A Sciatic Neuralgia Case of an Entrapment Neuropathy Mimicking Piriformis Syndrome Due to Soft Tissue Hemangioma.

BACKGROUND: Lumbosacral pain is commonly seen in daily clinical practice. In fact, entrapment of the part of the sciatic nerve after the sacral foramen causes some of these pains, which should not be overlooked. The sciatic nerve may be compressed during its course after the sacral foramen for a variety of reasons. We aimed in this article to review extra-spinal compressive sciatic neuropathy reasons and abnormal magnetic resonance imaging (MRI) by presenting a sciatic neuralgia case of an entrapment neuropathy mimicking piriformis syndrome due to soft tissue hemangioma. CASE PRESENTATION: A 30-year-old male patient was admitted with complaints of lumbosacral pain spreading to the leg that had been worsening over the previous 10 days. With the preliminary diagnosis of labral damage and piriformis syndrome, the patient was referred to the radiology clinic for a hip MRI. In the hip MR images, a mass lesion suggestive of heterogeneously enhanced soft tissue hemangioma after the injection of paramagnetic contrast material was observed in the proximal left thigh. The soft tissue hemangioma extends towards the obturator foramen and compresses the sciatic nerve proximal to the femur after the sciatic foramen. CONCLUSION: The diagnosis of lower extremity entrapment neuropathy is frequently misdiagnosed. In these cases, MRI becomes more important for accurate diagnosis. The radiologists' knowledge of the sciatic nerve in MRI, regional anatomy during the course of the sciatic nerve, and abnormal nerve imaging findings will aid in the diagnosis.

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.

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.

Sciatic nerve and its variations: is it possible to associate them with piriformis syndrome?

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.

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.

Novel t(1;2)(p36.1;q23) and t(7;19)(q32;q13.3) chromosomal translocations in ischemic fasciitis: expanding the spectrum of pseudosarcomatous lesions with clonal pathogenetic link.

BACKGROUND: Ischemic fasciitis is a distinctive pseudosarcomatous entity with a marked predilection for elderly and physically debilitated or immobilized patients. The etiology of these lesions is unknown but felt to be related to ischemic vascular events. CASE PRESENTATION: Herein, we report for the first time, two cytogenetic translocations, t(1;2)(p36.1;q23) and t(7;19)(q32;q13.3) in a 75 year-old ambulating female with a history of left total hip arthroplasty 20 years ago. CONCLUSION: These translocations suggest a possible clonal pathogenetic link though their significance remains to be established.

Anthropometric Study of the Piriformis Muscle and Sciatic Nerve: A Morphological Analysis in a Polish Population.

BACKGROUND The aim of this study was to determine relationships between piriformis muscle (PM) and sciatic nerve (SN) with reference to sex and anatomical variations. MATERIAL AND METHODS Deep dissection of the gluteal region was performed on 30 randomized, formalin-fixed human lower limbs of adults of both sexes of the Polish population. Anthropometric measurements were taken and then statistically analyzed. RESULTS The conducted research revealed that, apart from the typical structure of the piriformis muscle, the most common variation was division of the piriformis muscle into two heads, with the common peroneal nerve running between them (20%). The group with anatomical variations of the sciatic nerve course displayed greater diversity of morphometric measurement results. There was a statistically significant correlation between the lower limb length and the distance from the sciatic nerve to the greater trochanter in the male specimens. On the other hand, in the female specimens, a statistically significant correlation was observed between the lower limb length and the distance from the sciatic nerve to the ischial tuberosity. The shortest distance from the sciatic nerve to the greater trochanter measured at the level of the inferior edge of the piriformis was 21 mm, while the shortest distance to the ischial tuberosity was 63 mm. Such correlations should be taken into account during invasive medical procedures performed in the gluteal region. CONCLUSIONS It is possible to distinguish several anatomical variations of the sciatic nerve course within the deep gluteal region. The statistically significant correlations between some anthropometric measurements were only present within particular groups of male and female limbs.

[Pyrimidal syndrome and anatomical variations as a cause of insidious sciatic pain]. / Síndrome piramidal y variaciones anatómicas como causa de dolor ciático insidioso.

The case is presented of a 42 year old woman who had been suffering a loss of strength in her left leg for six years. After an extensive diagnostic study, the pain was classified as of functional origin by a diagnosis of exclusion. Since then, the patient has tried all kind of drug treatments and conservative techniques without improvement. After an exhaustive study with inconclusive results, the case was discussed with the Orthopaedics Department, who performed an exploratory surgery, in which compression of the sciatic nerve due to an anatomical variation of the piriformis muscle was observed. Part of the muscle was resected during surgery and the sciatic nerve was freed, after which the patient experienced a great improvement.

Piriformis syndrome: a case with non-discogenic sciatalgia.

Piriformis syndrome is a clinical picture of non-discogenic sciatica caused by compression of the sciatic nerve by the piriformis muscle. It has variable etiologies and the patho-physiology is not fully understood. The major etiology was known to be the spasm, edema and inflammation of the piriformis muscle and sciatic nerve compression of the muscle later on. Patients can be diagnosed immediately with a comprehensive clinical examination and early diagnosis makes the treatment much easier. Diagnosis of the piriformis syndrome, a very rare cause of low back pain, first requires that this syndrome is remembered, and then a differential diagnosis should be performed. A case of piriformis syndrome diagnosed in a patient who presented with low back pain is reported in this study.

Anatomical variations between the sciatic nerve and the piriformis muscle: a contribution to surgical anatomy in piriformis syndrome.

PURPOSE: To detect the variable relationship between sciatic nerve and piriformis muscle and make surgeons aware of certain anatomical features of each variation that may be useful for the surgical treatment of the piriformis syndrome. METHODS: The gluteal region of 147 Caucasian cadavers (294 limbs) was dissected. The anatomical relationship between the sciatic nerve and the piriformis muscle was recorded and classified according to the Beaton and Anson classification. The literature was reviewed to summarize the incidence of each variation. RESULTS: The sciatic nerve and piriformis muscle relationship followed the typical anatomical pattern in 275 limbs (93.6 %). In 12 limbs (4.1 %) the common peroneal nerve passed through and the tibial nerve below a double piriformis. In one limb (0.3 %) the common peroneal nerve coursed superior and the tibial nerve below the piriformis. In one limb (0.3 %) both nerves penetrated the piriformis. In one limb (0.3 %) both nerves passed above the piriformis. Four limbs (1.4 %) presented non-classified anatomical variations. When a double piriformis muscle was present, two different arrangements of the two heads were observed. CONCLUSIONS: Anatomical variations of the sciatic nerve around the piriformis muscle were present in 6.4 % of the limbs examined. When dissection of the entire piriformis is necessary for adequate sciatic nerve decompression, the surgeon should explore for the possible existence of a second tendon, which may be found either inferior or deep to the first one. Some rare, unclassified variations of the sciatic nerve should be expected during surgical intervention of the region.

The piriformis muscle syndrome: an exploration of anatomical context, pathophysiological hypotheses and diagnostic criteria.

INTRODUCTION: The piriformis muscle syndrome (PMS) has remained an ill-defined entity. It is a form of entrapment neuropathy involving compression of the sciatic nerve by the piriformis muscle. Bearing this in mind, a medical examination is likely to be suggestive, as a classical range of symptoms corresponds to truncal sciatica with frequently fluctuating pain, initially in the muscles of the buttocks. PATHOPHYSIOLOGICAL HYPOTHESES: The piriformis muscle is biarticular, constituting a bridge in front of and below the sacroiliac joint and behind and above the coxo-femoral joint. It is essentially a lateral rotator but also a hip extensor, and assumes a secondary role as an abductor. Its action is nonetheless conditioned by the position of the homolateral coxo-femoral joint, and it can also function as a hip medial rotator, with the hip being flexed at more than 90°. The main clinical manoeuvres are derived from these types of biomechanical considerations. For instance, as it is close to the hip extensors, the piriformis muscle is tested in medial rotation stretching, in resisted contraction in lateral rotation. On the other hand, when hip flexion surpasses 90°, the piriformis muscle is stretched in lateral rotation, and we have consequently laid emphasis on the manoeuvre we have termed Heel Contra-Lateral Knee (HCLK), which must be prolonged several tens of seconds in order to successfully reproduce the buttocks-centred and frequently associated sciatic symptoms. CONCLUSION: A PMS diagnosis is exclusively clinical, and the only objective of paraclinical evaluation is to eliminate differential diagnoses. The entity under discussion is real, and we favour the FAIR, HCLK and Freiberg stretching manoeuvres and Beatty's resisted contraction manoeuvre.

Injection site pseudosarcoma in piriformis syndrome.

AIMS: Pseudosarcomatous reactive myofibroblastic proliferations have been described following surgery or trauma at a variety of anatomical sites. These types of reactions have not been previously described at injection sites. Here we evaluated prevalence, morphologic patterns and clinical resolution of such lesions. METHODS AND RESULTS: We analyzed 266 surgical resection specimens obtained during the definitive treatment of piriformis syndrome. Three cases showed exuberant reactive fibroblastic/myofibroblastic intramuscular proliferations, mimicking a sarcoma. In all three cases the surgeries were found to be preceded by local injections of cortisone and bupivacaine. Clinical follow-up revealed no uncontrolled growth. CONCLUSIONS: As the clinical history of injections is often not provided, it is important to be aware of this pitfall when reviewing skeletal muscle resections for entrapment syndromes.

Entrapment neuropathies III: lower limb.

Clinicians frequently encounter compressive neuropathies of the lower extremity. The clinical history and physical examination, along with electrodiagnostic testing and imaging studies, lead to the correct diagnosis. The imaging characteristics of the compression neuropathies can include acute and chronic changes in the nerves and the muscles they innervate. We provide a detailed review of compression neuropathies of the lower extremity with an emphasis on magnetic resonance (MR) imaging characteristics. We discuss the clinical presentation, etiology, anatomical location, and MR imaging appearance of these neuropathies, including the piriformis syndrome, iliacus syndrome, saphenous neuropathy, obturator neuropathy, lateral femoral cutaneous neuropathy (meralgia paresthetica), proximal tibial neuropathy, common peroneal neuropathy, deep peroneal neuropathy, superficial peroneal neuropathy, tarsal tunnel syndrome, Baxter's neuropathy, jogger's foot, sural neuropathy, and Morton's neuroma.

Sciatic nerve division: a cadaver study in the Indian population and review of the literature.

INTRODUCTION: The sciatic nerve is the largest nerve, with a long course in the inferior extremity. Its division into the tibial and common peroneal nerves can occur at any level from the sacral plexus to the inferior part of the popliteal space. These anatomical variations may contribute to clinical conditions such as piriformis syndrome, sciatica and coccygodynia. METHODS: This study was performed on cadavers in order to study the level of sciatic nerve division. The inferior extremities of 43 cadavers were classified into six groups depending on the level of sciatic nerve division in the gluteal region, the upper, middle and lower parts of the back of the thigh, and the popliteal fossa. RESULTS: The highest incidence of sciatic nerve division (40.7 percent) was observed in the lower part of the posterior compartment of the thigh. In 34.9 percent of the specimens, the sciatic nerve was divided into tibial and common peroneal nerves in the popliteal fossa. 16.3 percent of extremities showed sciatic nerve division proximal to its entrance in the gluteal region. CONCLUSION: In sciatic nerve neuropathies, the extent of neurological deficits depends on the level of sciatic nerve division. Sciatic nerve division into tibial and common peroneal components at a higher level can result in the involvement of only one out of the two divisions from sciatic neuropathy. It can also result in a failure of the sciatic nerve block while performing popliteal block anaesthesia.

Piriformis syndrome--an attempt to understand its pathology.

OBJECTIVE: Gross anatomy of the hip rotators and histology of the sciatic nerves in adult cadavers were studied, aiming to the identification of possible pathologic changes related to the piriformis syndrome (PS). MATERIAL: 50 cadavers were dissected; in 17 cases with macroscopical findings the sciatic nerves were harvested (34 sciatic nerves; 17 cadavers). History of low back or leg pain was not available. METHOD: Site anatomy and additional findings at the harvesting sites were recorded, such as anatomical variations, adhesions, hematomas etc. All nerves were additionally microscopically analyzed. In cases with findings at the dissection, the contralateral unaffected nerves served as controls. All the dissected nerves were conserved in 10% formalin solution, embedded in paraffin, stained with Hematoxylin and Eosin (H&E) and immunolabeled with antibodies against Neurofilament (NF). RESULTS: Both the H&E staining as well as the performed immunohistochemistry showed, to a variable degree, significant alterations in the structure of the affected nerves compared to the controls. CONCLUSIONS: These findings both in the local anatomy and sciatic nerve correspond to lesions that are expected in PS. Nevertheless, since this was a cadaveric study, unassociated to a certain pain patient's history, results should be considered and interpreted as an indication of a sciatic nerve injury in PS.

Variations of the piriformis and sciatic nerve with clinical consequence: a review.

The deep gluteal region is often encountered when performing injections, when performing surgery such as total hip replacements, or diagnosing problems of this region or lower limbs using clinical or imaging techniques. Previously, the prevalence figures of piriformis and sciatic nerve anomalies have ranged from 1.5 to 35.8% in dissected specimens. This study systematically reviews and meta-analyses the prevalence of piriformis and sciatic nerve anomalies in humans using previously published literature. A further review is conducted regarding the anatomical abnormalities present in surgical case series of procedures for patients suffering from piriformis syndrome. After pooling the results of 18 studies and 6,062 cadavers, the prevalence of the anomaly in cadavers was 16.9%; 95% confidence interval (CI) 16.0-17.9%. The prevalence of the piriformis and sciatic nerve anomaly in the surgical case series was 16.2%, 95% CI: 10.7-23.5%. The difference between the two groups was not found to be significant 0.74%; 95% CI: -5.66 to 7.13; P = 0.824. Because of the high likelihood of an anomaly being present in a patient, clinicians and surgeons should be aware of the potential complications this anomaly may have on medical or surgical interventions. Furthermore, because the prevalence of the anomaly in piriformis syndrome patients is not significantly different from what is thought to be a normal population, it indicates that this anomaly may not be as important in the pathogenesis of piriformis syndrome as previously thought.