Arterial supply to the sciatic nerve in the gluteal region

Transarterial Embolization of Bone Metastases

Embolization of bone metastases is most commonly performed for hypervascular tumors prior to surgical resection. When employed in this fashion embolization can significantly decrease perioperative hemorrhage and improve surgical outcomes. In addition, embolization of bone metastases may lead to local tumor control and decreased tumoral associate bone pain. Careful techniques and choice of embolic material are required when performing embolization of bone lesions to ensure low procedural complications and high rates of clinical success.⁴ The indications, technical considerations, and complications associated with embolization of metastatic hypervascular bone lesions will be discussed in this review with subsequent case examples.

Pudendal, but not tibial, nerve stimulation modulates vulvar blood perfusion in anesthetized rodents

INTRODUCTION AND HYPOTHESIS

Preclinical studies have shown that neuromodulation can increase vaginal blood perfusion, but the effect on vulvar blood perfusion is unknown. We hypothesized that pudendal and tibial nerve stimulation could evoke an increase in vulvar blood perfusion.

METHODS

We used female Sprague-Dawley rats for non-survival procedures under urethane anesthesia. We measured perineal blood perfusion in response to 20-minute periods of pudendal and tibial nerve stimulation using laser speckle contrast imaging (LSCI). After a thoracic-level spinalization and a rest period, we repeated each stimulation trial. We calculated average blood perfusion before, during, and after stimulation for three perineal regions (vulva, anus, and inner thigh), for each nerve target and spinal cord condition.

RESULTS

We observed a significant increase in vulvar, anal, and inner thigh blood perfusion during pudendal nerve stimulation in spinally intact and spinalized rats. Tibial nerve stimulation had no effect on perineal blood perfusion for both spinally intact and spinalized rats.

CONCLUSIONS

This is the first study to examine vulvar hemodynamics with LSCI in response to nerve stimulation. This study demonstrates that pudendal nerve stimulation modulates vulvar blood perfusion, indicating the potential of pudendal neuromodulation to improve genital blood flow as a treatment for women with sexual dysfunction. This study provides further support for neuromodulation as a treatment for women with sexual arousal disorders. Studies in unanesthetized animal models of genital arousal disorders are needed to obtain further insights into the mechanisms of neural control over genital hemodynamics.

Ultrasound Detection of Arteria Comitans: A Novel Technique to Locate the Sciatic Nerve

In the gluteal and thigh region, the arteria comitans accompanies the sciatic nerve for a short distance, then penetrates the nerve and runs to the lower part of the thigh. There is no study that recognizes this artery as a guide to the location of the sciatic nerve. In this report, we describe a series of 6 knee arthroplasty patients in whom ultrasound-guided sciatic nerve block was successfully performed using color Doppler and pulsed wave Doppler to visualize the arteria comitans as a guide to the location of the sciatic nerve. We have found that detecting the arteria comitans as a landmark is novel and may offer an additional tool with the existing methods for sciatic nerve block.

Anatomical and MR correlative study of the proximal sciatic nerve vasculature

OBJECTIVE

The aim of our study is to demonstrate that increased T₂ signal on MRI could be due to intraneural vessels in asymptomatic individuals, and may therefore be a normal finding.

METHODS

An initial anatomic cadaveric study was undertaken to gain a better understanding of the vascular supply of the proximal sciatic nerve. Secondly, a retrospective study of MR imaging of patients without sciatic symptoms was performed to assess the prevalence of intraneural vessels, defined as hyperintensity on at least three consecutive slices on both T₂ and gadolinium enhanced T₁ weighted imaging, visible on routine MSK pelvic imaging.

RESULTS

The anatomical study demonstrated a relatively abundant blood supply in the peri-ischiatic region. In the MR study, 20/76 (26%) patients showed visible intraneural vessels. More than one intraneural vessel was depicted in two of the sciatic nerves. Direct branching between the extrinsic and intrinsic systems was seen in only five cases.

CONCLUSION

Normal intraneural vessels can frequently be seen within the sciatic nerve on routine musculoskeletal pelvic imaging. Advances in knowledge: T₂ hyperintensity in the proximal sciatic nerve can be due to intraneural vessels and should not necessarily be reported as abnormal.

Deep gluteal space problems: piriformis syndrome, ischiofemoral impingement and sciatic nerve release

BACKGROUND

Deep gluteal syndrome (DGS) is an underdiagnosed entity characterized by pain and/or dysesthesias in the buttock area, hip or posterior thigh and/or radicular pain due to a non-discogenic sciatic nerve entrapment in the subgluteal space. Multiple pathologies have been incorporated in this all-included "piriformis syndrome", a term that has nothing to do with the presence of fibrous bands, obturator internus/gemellus syndrome, quadratus femoris/ischiofemoral pathology, hamstring conditions, gluteal disorders and orthopedic causes.

METHODS

This article describes the subgluteal space anatomy, reviews known and new etiologies of DGS, and assesses the role of the radiologist and orthopaedic surgeons in the diagnosis, treatment and postoperative evaluation of sciatic nerve entrapments.

CONCLUSION

DGS is an under-recognized and multifactorial pathology. The development of periarticular hip endoscopy has led to an understanding of the pathophysiological mechanisms underlying piriformis syndrome, which has supported its further classification. The whole sciatic nerve trajectory in the deep gluteal space can be addressed by an endoscopic surgical technique. Endoscopic decompression of the sciatic nerve appears useful in improving function and diminishing hip pain in sciatic nerve entrapments, but requires significant experience and familiarity with the gross and endoscopic anatomy.

LEVEL OF EVIDENCE

IV.

Delayed Presentation of Gluteal Compartment Syndrome: The Argument for Fasciotomy

A male patient in his fifties presented to his local hospital with numbness and weakness of the right leg which left him unable to mobilise. He reported injecting heroin the previous morning. Following an initial diagnosis of acute limb ischaemia the patient was transferred to a tertiary centre where Computed Tomography Angiography was reported as normal. Detailed neurological examination revealed weakness in hip flexion and extension (1/5 on the Medical Research Council scale) with complete paralysis of muscle groups distal to this. Sensation to pinprick and light touch was globally reduced. Blood tests revealed acute kidney injury with raised creatinine kinase and the patient was treated for rhabdomyolysis. Orthopaedic referral was made the following day and a diagnosis of gluteal compartment syndrome (GCS) was made. Emergency fasciotomy was performed 56 hours after the onset of symptoms. There was immediate neurological improvement following decompression and the patient was rehabilitated with complete nerve recovery and function at eight-week follow-up. This is the first documented case of full functional recovery following a delayed presentation of GCS with sciatic nerve palsy. We discuss the arguments for and against fasciotomy in cases of compartment syndrome with significant delay in presentation or diagnosis.

An internal iliac artery aneurysm causing sudden buttock ischemia and nerve root compression

Acute buttock ischemia can be a consequence of aneurysmatic disease and has a dramatic presentation. This case report describes an otherwise healthy patient with a simultaneous onset of buttock ischemia combined with sciatic nerve compression caused by a small distal internal iliac artery aneurysm. Coiling of the aneurysm prevented thromboembolism recurrence but was only partially successful in reducing the symptoms of nerve compression. Given the serious consequences, prophylactic treatment independent of aneurysm diameter can be considered.

The medial circumflex femoral artery origin variability and its radiological and surgical intervention significance

The medial circumflex femoral artery usually arises from the deep femoral artery. It supplies the supplies adductors and hamstring group as well as sciatic nerve and femoral head and neck through anastomosis. In current study includes 342 dissected hemipelvis to clarify the origin of medial circumflex femoral artery. The medial circumflex femoral artery arose from the common and deep femoral artery in 39.3% and 57%. Infrequently, it arose from the superficial femoral artery in 2.5% whereas it arose from the lateral circumflex femoral artery in 0.6%. In contrast, it found to be congenital absent in 0.6%. In current study, the usual origin level of medial circumflex femoral artery found to be proximal to lateral circumflex femoral artery in 52% and distal to the deep femoral artery in 57.3%. Knowing the medial circumflex femoral artery limits avascular necrosis of the femoral head such as embolization procedure. Therefore, knowing the origin variability of the medial circumflex femoral artery may lead to avoid iatrogenic fault in several procedures such as arterial bypass procedure to protect vascular supply of lower limb. Radiologists as well as orthopedics and vascular surgeons have to be aware of the medial circumflex femoral artery variation.

External iliac artery thrombus masquerading as sciatic nerve palsy in anterior column fracture of the acetabulum

We report a case of ischemic neuropathy of the sciatic nerve in a patient with an anterior column fracture of the acetabulum operated by ilioinguinal approach. It resulted from occlusion of the blood supply to the sciatic nerve. There were no signs of a vascular insult until ischemic changes ensued on the 6(th) postoperative day on the lateral part of great toe. The patient underwent crossover femoro-femoral bypass grafting and there was a complete reversal of the ischemic changes at 6 months. The sciatic nerve palsy continued to recover until the end of 1 year; by which time the only deficit was a Grade 4 power in the extensor hallucis longus (EHL) and the extensor digitorum longus (EDL). There was no further recovery at 2 years followup.

Variations of the sciatic nerve anatomy and blood supply in the gluteal region: a review of the literature

Variations of the sciatic nerve anatomy and blood supply are complex and largely not dealt with in common anatomy texts. Variations of the sciatic nerve anatomy can be divided into the height of division of its branches, relation of the branches to the piriformis muscle, and its blood supply. These variations should be well known to any surgeon operating in this anatomical region. It is unknown whether these variations increase the risk of surgical injury and consequent morbidity. This paper will review the current knowledge regarding anatomical variations of the sciatic nerve and its blood supply.

Similarities and dissimilarities of the blood supplies of the human sciatic, tibial, and common peroneal nerves

The aim was to investigate the arterial supply of the sciatic, tibial, and common peroneal nerves. Thirty-six lower limbs of 18 human fetuses were studied. The fetuses had been fixed in buffered formalin and the blood vessels injected with barium sulfate. Fetal age ranged from 12 to 28 weeks of gestation. Microdissection of the fetal lower extremities was done under ×5 magnifying lenses. The sciatic nerves of 10 lower extremities were dissected and excised and radiographs taken. The extraneural arterial chain of the sciatic nerve was composed of 2-6 arterial branches of the inferior gluteal artery, the medial circumflex femoral artery, the perforating arteries, and the popliteal artery. The extraneural arterial chain of tibial nerve was composed of 2-5 arteries, which were branches of the popliteal, the peroneal, and the posterior tibial arteries. Radiographs showed the presence of complete intraneural arterial chains in the sciatic and tibial nerves, formed from anastomosing vessels. Dissection showed that, in 97.2% of the specimens, the common peroneal nerve was supplied only by one popliteal artery branch, the presence of which was confirmed radiologically. The sciatic and tibial nerves are supplied by numerous arterial branches of different origins, which provide for collateral circulation. In contrast, the common peroneal nerve is most frequently supplied only by one elongated longitudinal blood vessel, a branch of the popliteal artery. Such a vascular arrangement may make the common peroneal nerve less resistant to stretching and compression.

Sciatic palsy after total hip arthroplasty associated with vascular graft occlusion

Sciatic nerve palsy is a well-recognised complication of total hip arthroplasty, and causes include direct injury during surgery (crushing or electrocautery), compression or stretching of the nerve, thermal damage caused by leaked bone cement, trauma during dislocation or reduction of the hip, haematoma, traction caused by leg lengthening or inadvertent intraneural injection from nerve blocks. We describe what we believe to be a case of sciatic nerve ischemia due to intra-operative arterial occlusion, and we discuss the vascular anatomy which may have contributed.

Ruptured persistent sciatic artery aneurysm managed by endovascular embolization

Persistent sciatic artery (PSA) is a rare vascular anomaly present in 0.025% to 0.05% of the population. They are particularly prone to aneurysmal degeneration, potentially leading to distal ischemia, sciatic neuropathy, or rarely rupture. Here, we describe a case of a ruptured PSA aneurysm managed by endovascular embolization. A 70-year-old man initially presented with acute left lower extremity ischemia. He was found to have a popliteal embolus originating from a complete persistent sciatic artery aneurysm. He underwent thrombolysis followed by a femoropopliteal bypass and ligation of the proximal popliteal artery to exclude the PSA. Four weeks later he re-presented with severe pain, a pulsatile buttock mass, and anemia in the setting of hemodynamic instability. A ruptured PSA aneurysm was confirmed by computed tomography angiography (CTA). This was managed emergently by endovascular exclusion of the inflow and outflow vessels using Amplatzer vascular plugs. His postoperative course was complicated by both a foot drop, likely secondary to sciatic nerve ischemia, and a buttock abscess. To our knowledge, this is the first report detailing the endovascular management of a ruptured PSA aneurysm. The etiology, management, and complications associated with the treatment of this rare vascular entity are discussed.