Four symptoms define the piriformis syndrome: an updated systematic review of its clinical features

Use of Diagnostic Musculoskeletal Ultrasound in the Evaluation of Piriformis Syndrome: A Review for Rehabilitation Providers

Piriformis Syndrome (PS) is a neuromuscular condition caused by the entrapment of the sciatic nerve at the level of the piriformis muscle (PM) and can cause significant discomfort and disability. PS is often misdiagnosed due to its overlapping symptoms with other lumbar and sciatic issues and as such, diagnosing PS remains challenging despite recent invasive and non-invasive diagnostic methods. Diagnostic musculoskeletal ultrasound (MSK US) offers a non-invasive, cost-effective alternative for the identification and evaluation of PS, providing dynamic, real-time imaging of the PM and adjacent structures. This article reviews the applications, advantages, and procedural insights of MSK US in the diagnosis of PS, emphasizing its relevance in rehabilitation settings. We discuss the technical aspects of ultrasound use, interpretation of findings, and integration into clinical practice, aiming to enhance the diagnostic accuracy and therapeutic outcomes for patients with suspected PS.

Effective Stretching Positions of the Piriformis Muscle Evaluated Using Shear Wave Elastography

CONTEXT

Piriformis syndrome is often associated with muscle spasms and shortening of the piriformis muscle (PM). Physical therapy, including static stretching of the PM, is one of the treatments for this syndrome. However, the effective stretching position of the PM is unclear in vivo. This study aimed to determine the effective stretching positions of the PM using ultrasonic shear wave elastography.

DESIGN

Observational study.

METHODS

Twenty-one healthy young men (22.7 [2.4] y) participated in this study. The shear elastic modulus of the PM was measured at 12 stretching positions using shear wave elastography. Three of the 12 positions were tested with maximum internal rotation at 0°, 20°, or 40° hip adduction in 90° hip flexion. Nine of the 12 positions were tested with maximum external rotation at positions combined with 3 hip-flexion angles (70°, 90°, and 110°) and 3 hip-adduction angles (0°, 20°, and 40°).

RESULTS

The shear elastic modulus of the PM was significantly higher in the order of 40°, 20°, and 0° of adduction and higher in external rotation than in internal rotation. The shear elastic modulus of the PM was significantly greater in combined 110° hip flexion and 40° adduction with maximum external rotation than in all other positions.

CONCLUSION

This study revealed that the position in which the PM was most stretched was maximum external rotation with 110° hip flexion and 40° hip adduction.

A controlled clinical trial investigating the effects of stretching and compression exercises on electromyography of calf muscles in chronic LBP patients with a deep gluteal syndrome

BACKGROUND

In deep gluteal syndrome (DGS), the piriformis muscle could impinge the sciatic nerve. The FAIR (flexion adduction internal rotation) test is a provocation test used to identify sciatic nerve irritation caused by this muscle. Compression and stretching exercises are usually prescribed to treat this syndrome. The aim of this study was to compare the effects of these two treatments on surface electromyography (sEMG) of the gastrocnemius and tibialis anterior in patients with low back pain (LBP) and DGS.

MATERIALS AND METHODS

Forty-five participants were allocated to three groups of stretching exercise, compression or control. In addition to 15 min of heat and 15 min of electrical nerve stimulation for pain relief, participants in the compression exercise (CE) group received self-compression exercise, those in the stretching exercise (SE) group received self-stretching exercise and those in the control group received no extra interventions. For the two intervention groups, three sets of two minutes of exercise with two minutes of rest in between were applied. The sEMG amplitude values of the gastrocnemius and tibialis anterior muscles of the affected buttock side of any one group while performing the FAIR test were compared to the others. Pain and disability were assessed and the changes were compared between the two groups.

RESULTS

After the intervention period, no group demonstrated a change in the sEMG of the gastrocnemius or tibialis anterior muscles (p > 0.05). There was no difference in the change in this variable between groups (Mean difference (95% CI) of gastrocnemius was ranged over= -4.04 to 7.72 (-19.44 to 23.14); p = 0.603); (Mean difference (95% CI) of tibialis anterior muscles was ranged from - 2.44 to -6.43 (-18.28 to 9.31); p = 0.550).; Pain and disability also decreased significantly in all three study groups (p < 0.05). However, only the disability of patients who performed stretching exercises improved compared to the compression exercise group (Mean difference (95% CI) = -12.62 (-20.41 to -4.38); p = 0.009).

CONCLUSION

Neither stretching nor compression exercises altered the sEMG of the gastrocnemius and tibialis anterior muscles in patients with DGS. Furthermore, performing stretching exercises improved disability compared to the other interventions.

TRIAL REGISTRATION

The trial was retrospectively registered in the Iranian Registry of Clinical Trials ( www.irct.ir ) on 10/01/2017 as IRCT201604178035N4. URL of the record: https://en.irct.ir/trial/8473 .

Division of neuromuscular compartments and localization of the center of the intramuscular nerve-dense region in pelvic wall muscles based on Sihler's staining

The innervation of the pelvic wall muscles is not very clear. This study aimed to reveal the division of neuromuscular compartments and localize the surface position and depth of the center of the intramuscular nerve-dense region (CINDR) of the pelvic wall muscles based on Sihler's staining. Twenty-four adult cadavers were used. To localize the CINDR of the pelvic wall muscles, horizontal (H) and longitudinal (L) reference lines were drawn, and Sihler's staining was used to reveal the intramuscular nerve distribution. The CINDR projection points (P and P' points) behind and in front of the body surface, the positions of the P points projected onto the H and L lines (PH and PL points), and the depth of CINDR were determined by spiral computed tomography scanning. The piriformis and obturator internus muscles can be divided into two and three neuromuscular compartments, respectively. The PH of CINDR of the piriformis muscle was located at 22.61 ± 2.66% of the H line, the PL was at 28.53 ± 6.08% of the L line, and the puncture depth of the piriformis muscle was at 24.64 ± 2.16% of the PP' line. The PH of CINDR of the obturator internus muscle was at 16.49 ± 1.20% of the H line, the PL was at 10.94 ± 1.09% of its L line, and the puncture depth was 6.26 ± 0.38 cm. These findings may guide the design of the compartmentalized transplantation of the pelvic wall muscles and improve the target localization efficiency and efficacy for injecting botulinum toxin A to treat pelvic wall muscle spasm.

Could dry needling change the kinematics of gait in individuals with piriformis muscle syndromes? Secondary analysis of a randomized controlled trial

INTRODUCTION

Piriformis muscle syndrome (PMS) is a condition that can lead to symptoms including gluteal pain, local tenderness, and limitation of hip joint motion in daily activities, and it may have a major impact on some daily functions such as gait. We proposed that dry needling (DN) can improve the gait of individuals with PMS.

METHODS

Thirty-two individuals with PMS were assigned equally and randomly to the treatment group or the wait-list control group. Subjects in the treatment group received three sessions of DN of the piriformis muscle. All participants in both groups were educated to correct their lifestyles. The outcome measures were the gait-related parameters (walking speed, peak hip flexion, peak hip extension, time to peak internal and external hip rotation, and knee sagittal range of motion), which were evaluated at baseline and after treatment. To compare different outcomes, analysis of covariance (ANCOVA) was used, with baseline as the covariance and groups as a factor.

RESULT

After DN sessions, peak hip extension during gait showed a statistically significant difference [adjusted MD 1.9 (3.7-0.08), p < 0.05, d = 0.56 (0.1-1.28)] in favor of the DN group. Peak hip flexion, on the other hand, exhibited a marginal statistically significant difference [adjusted MD -3.2 (-6.51 to 0.01), p = 0.053, d = 0.44 (1.16 to -0.02)] compared to the control group.

CONCLUSION

The findings suggest that participants in DN showed significantly greater peak extension angle of the hip during walking in individuals with PMS than in the control group.

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.

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.

Evaluation of the Efficacy of Ultrasound-Guided Dry Needling Therapy and Exercise in Piriformis Muscle Syndrome

BACKGROUND

 Piriformis muscle syndrome (PMS) is characterized by symptoms of buttock pain and numbness radiating to the back of the thigh due to irritation of the sciatic nerve. This study aimed to evaluate the efficacy of dry needling (DN) therapy and exercise programs on pain, neuropathic pain, physical function, and disability in patients with PMS.

METHODS

 Forty-four patients with PMS were included in the study. Patients were divided into two groups, those who were treated with DN three times once per week under ultrasound guidance and those who had an exercise program for three weeks. To identify the outcomes of the treatment modalities, pre-treatment and post-treatment first-month and third-month visual analog scale (VAS), Oswestry Disability Index (ODI) questionnaire, Lower Extremity Functional Scale (LEFS), and Douleur Neuropathique 4 (DN4) questionnaire scores were used.

RESULTS

 There was no statistically significant difference between the groups in baseline scores of VAS (p = 0.548), DN4 (p = 0.446), and LEFS (p = 0.880), but in the DN group, baseline ODI scores were significantly higher than in the exercise group (p = 0.001). The group comparisons showed no statistically significant differences in decreasing pain, reducing disability, and increasing functional status scores among the groups at post-treatment first-month and third-month assessments (p > 0.05).

CONCLUSION

Both treatment modalities are beneficial in reducing pain and disability, and increasing the functional status of the patients with PMS in three months of follow-up. In patients who cannot adapt to exercise programs, DN treatment under ultrasound guidance should be kept in mind as a minimally invasive treatment modality with no adverse effects.

Cachexia, chorea, and pain in chronic nonbacterial osteitis and inflammatory bowel disease: a case report

BACKGROUND

Inflammatory bowel disease is an inflammatory disorder that primarily impacts the gastrointestinal tract, leading to malnutrition and chronic microscopic intestinal blood loss. Uncontrolled systemic inflammation can impact other parts of the body, known as extraintestinal manifestations. Up to 25% of patients with inflammatory bowel disease are reported to have these complications in their skin, joints, bones, eyes, liver, lung, and pancreas (Rogler et al. in Gastroenterology 161(4):1118-1132, 2021). Neurologic involvement as extraintestinal manifestations are less common, reported at 3-19%, including neuropathies, demyelination, and cerebrovascular events (Morís in World J Gastroenterol. 20(5):1228-1237, 2014).

CASE PRESENTATION

A 13-year-old Caucasian boy presented with 1 month of progressive lower-extremity pain, weakness, and weight loss. His physical examination was notable for cachexia, lower-extremity weakness, and chorea. Labs revealed normocytic anemia and systemic inflammation. Imaging revealed symmetric abnormal marrow signal in the pelvis and upper femurs. Pathologic examination of the bone revealed chronic inflammation consistent with chronic nonbacterial osteitis. Endoscopy revealed colonic inflammation consistent with inflammatory bowel disease.

CONCLUSIONS

Children and adolescents with musculoskeletal pain lasting more than 2 weeks with systemic signs or symptoms like weight loss should prompt evaluation for systemic inflammatory disorders such as chronic nonbacterial osteitis, which can occur in isolation or associated with inflammatory bowel disease. This patient also had a nonspecific neurologic abnormality, chorea, which resolved with treatment of underlying inflammatory disorder. These extraintestinal manifestations may be concurrent with or precede intestinal inflammation, requiring a high index of suspicion when investigating nonspecific systemic inflammation.

Association of Piriformis Thickness, Hip Muscle Strength, and Low Back Pain Patients with and without Piriformis Syndrome in Malaysia

Low back pain is a serious threat to human health and the illness jeopardizes the human workforce and pressurizes the health system in the community. Low back pain might be related to piriformis syndrome (PS), which is a disorder presented as muscular spasm and hypertrophy that is strongly associated with piriformis thickness. Nevertheless, the relationship between piriformis thickness and morphological and functional changes of the gluteal muscles in PS remains unclear. This study aimed to investigate the association between the thickness, strength, and activation of piriformis and gluteus muscles (maximus and medius) among low back pain (LBP) patients with and without PS. This is a case-control study conducted at HSNZ and UiTM from 2019-2020. A total number of 91 participants (LBP + PS (n = 36), LBP - PS (n = 24), and healthy (n = 31)) were recruited in this study. Negative radiography, specific symptoms, and a positive PS test were applied for PS diagnoses. The thickness, strength, and activation of piriformis and gluteus muscles were measured using ultrasonography (USG) and a surface electromyogram, respectively. Resultantly, the one-way ANOVA test demonstrated no significant difference in piriformis thickness between LBP + PS and LBP - PS (p > 0.01). Piriformis thickness was inversely correlated with gluteus maximus strength (r = -0.4, p < 0.05) and positively correlated with gluteus medius activation (r = 0.48, p < 0.01) in LBP + PS. Stepwise linear regression for LBP + PS revealed a significant association between piriformis thickness and gluteus maximus strength (R = -0.34, accounted for 11% of the variance) and gluteus medius activation in prone lying with the hip in an externally rotated, abducted, and extended (ERABEX) position (R = 0.43, accounted for 23% of the variance). With the adjustment of age and gender, piriformis thickness, gluteus maximus strength, and gluteus medius activation in prone lying with hip ERABEX demonstrated a significant association, but no independent effect of age and gender was detected within the range. Meanwhile, a significant association between piriformis thickness and gluteus maximus thickness was observed (R = 0.44, accounted for 19% of the variance) in the LBP - PS group. These findings may assist to elucidate the actions and functions of piriformis and gluteus muscle in LBP with and without PS.

A human donor (cadaveric) observation study of three needle placements in the piriformis muscle

OBJECTIVE

To compare the safety and accuracy of three dry needling locations in the piriformis muscle using human donors.

DESIGN

Observational dissection study of embalmed human donors.

METHODS

A licensed physical therapist of 17 years clinical experience and 5 years teaching dry needling placed three needles in a medial, midpoint, and lateral location of 14 piriformis muscles of seven embalmed human donors. Block dissection allowed for observation of tissues the needles traversed and recording of the structures that the needles pierced.

RESULTS

The lateral needle pierced piriformis in 3/14 trials, and contacted sciatic nerve in 0/14 trials. The medial needle pierced both piriformis and sciatic nerve in 11/14 trials. The midpoint needle pierced the piriformis in 11/14 trials, and contacted sciatic nerve in 3/14 trials. Fisher's Exact test (p < 0.001) found a nonrandom association between dry needle placement, and dry needle contact.

CONCLUSIONS

When dry needling the piriformis, a lateral approach can avoid the sciatic nerve, but cannot accurately pierce the piriformis tendon. Furthermore, while a midpoint and medial approach finds the piriformis muscle with the same accuracy, the midpoint location avoided the sciatic nerve more often.

Long-Term Aesthetic and Functional Evaluation of Intramuscular Augmentation Gluteoplasty with Implants

BACKGROUND

The insertion of gluteal silicone implants by intramuscular technique leads patients to develop gluteus maximus muscle atrophy. The objective of the present study was to correlate the muscular atrophy of the gluteus maximus proportional to the volume of the silicone implants used. The secondary objectives were to assess volumetry of the gluteus maximus muscle in the late follow-up, to assess the positioning of the implants, and to verify the association between volumetric muscle recovery and practice of physical exercise.

METHODS

This is a prospective study. The sample was composed of 22 patients who were operated and followed up on an outpatient basis and through gluteus computed tomography at three different moments: preoperatively, 12 months postoperatively, and late postoperatively (≥96 months).

RESULTS

Computed tomographic three-dimensional reconstruction and volumetric analysis showed a median atrophy of 6.68% of the gluteus maximus muscle volume in 12 months and 7.47% in the late postoperative period. The correlation between relative volume of the implant and atrophy percentage of the gluteus maximus did not present statistically significant results. There was an association between the practice of physical exercise and volumetry recovery of the gluteus maximus. No patient presented gluteal implant rotation.

CONCLUSIONS

There is no correlation between proportional volume of implants and atrophy percentage of gluteus maximus muscle, when using implants up to 400 cm 3 . The gluteus maximus muscle presents atrophy in the late follow-up of augmentation gluteoplasty with implants. There is recovery of muscle volumetry in the patients who practice physical activities. Intramuscular plane implants demonstrated stability in their long-term positioning.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

Özkan F. Radiological Comparison of Femoral Neck-Shaft Angle in Piriformis Syndrome: A Case-Control Study

Introduction

Variations in osseous, neural and muscular anatomical structures in the gluteal region have been investigated for their role in causing deep gluteal pain syndromes including piriformis syndrome. This study aimed to radiologically determine whether the femoral neck-shaft angle (NSA) in piriformis syndrome differs from that in a healthy population.

Methods

Two groups of participants comprising 23 piriformis syndrome patients and 22 healthy controls were included in the present study. Piriformis syndrome was diagnosed based on clinical findings and the diagnosis was confirmed by intramuscular local anaesthetic injection. Femoral NSAs were measured from the anteroposterior pelvic radiographs and compared between the control and piriformis syndrome-affected groups.

Results

The age, height, body weight, body mass index and gender distribution differences between the two groups (control and piriformis) were not statistically significant. The femur NSA was significantly lower in the piriformis group than in the control group. The receiver operating characteristic analysis revealed that the area under the curve, sensitivity and specificity for predicting the risk of piriformis syndrome (PS) were 0.946%, 100% and 86.36%, respectively, at an NSA cut-off of 127°.

Conclusions

Reduced femoral NSA is related to PS. However, studies with a larger study sample are needed to further substantiate this finding.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-022-00736-y.

Novel anatomical findings with implications on the etiology of the piriformis syndrome

PURPOSE

The cause of the piriformis-related pelvic and extra-pelvic pain syndromes is still not well understood. Usually, the piriformis syndrome is seen as extra-pelvic sciatica caused by the entrapment of the sciatic nerve by the piriformis in its crossing through the greater sciatic foramen. However, the piriformis muscle may compress additional nerve structures in other regions and cause idiotypic pelvic pain, pelvic visceral pain, pudendal neuralgia, and pelvic organ dysfunction. There is still a lack of detailed description of the muscle origin, topography, and its possible relationships with the anterior branches of the sacral spinal nerves and with the sacral plexus. In this research, we aimed to characterize the topographic relationship of the piriformis with its surrounding anatomical structures, especially the anterior branches of the sacral spinal nerves and the sacral plexus in the pelvic cavity, as well as to estimate the possible role of anatomical piriformis variants in pelvic pain and extra-pelvic sciatica.

METHODS

Human cadaveric material was used accordingly to the Swiss Academy of Medical Science Guidelines adapted in 2021 and the Federal Act on Research involving Human Beings (Human Research ACT, HRA, status as 26, May 2021). All body donors gave written consent for using their bodies for teaching and research. 14 males and 26 females were included in this study. The age range varied from 64 to 97 years (mean 84 ± 10.7 years, median 88).

RESULTS

three variants of the sacral origin of the piriformis were found when referring to the relationship between the muscle and the anterior sacral foramen. Firstly, the medial muscle origin pattern and its complete covering of the anterior sacral foramen by the piriformis muscle is the most frequent anatomical variation (43% in males, 70% in females), probably with the most relevant clinical impact. This pattern may result in the compression of the anterior branches of the sacral spinal nerves when crossing the muscle.

CONCLUSIONS

These new anatomical findings may provide a better understanding of the complex piriformis and pelvic pain syndromes due to compression of the sacral spinal nerves with their somatic or autonomous (parasympathetic) qualities when crossing the piriformis.

Hydroxyapatite crystal deposition disease around the hip: a rare cause of piriformis syndrome and ischiofemoral impingement

Hydroxyapatite crystal deposition disease (HADD) around the hip is typically described involving the gluteal tendons. However, HADD can occur in any location and result in varied clinical presentations. Even with small deposits, symptoms can be significant and imaging findings may appear aggressive, mimicking infection and malignancy particularly when in an atypical location.

We illustrate cases of both common and rare locations of HADD around the hip, in particular presenting as greater trochanteric pain syndrome, piriformis syndrome and ischiofemoral impingement. The latter two manifestations have not been previously described in the literature.

Low signal deposits were identified on MRI at the greater trochanter (gluteus medius tendon), proximal piriformis (adjacent to the sciatic nerve), and quadratus femoris (in the ischiofemoral space), respectively. Associated inflammatory changes with tendinopathy, bursitis and oedema were also demonstrated. The patient with piriformis syndrome underwent steroid injections and shockwave therapy with significant symptom improvement.

HADD should be within the differential diagnosis for hip pain and nerve compression syndromes. Knowledge of tendon anatomy and correlation with radiographs or CT, even after MRI, is crucial in recognising unusual manifestations and preventing unnecessary investigation. Therefore, we review the spectrum of imaging features of HADD, as well as the current evidence on its management, to confidently diagnose this condition.

Female Athlete Hip Injuries: A Narrative Review

OBJECTIVE

In this narrative review, we highlight sex-specific anatomic and biomechanical features of the hip region in female athletes, as well as the potential impact of these characteristics on observed disparities in both intra-articular and extra-articular injury patterns between female and male athletes. It is our goal to broaden the scope of knowledge related to hip pathology in active female athletes among sports medicine providers with the hope of better optimizing sport participation and performance in female athletes.

DATA SOURCES

A literature review was conducted using PubMed database and Google Scholar search engine. Search terms included sport, female, athlete, sex differences, injury, hip, and all diagnoses discussed in this review. Cross-reference of these articles identified additional resources.

MAIN RESULTS

Sex-specific differences in both static design and dynamic function contribute to disparities in hip injury patterns between female and male athletes. Intra-articular injuries, including labral and ligamentum teres pathology, as well as extra-articular injuries, including iliopsoas tendon dysfunction, gluteal and proximal hamstring tendinopathy, ischiofemoral impingement, bone stress injuries, and certain nerve entrapment syndromes, seem to affect female athletes more commonly than male counterparts.

CONCLUSIONS

Given unique anatomic and functional considerations, the growing population of female athletes worldwide warrants specialized care and consideration. Potential predisposition to specific hip injuries should be taken into consideration during diagnostic evaluation of hip pain in the female athlete.

Overview of the anatomical basis of the piriformis syndrome-dissection with magnetic resonance correlation

The piriformis syndrome is one of the most commonly misdiagnosed causes of lower back and gluteal pain caused by the compression of the sciatic nerve and the internal pudendal neurovascular bundle by the piriformis muscle. Although this syndrome was first suggested over 90 years ago, its diagnosis still represents a challenge for clinicians. In the present study, dissection was used to determine the intra- and extrapelvic anatomical course of the internal pudendal nerve and the data were compared with the information obtainable through MRI examination, in order to identify the piriformis syndrome and to differentiate it from other causes of internal pudendal neuralgia. Thorough dissections of the pelvis and deep gluteal region were conducted on female cadavers, which were correlated with MRI scans, in order to describe the course of the internal pudendal nerve in contact with the piriformis muscle. The dissection findings and MRI scans obtained allowed us to describe and demonstrate the compression points along the course of the sciatic nerve and the internal pudendal bundle, the anatomical correlations between the piriformis muscle and the nervous structures around it, emphasizing the areas most susceptible to possible nerve impingement syndromes. In the anatomic trajectory of the sciatic nerve and the internal pudendal bundle there are multiple contact points with anatomical structures that may lead to compression of the nerve structures, generating symptoms that comprise the piriformis syndrome. The present study sought to establish clear osseous landmarks that may help evaluate these associations and possible nerve compressions on pelvic MRI examination.

[New treatment options for piriformis syndrome]

This paper discusses modern approaches to the diagnosis and management of patients with piriformis syndrome. Epidemiological data on the prevalence of this syndrome in neurological practice are presented. The anatomical features of this region, leading to the formation of piriformis syndrome, are described in detail. The authors provide diagnostic criteria based on neurological examination and manual muscle testing and discuss the differential diagnosis of piriformis syndrome. New possibilities of treating this syndrome using a fixed combination of diclofenac and orphenadrine registered in the Russian Federation as a drug for intravenous infusion neodolpasse are discussed in detail. The authors cite materials from their own work, a clinical case of managing a patient with piriformis syndrome using neodolpasse is analyzed.

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.

Effect of integrated neuromuscular inhibition technique compared with positional release technique in the management of piriformis syndrome

CONTEXT

Studies have indicated that the muscle energy technique (MET) and the positional release technique (PRT) are effective in the management of piriformis syndrome (PS); however, evidence is scarce regarding the combination of these techniques in the form of an integrated neuromuscular inhibition technique (INIT) in the management of individuals with PS. Although a previous trial investigated the effect of INIT for PS, that study did not integrate Ruddy's reciprocal antagonist facilitation (RRAF) method into the INIT protocol, nor did the authors diagnose PS according to established criteria.

OBJECTIVES

To examine the effects of INIT with integrated RRAF compared with PRT in the management of patients diagnosed with PS.

METHODS

This study was designed as a single blind randomized clinical trial in which participants diagnosed with PS were randomly allocated into INIT and PRT groups. Each group attended two treatment sessions per week for 8 weeks. Patients in the INIT group received a protocol in which the patient's tender point or trigger point was palpated in the belly of the piriformis approximately halfway between the inferior lateral angle of the sacrum and the greater trochanter, at which point the therapist applied an intermittent or sustained pressure and maintained the pressure for 20-60 seconds (depending on the participant's response to pain reduction). For INIT patients, that protocol was also followed by RRAF, a method in which a patient introduces a series of tiny/miniature contractions or efforts (20 times per 10 seconds) against a therapist's resistance. Patients in the PRT group were treated by palpating the same trigger point described in the INIT group, followed by application of light pressure at the location of the trigger point, which was maintained the pressure for 2 minutes or until the pain subsided (determined by asking the participant to report a pain score using a visual analog scale at 30 second intervals). For both groups, three repetitions of the INIT or PRT treatment were performed over 10 minutes at each clinical visit. Additionally, each group also received stretching exercises immediately after the INIT or PRT treatment session. Each participant was assessed at baseline, immediately posttreatment, and at 4 months posttreatment for pain, sciatica, functional mobility, quality of life, hip abduction, and internal rotation. A repeated measures analysis of variance (ANOVA) of within-between group interactions was used to analyze the treatment effect.

RESULTS

Forty eight participants (age range, 25-47 years; mean age ± standard deviation, 32.81 ± 3.27 years) were randomized into the INIT and PRT groups, with 24 participants in each group. No significant between-group differences (p>0.05) were observed in the baseline demographic and clinical variables of the participants. A repeated-measures ANOVA indicated that there was a significant time effect for all outcomes, with a significant interaction between time and intervention (p<0.001). The Bonferroni post hoc analyses of time and intervention effects indicated that the INIT group improved significantly compared with the PRT group in all outcomes (p<0.05) immediately posttreatment and at the 4 months follow up period.

CONCLUSIONS

INIT was more effective than PRT in the management of individuals with PS. It should be noted the significant improvement achieved in both the groups may have also been contributed to by the stretching exercises that were used as adjunct therapies by both groups.

Little needle-scalpel for piriformis syndrome: A protocol for systematic review and meta-analysis

BACKGROUND

Piriformis syndrome (PS) is a condition in which the sciatic nerve is compressed when passing through the inferior mouth of the piriformis muscle, mainly caused by pain in one hip and leg. In severe cases, patients may experience severe buttock and lower limb pain, discomfort, difficulty walking, and claudication. It is estimated that the annual incidence of low back pain and sciatica is about 40 million cases, and the annual incidence of piriformis syndrome is about 2.4 million cases. The aim of this systematic review is to assess the effectiveness and safety of Little needle-scalpel therapy for Piriformis syndrome.

METHODS

Two reviewers will electronically search the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; China National Knowledge Infrastructure (CNKI); Chinese Biomedical Literature Database (CBM); Chinese Scientific Journal Database (VIP database); and Wan-Fang Database from the inception, without restriction of publication status and languages. Additional searching including researches in progress, the reference lists, and the citation lists of identified publications. Study selection, data extraction, and assessment of study quality will be performed independently by 2 reviewers. If it is appropriate for a meta-analysis, RevMan 5.4 statistical software will be used; otherwise, a descriptive analysis will be conducted. Data will be synthesized by either the fixed-effects or random-effects model according to a heterogeneity test. The results will be presented as risk ratio (RR) with 95% confidence intervals (CIs) for dichotomous data and weight mean difference (WMD) or standard mean difference (SMD) 95% CIs for continuous data.

RESULTS

This study will provide a comprehensive review of the available evidence for the treatment of Little needle-scalpel with piriformis syndrome.

CONCLUSIONS

The conclusions of our study will provide an evidence to judge whether Little needle-scalpel is an effective and safe intervention for patients with piriformis syndrome.

ETHICS AND DISSEMINATION

This systematic review will be disseminated in a peer-reviewed journal or presented at relevant conferences. It is not necessary for a formal ethical approval because the data are not individualized.

TRIAL REGISTRATION NUMBER

INPLASY2020110092.

Piriformis syndrome: pain response outcomes following CT-guided injection and incremental value of botulinum toxin injection

PURPOSE

Piriformis syndrome is a common pain condition affecting the buttock and posterior hip with or without radiation to the leg, and management of the condition involves many treatments. In this study, we hypothesize that a CT-guided injection with botulinum toxin is more effective in providing pain relief than a CT-guided injection without Botox.

METHODS

Overall, 97 consecutive patients with piriformis syndrome presented for a CT-guided injection of the piriformis muscle and perineural injection of the sciatic nerve. After the injection, the patients received a visual analog scale pain log to record their pain level until the follow-up appointment. P values of less than 0.2 were considered as confounder and adjusted by inverse probability of treatment weighting (IPTW) via propensity score. The effect of botulinum toxin on 48-hour response and duration of response was tested using weighted chi-square test and weighted Kaplan-Meier analysis.

RESULTS

There was a total of 97 patients in the study, and 111 injections, as some patients had bilateral injections. Patients in the Botox group had more 48-hour response than patients in the non-botulinum toxin group (P < 0.001 with IPTW, P = 0.005 without IPTW). Median pain-free survival was 30 days for Botox group and 1 day for non-Botox group (P = 0.059 with IPTW, P = 0.10 without IPTW).

CONCLUSION

CT-guided injections with botulinum toxin for patients with piriformis syndrome are more likely to lead to a positive response and a longer duration of response than patients who receive a CT-guided injection without botulinum toxin. We hope that this study facilitates future prospective randomized blind trials for patients with suspected piriformis syndrome.

The why, where, and how clinical reasoning model for the evaluation and treatment of patients with low back pain

BACKGROUND

There is considerable overlap between pain referral patterns from the lumbar disc, lumbar facets, the sacroiliac joint (SIJ), and the hip. Additionally, sciatic like symptoms may originate from the lumbar spine or secondary to extra-spinal sources such as deep gluteal syndrome (GPS). Given that there are several overlapping potential anatomic sources of symptoms that may be synchronous in patients who have low back pain (LBP), it may not be realistic that a linear deductive approach can be used to establish a diagnosis and direct treatment in this group of patients.

OBJECTIVE

The objective of this theoretical clinical reasoning model is to provide a framework to help clinicians integrate linear and non-linear clinical reasoning approaches to minimize clinical reasoning errors related to logically fallacious thinking and cognitive biases.

METHODS

This masterclass proposes a hypothesis-driven and probabilistic approach that uses clinical reasoning for managing LBP that seeks to eliminate the challenges related to using any single diagnostic paradigm.

CONCLUSIONS

This model integrates the why (mechanism of primary symptoms), where (location of the primary driver of symptoms), and how (impact of mechanical input and how it may or may not modulate the patient's primary complaint). The integration of these components individually, in serial, or simultaneously may help to develop clinical reasoning through reflection on and in action. A better understanding of what these concepts are and how they are related through the proposed model may help to improve the clinical conversation, academic application of clinical reasoning, and clinical outcomes.

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,

Complete resolution of recurrent piriformis syndrome after piriformis resection with 3 years' follow up: A case report

•

Some of piriformis syndrome intractable with conservative treatment.

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Surgery was indicated for intractable piriformis syndrome.

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Piriformis resection can be a feasible option for intractable piriformis syndrome.

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Piriformis resection decrease visual analog scale in intractable piriformis syndrome.

Introduction

Piriformis syndrome (PS) is an uncommon neuromuscular condition characterized by buttock pain radiating to the leg. Although the goal of PS treatment is symptom relief, it is difficult in some patients using conservative treatment alone.

Presentation of case

A 72-year-old male underwent piriformis resection after failed sequential steroid injection of the piriformis. The patient ultimately underwent surgery for resection of the piriformis muscle and experienced satisfactory pain relief (pain reduction > 75% according to visual analog scale for at least 12 months) following surgery and in the 3-year follow-up period.

Discussion

Conservative treatment is first-choice treatment for managing PS. Surgery was indicated when the patient did not achieve satisfactory pain relief with conservative treatment. Surgical resection of the piriformis muscle has been shown to be effective and feasible.

Conclusion

Piriformis resection is effective and can be a feasible option for the treatment of PS following failure of appropriate conservative treatment(s).

‘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.

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.

Gait analysis of patients with piriformis muscle syndrome compared to healthy controls

BACKGROUND

Piriformis muscle syndrome (PMS) is a condition that can causes local buttock pain and tenderness. The symptoms of PMS are related to the hip joint position and may affect repetitive daily tasks such as walking.

OBJECTIVES

What is the difference between the gait characteristics of patients with PMS and those of matched-healthy controls?

DESIGN

Observational study.

METHODS

Thirty patients with PMS and 30 age-, sex-, and height-matched healthy participants underwent three-dimensional walking analysis.

RESULTS

The results showed no significant differences in the spatiotemporal characteristics of gait between the groups (p > 0.1). The PMS group flexed the hip joint significantly more (-7.2 [-11.9 to -2.2], p = 0.003) and extended the hip joint to a lesser degree (-2.48 [-4.91 to -0.5], p = 0.04) than the control group. Patients with PMS needed a statistically significantly longer time to reach the peak angles of hip internal (1.3 [1 to 1.9], p = 0.003) and external (5.5 [0.9 to 10.1], p = 0.01) rotations during the gait cycle. Further, the results showed that the sagittal range of motion of the knee joint was significantly lesser in patients with PMS than in controls (3.45 [0.4 to 6.4], p = 0.02).

CONCLUSIONS

Patients with PMS seem to have different kinematic changes during level walking. Changing the peak flexion and extension of the hip joint is considered a strategy to enable pain-free gait in patients with PMS. Further, the knee kinematics are modified consequent to the change of hip joint kinematics.

A critical overview of the current myofascial pain literature - July 2020

We are sad to report that following this issue, Dr. Li-Wei Chou will no longer be able to contribute to this quarterly literature overview. Unfortunately, his work responsibilities have increased to such an extent that they need to take priority. On behalf of the team, we would like to thank Dr. Chou for his thoughtful and balanced reviews during the past few years. Not only were we able to include an occasional Chinese-language study, he also was able to assist us in interpreting more complex medical studies. Li-Wei, we wish you all the best professionally and personally, and of course, we cannot wait until our paths will cross again sometime in the future! You may have noted that this overview article was missing from the January 2020 issue of the journal due to an administrative mix up. With the current issue we aimed to catch up and therefore, you will find a greater number of reviewed articles than usual. It becomes increasingly challenging to cover the wide range of the published myofascial pain and trigger point (TrP) literature just due to its volume. In this edition, we included 10 basic research articles, 4 reviews, 14 articles on dry needling (DN), acupuncture, and injections, 3 on manual therapies, and 4 on other clinical approaches.

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.

Compression of the S1 Nerve Root by an Extradural Vascular Malformation: A Case Report and Discussion of Atypical Causes of Lumbar Radiculopathy

We present a case of lumbar radiculopathy due to a vascular malformation in the lumbar spine and discuss various causes of atypical lumbar radiculopathy. Lumbar radiculopathy is a condition of neurologic deficits and painful symptoms of the lower extremities due to nerve root compression, most commonly at the L5 and S1 levels. Several factors contribute to lumbar radiculopathy, including intervertebral disc herniation, foraminal stenosis, and spinal instability. There are also a number of atypical causes, including medication side effects or metabolic disorders, which produce symptoms of radiculopathy but do not involve compression of the nerve root. Anatomic variations in the nerve roots or vascular supply surrounding the nerve root may also increase the risk of developing radiculopathy and serve as an obstacle to interpreting imaging during a preoperative workup. A 38-year-old woman presented with sudden onset radicular symptoms in her right lower extremity. Lumbar magnetic resonance imaging demonstrated a right-sided L5-S1 extruded nucleus pulposus. Her symptoms failed to improve after conservative management so she underwent surgical decompression of L4-S1. Intraoperatively, we discovered an extensive, extradural vascular malformation present at the L5-S1 level and believed this to be the true cause of her radiculopathy. This case represents an atypical cause of lumbar radiculopathy and demonstrates the importance of considering atypical causes during diagnostic workup and preoperative planning.

Pressure Pain Threshold in Subjects With Piriformis Syndrome: Test-Retest, Intrarater, and Interrater Reliability, and Minimal Detectible Changes

OBJECTIVE

This study aimed to assess the test-retest, intrarater, and interrater reliability of using the pressure pain threshold (PPT) in healthy and affected piriformis muscles and to estimate its absolute reliability. As a secondary objective, the degree of tenderness of the affected piriformis muscles was compared with healthy piriformis muscles.

STUDY DESIGN

This study used a comparative and reliability-based design.

SETTING

Rehabilitation clinic.

PARTICIPANTS

Patients (N=30) with unilateral piriformis muscle syndrome (30 affected and 30 healthy piriformis muscles) were recruited, and the PPT of both the healthy and affected piriformis muscles was recorded using digital algometry. Measurements of PPT were done by 2 raters (rater 1 and 2), which were selected at random order. Rater 1 repeated the PPT measurements 24-72 hours after initial assessment.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

PPT.

RESULTS

Excellent intrarater intraclass correlation coefficient (ICC) values were observed for the PPT of the affected piriformis (ICC: 0.86-0.96) and the healthy piriformis (ICC: 0.88-0.96) in the same session. The PPT measurements using digital algometry showed good-to-excellent interrater reliability (ICC: 0.64-0.92) and test-retest reliability (ICC: 0.72-0.95) in both the healthy and affected piriformis muscles. The findings revealed a significant decrease in the PPT of the affected piriformis muscle in comparison to the healthy piriformis muscle (mean difference 12.76; 95% confidence interval, 15.69-9.82; P<.001).

CONCLUSIONS

Digital algometry is a reliable tool for measuring piriformis PPT, regardless of the testing session and the rater. Patients with unilateral piriformis muscle syndrome have increased tenderness and decreased PPT in the affected piriformis muscle in comparison to the healthy piriformis muscle.

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.

Current Evidence for Diagnosis of Common Conditions Causing Low Back Pain: Systematic Review and Standardized Terminology Recommendations

OBJECTIVE

The purpose of this systematic review is to evaluate and summarize current evidence for diagnosis of common conditions causing low back pain and to propose standardized terminology use.

METHODS

A systematic review of the scientific literature was conducted from inception through December 2018. Electronic databases searched included PubMed, MEDLINE, CINAHL, Cochrane, and Index to Chiropractic Literature. Methodological quality was assessed with the Scottish Intercollegiate Guidelines Network checklists.

RESULTS

Of the 3995 articles screened, 36 (8 systematic reviews and 28 individual studies) met final eligibility criteria. Diagnostic criteria for identifying likely discogenic, sacroiliac joint, and zygapophyseal (facet) joint pain are supported by clinical studies using injection-confirmed tissue provocation or anesthetic procedures. Diagnostic criteria for myofascial pain, sensitization (central and peripheral), and radicular pain are supported by expert consensus-level evidence. Criteria for radiculopathy and neurogenic claudication are supported by studies using combined expert-level consensus and imaging findings.

CONCLUSION

The absence of high-quality, objective, gold-standard diagnostic methods limits the accuracy of current evidence-based criteria and results in few high-quality studies with a low risk of bias in patient selection and reference standard diagnosis. These limitations suggest practitioners should use evidence-based criteria to inform working diagnoses rather than definitive diagnoses for low back pain. To avoid the unnecessary complexity and confusion created by multiple overlapping and nonspecific terms, adopting International Association for the Study of Pain terminology and definitions is recommended.

Development of an Evidence-Based Practical Diagnostic Checklist and Corresponding Clinical Exam for Low Back Pain

OBJECTIVE

The purpose of this study was to use scientific evidence to develop a practical diagnostic checklist and corresponding clinical exam for patients presenting with low back pain (LBP).

METHODS

An iterative process was conducted to develop a diagnostic checklist and clinical exam for LBP using evidence-based diagnostic criteria. The checklist and exam were informed by a systematic review focused on summarizing current research evidence for office-based clinical evaluation of common conditions causing LBP.

RESULTS

Diagnostic categories contained within the checklist and exam include nociceptive pain, neuropathic pain, and sensitization. Nociceptive pain subcategories include discogenic, myofascial, sacroiliac, and zygapophyseal (facet) joint pain. Neuropathic pain categories include neurogenic claudication, radicular pain, radiculopathy, and peripheral entrapment (piriformis and thoracolumbar syndrome). Sensitization contains 2 subtypes, central and peripheral sensitization. The diagnostic checklist contains individual diagnostic categories containing evidence-based criteria, applicable examination procedures, and checkboxes to record clinical findings. The checklist organizes and displays evidence for or against a working diagnosis. The checklist may help to ensure needed information is obtained from a patient interview and exam in a variety of primary spine care settings (eg, medical, chiropractic).

CONCLUSION

The available evidence informs reasonable working diagnoses for many conditions causing or contributing to LBP. A practical diagnostic process including an exam and checklist is offered to guide clinical evaluation and demonstrate evidence for working diagnoses in clinical settings.

Ultrasound-guided dry needling decreases pain in patients with piriformis syndrome

INTRODUCTION

Piriformis muscle syndrome (PMS) is a disorder that can lead to symptoms of buttock pain and limited hip-joint mobility, and may have an impact on quality of life.

METHODS

Thirty-two patients with PMS were randomized to the treatment group, which included three sessions of ultrasound-guided dry needling (DN) of the piriformis muscle (n = 16), or a waitlist control group (n = 16). The primary outcome was pain intensity measured on the visual analog scale recorded at baseline and then at 72 hours and 1 week after treatment.

RESULTS

At 1-week follow-up, pain intensity was significantly less in the DN group than in the waitlist control group (-2.16 [-1.01 to -3.32], P = .007) by an amount consistent with clinically meaningful improvement.

DISCUSSION

The findings suggest that DN resulted in clinically meaningful short-term improvement in pain intensity of patients with PMS.

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.

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.

Ultrasound elastography findings in piriformis muscle syndrome

Background:

Piriformis muscle syndrome (PMS) is relatively less known and underestimated because it is confused with other clinical pathological conditions. Delays in its diagnosis may lead to chronic somatic dysfunction and muscle weakness.

Objective:

Here, we aimed to evaluate the diagnostic performance of the ultrasound elastography (UE) as an easy, less-invasive, and cost-effective method for early diagnosis of PMS.

Materials and Methods:

Twenty-eight cases clinically diagnosed as PMS at the outpatient clinic were evaluated by UE. The elastographic strain ratio was calculated by dividing the strain value of the subcutaneous fat tissue by the mean stress value of the muscle beneath. The diagnostic performances of the strain rate measures were compared using the receiver operating characteristic curve analysis.

Results:

Twenty-one (N = 21) cases were female, and seven (N = 7) of the cases were male. The mean age was 45 years (ranged 24–62 years). The strain rates of piriformis muscle (PM) and gluteus maximus (GM) muscles were significantly higher on the PMS-diagnosed side (P < 0.001). The cutoff value of UE strain ratio for the PM and GM were 0.878 [95% confidence interval (CI) 0.774–0.981] and 0.768 (95% CI 0.622–0.913), respectively, and the sensitivity and specificity values were, respectively, 80.95% and 85.71% for the PM, and they were, respectively, 85.71% and 66.67% for the GM.

Conclusion:

We showed that the muscle elasticity and tissue hardening increased on the problematic side both on PM and GM. UE may provide early diagnosis of PMS, thereby increasing the possibility of treatment with less invasive methods.

The majority of piriformis muscles are innervated by the superior gluteal nerve

The piriformis muscle is clinically implicated in pain disorders, posterior approaches for total hip arthroplasty, and iatrogenic injury to the muscle and the surrounding nerves. The piriformis muscle has been said to receive innervation from L5 to S3 ventral rami with most sources using S1 and S2 ventral rami as the most common innervation this muscle. However, descriptions of the nerve in the literature are vague. Therefore, the aim of this study was to clarify the anatomy of the nerve supply to the piriformis muscle. Twenty sides from ten fresh-frozen cadavers were studied. Specifically, via anterior dissection of the sacral plexus, branches to the piriformis were identified. Once identified, the nerves to the piriformis muscle were traced proximally to clarify their origin. Nerves supplying the piriformis muscle existed on all sides. On 80% of sides, the piriformis was innervated by two to three nerves. The origin of these nerves was from the superior gluteal nerve on 14 sides (70%), inferior gluteal nerve on one side (5%), L5 ventral ramus on one side (5%), S1 ventral ramus on 17 sides (85%), and S2 ventral ramus on 14 sides (70%), respectively. The most common nerve branches to the piriformis are from the superior gluteal nerve, and the ventral rami of S1 and S2. Based on our study, a single "nerve to piriformis" does not exist in the majority of specimens thus this term should be abandoned. Clin. Anat. 32:282-286, 2019. © 2018 Wiley Periodicals, Inc.