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Year : 2017  |  Volume : 5  |  Issue : 1  |  Page : 79-81

Unusual case of sciatic nerve and deep pelvic endometriosis with lumbosacral plexus spread presenting with muscular atrophy and foot drop

1 Department of Radiology, Dr. Rajendra Prasad Government Medical College, Tanda, Kangra, Himachal Pradesh, India
2 Department of Pathology, Dr. Rajendra Prasad Government Medical College, Tanda, Kangra, Himachal Pradesh, India
3 Department of Gynecology, Dr. Rajendra Prasad Government Medical College, Tanda, Kangra, Himachal Pradesh, India

Date of Web Publication16-Jun-2017

Correspondence Address:
Narvir Singh Chauhan
Dr. Rajendra Prasad Government Medical College Campus, Tanda, Kangra - 176 001, Himachal Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/amhs.amhs_128_16

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Endometriosis is an important disorder which affects women in the childbearing age group. In addition to the commonly observed intrapelvic sites, it can very rarely affect extrapelvic location such as the sciatic nerve. We describe an uncommon case of sciatic endometriosis leading to gross muscular atrophy and foot drop. The patient additionally had perineural extension of endometriosis along the ipsilateral lumbosacral trunk and coexisting intrapelvic endometrial implants in retrocervical area, uterosacral ligament, and urinary bladder wall.

Keywords: Deep pelvic endometriosis, foot drop, sciatic endometriosis

How to cite this article:
Chauhan NS, Kaul R, Thakur S, Nimkar K. Unusual case of sciatic nerve and deep pelvic endometriosis with lumbosacral plexus spread presenting with muscular atrophy and foot drop. Arch Med Health Sci 2017;5:79-81

How to cite this URL:
Chauhan NS, Kaul R, Thakur S, Nimkar K. Unusual case of sciatic nerve and deep pelvic endometriosis with lumbosacral plexus spread presenting with muscular atrophy and foot drop. Arch Med Health Sci [serial online] 2017 [cited 2022 Dec 8];5:79-81. Available from: https://www.amhsjournal.org/text.asp?2017/5/1/79/208187

  Introduction Top

Lower limb pain as a result of sciatic nerve endometriosis is a very rare entity, and patients presenting with gross muscular atrophy and foot drop are rarer still. We report a case of this uncommon entity that also had associated infiltrating pelvic endometrial disease. The peculiar radiological findings observed on magnetic resonance imaging (MRI) are described. The diagnosis of endometriosis was histologically proven on biopsy.

  Case Report Top

A 39-year-old female presented in the Gynaecology Department with complaints of deep pelvic pain and right foot drop. She had past history of undergoing cystectomy for an ovarian endometrioma 5 years ago. On examination, a firm mass was palpable in the pouch of Douglas. The patient was admitted under suspicion of malignancy, and ultrasound of pelvis was recommended. It showed a sheet-like hypoechoic thickening in the pouch of Douglas and retrocervical area [Figure 1]a. MRI pelvis was done subsequently for better characterization of pelvic thickening and revealed a spiculated mass-like lesion in the greater sciatic notch on the right side with marked atrophy of muscles along with thickening in retrocervical region and uterosacral ligament. The signal intensity was hypointense on T2-weighted (T2W) images and iso to slightly hyperintense on T1-weighted (T1W) images [Figure 1]b and [Figure 1]c. Ipsilateral S1 and L5 nerves proximal to the lesion were enlarged with hyperintense signal on T2W and postgadolinium enhancement [Figure 2]a. The MRI also revealed a minute (0.6 cm) implant in urinary bladder wall and small left ovarian endometrioma (1.2 cm). Both these lesions showed hyperintense signal on T1W and hypointense signal on T2W [Figure 2]b and were not appreciable on ultrasound. An inquiry into patient's history revealed she had cyclical sciatica for the past 5 years and her lower limb atrophy had occurred gradually during this period. Considering the patient's typical history and MRI findings, a possibility of sciatic endometriosis with multiple deep pelvic endometrial implants was given. Ultrasound-guided biopsy was done subsequently from the sciatic nerve lesion showed endometrial glands, pseudoxanthoma cells, and focal hemorrhagic areas consistent with endometriosis [Figure 2]c.
Figure 1: Transabdominal ultrasound of pelvis (a) showing band-like hypoechoic thickening in the retrocervical region (arrows). Axial T2-weighted and T1-weighted images (b and c) at the level of sciatic notch showing the sciatic endometriosis (arrows) and nodular-/band-like endometrial implant in the retrocervical region and uterosacral ligament (arrowheads)

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Figure 2: Coronal T2-weighted fast spin echo image (a) showing the abnormal hyperintensity along the nerve course (arrows) and axial T1-weighted (b) image showing a minute endometrial implant in posterior wall of urinary bladder (curved arrow). Photomicrograph (H and E stain) of the biopsy (c) shows evidence of endometrial glands and focal area of hemorrhage consistent with endometriosis

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The patient was unwilling for surgery and has been given injectable long-acting depot medroxyprogesterone acetate (150 mg) with advice for follow-up after 2–3 months.

  Discussion Top

Endometriosis is an important gynecologic disorder affecting 1%–5% of women in reproductive age group. Although it most commonly involves the ovaries, other pelvic organs such as cul-de-sac, broad ligament, uterosacral ligament, uterus, fallopian tubes, sigmoid colon, ureter, and small intestine can also be involved.[1] Endometrial implantation in the sciatic nerve is uncommon, and it is proposed that a peritoneal diverticulum facilitates the migration of endometrial tissue from its pelvic site to the nerve. Hematologic migration has also been suggested as a cause. More recently, a perineural pattern of spread is proposed as an alternative mechanism which hypothesizes that endometriotic cells advance from adenomyotic nodules to pelvic autonomic nerves and sciatic plexus from where they spread distally to sciatic nerve or proximally to spinal nerves.[2] After implantation in the nerve, the endometrial tissue constantly invades the epineurium and perineurium of the nerve.[3]

Sciatic endometriosis characteristically manifests as cyclical episodes of radiating pain along the nerve course coinciding with menstrual periods. Other symptoms such as motor weakness, sensory loss, or reflex alterations may also be present. If not treated, a sensorimotor mononeuropathy of the sciatic nerve may eventually result. The cause of nerve damage is cyclical hemorrhage in the endometrial implants which incites inflammation.[4]

Sciatic endometriosis is reported to show a predisposition for right side involvement possibly due to the presence of sigmoid colon on the left side which hinders implantation.

Diagnosis of sciatic endometriosis is often elusive, and the patient is often subjected to a myriad of investigations such as nerve conduction tests, ultrasound, and computed tomography/MRI before the diagnosis is established. Ultrasound is helpful in cases with ovarian disease, and 95% ovarian endometriomas will be diagnosed based on their classical appearance of unilocular, hypoechoic lesions with low-level internal echoes. In our case, ultrasound missed the ovarian endometrial cyst because of its small size, but the deep pelvic endometrial implants in the retrocervical region and uterosacral ligament were identified as hypoechoic band-like thickening.

MRI is often diagnostic for sciatic endometriosis when combined with a history of cyclical sciatica. It is seen as a mass-like lesion in greater sciatic notch exhibiting a high signal on T1W and a mixed hypo- and hyperintense signal on T2W images.[2],[4] A surrounding hypointense rim on T1W and T2W images may sometimes be seen, representing the fibrous capsule or granular tissue with hemosiderin laden macrophages. Pelvic endometriosis also shows similar MRI imaging characteristics. The overall signal intensity pattern on MRI depends on the quantity and time of hemorrhage. Our case exhibited an iso to slightly hyperintense signal on T1W, hypointense signal on T2W, and patchy heterogeneous enhancement which was likely due to surrounding inflammation. In addition, MRI revealed the involvement of ipsilateral lumbosacral nerves and deep pelvic endometriosis with implants in retrocervical region, uterosacral ligament, and urinary bladder wall.

The main differential diagnosis of sciatic endometrioma is a neurogenic tumor such as schwannoma or neurofibroma. On MRI, both these tumors appear hypointense on T1W and hyperintense on T2W.[4] The neurofibroma may sometimes show a central hypointense signal with peripheral hyperintensity on T2W (target sign) which is distinct from the peripheral hypointense rim of endometriosis. Tumors also show postgadolinium enhancement in contrast to endometrial implant which shows variable or no enhancement.[4] The inflammatory reaction in soft tissues surrounding the endometrial implant may, however, show enhancement. In the index case, the possibility of neurogenic tumor was ruled out based on the history, characteristic MRI signal, and biopsy findings.

Treatment involves pain control, hormone therapy, or surgical resection in advanced cases. Early diagnosis is of paramount importance as repeated cycles of hemorrhage and fibrosis can result in sensorimotor neuropathy.

  Conclusion Top

Endometriosis can very rarely involve unusual extrapelvic site such as sciatic nerve which can result in permanent neuropathy. An awareness of this entity and knowledge of its radiological appearances is immensely helpful in making early diagnosis and initiating a timely treatment.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Barrow TA, Elsayed M, Liong SY, Sukumar SA. Complex abdominopelvic endometriosis: The radiologist's perspective. Abdom Imaging 2015;40:2541-56.  Back to cited text no. 1
Siquara de Sousa AC, Capek S, Howe BM, Jentoft ME, Amrami KK, Spinner RJ, et al. Magnetic resonance imaging evidence for perineural spread of endometriosis to the lumbosacral plexus: Report of 2 cases. Neurosurg Focus 2015;39:E15.  Back to cited text no. 2
Teixeira AB, Martins WA, d'àvila R, Stochero L, Alberton L, Bezerra S, et al. Endometriosis of the sciatic nerve. Arq Neuropsiquiatr 2011;69:995-6.  Back to cited text no. 3
Baskan O, Ozdemir F. Endometriosis of the sciatic nerve with cyclic sciatica. Acta Med Lituanica 2014;21:99-102.  Back to cited text no. 4


  [Figure 1], [Figure 2]


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