Sciatic Foramen Research Articles

Sciatic Nerve Schwannoma at Sciatic Foramen: Importance of Transvaginal Sonography Guided Biopsy and Magnetic Resonance Imaging in its Diagnosis

Sciatic Nerve Schwannoma at Sciatic Foramen: Importance of Transvaginal Sonography Guided Biopsy and Magnetic Resonance Imaging in its Diagnosis

Sclerotherapy for Rectal Varices by a Small-Bore Needle Puncture Through the Greater Sciatic Foramen

To report a sclerotherapy technique for rectal varices consisting of direct puncture of the superior rectal vein with a small-bore sheathed needle via the greater sciatic foramen without insertion of a sheath or catheter. The subjects of this retrospective study were three consecutive patients who underwent embolization of rectal varices, two for rupture of rectal varices and one for hepatic encephalopathy and hyperammonemia. A 5% solution of ethanolamine oleate with iodinated contrast agent (5% EOI) was injected through puncture of the superior rectal vein and carried in the blood flow, after which n-butyl cyanoacrylate mixed with lipiodol (NBCA-Lip) was immediately injected to stop the blood flow. The 5% EOI and NBCA-Lip were successfully injected in all three patients. There was no movement of NBCA-Lip on plain radiographs or computed tomography (CT) immediately after injection, and the 5% EOI remained within the rectal varices. The mean procedure time was 53min (42-60min). On contrast-enhanced CT 1month after the procedure, there was no contrast enhancement of the rectal varices that had been seen on preoperative CT in any of the three patients, confirming that the rectal varices had disappeared. Sclerotherapy for rectal varices using an approach for puncture of the superior rectal vein with a small-bore sheathed needle via the greater sciatic foramen was technically feasible and clinically effective.

Combined anterior-posterior approach with enlarged sciatic foramen to remove sciatic notch dumbbell-shaped tumors.

To explore a new method for resecting huge sciatic notch dumbbell-shaped tumors. Preoperative thin-slide scanning magnetic resonance images (MRI) and computerized tomography angiography (CTA) scans were conducted. The images were processed to reconstruct a 3-dimensional (3D) model. The relationship between the tumor and surrounding anatomical structures was accurately identified. By combining an anterior-posterior approach, about 1.0 × 5.0 cm2 c-shaped bone around the greater sciatic foramen was removed using piezosurgery osteotomy to enlarge the sciatic notch, after which retroperitoneal dumbbell-shaped tumors in the four patients were excised. Tumors in four patients were completely removed. Two patients obtain a total en bloc tumor resection; one patient was clinically determined to be a benign nerve-sheath tumor which was removed within the sciatic nerve sheath, and one patient had an extremely asymmetric tumor shape. The tumor unexpectedly split at the dumbbell isthmus across the greater sciatic foramen during blunt dissection, while both sections were completely removed. The combined anterior-posterior approach with an enlarged sciatic notch is an effective method to remove sciatic notch dumbbell-shaped tumors. Compared to the reported study, it is a new method probably helpful for selected patients.

Treatment of severe neuropatic pain for patients with the syndrome of Klippel-Trenaunay-Weber: case report

Introduction: Klippel-Trenaunay-Weber syndrome is a rare congenital anomaly whose etiology has not yet been elucidated. It is characterized by the triad of vascular malformations, cutaneous hemangiomas and overgrowth of bone and soft tissue adjacent. Pain is a common symptom and can be triggered in the following situations: venous disease, scoliosis by the different members and hemangiomas that affect the body surface, the deep planes or viscera. Case report: A female patient, 17, sent from the SARAH Hospital - Fortaleza to the Institute of Clinic Pain José Frota diagnosed with cerebral palsy type triplegia on right eye and anophthalmia featuring an expansive process of vascular origin extending to the paraspinal region, surpassing sciatic foramen and affecting posterior muscles of the left thigh and leg. There are signs of involvement of the sciatic nerve and deep femoral vessels. He was diagnosed with Klippel-Trenaunay-Weber syndrome. She had continuous pain in shock and burning, EVA 10, extending from the lower back, groin and left leg region. The source of hospital treatment consisted of gabapentin 180mg 12/12h, codeine 10mg 12/12h, ibuprofen 300mg 12/12h, codeine/paracetamol 30mg 12/12h and morphine oral 10mg while in pain, but without pain relief. She also used paroxetine 20mg daily, due to depression. The painful condition prevented sleep, caused irritation and worsened the quality of life of the patient. She continued treatment with gabapentin 300mg 12/12h, dipyrone 500mg 12/12h, Methadone 5mg 12/12h and reassessed two weeks showing significant improvement in pain symptoms and sleep, EVA 2. Conclusion: Pain is a symptom commonly described in the clinical picture of patients with this syndrome. The treatment of this disease is still a challenge. The malformations great gifts made it not always possible embolization or painkillers locks. The therapeutic results with strong opioid were satisfactory and have improved the quality of life of the patient.

Peculiar Problems Affecting the Sciatic Nerve.

Most insults to the sciatic nerve arise from intervertebral disc conditions or spinal stenosis. However, beyond these common etiologies for sciatic-nerve problems are a host of other, rarer causes. This month’s “Case Connections” explores 4 such peculiar examples. In the October 12, 2016, edition of JBJS Case Connector, Lee et al. reported on 3 patients who had persisting sciatica due to entrapment neuropathy caused by acetabular paralabral cysts. All 3 patients were managed successfully with arthroscopic decompression. The 2 men and 1 woman (mean age, 46.3 years) presented with radiating pain to the posterior aspect of the lower extremity, plus foot soreness or numbness. The symptoms had begun at a mean of 18 months prior to presentation but recently had become aggravated. None of the patients had range-of-motion limitations, but all had tenderness of the sciatic notch. In all 3 patients, MRI showed compression of the sciatic nerve by a perineural cyst arising from a paralabral cyst (Fig. 1) that extended into the greater sciatic foramen. Imaging showed no other abnormalities of the lumbar spine in any of the patients. Fig. 1 Axial MRI showing a paralabral cyst forming a perineural cyst around the sciatic nerve (arrow). All patients underwent arthroscopic decompression, during which surgeons incised and drained the perineural cysts by cutting in the same direction as the nerve with an arthroscopic knife. Surgeons observed drainage from all the perineural cysts after decompression, and postoperatively, all patients experienced marked reductions in pain. Two patients reported complete relief after a mean postoperative follow-up period of 52 months. The third patient reported partial relief, with some persistent mild pain and hypoesthesia. MRI scans that were made 2 years after surgery showed either no evidence of perineural cyst recurrence or only a small, clinically insignificant remnant. While Lee et al. conceded that “total …

The sciatic nerve in human cadavers - high division or low formation?

Variations of the sciatic nerve have been extensively studied in the past including its relationship with the piriformis muscle and associated clinical conditions like piriformis syndrome and sciatica. In the present study we noticed some interesting variations of the sciatic nerve, which were slightly different from the cases described earlier. In the previous studies most of the authors described the higher division of sciatic nerve and none of them discussed its formation. In this study we tried to look its formation from the sacral plexus and its divisions in the thigh. We noticed that in one cadaver the two components of the sciatic nerve originated directly from the sacral plexus and coursed down without merging in the thigh. Should this be called a higher division or non formation of the sciatic nerve? On the other hand in two other cadavers, the two divisions after emerging separately from the sacral plexus, united in the gluteal region and in the thigh respectively. Should we call this as higher division or low formation of the sciatic nerve? In two other cadavers the sciatic nerve emerged from the greater sciatic foramen below the piriformis and divided in the gluteal region itself. Ideally this should be called as higher division of sciatic nerve.

Lumbosciatalgia Due to Pyramidal Syndrome

Piriformis syndrome is a poorly known cause of sciatica and there are few cases reported in the international literature where sciatica is the form of presentation. It is caused by compression or entrapment of the sciatic nerve due to piriformis muscle pathology. A 65-year-old Caucasian man was admitted in Department of Neurology because he suffered from sciatica and weakness of the left lower limb, so initially a disc herniation was suspected. Upon physical examination, he presented marked gluteal muscle atrophy, mild quadriceps muscle atrophy and paresis of the left lower extremity with distal dominance. Electroneuromyography provided evidence of left sciatic nerve injury of severe intensity and profuse signs of active denervation present. MRI lumbar plexus revealed asymmetrical enlargement of the left piriformis muscle that obliterated the ipsilateral greater sciatic foramen, compressing the left sciatic nerve. As a result, secondary atrophy of the gluteus maximus and medius can be observed on this side. Due to the severity of the symptoms, surgery was performed to release the nerve. Piriformis syndrome rarely occurs as sciatica. The diagnosis is usually delayed because of the absence of further pathognomic testing and established diagnostic criteria, which are based on clinical manifestations. This syndrome is often confused with lumbar-sacral or hip disease. So, in a disease such as the case presented, the piriformis syndrome should be considered. We think that it is very interesting to know that a piriformis syndrome can debut as a lumbosciatalgia and it can be confused with lumbar disc pathology, so this may delay the diagnosis and cause further suffering to the patient. J Med Cases. 2016;7(6):248-251 doi: http://dx.doi.org/10.14740/jmc2503w

A rare case of bilateral supra‐piriformis pelvic exit of the common fibular nerve and its clinical relevance

Bilateral supra‐piriformis pelvic exit of the common fibular nerve (CFN) was observed during dissection of the pelvis and gluteal region. The donor was a 70‐year old Caucasian female who died of coronary vascular disease. The sciatic nerve (SN) is an integrated lumbosacral plexus of nerves that exits the pelvis through the greater sciatic foramen inferior to the piriformis muscle and later divides into the tibial nerve (TN) and CFN. In the present case, the right and left CPN exited the pelvis superior to the piriformis muscle while the TN exited inferior to the muscle. Further pelvic dissection showed that TN and CFN followed an independent course and did not unite to form the SN prior to pelvic exit. The TN exited inferior to piriformis and descended in the middle of the thigh whereas the CFN pursued a lateral course through the gluteal region, posterior thigh and popliteal fossa. Variations in the pelvic exit of the TN, CFN and the SN have been observed and classified. Knowledge of the potential alterations in the course of the sciatic, TN and/or the CFN are of clinical importance when performing such procedures as hip arthroplasty, piriformis tendon release for treatment of piriformis syndrome or, sciatic anesthesia in the popliteal fossa for foot and ankle surgery. This poster will depict a number of actual images of the variation and its’ classification based on previously established classification systems.Support or Funding InformationThis study was supported by the Department of Biomedical Sciences.

A novel method for sciatic nerve decompression: Cadaveric feasibility study with potential application to patients with piriformis syndrome

IntroductionApproaches for proximal sciatic nerve decompression use a transgluteal route, but are associated with morbidity and complications. An alternative anterior approach to the sciatic nerve was designed. MethodsFive adult human cadavers (10 sides) were used. In the supine position and with lower limbs abducted, an incision was made 3-cm inferolateral to the pubic tubercle of each specimen. With blunt dissection, a muscle-splitting approach through the obturator foramen was performed through the underlying adductor muscles and deeper obturator muscles that traversed the obturator foramen. Within the pelvis, a laparoscope was inserted in the surgical corridor, which was extraperitoneal. The obturator neurovascular bundle was identified medially and followed posterolaterally toward the greater sciatic foramen. The sciatic nerve was identified. The piriformis muscle was identified as it exited the greater sciatic foramen. Microscissors were inserted and under visualization with the laparoscope, the piriformis muscle was transected near the spine. ResultsThe piriformis was well visualized and transected. The muscle was best visualized inferolateral to the sciatic nerve. No gross damage to the sciatic nerve or surrounding neurovascular structures occurred. Mean distance from the superomedial edge of the obturator foramen to the ischial spine was 7.2 cm for left sides and 7.3 cm for right sides. ConclusionsUse of a laparoscope to approach the piriformis muscle from an anterior intrapelvic, extraperitoneal approach via the obturator foramen is feasible. Clinical use of this method is in order to demonstrate use in patients with suspected compression of the sciatic nerve by the piriformis muscle.

Anatomical variation in bifurcation and trifurcations of sciatic nerve and its clinical implications: in selected university in Ethiopia.

BackgroundThe Sciatic nerve is the widest nerve of the body. It consists of two components, namely: the tibia and the common peroneal components derived from the ventral rami of L4 to S3 spinal nerves of the lumbosacral plexus. It exits the pelvis through the greater sciatic foramen below the Piriformis muscle and descends between the greater trochanter of the femur and ischial tuberosity of the pelvis to the knee. The purpose of this study is to identify the course and variations in branching pattern of the sciatic nerve which may lead to various clinical manifestations.MethodsTwenty-eight formalin fixed cadavers comprising of 56 lower limbs are used for this study, of which six specimens were female cadavers. Dissection of gluteal region and posterior compartment of the thigh was done to expose the sciatic nerve. Variations in the sciatic nerve anatomy; their relationship to Piriformis muscle and a point of bifurcation and trifurcation were noted and recorded.ResultsForty-two lower limbs (75 %) showed normal anatomy of sciatic nerve. Fourteen regions (25 %) showed variations in the sciatic nerve, of which six regions (11 %) showed a variation of the sciatic nerve in relation to Piriformis muscle, three regions (5 %) showed trifurcation of the sciatic nerve and five regions (9 %) showed variation in the origin of the sural nerve.ConclusionThe knowledge regarding the level of division and distribution of the sciatic nerve and its location is of great importance. The sciatic nerve is frequently involved in daily medical practice of neurology, orthopedics, rehabilitation and anesthesia. Its long course makes it vulnerable to nerve injury. Even in this era the cadaver is the best means to study anatomy. It emphasizes proper clinical implications, for the surgeons to practice efficient surgical recombination and avoid errors.

Sciatic hernia with incarcerated urinary bladder: Laparoscopic transabdominal extraperitoneal repair with a mesh plug

An 87-year-old man experiencing abrupt and severe lower abdominal pain was found to have a pulsatile right hip mass. An abdominal computed tomography scan demonstrated that a portion of the redundant urinary bladder was herniating through the right sciatic foramen and into the right gluteus maximus muscle. Laparoscopic transabdominal extraperitoneal repair with a synthetic mesh plug was performed. The patient recovered uneventfully, without recurrence during 3 years of follow-up. The pathogenesis, clinical manifestation, imaging studies, and treatment of sciatic hernia were reviewed.

Level of division of sciatic nerve in fetuses

Objective: The sciatic nerve is the largest branch of the sacral plexus (L 4 -S 3 ) that is formed within the pelvis before its entry into the greater sciatic foramen. It leaves the pelvic cavity by passing through the greater sciatic foramen below the piriformis and descends along the back of the thigh, and usually divides into the common peroneal nerve and the tibial nerve just proximal to the knee. The present study aimed to study the level of division of the sciatic nerve. Materials and Methods: This study was carried out in 25 fetuses of 27-40 weeks of gestation obtained from the Department of Obstetrics and Gynecology, Regional Institute of Medical Sciences (RIMS), Imphal. The lower limbs of 25 fetuses were dissected and the sciatic nerve traced up to the level of the popliteal fossa. Results: In the present study, the lowest incidence of sciatic nerve division was found in the gluteal region (2%). In 12% of the fetuses the sciatic nerve was found to divide in the pelvic cavity before it entered into the gluteal region. The highest incidence of sciatic nerve division was found in the popliteal fossa (86%). Conclusion: Various possible variations of the sciatic nerve should be kept in mind during a surgical procedure or at the time of giving anesthesia to avoid any unwanted events. The high level of division of the sciatic nerve into the common peroneal nerve and the tibial nerve results in the involvement of only one out of the two divisions from sciatic neuropathy.

Arterial Supply of Sciatic Nerve and Its Impact on Clinical Practice

Sciatic nerve is the nerve of the posterior compartment of thigh; it is formed in the pelvis from the ventral rami of L4 to S3 spinal nerves. It leaves the pelvis via the greater sciatic foramen below piriformis and divides into common peroneal nerve and tibial nerve at the level of the upper angle of the popliteal fossa. The vasculature of peripheral nerves is adapted specifically to their structure and function. Arterial vessels that reach main nerve trunks originate from the adjacent main arteries or their muscular or cutaneous branches. Although variability in arterial supply of sciatic nerve was discussed by some authors it is still deficient. To minimize sciatic nerve ischemia and its concomitant problems, an understanding of the origin and course of the arteries supplying it in the gluteal region and the posterior compartment of thigh is important. The present study aimed to detect the different arteries supplying the sciatic nerve in the gluteal and posterior thigh regions and to study the importance of this in clinical practice. Three cases subjected to vascular surgery and twenty lower limbs of ten formalin preserved male cadavers were used. Higher division of sciatic nerve was observed in all specimens. In 6 specimens (30%), arterial supply of sciatic nerve originated from the inferior gluteal artery, 6 specimens (30%)from first, second and third perforating arteries, 5 specimens (25%)from the lateral circumflex femoral artery and 3 specimens (15%)from internal pudendal artery. Anastomosis between internal iliac artery through its internal pudendal branch and external iliac artery through perforating arteries was observed. It was concluded that there is a good anastomosis between internal iliac and profunda femoris artery on the same side but cross pelvic anastomosis is absent or deficient and in case of profunda femoris occlusion we should preserve internal pudendal artery and the reverse.

A case of piriformis syndrome presenting as radiculopathy

Piriformis syndrome has always remained as a diagnostic dilemma because of its varied presentation. Piriformis syndrome is myofascial dysfunction syndrome which causes pain not only because of trigger points within the muscle but also due to peripheral neuritis of the sciatic nerve. The sciatic neuritis is due to compression of the nerve as it passes through the greater sciatic foramen. The symptoms of sciatic nerve entrapment caused by the piriformis syndrome can be easily mistaken for radiculopathy as the nerve entrapment causes pain which radiates down below the knee and can go up to the foot. Electromyography (EMG) and nerve conduction velocity (NCV) studies can help differentiating these two conditions and can eliminate the need for the magnetic resonance imaging (MRI). In this paper, we have reported a case of piriformis syndrome which mimicked S 1 radiculopathy, where diagnosis was confirmed by diagnostic piriformis injection.

The microvascular anatomy of superior and inferior gluteal artery perforator (SGAP and IGAP) flaps: a fresh cadaveric study and clinical implications.

Our study aimed to highlight anatomical similarities, differences, and variations in the microvascular anatomy between superior and inferior gluteal artery perforator (SGAP and IGAP) flaps. Thirty gluteal flaps (15 SGAP and 15 IGAP) were studied on 22 adult fresh cadavers. We recorded the number and location of perforators, the characteristics of the main perforator (course, length, and diameter at the level of division at the greater sciatic foramen), and the anatomical variations of the submuscular venous plexus. The mean number of perforators was similar in both flaps (n = 7). We found a statistically significant difference in the total length of the vascular pedicle between SGAP (mean = 9.80 cm) and IGAP (mean = 13.36 cm) flaps, which correlated strongly with the difference in the intramuscular length (mean difference = 3.40 cm) of the perforator. There was no statistically significant difference in the diameter of the superior and inferior gluteal vessels at the point of pedicle division. The complex submuscular venous plexus, which is typically found on SGAP flaps deep to the sacral fascia, was never encountered on IGAP flaps. Perforators originating from the inferior gluteal artery were found on the lower half of five superior gluteal flaps. These were dominant perforators in two cases. We also report a rare anatomical communication between superior and inferior gluteal vessels deep to the piriformis muscle and a case of atheromatous disease of the inferior gluteal artery. Our findings are highly relevant to clinical practice and contribute to the understanding of the vascular anatomy of SGAP and IGAP flaps and the successful use of these challenging flaps. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Laparoscopic repair of a ureteric sciatic hernia: report of a case.

Ureteric sciatic hernias are extremely rare. Here we report a case of a 78-year-old woman presented with colicky left abdominal pain. Computed tomography revealed a ureteric sciatic hernia, and drip infusion pyelography revealed dilated left ureter with herniation of the ureter into the sciatic foramen. The hernia was successfully repaired laparoscopically. We have described the diagnosis and management of the patient, followed by a review of the literature on sciatic hernias.

Study on variant anatomy of sciatic nerve.

Sciatic Nerve (SN) is the nerve of the posterior compartment of thigh formed in the pelvis from the ventral rami of the L4 to S3 spinal nerves. It leaves the pelvis via the greater sciatic foramen below piriformis and divides into Common Peroneal Nerve (CPN) and Tibial Nerve (TN) at the level of the upper angle of the popliteal fossa. Higher division of the sciatic nerve is the most common variation where the TN and CPN may leave the pelvis through different routes. Such variation may lead to compression of the nerve and lead to Non-discogenic sciatica. Fifty lower limbs were used for the study from Department of Anatomy, J.J.M.M.C Davangere, Karnataka, India. In our study on 25 cadavers (50 lower limbs), we have observed 4 (8 %) lower limbs high division of sciatic nerve was noted. High division of sciatic nerve in the back of thigh was noted in one specimen (2%), while high division within the pelvis was noted in 3 specimens (6%), while in 46 (92%) it occurred outside the pelvis. Knowledge regarding such variation and differences in the course of SN is important for the surgeons to plan for various surgical interventions pertaining to the gluteal region. The variant anatomy of SN may cause piriformis syndrome and failure of SN block. Hence present study is undertaken to know the level of division, exit, course, relationship to piriformis and variations in the branching pattern of SN.

Higher division of sciatic nerve and its clinical importance

The Sciatic Nerve after originating from sacral plexus leaves the pelvis through the lower part of greater sciatic foramen into the gluteal region and divides into two components at any level from its origin to its usual division inside the upper part of popliteal fossa. The Present study was conducted in the Department of Anatomy Government Medical College Srinagar to study the variations in the level of division of the sciatic nerve during usual dissection for academic purposes. Both lower limbs of a middle aged formalin preserved Indian male cadaver were dissected out for routine teaching and simultaneously recording observations. It was observed that the left sided sciatic nerve divided into its two components inside the pelvis. The tibial and common peroneal nerves after leaving through greater sciatic foramen sandwiched piriformis muscle in the gluteal region. The common peroneal nerve passed above the piriformis where as the tibial nerve passed inferior to this muscle. The sciatic nerve on the other side of this cadaver followed the normal anatomical course. The higher division of sciatic nerve inside the pelvis though rare is of great academic and clinical significance in Neurology, General Surgery, Orthopaedics, Anaesthesiology, Sports medicine and physiotherapy. The knowledge of this variation is also important for paramedics who frequently give intramuscular injections into the gluteal region.

Giant gluteal lipoma presenting as a sciatic hernia

Sciatic hernia is considered to be the rarest hernia of pelvic floor with less than one hundred reports published worldwide. Lipoma in the hernia sac is even more unique pathology with only few cases reported in the literature. We report a case of gluteal lipoma protruding into pelvis, displacing rectum with bladder and presenting as a sciatic hernia. A 53-year-old male presented with an expanding, slightly reducible, right gluteal painful mass, back pain, dull pressure in lower abdomen and perianal region radiating to the right buttock, urgent urination and defecation. Lower back pain lasts for more than 7years, other symptoms-6months. No spinal pathology was found on X-ray. On examination patient seemed well nourished, BMI 29, abdomen was soft, without palpable masses or signs of peritonitis. Digital rectal examination showed no pathology. There was a reducible lump on the lateral side of right gluteus. Computer tomography (CT scan) demonstrated a large intra- and extra-pelvic fatty mass traversing the greater sciatic foramen. The tumor was surgically removed through lower middle laparotomy approach. Subsequent pathological examination revealed lipoma. The patient recovered uneventfully, was discharged 8days later. MRI scan was advised following 1year after the surgery. The presence of a gluteal mass should always suggest the possibility of a sciatic hernia.

A sciatic nerve with three roots and its perforation by the enlarged ischiadic artery

Knowledge about the variations of the sciatic nerve (SN) is important for many medical science disciplines. Its compression, entrapment or injury of any kind can result in loss of sensation, pain or motor disabilities in the lower limbs. We observed concurrent neurovascular variations in the gluteal region of an adult female cadaver. The SN had three roots as it emerged out of the greater sciatic foramen. The upper root passed above the piriformis; the middle and lower roots passed below the piriformis. The three roots joined to form the SN in the gluteal region. The inferior gluteal artery (IGA) was large, and it passed below the piriformis, between the middle and lower root of the SN. After a tortuous course, this artery continued down as the sciatic/ischiadic artery. The ischiadic artery (IA) was large in size and pierced the SN in the thigh. After piercing the nerve, it terminated by dividing into muscular branches. The inferior gluteal nerve emerged out from the pelvis through the greater sciatic foramen, above the level of the piriformis. The SN in this case was highly predisposed to compression by the piriformis, IGA or IA, which in turn may lead to altered cutaneous sensation or weakness of the muscles.