Variations Of Sciatic Nerve Research Articles

Sciatic nerve variations around the piriformis muscle and bifurcation level: An anatomical study

Sciatic nerve variations around the piriformis muscle and bifurcation level: An anatomical study

Evaluation of variations of sciatic nerve

Evaluation of variations of sciatic nerve

Anatomical Variations between Sciatic Nerve and Piriformis Muscle on Computed Tomography Images from Radiotherapy Patients

Abstract Background: The sciatic nerve has several topographic variations, some of them in relation to the piriformis muscle. Such variations provide meaning insight while addressing pathologies related to sciatic nerve. Hence, this study was undertaken to check the anatomical variations of sciatic nerve using computed tomography (CT) images. Methodology: Thirty-three CT image series from pelvic radiotherapy patients were reviewed, with a DICOM viewer to assess the relation between the sciatic nerve and piriformis muscles, according to Beaton and Aston’s classification. Results: Thirty-three CT image sets and 66 gluteal regions were assessed. Type A of Beaton and Aston was found in 84.85% of the samples and Type B was found in 15.15%. No other types were found. Sixty-six percentage of the Type B classifications were bilateral. Conclusion: There is a 15.15% of topographical variation of sciatic nerve consistent with other studies. The use of medical images for this kind of study will allow more reliable results.

Cadaveric Study on the Anatomical Variations of the Sciatic Nerve

A cadaveric study on the anatomical variations of the sciatic nerve involves the examination and analysis of the sciatic nerve in human cadavers to understand the variations in its anatomical structure and distribution. The sciatic nerve is the longest and thickest nerve in the human body, arising from the lumbosacral plexus in the lower back and extending down through the buttocks and the back of the thigh, eventually branching out into the tibial and common fibular nerves. Cadaveric studies are an essential part of medical research, especially in anatomy and surgical disciplines. These studies provide detailed insights into the human body's structures and variations that might not be adequately represented in textbooks or imaging studies. By examining cadavers, researchers can observe the sciatic nerve's different courses, branching patterns, and relationships to surrounding anatomical structures. The current work aims to study the anatomical variations in branching pattern and division of sciatic nerve, to know the variations of sciatic nerve by observing and dissecting the formalin fixed lower limbs and to document the different variations of the division of the sciatic nerve for any surgical and diagnostic inventions.

A study of high division of sciatic nerve in human cadavers and its clinical significance

Background: Sciatic nerve is a mixed nerve which provide sensory and motor supply for skin and muscles of the lower limb by tibial and common peroneal nerve. Anatomical variations of sciatic nerve at high division have been reported by various authors. The path of the sciatic nerve is important while administration of intramuscular injection to prevent nerve injury and nerve blockage failure during anesthesia. This knowledge of high division helps in different surgical approach for sciatic nerve injury or hip dislocation. Aims and Objectives: The aim of the study was to describe incidences of high division variation of Sciatic nerve and different types in cadavers during routine dissection schedule. Materials and Methods: The study was conducted during routine dissection schedule in anatomy department for first MBBS students to observe sciatic nerve course in 30 gluteal regions from 15 adult cadavers fixed by formalin. Location of sciatic nerve in relation to piriformis muscle and its division whether in single nerve sheath or separate sheath and types was recorded. Results: In 12 cadavers (80%), sciatic nerve course found normal which leaves pelvis at inferior border of piriformis muscle and bifurcate in terminal branches tibial nerve and common peroneal nerve as it approaches at the apex of popliteal fossa. In 3 cadavers (20%), two male and one female, we found high division of sciatic nerve where terminal branches, tibial nerve, and common peroneal nerve leave the pelvis below piriformis separately in different sheaths. Conclusion: Knowledge of variations-related high division of sciatic nerve would help surgeons during different interventions related to sciatic nerve and for preventing further complications.

STUDY OF A VARIATION OF LUMBOSACRAL PLEXUS: SCIATIC NERVE AND ITS CLINICAL SIGNIFICANCE

Background: The pelvis is a home to pelvic parts of the sympathetic and parasympathetic nervous systems, the sacral and coccygeal plexuses, and the lumbosacral trunk. The lower spine’s sciatic nerve is made up of a combination of motor and sensory fibers from spinal nerves fourth lumbar to third sacral segment (ventral rami). The objective of study was to determine morphological variations in origin and formation of branching pattern of sciatic nerve. Methods: A descriptive cross-sectional study was conducted on twenty-four (forty-eight lower limbs) cadavers available in the Department of Anatomy at School of Basic Sciences, Chitwan Medical College. All damaged cadavers were excluded. The cadavers for undergraduate first year medical students dissected as per Cunningham’s Manual. The branching pattern of the sciatic nerve was noted. All Variation of each sacral plexus was photographed. Statistical analysis was done using Microsoft Excel and SPSS version 20. Both gluteal regions were studied for the locations and variation of the sciatic nerve. Results: Forty-eight lower limbs were examined. Among them forty-two lower limbs (87.5 percent) showed a normal anatomy of the sciatic nerve. Six lower limbs (12.5 percent) showed variations in the sciatic nerve. Conclusions: The study concluded that there are variations in origin and formation of branches of sciatic nerve. Variations of sciatic nerve observed could be beneficial for various surgical interventions like nerve release and pain management in compressed nerve.

VARIATIONS IN COURSE OF SCIATIC NERVE IN ADULT HUMAN CADAVERS

Most of the sciatic nerve course in individuals is normal and variations in sciatic nerve is seen in approximately sixteen to twenty five percent of cases. Often sciatica is misdiagnosed. Pseudo-sciatica occurs as a result of non-spinal etiological factors. Understanding the origin and course of sciatic nerve is needed to correctly diagnose sciatica. The present study is undertaken to determine the normal course of sciatic nerve, along with its variations. Material And Methods: The following study was conducted on variation of sciatic nerve found during routine dissection of 100 cadavers for teaching purpose, in the Department of Anatomy, Govt. Medical College, Kurnool and other medical colleges in Kurnool. There were no other gross anomalies or pathologies. The skin around the area was normal and no evidence of surgery was present. The gluteal region was dissected and Gluteus maximus muscle was reflected and exposing the sciatic nerve and Piriformis muscle. Result: The incidence of variation in sciatic nerve is very low and is noted firstly in the right side of the cadaver. The occurrence of variation is 16 in 100 cadavers. Eighty four cadavers showed normal course of sciatic nerve. Out of sixteen cadavers, ten cadavers showed variation related to type b ranging 62.5% of total variations seen. Four cadavers showed type c variation ranging 25 % of total variations. Two cadavers were seen with a variation of type e ranging 12.5%. Conclusion: Sciatic nerve is the thickest, largest and longest nerve in the body. Its pathologies are also frequent in occurrence in daily life. A thorough knowledge of its anatomy and variations of sciatic nerve is required to give proper treatment plan to the patient. Also the, significance of it should not be overlooked during surgical and popliteal nerve block anaesthetic procedures.

Factors Influencing Common Fibular Nerve Course Variability before Bifurcation into the Superficial Fibular Nerve and Deep Fibular Nerve: A Cadaveric Study

Background and Objectives: The common fibular nerve (CFN) has anatomical variance between individuals as it transitions from the posterior thigh to the anterior leg. The nerve’s course around the fibular neck is of particular interest, where it becomes vulnerable to injury at the lateral knee. Therefore, we sought to compare factors that may predict distal CFN variability, such as height, age, sex, fibular length, and proximal sciatic variations, which individually or cumulatively play a role in predicting clinically significant locations where the CFN commonly transitions among certain populations. Methods: In this cadaveric study, twenty anatomically-fixed specimens were analyzed, ten males and ten females. Data gathered included age, sex, height, CFN transition point measured from the proximal head of the fibular to the point 90 degrees off the midline of the fibula where the CFN courses around the fibular neck, fibular length, and proximal sciatic nerve variations characterized based on the Beaton and Anson classification system. Factors were compared and statistical values were generated. Results: There was a statistically significant difference between CFN transition points compared to fibular lengths, heights, and between sexes. Sciatic nerve (SN) bifurcation levels and exits were bilaterally identical on all cadavers. All SN exits were Beaton and Anson type 1 (undivided nerve below and undivided piriformis), and bifurcation levels were 20% high, 25% middle, and 55% low. Conclusions: This study highlights the importance of considering a person’s height, fibular length, and sex when addressing injuries involving the CFN at the lateral leg.

Anatomic Variation of the Sciatic Nerve: A Study on the Prevalence, and Bifurcation Loci in Relation to the Piriformis and Popliteal Fossa.

To examine and identify sciatic nerve variations in relation to the piriformis muscle, its prevalence, pattern and the course of its bifurcation loci. Twenty-eight formalin fixed male cadavers comprising 56 lower limbs were used for this study. Dissection of the gluteal region and posterior compartment of the thigh was conducted to expose the sciatic nerve. Variations in the sciatic nerve anatomy, their relationship to the piriformis muscle and points of bifurcation, and other observable features were noted and recorded. Fifty-two lower limbs (93%) showed normal anatomy of the sciatic nerve. Four regions (7.1%) showed variations in the morphology of the sciatic nerve. Of these, one (1.8%) showed a variation of the sciatic nerve with the piriformis muscle. This single case showed a common peroneal nerve emerging on the left between the heads of a double piriformis muscle - a variant not described in the original Beaton and Anson classification, with the tibial nerve deep to the muscle. In two other limbs, the sciatic nerves showed a normal relationship with the piriformis, but had variations in the bifurcation loci (bilateral). The divisions were in upper third and middle third of the right and left thighs respectively. Knowledge of the level of bifurcation and distribution of the sciatic nerve and its location is important. This nerve is commonly encountered by neurologists, orthopaedics, and anaesthesiologists. The uncommon anatomical findings described are relevant to surgeons to enable them to perform efficient surgical procedures and avoid errors.

The sciatic nerve and and its relation to the piriformis muscle syndrome regarding daily clinical practice. A review

IntroductionThe sciatic nerve innervates most of the muscles of the lower limb, so any alteration in it'sits function or clinical presentation could directly affect the functioning of the lower limb. Therefore, the normal anatomy, anatomical variants and how these can influence clinical implications in the gluteal region are of importance in daily clinical practice.MethodsodologyA systematic review was carried out in the scientific literature to answer our research question. We searched in the databases MEDLINE, SCOPUS, WOS, Scielo, GOOGLE SCHOLAR and other scientific sources, using search terms in relation to our stated objectives and connected through Boolean terms.ResultsThe results of this study show that the variations of the sciatic nerve can be ample, which associated to the variability in the geographic regions of the studies, sex of the sample and incidence of the variation, will make it necessary to consider different multifactorial components for the anatomical analysis of sciatic nerve variations and for clinical considerations in patients with and without these anatomical variations.ConclusionWith the results of our review, we can infer that the sciatic nerve presents a variability of distribution patterns, which may be presented in the classical anatomical literature as a variability that is found differently in the population. In addition to inferring that the variation of the sciatic nerve can be little attributed to the symptoms of the piriformis muscle syndrome.

Neuromuscular variations in the gluteal region - Embryological basis and clinical significance.

Piriformis, is a key muscle in the gluteal region. Under its lower border sciatic nerve and inferior gluteal nerves exit. During routine educational dissection of the lower limb, bilateral gluteal regions in fifteen cadavers (30 gluteal regions) focusing on the variations of inferior gluteal nerve and sciatic nerve with respect to piriformis muscle were observed in the department of anatomy, All India Institute of Medical Sciences, New Delhi, India. In one of the left sided specimens, inferior gluteal nerve had an abnormal course, piercing superior belly of piriformis muscle instead of emerging through the lower border of it along with variation of the sciatic nerve. The common peroneal component of the sciatic nerve was coming out between the two anomalous tendinous slips of the piriformis muscle, whereas the tibial component, emerged along lower border of the piriformis muscle bilaterally in the same cadaver. In the remaining cadavers, there were no variations of the inferior gluteal nerve with respect to the piriformis muscle. But in another cadaver, there was a similar variation of the sciatic nerve bilaterally. Inferior gluteal and sciatic nerves, when compressed by muscle belly or tendinous slips of the piriformis muscle, may cause lurching gait and sciatica respectively. Knowledge of the different variations of these peripheral nerves with respect to the piriformis muscle is important to clinicians and surgeons for the accurate diagnosis and intervention.

Variations in the gluteal region and its clinical significance – A cadaveric study

Anatomical structures involving muscles and nerves in the gluteal region are important as any variations of Sciatic nerve (SN) and its surrounding muscles like piriformis muscle (PM) can lead to entrapment or compression of this nerve causing sciatica and piriformis syndrome. To find out variations in the gluteal region related to piriformis muscle and the nerves surrounding it. The study was done on 20 embalmed cadavers (total 40 gluteal regions) during routine cadaveric dissection. The anatomical relations of the piriformis and surrounding nerves i.e. sciatic nerve, its divisions and gluteal nerves were studied. The dissection was done on 40 gluteal regions. In 36 gluteal regions (90%) the sciatic nerve emerged below the piriformis as a single trunk. While in 4 gluteal regions (10%) there was a higher division of sciatic nerve. In one cadaver we observed an accessory piriformis muscle just inferior to the main piriformis muscle. The sciatic nerve was also dividing higher up into common peroneal nerve and tibial nerve in the gluteal region. The common peroneal nerve (CPN) was observed emerging between the main and the accessory piriformis muscle. Along with it the inferior gluteal nerves were also seen traversing between the main and the accessory piriformis muscle.Knowledge of anatomical variations in the gluteal region is important to explain the myalgia and neuropathies in this region. This knowledge is also important in performing hip surgeries and giving intramuscular injections in the gluteal region.

An Anatomical Variation of Sciatic Nerve Encountered during Kocher - Langenbeck Approach to the Acetabulum

We are describing a variation of sciatic nerve (SN) found during Kocher-Langenbeck (KL) approach in a case of acetabular fracture. The Sciatic nerve, in our case had two separate components before uniting. Common peroneal component (CPN) was passing right through the piriformis muscle (PM) before exiting whereas the tibial component (TN) was lying underneath (anterior to) the piriformis. (Type B as per Beaton and Anson classification). From literature review, we found that anatomical variations of SN have been described to be around 13% across both cadaveric studies and magnetic Resonance Imaging (MRI) based studies. Type B is the most common variant which has been found in 8% of cases. However, amongst cadaveric studies done in India, it has been found to an extent of just 2%. Knowledge of variations in anatomy of SN in relation to PM is important for acetabular surgeons to avoid iatrogenic injury to the sciatic nerve.

Sciatic Nerve Variants and the Piriformis Muscle: A Systematic Review and Meta-Analysis.

The present systematic review and meta-analysis provides a comprehensive assessment of the sciatic nerve (SN) variants relative to the piriformis muscle (PM) and compares those variants’ prevalence among different geographical populations with respect to gender and laterality. A database search was conducted to identify cadaveric studies pertinent to SN variants relative to the PM. A total of 44 articles were included. The typical morphological pattern (type A, with the SN passing undivided below the PM) was found to be the most common variant, with 90% pooled prevalence. SN variants were more common among East Asians, with a 31% pooled prevalence of total variants. No significant differences were established with respect to gender and laterality. In greater than 10% of the population, the SN coursed through or above piriformis. Patients’ epidemiological characteristics may predispose them to certain variants. The common peroneal nerve (CPN) is more susceptible to injury during a total hip arthroplasty or a hip arthroscopy where anomalies are encountered. As anatomical variants are commonly associated with piriformis syndrome, they should always be considered during diagnosis and treatment.

Sciatic Nerve Variants in Patients Diagnosed With Sciatica: Is There a Correlation?

Compression of the sciatic nerve in its path along the piriformis muscle can produce sciatica-like symptoms. There are 6 predominant types of sciatic nerve variations with type 1 being the most common (84.2%), followed by type 2 (13.9%). However, there is scarce literature on the prevalence of sciatic nerve variation in those diagnosed with sciatica. The charts of 95 patients clinically diagnosed with sciatica who had a magnetic resonance imaging of the pelvis/hip were retrospectively studied. All patients had T1-weighted axial, coronal, and sagittal images. Magnetic resonance imagings were interpreted separately by 2 board-certified fellowship-trained musculoskeletal radiologists to identify the sciatic nerve variant. Seven cases were excluded because of inadequate imaging. Of the remaining 88 patients, 5 had bilateral sciatica resulting in a sample size of 93 limbs. Fifty-two (55.9%) had type 1 sciatic nerve anatomy, 39 (41.9%) had type 2, and 2 (2.2%) had type 3. The proportions of type 1 and 2 variations were significantly different from the normal distribution (P < 0.001), whereas type 3, 4, 5, and 6 variants were not (P = 1.00). There is strong statistical significance regarding the relationship between sciatic nerve variation and the clinical diagnosis of sciatica. Preoperative magnetic resonance imaging can be considered in sciatica patients to prevent iatrogenic injury in pelvic surgery.

Unusual Anatomic Split with Reunification of the Mid-Thigh Sciatic Nerve Utilizing Sonography

Variant sciatic nerve anatomy in the thigh occurs in about 4% of cadaveric specimens. Its significance is relevant in both clinical and surgical settings. This case describes a rare asymptomatic split with reunification of the sciatic nerve in the thigh utilizing sonography. A 27-year old male presented as a participant in a sonography research study (in preparation for publication). He was a healthy control subject without low back pain or radicular symptoms. A bilateral sonographic examination was performed to assess the sciatic nerve in the long (sagittal) and short (axial) planes. Incidentally demonstrated was a split of the sciatic nerve occurring approximately 8 cm distal to the ischial tuberosity. The finding was symmetric and bilateral. The split was maintained for 12 cm with a perpendicular epineural bridge connecting the two branches, reuniting proximal to the sciatic nerve bifurcation. Sciatic nerve variants are often described at the level of the piriformis. In contrast, there are few studies that describe variant anatomy of the sciatic nerve in the mid-thigh. Sonography provides a safe, easy, and available resource for depicting anatomic morphology of the sciatic nerve.

Is it painful to be different? Sciatic nerve anatomical variants on MRI and their relationship to piriformis syndrome.

To investigate the purported relationship between sciatic nerve variant anatomy and piriformis syndrome. Over 49 months, 1039 consecutive noncontrast adult hip MRIs were completed for various clinical indications. Repeat and technically insufficient studies were excluded. Radiologists categorized sciatic nerve anatomy into Beaton and Anson anatomical types. Chart review using our institution's cohort search and navigation tool determined the prevalence of the explicit clinical diagnosis of piriformis syndrome (primary endpoint) and sciatica and buttock pain (secondary endpoints). A Z-test compared the prevalence of each diagnosis in the variant anatomy and normal groups. Seven hundred eighty-three studies were included, with sciatic nerve variants present in 150 hips (19.2%). None of the diagnoses had a statistically significant difference in prevalence between the variant and normal hip groups. Specifically, piriformis syndrome was present in 11.3% of variant hips compared with 9.0% of normal hips (p = 0.39). There were no significant differences in the prevalence of piriformis syndrome, buttock pain, or sciatica between normal and variant sciatic nerve anatomy. This large-scale correlative radiologic study into the relationship between sciatic nerve variants and piriformis syndrome calls into question this purported relationship. • Large retrospective study relating variant sciatic nerve anatomy, present in 19.2% of hip MRIs, and piriformis syndrome • While sciatic nerve variant anatomy has previously been implicated in piriformis syndrome in small studies, no relationship was identified between sciatic nerve variants and piriformis syndrome.

A rare bifurcation pattern of the sciatic nerve

Variations in branching patterns of the sciatic nerve are thought to be clinically significant because of the nerve’s extensive distribution area. Here we report a rare and unusual branching pattern of the sciatic nerve which was observed in a male cadaver. Sciatic nerve underwent a high division inside the pelvic cavity, and entered the gluteal region as separate tibial and common fibular nerves. Subsequent distal courses of both nerves into the leg were normal. Knowledge of sciatic nerve variations is useful in treating lower limb neuropathies, such as piriformis syndrome, which tends to be caused by the compression of the sciatic nerve by the piriformis muscle.Keywords: Sciatic nerve bifurcation; sciatic nerve anomalies; piriformis syndrome

Sciatic neuromuscular variants on MR neurography: frequency study and interobserver performance.

To evaluate the frequency of sciatic neuromuscular variants on MR neurography and determine the interobserver variability. A retrospective evaluation of 137 consecutive lumbosacral plexus magnetic resonance neurography examinations was performed. All examinations were performed using nerve selective 3D imaging and independently reviewed by two readers for the presence of sciatic neuromuscular variants and piriformis muscle asymmetry. Inter- and intraobserver performance were evaluated. There were a total of 44/268 (16.4%) extremities with sciatic neuromuscular variants. The interobserver performance in the identification of sciatic nerve variants was excellent (kappa values from 0.8-0.9). There was a total of 45/134 (33.6%) patients with piriformis muscle asymmetry. Of these, 7/134 (5.2%) had piriformis muscle atrophy and 38/134 (28.4%) had piriformis muscle hypertrophy. The interobserver performance in the identification of piriformis muscle atrophy and hypertrophy was moderate to good (kappa values from 0.39-0.61). The intraobserver performance revealed kappa values of 0.735 and 0.821 on right and left, respectively. Sciatic neuromuscular variants and piriformis muscle asymmetry are frequent on lumbosacral plexus MRN with moderate to excellent interobserver performance. Advances in knowledge: Sciatic neuromuscular variants and piriformis asymmetry on MR neurography are frequent and the prevalence is similar to cumulative prevalence from available scientific series. Interobserver performance for identification of sciatic neuromuscular variants is excellent, and moderate-good for piriformis muscle asymmetry.

Anatomical structure and topographic anatomy of sciatic nerve in human fetuses

IntroductionSciatic nerve is the longest and thickest nerve of the human body which divides into two branches in popliteal fossa. Variations of sciatic nerve can be observed during the course of the nerve. These anatomical variations contribute to some clinical manifestations such as piriformis syndrome, sciatalgia. MethodsThis study was conducted on 60 aborted fetuses aged between 9 and 40 gestational weeks and with no gross anomalies. Morphometrical measurements related to the nerve and the neighboring structures were performed and also incidence of anatomical variations was determined. ResultsAll parametric data were seen increased with gestational age (p<0.05). Also, no statistical differences between the parameters from right and left were found (p>0.05). The sciatic nerve division was observed in 99 (82.5%) lower extremities in the popliteal fossa, 19 (15.83%) at a level above the popliteal fossa, and in 2 lower extremities (1.67%), high division was observed. Also, the status of sciatic nerve was assessed in regard to piriformis muscle. In 118 of the lower extremities (98.3%), sciatic nerve was observed leaving from underneath the piriformis muscle as one piece and the remaining 2 (1.67%) were observed as giving division at higher levels. In one of these lower extremities of the right side, tibial nerve branch was observed following a path under piriformis muscle and common peroneal nerve was observed passing through the piriformis nerve. DiscussionWe believe that our study will provide data regarding the development of sciatic nerve in fetal period and that data will contribute to related clinical studies and applications.