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

Abstract

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.

Sciatic endometriosis: A narrative review of an unusual neurogynecologic condition

“…17,37 Studies show that the average delay in onset of symptoms and diagnosis of sciatica is approximately 3.7 years. 38 Approximately two-thirds of the reported cases are right-sided 4,24 possibly because the position of the sigmoid is protective of the left sacral plexus. 4…”

“…Sciatic endometriosis is a critical consideration in the differential diagnosis for a woman with symptoms of menstruation-linked sciatica and sensorimotor changes. 43 However, a poor history or the loss of the cyclical nature of pain should alert the physician to rule out “lumbar disc herniation, spondylolisthesis, hip-joint arthritis, infection, ischemic or entrapment neuropathies, degeneration, and space-occupying lesions.” 4,40 When sciatic endometriosis is suspected, a complete clinical evaluation through history and physical examination is necessary. 44 Figure 2 illustrates an algorithm for a standard evaluation of this condition.…”

“…48 Endometriotic lesions appear as “solid spiculated nodules” or as focal cystic lesions with varying wall thickness and signal intensities indicative of blood products. 4,49 Susceptibility-weighted imaging exhibits high senstivity on T1- and T2-weighted sequences in detecting hemorrhagic phases, that is, endometriomas, secondary to endometriosis. 50 These phases depend on the duration and quantity of hemorrhage, as well as the fraction of cells, glands, and stroma.…”

“…Extremely acute blood has “intermediate signal intensity on T1-weighted sequences” and “high signal intensity on T2-weighted sequences.” 4,49 Acute blood has “intermediate signal intensity on T1-weighted sequences” and “low-intermediate signal intensity on T2-weighted sequences.” 4,49 Early and late subacute blood shows “high signal intensity on T1-weighted sequences” but respective “low and high signal intensity” on T2-weighted sequences. 4,49 Chronic blood shows low signal intensity on T1- and T2-weighted sequences. 4,49 “ Shading sign ,” or low signal intensity on MRI, can discriminate endometrioma from other lesions with blood.…”

“…3 A rare but important extrapelvic manifestation involves implantation of endometrial tissue, that is, glands and stroma, within the sciatic nerve, causing compression and irritation. 4–6 In some instances, endometriosis over the sciatic nerve will be present in isolation without apparent endometriosis in the pelvic cavity. 7 Sciatica is defined as sciatic nerve-sourced pain, which is usually is experienced in the back, buttocks, the hips, and radiates to the leg.…”