clinical PS scoring examination and US and MRI assessment of the bilateral piriformis muscles. The areas under the receiver operating characteristic curves (AUROCs) of the US parameters (i.e., increased thickness [iTh] and increased cross-sectional area [iCSA]) for piriformis muscle were evaluated.

RESULTS

On US and MRI, the thickness and CSA were increased in PS patients. The AUROCs for the iTh and iCSA for discriminating stage 0 (healthy volunteers) from stage 1 through stage 3 (PS patients) were 0.88 and 0.95, respectively.

DISCUSSION

US may be a reliable technique for the clinical diagnosis of PS. Muscle Nerve 59:411-416, 2019.

Evaluation of neural therapy effect in patients with piriformis syndrome

BACKGROUND

The aim of this study was to explore the effect of neural therapy on pain and functionality in patients with low back pain due to piriformis syndrome. It also aimed to find out any possible links between the clinical changes and demographic features.

METHOD

One hundred and two patients were randomly divided into two groups (neural therapy and control). All patients were given stretching exercises for the piriformis muscle. The patients in the neural therapy group additionally received 6 sessions of neural therapy. The visual analog scale (VAS) and Oswestry Disability Index (ODI) were noted before and after the treatment in both groups.

RESULTS

The VAS and ODI improved in both groups. However, improvement of the VAS and ODI scores were more obvious in the neural therapy group. The changes of VAS and ODI values did not show any correlations with the demographic features.

CONCLUSION

After the neural therapy, the patients with low back pain due to piriformis syndrome may have improvement in both pain and functioning.

EMG in piriformis syndrome diagnosis: Reliability of peroneal H-reflex according to results obtained after surgery, Botox injection and medical treatment

Diagnosing piriformis syndrome (PS) throughout the past decades was not that easy, however peroneal H-reflex was proved as reliable test for PS with the change in wave amplitude and delay in conduction as parameters for diagnosis. We interpreted these parameters according to treatment's results carried out for patients presenting clinical PS, aiming to define a threshold value for peroneal H-reflex delay to accurately diagnose. A retrospective mono-centric review of 27 patients, 9 females and 18 males, aged 22-65 years, benefited from peroneal H-reflex test and treated for clinical PS. These patients were classified into 3 groups according to treatment modality they received: 11 patients underwent surgical treatment, 7 patients underwent Botox injections (4 of them benefited from surgery later on) and 9 patients received pharmacological treatment. From 11 operated patients with 4 < delay < 9 ms, 10 had complete improvement and 1 remained in pain. For 7 patients having injection of Botox 100-300 IU, with 5 < delay < 7 ms had a transient recovery, 4 of them have benefited later from surgery, the 3 others reproved pain. Between 9 patients who have declined invasive treatment, 7 patients with 4 < delay < 10 ms didn't demonstrate any improvement after medical treatment and are suspected of PS, 2 others with delay < 4 ms recovered from a non-confirmed PS. A threshold value to diagnose PS was reached through peroneal H-reflex delay ranges, classified as: high with a delay > 5 ms, moderate: 4 < delay < 5 ms and poor: <4 ms.

Does endoscopic piriformis tenotomy provide safe and complete tendon release? A cadaver study

BACKGROUND

Endoscopic piriformis release (EPR) is among the available treatments for piriformis syndrome. This procedure typically involves dividing the muscle near the sciatic nerve in the sub-gluteal space, which contains numerous blood vessels and nerves. The objectives of this prospective cadaver study were: 1) to assess the reproducibility and quality of endoscopic piriformis tenotomy near the greater trochanter; 2) to detect iatrogenic injuries to the lateral hip rotators, nerves, and vessels; 3) and to define the surgical safety margins relative to the sciatic nerve and inferior gluteal bundle.

HYPOTHESIS

EPR at the greater trochanter ensures full release of the muscle with a limited risk of neuro-vascular injury.

MATERIAL AND METHODS

EPR was performed via two portals on 10 cadaver hips preserved in zinc chloride and placed in the prone position. A third, ancillary portal was required in 7 cases. The area was then dissected with the Kocher-Langenbeck approach to allow an assessment of the tenotomy, detect iatrogenic injuries, and measure the distances separating the tenotomy site from the sciatic nerve and inferior gluteal artery.

RESULTS

Complete tenotomy was achieved in 9 (90%) cases. The tendon adhered to the capsule in 2 (20%) cases and showed acquired avulsion in 1 case. No injuries to the sciatic nerve or inferior gluteal artery occurred. Mean distances from the tenotomy site were 5.21±0.59cm (range, 4.5-6.6cm) for the sciatic nerve and 7.1±0.89cm (range, 5.4-8.5cm) for the inferior gluteal artery.

DISCUSSION

EPR by a tenotomy at the greater trochanter without sciatic nerve release provides full release of the muscle with satisfactory safety margins and a short learning curve.

LEVEL OF EVIDENCE

III, prospective cadaver case-control study.

A critical overview of the current myofascial pain literature - July 2018

In the current issue of this clinical overview, we are pleased to include several basic research studies ranging from the differentiation of radicular and non-radicular low back pain based on the presence of trigger points (TrPs) to the role of TrPs in patients with osteoarthritis, the diagnostic criteria of TrP, the accurate placement of needles in the piriformis muscle with dry needling (DN), and the reliability of TrP identification, among others. As usual, there are many new DN studies, but also several review papers, and manual TrP research. Contributing authors come from as many as 15 different countries!

Ultrasound-Guided Subgluteal Sciatic Nerve Perineural Injection: Report on Safety and Efficacy at a Single Institution

OBJECTIVES

To determine the safety and efficacy of ultrasound (US)-guided subgluteal sciatic nerve injections.

METHODS

A retrospective chart review of US-guided subgluteal sciatic nerve injections at our institution was performed.

RESULTS

Of 221 US-guided subgluteal sciatic nerve injections, 100% achieved technical success, with no postprocedure complications. Sixty-eight percent of patients with follow-up reported symptom relief. Most patients with no relief had suboptimal preprocedure screening.

CONCLUSIONS

With appropriate screening, our technique of US-guided subgluteal sciatic nerve injection is safe and effective.

Piriformis muscle syndrome with assessment of sciatic nerve using diffusion tensor imaging and tractography: a case report

Piriformis muscle syndrome (PMS) is difficult to diagnose by objective evaluation of sciatic nerve injury. Here we report a case of PMS diagnosed by diffusion tensor imaging (DTI) and tractography of the sciatic nerve, which can assess and visualize the extent of nerve injury. The patient was a 53-year-old man with a 2-year history of continuous pain and numbness in the left leg. His symptoms worsened when sitting. Physical examination, including sensorimotor neurologic tests, the deep tendon reflex test, and the straight leg raise test, revealed no specific findings. The hip flexion adduction and internal rotation test and resisted contraction maneuvers for the piriformis muscle were positive. There were no abnormal findings on magnetic resonance imaging (MRI) of the lumbar spine. The transverse diameter of piriformis muscle was slightly thicker in affected side on MRI of the pelvis. A single DTI sequence was performed during MRI of the pelvis. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve were quantified at three levels using the fiber-tracking method. FA values were significantly lower and ADC values were significantly higher distal to the piriformis muscle. We performed endoscopic-assisted resection of the piriformis tendon. Intraoperatively, the motor-evoked potentials in the left gastrocnemius were improved by resection of the piriformis tendon. The patient's symptoms improved immediately after surgery. There was no significant difference in FA or ADC at any level between the affected side and the unaffected side 3 months postoperatively. MRI-DTI may aid the diagnosis of PMS.

Sensitivity for palpating lumbopelvic soft- tissues and bony landmarks and its associated factors: A single-blinded diagnostic accuracy study

BACKGROUND

Evidence on the diagnostic performance of palpatory methods and possible confounding factors is scarce.

OBJECTIVES

To examine the sensitivity of palpatory methods for location of lumbopelvic landmarks and to assess its association with personal characteristics.

METHODS

Eighty-three participants (41 men, 55.6 (16.5) years, 25.9 (4.8) kg/m2 [mean (SD)]) were enrolled in this single-blinded study. Fourteen body and softy-tissue landmarks were sequentially palpated from the spinous process of L4 to the ischial tuberosity. CT-scan images were used to assess what landmark was located.

RESULTS

Sensitivity for location was in range 22-86% for soft-tissues and 26-69% for bony landmarks. Reduction in sensitivity was observed from the quadratus lumborum to the inferior and lateral angle of the sacrum (86-26% and 75-33%, left and right sides, respectively). Palpations of L4 and L5 spinous processes were systematically more cephalic than other landmarks. Gender was weakly correlated to almost all landmarks (rp⁢b= 0.333 or weaker). Body mass index was weakly correlated to the accurate location of ILAS and quadratus lumborum, great trochanter, PSIS, and piriformis (rp⁢b=-0.307 or weaker).

CONCLUSIONS

Systematic and propagation errors were present using sequential palpatory methods. Palpation in men was more sensitive and higher BMI was associated with lower sensitivity for lumbopelvic landmarks.

Accuracy and safety of dry needle placement in the piriformis muscle in cadavers

Objectives

The purpose of this anatomic investigation is to (1) establish accuracy of dry needle placement into the medial third of the piriformis muscle as it exits the pelvis from the greater sciatic notch in unembalmed cadaveric specimens, while avoiding puncture of the sciatic nerve, and (2) establish guidelines for dry needle length selection.

Methods

Dry needles were placed in nineteen unembalmed cadaveric posterior hips. Dissection of the posterior hip musculature was performed to confirm location of the needle. A binary decision (yes/no) was made to determine whether the needle reached the piriformis muscle, went through the piriformis muscle, and/or pierced the sciatic nerve. Additionally, mean adipose tissue thickness, gluteus maximus muscle thickness, and perpendicular distance from the needle to the exiting sciatic nerve were recorded.

Results

The needle reached the medial third of the piriformis in 16 out of 19 hips (84.2% accuracy) and never punctured the sciatic nerve. There was a fair (r = 0.493) and good (r = 0.759) correlation between the needle length and the mean fat thickness for the left and right hips, respectively.

Discussion

A physical therapist was able to use bony landmark palpation to locate the piriformis muscle and use estimated adipose tissue thickness to choose a sufficient needle length to reach the medial third of the piriformis muscle. While the needle placement technique was safe and no sciatic nerve puncture occurred, the proximity of the piriformis muscle to the sciatic nerve warrants caution during needle placement.

Level of Evidence

2c.

Surgical Treatment of Piriformis Syndrome

Background

Piriformis syndrome (PS) is an uncommon disease characterized by symptoms resulting from compression/irritation of the sciatic nerve by the piriformis muscle. Uncertainty and controversy remain regarding the proper diagnosis and most effective form of treatment for PS. This study analyzes the diagnostic methods and efficacy of conservative and surgical treatments for PS.

Methods

From March 2006 to February 2013, we retrospectively reviewed 239 patients who were diagnosed with PS and screened them for eligibility according to our inclusion/exclusion criteria. All patients underwent various conservative treatments initially including activity modification, medications, physical therapy, local steroid injections into the piriformis muscle, and extracorporeal shock wave therapy for at least 3 months. We resected the piriformis muscle with/without neurolysis of the sciatic nerve in 12 patients who had intractable sciatica despite conservative treatment at least for 3 months. The average age of the patients (4 males and 8 females) was 61 years (range, 45 to 71 years). The average duration of symptoms before surgery was 22.1 months (range, 4 to 72 months), and the mean follow-up period was 22.7 months (range, 12 to 43 months). We evaluated the degree of pain and recorded the responses using a visual analog scale (VAS) preoperatively and 3 days and 12 months postoperatively.

Results

Buttock pain was more improved than sciatica with various conservative treatments. Compared with preoperatively, the VAS score was significantly decreased after the operation. Overall, satisfactory results were obtained in 10 patients (83%) after surgery.

Conclusions

PS is thought to be an exclusively clinical diagnosis, and if the diagnosis is performed correctly, surgery can be a good treatment option in patients with refractory sciatica despite appropriate conservative treatments.

Diffusion tensor imaging and tractography of the sciatic nerve: assessment of fractional anisotropy and apparent diffusion coefficient values relative to the piriformis muscle, a preliminary study

OBJECTIVE

Piriformis muscle syndrome (PMS) is underdiagnosed. To evaluate the potential of diffusion tensor imaging and diffusion tensor tractography as innovative tools for the diagnosis of PMS by functional assessment of the sciatic nerve, the aims of this study are to assess the reproducibility and to evaluate the changes in the parameters at levels proximal and distal to the piriformis.

MATERIALS AND METHODS

Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve at three levels were quantified twice each by two examiners using the fiber-tracking method. In the first part of the study, laterality and reproducibility were evaluated using intraclass correlation coefficients (ICC) in ten healthy volunteers. In the second part of the study, the healthy side and symptomatic side were assessed in ten consecutive patients with sciatica. There were three patients with no findings on lumbar magnetic resonance imaging (MRI).

RESULTS

There was no laterality in either FA or ADC values in asymptomatic patients at any level. The mean intra-rater ICC was 0.90 and the mean inter-rater ICC was 0.87. FA was significantly lower and ADC significantly higher on the symptomatic side at each level in patients with sciatica. In the three sciatica patients with no findings on lumbar MRI, FA was significantly lower and ADC was significantly higher only at levels distal to the piriformis. These patients experienced full pain relief after ultrasound-guided injection of local anesthesia.

CONCLUSIONS

Diffusion tensor imaging and diffusion tensor tractography might be innovative tools for the diagnosis of PMS.

[Tendinopathies of the hip : Treatment recommendations according to evidence-based medicine]

Tendinopathies of the hip are a differential diagnostic challenge. The spatial proximity of these structures is challenging and many of the structures are located in very deep positions in an individual-specific manner and are covered by other tissues resulting in difficult accessibility for a clinical examination. Furthermore, the definition of the different syndromes is not consistent in the literature, which makes a comparability and assessment difficult. This article demonstrates the most frequent tendinopathies and associated syndromes with their typical clinical presentation, diagnostics and therapy options. Finally, a critical assessment of these aspects is presented based on the current literature.

Posterior, Lateral, and Anterior Hip Pain Due to Musculoskeletal Origin: A Narrative Literature Review of History, Physical Examination, and Diagnostic Imaging

OBJECTIVE

The purpose of this study was to present a narrative review of the literature of musculoskeletal causes of adult hip pain, with special attention to history, physical examination, and diagnostic imaging.

METHODS

A narrative review of the English medical literature was performed by using the search terms "hip pain" AND "anterior," "lateral," and "posterior." Additionally, specific entities of hip pain or pain referral sources to the hip were searched for. We used the PubMed search engine through January 15, 2016.

RESULTS

Musculoskeletal sources of adult hip pain can be divided into posterior, lateral, and anterior categories. For posterior hip pain, select considerations include lumbar spine and femoroacetabular joint referral, sacroiliac joint pathology, piriformis syndrome, and proximal hamstring tendinopathy. Gluteal tendinopathy and iliotibial band thickening are the most common causes of lateral hip pain. Anterior hip pain is further divided into causes that are intra-articular (ie, labral tear, osteoarthritis, osteonecrosis) and extra-articular (ie, snapping hip and inguinal disruption [athletic pubalgia]). Entrapment neuropathies and myofascial pain should also be considered in each compartment. A limited number of historical features and physical examination tests for evaluation of adult hip pain are supported by the literature and are discussed in this article. Depending on the clinical differential, the gamut of diagnostic imaging modalities recommended for accurate diagnosis include plain film radiography, computed tomography, magnetic resonance imaging, skeletal scintigraphy, and ultrasonography.

CONCLUSIONS

The evaluation of adult hip pain is challenging. Clinicians should consider posterior, lateral, and anterior sources of pain while keeping in mind that these may overlap.

Ischiofemoral Impingement and Hamstring Syndrome as Causes of Posterior Hip Pain: Where Do We Go Next?

Recent advances in understanding hip joint anatomy and biomechanics have contributed to improvement of diagnosis and treatment decisions for distal causes of deep gluteal syndrome (DGS). Ischiofemoral impingement and hamstrings syndrome are sources of posterior hip pain that can simulate symptoms of DGS. The combination of a comprehensive history and physical examination with imaging and ancillary testing are critical for diagnosis. Six key physical examination tests are described to differentiate distal versus proximal sources of extrapelvic posterior hip pain. Outcomes depend on patient compliance and the understanding of the entire anatomy, biomechanics, clinical presentation, and open versus endoscopic treatment options.