Evidence for Asymmetric Distribution of Sciatic Nerve Endometriosis:

Entrapped by pain: The diagnosis and management of endometriosis affecting somatic nerves

Somatic nerve entrapment caused by endometriosis is an underrecognized and often misdiagnosed issue that leads to many women suffering unnecessarily. While the classic symptoms of endometriosis are well-known to the gynaecologic surgeon, the dermatomal-type pain caused by endometriosis impacting neural structures is not within gynecologic day-to-day practice, which often complicates diagnosis and delays treatment. A thorough understanding of pelvic neuroanatomy and a neuropelveologic approach is required for accurate assessments of patients with endometriosis and nerve entrapment. Magnetic resonance imaging is the preferred imaging modality for this presentation of endometriosis. Surgical management with laparoscopic or robotic-assisted techniques is the preferred approach to treatment, with excellent long-term results reported after nerve detrapment and endometriosis excision. The review calls for increased awareness and education on the links between endometriosis and the nervous system, advocating for patient-centered care and further research to refine the diagnosis and treatment of this challenging condition.

Isolated Deep Infiltrating Endometriosis of the Sciatic Nerve: A Case Report and Overview of the Literature

Isolated deep infiltrating endometriosis (DIE) of sacral nerve roots or major pelvic nerves, including the sciatic nerve, is considered to be extremely rare. Due to the overlap with sciatica symptoms, the diagnosis of sciatica DIE is difficult yet crucial, as it results in permanent neural damage if left untreated. We report a case of a 45-year-old woman who experienced a three-year-long and recently exacerbating pain in her right leg, accompanied by a tingling sensation and weakness in her right leg and foot, with difficulty walking. In between regular menstrual bleedings, when her aforementioned symptoms worsened, she had been experiencing mild 10-day extra-cyclical bleeding. Her neurologist's, orthopedist's, and gynecological examinations were unremarkable. Magnetic resonance imaging (MRI) showed an infiltrative lesion on the right sciatic nerve that was immunohistochemically confirmed to be endometriosis. The patient was treated with gonadotropin-releasing hormone analogues (GnRHa), which led to a significantly diminished size of the lesion on the control MRI, and endometriosis remission was obtained. For persistent mild, but cyclical, pain and muscle weakness, continuous progestagnes were administered, with advice for physical therapy provided for her neuro-muscle rehabilitation and a scheduled check-up in 6 months.

[Foot drop and cyclic sensory disturbance of the right lower limb due to endometriosis]

We report the case of a 40-year-old woman, with endometriosis, who presented with a history of foot drop and cyclic sensory disturbance of the right lower limb. She was initially diagnosed with lumbar disc herniation. Neurological examination revealed muscle weakness and sensory disturbance associated with the right sciatic nerve. Nerve conduction studies revealed a low amplitude sensory nerve action potential in the right superficial fibular and sural nerves. Pelvic magnetic resonance imaging revealed an endometriotic cyst in the right ovary, and an endometriotic lesion extending from the right ovary, pelvis, and the right sciatic nerve. Though her symptoms moderately improved with hormonal therapy, the foot drop remained. Our case and previous reports suggest that endometriosis with sciatic neuropathy shows cyclic neurological symptoms during menstruation, with a higher incidence on the right extremity. This case highlights that endometriosis should be considered as a potential differential diagnosis in women of reproductive age with sciatic nerve dysfunction. Its cyclic neurological manifestations should be investigated.

Sciatic foramen anatomy and common pathologies: a pictorial review

This article reviews the relevant anatomy, imaging features on computed tomography, magnetic resonance imaging, and management of common processes involving the sciatic foramen. The anatomy of the sciatic foramen is complex and provides an important conduit between the pelvis, gluteus, and lower extremity. This paper reviewed the anatomy, common pathologies, and imaging features of this region including trauma, infection, nerve entrapment, tumor spread, hernia, and vascular anomaly.

Carcinoma arising within sciatic nerve endometriosis: a case report

Endometriosis is a common condition with significant morbidity. There have been case reports of endometrial deposits affecting the sciatic nerve. Sciatic nerve endometriosis presents with cyclical sciatica and is often difficult to diagnose as it mimics many other causes of sciatica. We report the first case of histological proven endometrial carcinoma arising in a pre-existing sciatic nerve endometriosis. This was initially managed with radiotherapy however symptoms persisted and she opted to have surgery with the aim of better symptom control and long-term prognosis.

Magnetic resonance imaging for deep infiltrating endometriosis: current concepts, imaging technique and key findings

Endometriosis is an estrogen-dependent chronic disease affecting about 10% of reproductive-age women with symptoms like pelvic pain and infertility. Pathologically, it is defined by the presence of endometrial tissue outside the uterine cavity responsible for a chronic inflammatory process. For decades the diagnosis of endometriosis was based on surgical exploration and biopsy of pelvic lesions. However, laparoscopy is not a risk-free procedure with possible false negative diagnosis due to an underestimate of retroperitoneal structures such as ureters and nerves. For these reasons nowadays, the diagnosis of endometriosis is based on a noninvasive approach where clinical history, response to therapy and imaging play a fundamental role. Trans-vaginal ultrasound and magnetic resonance imaging are suitable for recognizing most of endometriotic lesions; nevertheless, their accuracy is strictly determined by operators’ experience and imaging technique. This review paper aims to make radiologists aware of the diagnostic possibilities of pelvic MRI and familial with the MR acquisition protocols and image interpretation for women with endometriosis.

Sciatic endometriosis: A narrative review of an unusual neurogynecologic condition

Endometriosis is a condition in which there is an ectopic growth of endometrial tissue. Sciatic endometriosis, otherwise known as catamenial sciatica, is a rare but exceedingly significant presentation of endometriosis. Symptoms include cyclic sciatic pain that peaks during the menstrual period; additionally, paresthesia, paresis, and areflexia may occur with this condition. Sciatic endometriosis can be presumptively diagnosed in response to empiric treatment (e.g. gonadotropin-releasing hormone analogs) or imaging studies, but a definitive diagnosis of sciatic endometriosis may occur from examining tissue obtained during surgery. Surgical removal of endometriosis from the sciatic nerve root can potentially eliminate symptoms while maintaining normal reproductive function, though poses particular surgical risks. Familiarity with this rare condition is paramount to making this diagnosis and the initiation of earlier treatment.

Extra-spinal sciatica and sciatica mimics: a scoping review

Not all sciatica-like manifestations are of lumbar spine origin. Some of them are caused at points along the extra-spinal course of the sciatic nerve, making diagnosis difficult for the treating physician and delaying adequate treatment. While evaluating a patient with sciatica, straightforward diagnostic conclusions are impossible without first excluding sciatica mimics. Examples of benign extra-spinal sciatica are: piriformis syndrome, walletosis, quadratus lumborum myofascial pain syndrome, cluneal nerve disorder, and osteitis condensans ilii. In some cases, extra-spinal sciatica may have a catastrophic course when the sciatic nerve is involved in cyclical sciatica, or the piriformis muscle in piriformis pyomyositis. In addition to cases of sciatica with clear spinal or extra-spinal origin, some cases can be a product of both origins; the same could be true for pseudo-sciatica or sciatica mimics, we simply don’t know how prevalent extra-spinal sciatica is among total sciatica cases. As treatment regimens differ for spinal, extra-spinal sciatica, and sciatica-mimics, their precise diagnosis will help physicians to make a targeted treatment plan. As published works regarding extra-spinal sciatica and sciatica mimics include only a few case reports and case series, and systematic reviews addressing them are hardly feasible at this stage, a scoping review in the field can be an eye-opener for the scientific community to do larger-scale prospective research.

Extrapelvic Sciatic Nerve Endometriosis, the Role of Magnetic Resonance Imaging: Case Report and Systematic Review

Endometriosis (EN) is a common gynecological condition characterized by the presence of functional endometrium located outside the uterine cavity. Sciatic nerve (SN) is rarely affected by EN. Magnetic resonance imaging allows a direct visualization of the spinal and SN, and it is the modality of choice for the study of SN involvement in extrapelvic EN. We report a case of an endometrioma located in the right SN with a systematic review of the literature.

Endometriotic lesions

Endometriosis is a complex gynaecological condition affecting women of reproductive age. It is characterised by the presence of lesions containing endometrial glands and stroma outside the uterus. The disease is typically associated with pelvic pain (including dysmenorrhoea and dyspareunia), infertility and bowel-related symptoms. Endometriotic lesions have a highly variable presentation and most commonly occur in the abdominal cavity. These lesions are broadly classified into peritoneal, ovarian and deep infiltrating endometriosis. There have been observations of increased density of nerve fibres and neurological molecules in the endometriotic lesions compared to the uninvolved peritoneum of women without endometriosis and the presence of unmyelinated nerve fibres were higher near the glands. The lesion sites are characterised by a range of immunological alterations, and specific immune cell populations have also been known to synthesise and secrete neurogenic factors. Endometriotic lesions are capable of producing prostaglandins which are direct generators of pain and are capable of inducing inflammation. Diagnosing the disease involves direct visualisation of the lesions through a laparoscopic or laparotomy, which is followed by histopathological examination of biopsied or excised lesions. The staging of endometriosis due to its complexity is highly variable as presentation and gaps in knowledge pose a great challenge in the classification of the disease. The medical management of endometriosis aims at providing adequate analgesia and suppression of the activity of the lesion. A better understanding of endometriotic lesion relationships between innervations and specific clinical characteristics may elucidate aspects of pain mechanisms and infertility in endometriosis and facilitate the development of novel therapeutic approaches.

Back to the Original Question in Endometriosis: Implantation or Metaplasia?

The pathogenesis of some forms of endometriosis is still controversial. Different research approaches have been used to clarify this issue and an intense debate has derived over the years among scientists. This paper presents and discusses aged and modern ideas derived from various observations in different research areas on this specific topic. More specifically, data derived from histological results, animal studies, anatomical findings and basic research activity are presented.

Although an increasing body of evidence tends to support the implantation theory, which currently represents the most recognized pathogenic model for endometriosis, some aspects of this disease remain obscure and the scientific and medical communities have still not made significant progress in terms of completely elucidating the histogenesis of some forms of the disease.

MR imaging of endometriosis: Spectrum of disease

Endometriosis is a common gynecological disorder defined by the presence of endometrial tissue outside the uterus. It is the most common cause of chronic pelvic pain and typically affects the ovaries, uterine ligaments, peritoneum, tubes, rectovaginal septum and bladder. It may, however, be found at various extrapelvic sites, including the perineum, liver, pancreas, lung or even the central nervous system, and in such cases, diagnosis may be quite challenging. Even though definitive diagnosis requires laparoscopy, preoperative identification of endometriosis is important not only to differentiate it from other diseases with similar clinical presentations but also, for accurate presurgical mapping, since complete removal of all endometriotic foci is critical for the effective treatment of the patient's symptoms. Ultrasound is performed initially, but magnetic resonance imaging (MRI) is increasingly being used, particularly when sonographic findings are unclear, when deep pelvic endometriosis is suspected or when surgery is planned, as it provides better contrast resolution and a larger field of view compared to ultrasound. In this article, we will discuss distinctive MRI appearances of endometriotic foci and we will review common and uncommon locations of endometriosis within the body, in an attempt to familiarize radiologists with its wide spectrum of manifestations.

Sciatic endometriosis induces mechanical hypersensitivity, segmental nerve damage, and robust local inflammation in rats

BACKGROUND

Endometriosis is a common cause of pain including radicular pain. Ectopic endometrial tissue may directly affect peripheral nerves including the sciatic, which has not been modelled in animals.

METHODS

We developed a rat model for sciatic endometriosis by grafting a piece of autologous uterine tissue around the sciatic nerve. Control animals underwent a similar surgery but received a graft of pelvic fat tissue.

RESULTS

The uterine grafts survived and developed fluid-filled cysts; the adjacent nerve showed signs of swelling and damage. Mechanical and cold hypersensitivity and allodynia of the ipsilateral hindpaw developed gradually over the first 2 weeks after the surgery, peaked at 2-5 weeks, and was almost resolved by 7 weeks. Control animals showed only minor changes in these pain behaviours. Histological signs of inflammation in the uterine graft and in the adjacent nerve were observed at 3 weeks but were resolving by 7 weeks. In vivo fibre recording showed increased spontaneous activity, especially of C-fibres, in sciatic nerve proximal to the uterine graft. Several pro-inflammatory cytokines including interluekin-18, VEGF, fractalkine, and MIP-1α, were elevated in the uterine graft plus sciatic nerve samples, compared to samples from normal nerve or nerve plus fat graft. Growth associated protein 43 (GAP43), a marker of regenerating nerve fibres, was observed in the adjacent sciatic nerve as well as in the uterine graft.

CONCLUSIONS

This model shared many features with other rat models of endometriosis, but also had some unique features more closely related to neuropathic pain models.

WHAT DOES THIS STUDY/REVIEW ADD

Some especially painful forms of endometriosis are essentially neuropathic, because peripheral nerves are directly affected by nearby ectopic endometrial tissue. We modelled endometriosis by implanting autologous uterine tissue around rat sciatic nerve. We observed mechanical and cold pain behaviours along with signs of inflammation and nerve damage and increased pro-inflammatory cytokines at the implant site. Pain behaviours correlated with signs of nerve inflammation and damage rather than with cyst survival.

Magnetic resonance neurography for the diagnosis of extrapelvic sciatic endometriosis

OBJECTIVE

To illustrate magnetic resonance neurography findings of severe sciatic injury and muscle denervation related to deep gluteal endometriosis at the sciatic notch.

DESIGN

Case report.

SETTING

Academic teaching hospital.

PATIENT(S)

A 39-year-old woman with a 4-year history of sciatica related to the menstrual cycle.

INTERVENTION(S)

Surgical exploration of the sciatic notch for diagnostic confirmation, external neurolysis of the sciatic nerve, and eventual pharmacologic treatment.

MAIN OUTCOME MEASURE(S)

Magnetic resonance neurography imaging revealed severe neuropathic injury and muscle denervation related to a deep infiltrative endometriotic focus at the sciatic notch, which was confirmed histologically on surgical exploration. Detailed electrodiagnostic and clinical neurologic examinations at initial presentation and during follow-up were obtained for further assessment of nerve degeneration, muscle denervation, and clinical recovery.

RESULT(S)

Initial gynecologic and eventual laparoscopic evaluation on persisting complaints were without pathological findings. When a progressive weakness of the leg was noted, magnetic resonance neurography revealed a severe axonal damage to the sciatic nerve and denervation of distal target muscles related to a diffuse infiltrative lesion at the sciatic notch. On surgical exploration, extragenital endometriosis was confirmed histologically. Considerable improvement in pain and strength occurred after pharmacologic therapy with a GnRH analogue.

CONCLUSION(S)

This is the first report to describe imaging findings of magnetic resonance neurography in severe neuropathic injury of the sciatic nerve and subsequent muscle denervation related to a deep infiltrative gluteal endometriotic focus.

Sonography of endometriosis in infrequent sites

We reviewed the sonographic features of endometriosis in infrequent sites, including the abdominal wall, appendix, perineum, and bladder. Familiarity with the clinical setting and the sonographic appearance of endometriosis in both frequent and infrequent sites can help facilitate prompt, accurate diagnosis and treatment.

Cyclical sciatica

We describe a case of sciatic endometriosis in a 25-year-old woman diagnosed by MRI and histology with no evidence of intrapelvic disease.

The presentation, diagnosis and management of this rare condition are described. Early diagnosis and treatment are important to prevent irreversible damage to the sciatic nerve.

Endometriosis of the superior gluteal nerve

Endometriosis that involves nerves is rare and usually occurs in the pelvis. We describe a case of extra-pelvic endometriosis that involved the superior gluteal nerve. The patient presented with ill-defined buttock and thigh pain and a Trendelenberg gait. MRI demonstrated atrophic changes in the gluteus minimus, gluteus medius and tensor fascia lata muscles indicating involvement of the superior gluteal nerve. MRI showed a mass in the line of the superior gluteal nerve. The mass was hyperintense on STIR and T1-weighted images and did not enhance after intravenous contrast although surrounding edema did enhance. Histological examination of material obtained at open biopsy showed endometriosis. The patient was commenced on hormonal treatment to suppress ovarian activity.

Piriformissyndrom infolge einer extragenitalen Endometriose

We report on a 44-year-old woman with a history of sciatica fluctuating with her menstrual cycle and going back over 10 years; ultimately it was present continuously and became disabling. Over the years the patient developed ipsilateral foot-drop, a sensory disorder in the lateral aspect of the lower limb and back of the foot, and atrophy of the gluteus muscle. MRI confirmed the suspicion of extragenital endometriosis, which had caused piriformis syndrome by compression with consequent damage to the sciatic and inferior gluteal nerves. After hormonal therapy had been tried without success, the endometrioma was excised to relieve the pressure on the nerves, and the diagnosis was confirmed histopathologically. The motor deficit remained up to the 15 months since surgery, but the patient is now free of pain.

Deeply infiltrating endometriosis: pathogenetic implications of the anatomical distribution

BACKGROUND

To investigate whether knowledge of the anatomical distribution of histologically proven deeply infiltrating endometriosis (DIE) lesions contributes to understanding the pathogenesis.

METHODS

Observational study between June 1992 and December 2004 (retrospective study between 1992 and 2000; prospective study between 2001 and 2004). Continuous series of 426 patients suffering from pelvic pain who underwent complete surgical exeresis of DIE. DIE lesions were classified according to four different possibilities: (i) Firstly, DIE lesions were classified as located in the anterior or posterior pelvic compartment. (ii) Secondly, DIE were classified as left, median and right. (iii) Thirdly, DIE lesions were classified as pelvic or abdominal. (iv) Fourthly, DIE lesions that could present in a right and/or left location were classified as unilateral or bilateral.

RESULTS

These 426 patients presented 759 histologically proven DIE lesions: bladder (48 lesions; 6.3%); uterosacral (USL) (400 lesions; 52.7%); vagina (123 lesions; 16.2%); ureter (16 lesions; 2.1%) and intestine (172, 22.7%). DIE lesions are significantly more often located in the pelvis (n=730 lesions) than in the abdomen (n=29 lesions) (P<0.0001). Pelvic DIE lesions are significantly more often located in the posterior compartment of the pelvis [682 DIE lesions (93.4%) versus 48 DIE lesions (6.6%); P<0.0001]. Pelvic DIE lesions are significantly more frequently located on the left side. For patients with unilateral pelvic DIE lesions, the anatomical distribution is significantly different in the three groups: left (172 lesions; 32.0%), median (284 lesions; 52.8%) and right (82 lesions; 15.2%) (P<0.0001). For patients with lateral lesions, left DIE lesions (172 lesions; 67.8%) were found significantly more frequently than right DIE lesions (82 lesions; 32.2%) (P<0.0001). A similar predisposition was observed when we included patients with bilateral pelvic DIE lesions (P=0.0031). The same significantly asymmetric distribution is observed for total (pelvic and abdominal) DIE lesions.

CONCLUSIONS

Our results demonstrate that distribution of DIE lesions is asymmetric. It is possible that this is related to the anatomical difference between the left and right hemipelvis and to the flow of peritoneal fluid. These findings support the hypothesis that retrograde menstruation of regurgitated endometrial cells is implicated in the pathogenesis of DIE.

Sciatic endometriosis diagnosed by computerized tomography–guided biopsy and CD10 immunohistochemical staining

OBJECTIVE

To report a case of sciatic endometriosis diagnosed by computerized tomography (CT)-guided biopsy in combination with CD10 immunohistochemical staining.

DESIGN

Case report.

SETTING

University hospital.

PATIENT(S)

A 33-year-old Japanese woman complaining of right-sided sciatica.

INTERVENTION(S)

Transgluteal computerized tomography (CT)-guided needle biopsy of a mass in the course of the right sciatic nerve was conducted for a histologic diagnosis.

MAIN OUTCOME MEASURE(S)

Histologic study with hematoxylin and eosin staining and CD10 immunohistochemical staining was performed.

RESULT(S)

Computerized tomography-guided biopsy was performed without any complication. CD10 staining distinguished endometrial stromal cells.

CONCLUSION(S)

Computerized tomography-guided biopsy followed by CD10 immunohistochemical staining is a minimally invasive procedure for accurate diagnosis of sciatic endometriosis.

Diagnosis of endometriosis with imaging: a review

Endometriosis corresponds to ectopic endometrial glands and stroma outside the uterine cavity. Clinical symptoms include dysmenorrhoea, dyspareunia, infertility, painful defecation or cyclic urinary symptoms. Pelvic ultrasound is the primary imaging modality to identify and differentiate locations to the ovary (endometriomas) and the bladder wall. Characteristic sonographic features of endometriomas are diffuse low-level internal echos, multilocularity and hyperchoic foci in the wall. Differential diagnoses include corpus luteum, teratoma, cystadenoma, fibroma, tubo-ovarian abscess and carcinoma. Repeated ultrasound is highly recommended for unilocular cysts with low-level internal echoes to differentiate functional corpus luteum from endometriomas. Posterior locations of endometriosis include utero-sacral ligaments, torus uterinus, vagina and recto-sigmoid. Sonographic and MRI features are discussed for each location. Although ultrasound is able to diagnose most locations, its limited sensitivity for posterior lesions does not allow management decision in all patients. MRI has shown high accuracies for both anterior and posterior endometriosis and enables complete lesion mapping before surgery. Posterior locations demonstrate abnormal T2-hypointense, nodules with occasional T1-hyperintense spots and are easier to identify when peristaltic inhibitors and intravenous contrast media are used. Anterior locations benefit from the possibility of MRI urography sequences within the same examination. Rare locations and possible transformation into malignancy are discussed.