Síndrome do piriforme: diagnóstico e tratamento: um estudo retrospectivo / Piriformis syndrome: diagnosis and treatment: a retrospective study

Introdução: A síndrome do piriforme (SP) é uma causa de dor ciática pouco entendida e conhecida, por isso, subdiagnosticada. Possui múltiplas possibilidades etiológicas e a abordagem terapêutica corrente privilegia o tratamento conservador. Objetivo: Neste estudo retrospectivo são destacados o diagnóstico, a etiologia, o diagnóstico diferencial e analisados os resultados do tratamento instituído. Métodos: 34 casos com seguimento mínimo de seis meses e máximo de 12 meses avaliados por uma escala simplificada de graduação de sintomas. Resultados: O tratamento clínico-conservador obteve excelentes resultados em 23 pacientes (67,6%), bom em nove pacientes (26,4%) e razoáveis (insatisfatórios) em dois pacientes (5,8%). Conclusões: Na dor com característica ciática, contínua ou intermitente e sem evidências de compressão radicular ou herniação discal lombar, deve-se pesquisar a possibilidade de síndrome do piriforme como um diagnóstico eminentemente clínico e de exclusão. O tratamento conservador apresenta resultados satisfatórios na maioria dos casos e a indicação cirúrgica está reservada como último recurso às falhas da terapia conservadora.

Introduction: Piriformis syndrome is a cause of sciatalgy barely understood and frequently unrecognized. It has multiple possible etiologic factors and the treatment of option is largely conservative. Objective: In this retrospective study, the diagnostic signs, the ethiology, the diferential diagnosis and the treatment results are discussed. Methods: 34 patients were followed-up for 6-12 months and evaluated by a simplified symptom rating scale. Results: Excellent results in 23 patients (67,6%), good in 9 patients (26,4%) and fair (unsatisfactory) in 2 patients (5,8%). Conclusions: In patients with sciatic pain without proved rachidian or discal lumbar disease, the possibility of Piriformis Syndrome must be investigated mainly by proper clinical examination and seen as a diagnosis of exclusion. The conservative treatment has satisfactory outcomes in most of cases and surgical procedure is reserved as a last resort in case of failure of the conservative management.

The absence of piriformis muscle, combined muscular fusion, and neurovascular variation in the gluteal region

The gluteal region contains important neurovascular and muscular structures with diverse clinical and surgical implications. This paper aims to describe and discuss the clinical importance of a unique variation involving not only the piriformis, gluteus medius, gluteus minimus, obturator internus, and superior gemellus muscles, but also the superior gluteal neurovascular bundle, and sciatic nerve. A routine dissection of a right hemipelvis and its gluteal region of a male cadaver fixed in 10% formalin was performed. During dissection, it was observed a rare presentation of the absence of the piriformis muscle, associated with a tendon fusion between gluteus and obturator internus, and a fusion between gluteus minimus and superior gemellus muscles, along with an unusual topography with the sciatic nerve, which passed through these group of fused muscles. This rare variation stands out with clinical manifestations that are not fully established. Knowing this anatomy is essential to avoid surgical iatrogeny.

Reporte de caso: origen del músculo piriforme a través de dos cabezas en forma de bíceps, propicia división del nervio isquiático en nervio fibular común y nervio tibial / Case report: origin of the piriformis muscle through two heads in the form of biceps, favorable division of the sciatic nerve in the common fibular nerve and tibial nerve

El músculo piriforme es un músculo pelvitrocantérico que recibe su nombre debido a su forma de pera, cuyo origen es de varios fascículos que se encuentran entre los forámenes anteriores del sacro, correspondiente a las segunda, tercera y cuarta vértebra. Estos fascículos se funden constituyendo un músculo aplanado, que se inserta en el trocánter mayor del fémur. Presenta una relación bien conocida con el nervio isquiático, el cual comúnmente emerge hacia la región glútea por el margen inferior de este músculo, sin embargo a través del tiempo, autores han descrito variaciones del paso de este nervio que podrían asociarse a alguna patología de compresión del nervio isquiático. En una disección rutinaria de dos individuos formolizados, uno femenino y otro masculino de la región glútea, encontramos que el músculo piriforme se originaba a través de dos cabezas, cada una con su propia fascia que se unían en un vientre común, en forma de bíceps y a través de un tendón cilíndrico se insertaban en la parte medial del trocánter mayor del fémur. El nervio isquiático se encontraba dividido, el nervio fibular común emergía a la región glútea a través de las cabezas, en tanto el nervio tibial por el margen inferior del músculo piriforme. Es importante comunicar las variaciones anatómicas para complementar el conocimiento de las mismas, las que pueden explicar ciertos trastornos físicos y dolorosos como el denominado síndrome del músculo piriforme.

The piriform muscle is a pelvitrochanteric muscle that gets its name due to its pear shape, whose origin are several fascicles located between the anterior foramina of the sacrum, corresponding to the second, third and fourth vertebrae. These fascicles are fused forming a flattened muscle, which is inserted into the greater trochanter of the femur. It has a well-known relationship with the sciatic nerve, which commonly emerges towards the gluteal region through the lower margin of this muscle, however over time, authors have described variations in the course of this nerve that could be associated with some compression pathology of the sciatic nerve. In a routine dissection of two formalized individuals, one female and one male, we found that the piriformis muscle originated through two heads, each with its own fascia that joined in a bicep-shaped common belly. Through a cylindrical tendon it is inserted into the medial part of the greater trochanter of the femur. The sciatic nerve was divided, the common fibular nerve emerged to the gluteal region through the heads, while in the tibial nerve divided through the inferior margin of the piriformis muscle. It is important to report on the anatomical variations to complement knowledge of these variations, which may explain certain physical and painful disorders such as the socalled piriformis muscle syndrome.

Sciatic nerve and its variations: is it possible to associate them with piriformis syndrome? / Nervo isquiático e suas variações: é possível associá-las à síndrome do piriforme?

ABSTRACT The sciatic nerve forms from the roots of the lumbosacral plexus and emerges from the pelvis passing inferiorly to the piriformis muscle, towards the lower limb where it divides into common tibial and fibular nerves. Anatomical variations related to the area where the nerve divides, as well as its path, seem to be factors related to piriformis syndrome. Objective: To analyze the anatomical variations of the sciatic nerve and its clinical implications. Methods: This was a systematic review of articles indexed in the PubMed, LILACS, SciELO, SpringerLink, ScienceDirect and Latindex databases from August to September 2018. Original articles covering variations of the sciatic nerve were included. The level of the sciatic nerve division and its path in relation to the piriformis muscle was considered for this study. The collection was performed by two independent reviewers. Results: At the end of the search, 12 articles were selected, characterized according to the sample, method of evaluation of the anatomical structure and the main results. The most prevalent anatomical variation was that the common fibular nerve passed through the piriformis muscle fibers (33.3%). Three studies (25%) also observed anatomical variations not classified in the literature and, in three (25%) the presence of a double piriformis muscle was found. Conclusion: The results of this review showed the most prevalent variations of the sciatic nerve and point to a possible association of this condition with piriformis syndrome. Therefore, these variations should be considered during the semiology of disorders involving parts of the lower limbs.

RESUMO O nervo isquiático forma-se a partir das raízes do plexo lombosacro e emerge da pelve passando inferiormente ao músculo piriforme, em direção ao membro inferior onde se divide em nervos tibial e fibular comum. Variações anatômicas relativas ao local onde ocorre a divisão desse nervo, bem como do seu trajeto, parecem ser fatores relacionados à síndrome do piriforme. Objetivo: Analisar as variações anatômicas do nervo isquiático e suas implicações clínicas. Materiais e Métodos: Trata-se de uma revisão sistemática de artigos indexados nas bases de dados PubMed, LILACS, SciELO, SPRINGERLINK, SCIENC DIRECT e LATINDEX. Foram incluídos artigos originais envolvendo as variações do nervo isquiático. Considerou-se para este estudo o nível de divisão do nervo isquiático e o seu trajeto em relação ao músculo piriforme. A coleta foi realizada por dois revisores independentes. Resultados: Ao final da busca foram selecionados 12 artigos, caracterizados quanto à amostra, método para avaliar a estrutura anatômica e principais resultados. A variação anatômica mais prevalente foi aquela em que o nervo fibular comum atravessa as fibras do músculo piriforme (33,3%). Três estudos (25%) observaram, ainda, variações anatômicas não classificadas na literatura e em outros três (25%) constatou-se a presença de um músculo piriforme duplo. Conclusão: Os resultados desta revisão mostram as variações mais prevalentes do nervo isquiático e apontam para uma possível associação dessa condição com a síndrome do piriforme. Desse modo, essas variações devem ser consideradas durante a semiologia dos distúrbios envolvendo os membros inferiores.

Piomiositis del músculo piriforme por Streptococcus pyogenes en un niño / Streptococcus pyogenes pyomyositis of the piriformis muscle in a child

La piomiositis aguda es una infección supurativa del músculo esquelético. El agente etiológico más frecuente es Staphylococcus aureus, y son infrecuentes los casos producidos por Streptococcus pyogenes. Las localizaciones más habituales son cuádriceps, glúteos e iliopsoas; es excepcional la afectación del músculo piriforme. Se presenta el caso de un varón de 8 años, previamente sano, que fue ingresado en nuestro hospital por una piomiositis aguda por Streptococcus pyogenes localizada en el músculo piriforme. El diagnóstico y el inicio precoz del tratamiento antibiótico permitieron el manejo conservador del cuadro y no fue necesaria la cirugía. La evolución fue satisfactoria y no presentó secuelas.

Acute pyomyositis is a suppurative infection of the skeletal muscle. Staphylococcus aureus is the most frequent etiological agent. Cases produced by Streptococcus pyogenes are uncommon. The most usual locations are quadriceps, buttocks and iliopsoas. The involvement of the piriformis muscle is very exceptional. We present the case of a previously healthy 8-year-old male who was admitted to our hospital for acute pyomyositis caused by Streptococcus pyogenes located in the piriformis muscle. Early diagnosis and prompt initiation of antibiotic treatment allowed the conservative management of the condition, and surgery was not necessary. The evolution was satisfactory without sequels.

Accessory Belly of the Piriformis Muscle as a Cause of Piriformis Syndrome: a Case Report with Magnetic Resonance Imaging and Magnetic Resonance Neurography Imaging Findings

Piriformis syndrome caused by an accessory belly of the piriformis muscle is very rare. Only a few cases have been reported. Here, we report a case of piriformis syndrome resulting from an extremely rare type of accessory belly of the piriformis muscle originated at the proximal third portion of the main piriformis muscle and attached separately to the greater trochanter inferior to the insertion of the main piriformis muscle. A definitive diagnosis of piriformis syndrome was made based on magnetic resonance imaging and magnetic resonance neurography findings that were consistent with results of nerve conduction study and needle electromyography.

Dolor del Músculo Piramidal en pacientes oncológicos. Tratamiento dirigido por Ultrasonido sin Hidrodisección Perineural del Ciático. Presentación de 10 casos / Pyramidal Muscle Pain in cancer patients. Treatment directed by Ultrasound without Perineural Hydrodissection of the Sciatic. Presentation of 10 cases

Introducción: El síndrome del músculo piramidal constituye el conjunto de signos y síntomas originados por la compresión del nervio ciático en su salida de la pelvis a través del canal situado entre el músculo piramidal y el gémino superior. Se presenta una serie de casos de pacientes oncológicos con este síndrome con el objetivo de describir el resultado terapéutico de la infiltración con esteroides en el músculo piramidal sin hidrodisección perineural del ciático. Métodos: Se realizó un estudio prospectivo de 10 casos, evaluados entre Febrero de 2014 y Mayo del 2015, en el servicio de dolor y cuidados paliativos del Instituto Oncológico Nacional "Dr. Juan Tanca Marengo"-Solca-Guayaquil. Ingresaron al estudio pacientes con cáncer de cualquier etiología y criterios diagnósticos de síndrome piramidal. Los pacientes fueron tratados con infiltraciones de corticoides sin hidrodisección perineural del ciático, dirigidas por ultrasonido del músculo piramidal afecto y terapia física. Resultados: Se incluyen 10 casos de pacientes con síndrome piramidal (9 mujeres). Con rangos de edad que entre 50 y 70 años. El lado afectado con mayor frecuencia fue el derecho en 5 casos. En 8 casos la Resonancia magnética fue normal y en 2 casos se describió hipertrofia muscular. El procedimiento de infiltración se realizó sin complicaciones y los pacientes recibieron adicionalmente fisioterapia. El EVA inicial fue > 6 en 8 pacientes y 2 casos con EVA de 5. Los pacientes tuvieron una limitación funcional de un 10-20 %. El EVA postbloqueo disminuyó hasta 0-1 en todos los casos. Conclusión: En la presente serie de casos el síndrome piramidal fue controlado satisfactoriamente con infiltración de esteroides sin hidrodisección perineural del ciático y terapia física.

Introduction: Pyramidal muscle syndrome is a signs and symptoms set caused by sciatic nerve compression and its exit from the pelvis through the channel between the pyramidal muscle and the superior genus. We present a series of cases of oncological patients with this syndrome with the aim of describing the therapeutic result of steroid infiltration in the pyramidal muscle without perineural hydrodissection of the sciatic nerve. Methods: A prospective study of 10 cases, evaluated between February 2014 and May 2015, in the pain and palliative care service of the National Oncological Institute "Dr. Juan Tanca Marengo "-SolcaGuayaquil. Patients with cancer of any etiology and diagnostic criteria of pyramidal syndrome entered the study. The patients were treated with corticosteroid infiltrations without perineural hydrodissection of the sciatic nerve, directed by pyramid-shaped muscle ultrasound and physical therapy. Results: Ten cases of patients with pyramidal syndrome (9 women) are included. With age ranges between 50 and 70 years. The most affected side was the right in 5 cases. In 8 cases the magnetic resonance was normal and in 2 cases muscle hypertrophy was described. The infiltration procedure was completed without complications and the patients received additional physiotherapy. The initial EVA was> 6 in 8 patients and 2 cases with VAS of 5. The patients had a functional limitation of 10-20%. The post-blocking EVA decreased to 0-1 in all cases. Conclusion: In the present series of cases the pyramidal syndrome was successfully controlled with steroid infiltration without perineural hydrodissection of the sciatic and physical therapy.

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.

Comparison of 0.075% and 0.1% ropivacaine in terms of motor dysfunction after piriformis muscle injection

BACKGROUND: Motor weakness occurs frequently after piriformis injection and it could put patients at risk of falls. We investigated the appropriate concentration and volume of ropivacaine required to minimize motor dysfunction. METHODS: A total of 120 patients who received piriformis injection were included in this study. Piriformis injections of triamcinolone 10 mg in various concentrations (0.1%, 0.075%) and volumes (8, 10, 12 ml) of ropivacaine were administered in 20 patients, respectively. One hour after the injection, we compared motor function according to the concentrations and volumes of ropivacaine. RESULTS: There were significant differences (P < 0.05) in the occurrence of motor dysfunction according to body mass index (BMI) and the concentration of ropivacaine. No significant differences were found in terms of gender, age, weight, height, or the volume of ropivacaine. Logistic regression analysis showed that the likelihood of motor dysfunction with administration of 0.1% ropivacaine was 58.249 times greater than that with administration of 0.075% concentration (P < 0.001), while BMI did not have a significant effect on motor dysfunction. CONCLUSIONS: According to the results of this study, 0.075% ropivacaine rather than 0.1% ropivacaine is appropriate in terms of reducing motor dysfunction after piriformis injection.

Endoscopic Excision of Schwannoma of Sciatic Nerve Using Hip Arthroscopy / 대한정형외과학회잡지

As the expertise of the surgeon improves in arthroscopic surgery of the hip, the number of conditions treated by it also increases. In this case, an arthroscopic treatment was performed on a patient with piriformis syndrome due to schwannoma on the sciatic nerve. Meticulous excision of the cystic lesion on the sciatic nerve was completely performed and neither recurrence nor complication of the surgery was observed. Endoscopic excision using arthroscopy is useful for reducing postoperative pain and achieving early return to activities for the patient.

Long-term assessment of clinical outcomes of ultrasound-guided steroid injections in patients with piriformis syndrome

PURPOSE: The purpose of this study was to evaluate the long-term efficacy of ultrasound (US)-guided steroid injections in patients with piriformis syndrome. METHODS: Between January 2010 and October 2012, 63 patients (23 men and 40 women; average age, 63.2 years; range, 24 to 90 years) were diagnosed with piriformis syndrome based on clinical history, electromyography, and flexion-adduction-internal rotation test results. They were divided into two groups. The first group (37 subjects) received a US-guided steroid injection around the piriformis muscle. The second group (26 subjects) received both piriformis muscle and spinal epidural injections. The therapeutic effect was categorized as improvement, partial improvement, or failure depending on the degree of symptom alleviation one month after injection, based on a review of each patient's medical records. RESULTS: In the first group, 15 patients (40.5%) showed improvement, seven (18.9%) showed partial improvement, and 15 (40.5%) failed to respond to the initial treatment. In the second group, eight patients (30.8%) showed improvement, 11 (42.3%) showed partial improvement, and seven (26.9%) failed to respond to the initial treatment. A second piriformis injection was performed in four cases, after which two patients showed improvement within 3 years, but the other two showed no therapeutic effect. CONCLUSION: US-guided steroid injection may be an effective treatment option for patients with piriformis syndrome.

Leg Weakness Caused by Bilateral Piriformis Syndrome: A Case Report

Piriformis syndrome (PS) is an uncommon neuromuscular disorder caused by the piriformis muscle (PM) compressing the sciatic nerve (SN). The main symptom of PS is sciatica, which worsens with certain triggering conditions. Because the pathophysiology is poorly understood, there are no definite diagnostic and therapeutic choices for PS. This case report presents a young woman who mainly complained of bilateral leg weakness. Electromyography revealed bilateral sciatic neuropathy and magnetic resonance imaging confirmed structural lesions causing entrapment of the bilateral SNs. After a laborious diagnosis of bilateral PS, she underwent PM releasing surgery. Few PS cases present with bilateral symptoms and leg weakness. Therefore, in such cases, a high level of suspicion is necessary for accurate and prompt diagnosis and treatment.

Anatomical variation of piriformis muscle as a cause of deep gluteal pain: diagnosis using MR neurography and treatment / Variação anatômica do músculo piriforme como causa de dor glútea profunda: diagnóstico por neurografia RM e seu tratamento

Female patient, 42 years old with a history of low back pain on the left for seventeen years in which the definitive diagnosis of the etiology of pain was evident after the completion of neurography magnetic resonance imaging of the sciatic nerve. In this test it was identified the presence of an anatomical variation in the relationship between the piriformis muscle and sciatic nerve. We discuss details of this imaging technique and its importance in the frames of refractory low back pain. We also describe the treatment given to the case. .

Paciente do sexo feminino, 42 anos, com histórico de lombociatalgia à esquerda havia 17 anos. O diagnóstico definitivo da etiologia da dor só foi evidenciado após a neurografia por ressonância magnética do ciático. Nesse exame identificou-se a presença de variação anatômica entre o músculo piriforme e o nervo ciático. Descrevemos detalhes sobre a técnica de imagem e sua importância nos quadros de lombociatalgia refratária, como também o tratamento instituído para o caso.

Observation on therapeutic effect of round-sharp needle of new nine-needle and elongated needle for piriformis syndrome with triple puncture method / 中国针灸

<p><b>OBJECTIVE</b>To compare the efficacy differences between round-sharp needle of new nine-needle and elongated needle for piriformis syndrome, and explore its action mechanism.</p><p><b>METHODS</b>Eighty cases were randomly divided into a round-sharp needle of new nine-needle group (round-sharp needle group) and an elongated needle treatment group (elongated needle group), 40 cases in each group. The round-sharp needle group was treated with round-sharp needle (0.60 mm x 125 mm) at three points in piriformis with triple puncture method, while the elongated needle group was treated with elongated needle of ordinary specifications (0.32 mm x 125 mm) at three points in piriformis with triple puncture method. Besides, the two groups were also treated with routine acupuncture at Weizhong (BL 40) and Yanglingquan (GB 34), 3 times every week, 2 weeks as one course of treatment. After one course of treatment, the clinical effect was evaluated and the pain threshold values were measured before and after treatment in the two groups.</p><p><b>RESULTS</b>The total effective rate in the round-sharp needle group was 92.5% (37/40), which was superior to 77.5% (31/40) in the elongated needle group (P < 0.05). Compared before treatment, the pain threshold values after treatment in two groups were improved significantly (both P < 0.01). The increment of pain threshold value in the round-sharp needle group was higher than that in the elongated needle group (P < 0.01).</p><p><b>CONCLUSION</b>Round-sharp needle of new nine-needle is effective in treatment of piriformis syndrome and is better than ordinary elongated needle, which is related to that it can effectively increase pain threshold value of the local tissue.</p>

Variaciones del Nervio Isquiático en Relación al Músculo Piriforme / Variations of the Sciatic Nerve in Relation to the Piriformis Muscle

El nervio isquiático nace del plexo sacro y sale de la pelvis a través del foramen isquiático mayor por debajo del musculo piriforme como un tronco común. En ocasiones, este nervio puede emerger dividido en sus dos componentes: el nervio fibular común y nervio tibial, encontrándose, variaciones que podrían dar origen a una condición de compresión nerviosa. En este trabajo se exponen dos variaciones del nervio isquiático en un mismo individuo, donde en la primera el nervio fibular común atraviesa el músculo piriforme y luego desciende junto al nervio tibial y la segunda, donde el nervio fibular común se forma a partir de un ramo superior que perfora el músculo piriforme y el otro inferior que pasa debajo de él, para unirse luego en el margen inferior de éste músculo y formar el nervio fibular común, que desciende junto al nervio tibial. Las variaciones del nervio isquiático en relación al músculo piriforme podrían explicar el síndrome del músculo piriforme.

The sciatic nerve arises from the sacral plexus and exits the pelvis through the greater sciatic foramen below the piriformis muscle as a common trunk. Sometimes this nerve can emerge divided into two components: the common fibular nerve and tibial nerve, finding variations that could give rise to a condition of nerve compression. In this paper we describe two variations of the sciatic nerve in the same individual, where in the first common fibular nerve passes through the piriformis and then descends along the tibial nerve and the second, where the common fibular nerve is formed from a higher branch that pierce to piriform muscle and a lower branch passing under him, then join at the inferior margin of this muscle and form the common fibular nerve, which descends with the tibial nerve. Variations of the sciatic nerve in relation to the piriformis muscle could explain the piriformis syndrome.

Piriformis Syndrome Following Transarterial Embolization of Bilateral Uterine Arteriovenous Malformation

Piriformis syndrome is a rare entrapment neuropathy in which the sciatic nerve is compromised by the piriformis muscle or other local structures. We report a case of sciatic and gluteal nerve lesions with infarction of the piriformis muscle following internal iliac artery embolization of the bilateral uterine vascular malformation. The surgical intervention revealed anatomical variation of the right sciatic nerve. To our knowledge, this is the first case of piriformis syndrome following endovascular treatment of uterine vascular malformation in Korea.

[ rare anatomical variation of sciatic nerve and its relationship with piriformis muscle]

Sciatic nerve is the thickest nerve of the body which is formed by ventral branches of L4, L5, S1, S2 and S3 of spinal nerves as a part of sacral plexus in pelvis. It leaves the pelvis via the greater sciatic foramen below piriformis muscle and descends between the greater trochanter and ischial tuberosity, along the back of the thigh and dividing into the tibial and common peroneal [fibular] nerves, at a varying level proximal to the knee. In addition, the piriformis muscle, the intrapelvic muscle, may compress the sciatic nerve and causes the piriformis syndrome. At present case, sciatic nerve was divided in the pelvis and left the pelvis via supera piriformis, inferapiriformis and interapiriformis. According to the reports about the variations of sciatic nerve regarding to its leaving and dividing point, it is important in surgical operations, muscular injection in gluteal regions and piriformis syndrome

Piriformis Muscle: Clinical Anatomy with Computed Tomography in Korean Population

BACKGROUND: The objective was to evaluate the distance from the skin and the diameter of the piriformis muscle and their relationship to the body mass index (BMI). METHODS: The study was a prospective study involving 60 patients. Patients were prepared on a radiological table in the prone position. Several images were obtained of each. In this view, the distance between the subcutaneous tissue and the piriformis muscle, and the diameter of the piriformis, were measured at three points (medially to laterally). RESULTS: The distance to the piriformis from the skin was 6.6 +/- 0.9 cm, 6.3 +/- 0.8 cm, and 5.2 +/- 0.9 cm in terms of the lateral, center, and medial measurement, respectively. The center of the piriformis had a greater diameter with 1.7 +/- 0.4 (0.9-2.5) cm. The distance to the piriformis increased with BMI. CONCLUSIONS: This study shows that the lateral of the piriformis muscle has a relatively greater distance from the skin. The center of the piriformis showed a greater diameter than other two portions. We found that the distance of the piriformis from subcutaneous tissues was correlated with BMI, but the diameter of the piriformis was not affected by BMI. These measurements can be used as a reference for determining the piriformis injection site in patients with piriformis syndrome.

Piriformis Syndrome in Knee Osteoarthritis Patients after Wearing Rocker Bottom Shoes

BACKGROUND: Rocker bottom shoes (RBS) are popular among patients with different foot, leg, or back problems in Korea. Patients with knee osteoarthritis concurrent weakness in the quadriceps femoris muscle, who wear these shoes, are often assumed to develop piriformis syndrome (PS). This study was performed to improve the understanding about the effect of wearing such shoes on duration of the syndrome in knee osteoarthritis. METHODS: We randomly assigned 150 patients with PS, who had used RBS daily for at least 6 months, to 2 groups, the S (stopped wearing) and K (kept wearing) groups. Both the groups were subdivided into the O and N groups, comprising patients with and without knee osteoarthritis, respectively. The effects of the treatment, including piriformis muscle injections and a home exercise program, were compared between the 2 groups by using a flexion-adduction-internal rotation (FAIR) test, a numeric rating scale (NRS), and the revised Oswestry disability index (ODI) during the 12-week follow-up. RESULTS: The positive FAIR test ratios, mean NRS scores, and revised ODIs were higher in the KO group than the SN group from 4?12 weeks after treatment. CONCLUSIONS: RBS may extend duration of the PS in osteoarthritis patients.