Recurrent intramedullary endometriosis of the conus medullaris: A case report of diagnostic pitfalls and a review of literature

Deshan Gomez: Conceptualization, Writing – original draft, Writing – review and editing, Visualization. Gayanga Kottegoda: Writing – review and editing. Thanuka Gunawardana: Writing – review and editing. Pathmanesan Pirakash: Visualization. Deepal Attanayake: Supervision.

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Deshan Gomez.

Intraspinal endometriosis is a rare but important differential diagnosis in the evaluation of a female in the reproductive age group with cyclical lower back pain and neurological symptoms. One must have a high degree of suspicion regarding it, in order to prevent protracted morbidity.

Endometriosis is a common gynaecologcial disorder affecting 10 % of women in the reproductive age group. It is characterized by the presence and implantation of endometrial epithelium and glandular stroma in an extrauterine location. The commonest location of endometriotic deposits is the ovary, followed by implants in the pelvic cavity (uterosacral ligament, broad ligament, Pouch of Douglas, rectovaginal septum), and rarely in the gastrointestinal tract, bladder, surgical scars and supradiaphragmatic locations [ 1 , 2 ]. The origin of endometriosis is still uncertain with Sampson's 1927 theory of retrograde menstruation and implantation being the most popular. Endometriotic tissue recruit their own neural and vascular supply through neuro-angiogenesis and maintain their endocrine responsiveness to cyclical fluctuations in oestrogens and progesterone resulting in cyclical bleeding, pain and chronic peritoneal irritation. The commonest symptoms of endometriosis are secondary dysmenorrhea, subfertility, deep dyspareunia, dysuria and dyschezia [ 1 , 2 ]. Endometriotic deposits of neurological interest have been well described for the peripheral nervous system with involvement of the lumbar plexus, sciatic and obturator nerves [ [14] , [15] , [16] ]. However, they have only been a few reports with regards to central nervous system involvement, both brain and spinal cord. Review of the literature has shown intraspinal endometriosis to involve the intramedullary, subarachnoid, intradural-extramedullary, and extradural compartments, including the vertebral bodies [ [3] , [4] , [5] , [6] , [7] , [8] , [9] , 14 ]. Symptoms due to intraspinal endometriosis will vary depending on the location and degree of compression of neural structures and may cause back pain, radiculopathy, motor and sensory weakness and loss of bladder and bowel control. The magnitude of the symptoms will fluctuate with the menstrual cycle especially when the deposit becomes haemorrhagic but may later become constant with the development of an inflammatory mass [ 17 ]. Intramedullary spinal cord haematomas are rarely encountered in neurosurgery and present similarly as above. Vascular causes such as arteriovenous malformations, aneurysms and cavernomas, and neoplastic causes such as astrocytoma, ependymomas, haemangioblastomas are the usual culprits. Intraspinal endometriosis is a rare cause of such haematomas. Reverse transport of endometrial tissue through the valveless venous plexus of Batson is the postulated mechanism but this remains controversial [ 11 , 15 , 18 ]. The above case describes a case of recurrent intraspinal intramedullary endometriosis for which surgical decompression was performed 3 times in the past and presented acutely with cauda equina syndrome. Over the past 3 years, she had cyclical lower back pain with lower limb weakness of varying degrees. Initial MRI revealed a small haematoma at the level of the conus medullaris suspicious of a cavernoma or bleeding into a tumour. Surgical decompression was performed and the cystic lesion evacuated. However, the histology was suggestive of an enterogenous cyst. Imaging and frozen section performed at the second surgery were suggestive of an ependymoma with formal histology not available. The lack of clinical suspicion, and radiological imaging supporting an alternate diagnosis, along with lack of histological confirmation led to the initial diagnostic dilemma and delays in starting long term endometrial suppression therapy. Recurrence and progression of symptoms was possibly both due to incomplete excision of the endometriotic deposit and failure of commencement of hormonal suppression resulting in development of progressive urinary symptoms. Histology obtained from the 3rd surgery raised suspicion of possible spinal endometriosis and she showed partial response to 6 months of hormone suppression before the current admission with cauda equina syndrome. This case highlights the importance of considering endometriosis as a differential diagnosis in a woman presenting with catamenial neurological symptoms, and interpreting radiological and histological reports with adequate consideration of this differential. The latter may prevent radiological and histological misdirections due to lack of proper clinical context, as may have occurred here. The authors wonder whether her morbidity could have been reduced if a high degree of suspicion had been maintained at the onset, and adequate surgical and early hormonal modulation was implemented ( Table 1 ). Table 1 Literature review of case reports of intraspinal intramedullary endometriosis. Table 1 Author Age Clinical presentation Location Treatment Outcome Lombardo et al. 1968 26 Cyclical left lower limb radiculopathy L1-L2 conus subarachnoid Laminectomy and excision of lesion with medical suppression Decreased symptoms Gortzen et al. 1995 38 L lower limb monoparesis T8-T9 subdural Long acting GnRH analogues Symptom free without neurological deficit Sun et al. 2002 27 Cyclical lower back pain and radicular pain, dysuria L3-L4 intradural Laminectomy and danazol postoperatively Symptom free Erbayraktar et al. 2002 28 Cyclical lower back pain conus Laminectomy and GnRH analogues Recurred – treated with laminectomy and oophorectomy Agrawal et al. 2006 40 Cyclical lumbosacral pain and radiculopathy L1-L2 conus T12-L2 laminectomy, oophorectomy and postop danazol Symtoms improved Sahu et al. 2013 28 Chronic cyclical lower limb radiculopathy with acute cauda equine syndrome L3 intramedullary mass L1-L4 laminectomy Recurrece – treated with antioestrogens Steinberg et al. 2014 29 Cyclical lumbosacral pain and radiculopathy L1 intramedullary Laminectomy and long term medical therapy Symtoms improved Beck et al. 2021 30 Acute bilateral lower limb numbness and weakness L1-L2 intramedullary lesion Laminectomy and GnRH analogues Symptoms improved *Present case 20 Recurrent cyclical backpain, bilateral lower limb pain, weakness and numbness T12-L1 intramedullary lesion Re-exploration of T12-L1 laminectomy site and excision of endometrial cyst and spinal cord decompression followed by continuous COCP's. Improvement in pain, weakness and numbness. Literature review of case reports of intraspinal intramedullary endometriosis.

Endometriosis is a common gynecological disorder affecting 10 % of females in the reproductive age group. It occurs due to the presence of ectopic endometrial tissue outside of the endometrium, commonly in the ovary, pelvis, bladder, surgical scars etc. It presents commonly with chronic pelvic pain, secondary dysmenorrhea, deep dyspareunia, subfertility and dysuria. Implanted endometrial tissue undergoes neuro-angiogenesis and retains its endocrine responsiveness both of which contribute to cyclical bleeding and pain with menstruation, eventually leading to chronic peritoneal irritation and formation of an inflammatory nidus [ 1 , 2 ]. Endometriotic manifestations of neurological interest have been described more commonly for the peripheral nervous system presenting with cyclical lumbar radiculopathy and catamenial sciatica due to involvement of the lumbar and pelvic nerve plexus, sciatic and obturator nerves. Central nervous system involvement is a rarer entity with only a handful of case reports [ [3] , [4] , [5] , [6] , [7] , [8] ]. Review of the literature has shown intraspinal endometriosis involves the intramedullary, subarachnoid, intradural-extramedullary, and extradural compartments, including the vertebral bodies [ [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] ]. Total excision of the endometriotic lesion, followed by bilateral oophorectomy and aromatase inhibitor therapy, has led to clinical improvement [ 2 ]. Here we describe a case of recurrent intraspinal haematoma due to intramedullary endometriosis of the conus medullaris. This case has been reported in line with the SCARE criteria 2020 [ 20 ].

A previously healthy 17-year-old, ethnic Tamil, Sri Lankan female, was initially referred to the neurosurgical clinic back in February 2020 with severe lower back pain and bilateral lower limb weakness and numbness. The neurological symptoms worsened with menstruation and there was no bladder or bowel involvement. There was no significant family history, past medical history or substance use. Initial magnetic resonance imaging (MRI) of the lumbar spine showed an 8x4x8mm haematoma in the posterior aspect of the conus medullaris suspicious of a cavernoma or a bleed into a tumour. She underwent a L1 laminectomy and T12, L2 partial laminectomy with excision of a haemorrhagic cystic lesion within the conus medullaris. Histology was reported as compatible with an enterogenous cyst. Symptoms improved for the next 3 months before recurring. Repeat MRI showed a 10 × 5 × 3 mm hyperintense lesion in T1 suggestive of residual intramedullary lesion. Re-exploration and excision of lesion was performed in July 2020 with intraoperative frozen section suggestive of an ependymoma. Formal histology report was not available for correlation. The patient was then lost to follow up during the next 2 years during which she had recurrent catamenial back pain with lower limb weakness along with overflow urinary incontinence. Repeat MRI in August 2022 showed evidence of residual haemorrhagic lesion in the conus medullaris and she underwent a third surgery with excision and aspiration of the intramedullary cystic lesion. Histology on this occasion was most suggestive of an enterogenous cyst but raised the possibility of an endometriotic cyst due to the presence of glands. Owing to this suspicion, endometrial suppression therapy with combined oral contraceptive pills (COCP's) was commenced, and transient symptom improvement was observed. Her current presentation to the neurosurgical clinic was due to recurrence and worsening severity of symptoms and she was brought in a wheelchair accompanied by her mother. She had bilateral lower limb weakness with MRC grade 4 power, lower limb numbness from L1-S1 dermatomes, overflow urinary incontinence and perianal anesthesia (S2-S4 dermatomes) suggestive of cauda equina syndrome. She was immediately admitted to hospital and MRI was repeated. This showed a well-defined intradural intramedullary lesion located in the conus medullaris level extending from T12 to L1 vertebra measuring 2.4 × 1.4 × 1 cm in size, confined to the spinal canal without evidence of extension into the neural foramen ( Fig. 1 , Fig. 2 ). Fig. 1 MRI images showing the lesion extending from lower border of T12 to L1 level (2.4 × 1.4 × 1 cm) with T1 high signal (left) and T2 (right) heterogenous signal characteristics. Fig. 1 Fig. 2 Well defined intradural intramedullary lesion at the conus medullary level confined to the spinal cord without extension to the neural foramen as seen on T1 (top right) and T2W (bottom right) films and myelogram (left). Fig. 2 MRI images showing the lesion extending from lower border of T12 to L1 level (2.4 × 1.4 × 1 cm) with T1 high signal (left) and T2 (right) heterogenous signal characteristics. Well defined intradural intramedullary lesion at the conus medullary level confined to the spinal cord without extension to the neural foramen as seen on T1 (top right) and T2W (bottom right) films and myelogram (left). Under general anesthesia in the prone position, the neurosurgeon re-explored the spinal column at T12-L1 level. Using the operating microscope, the dura was carefully separated from the overlying scar tissue and was split in the midline to reveal an intradural intramedullary cyst which ruptured spontaneously revealing a dark green, brown sludge. The green cyst wall was completely dissected off and edges curetted and sent for histopathological analysis. The dura was sutured watertight and routine closure of paraspinal muscles, subcutaneous tissue and the skin was performed. The early postoperative period was uneventful with improvement in backpain and lower limb pain ( Fig. 3 ). Fig. 3 Splitting of the dura exposing the endometrial “chocolate” cyst (left); excision of the greenish cyst wall (right). Fig. 3 Splitting of the dura exposing the endometrial “chocolate” cyst (left); excision of the greenish cyst wall (right). Histological analysis revealed the cyst wall was comprised of reactive glial tissue with evidence of chronic inflammation and old haemorrhage suggestive of an endometriotic cyst and tissue consisting of collections of hemosiderin laiden macrophages, reactive fibroblasts, and tortuous glands with simple columnar epithelium and surrounding stroma, all suggestive of endometrial tissue ( Fig. 4 ). Fig. 4 ×40 (top), ×100 (bottom) H&E staining of specimen revealed tortuous glands lined with simple columnar epithelium with surrounding stroma resembling endometrial tissue with proliferating blood vessels and focal fresh haemorrhages. Fig. 4 ×40 (top), ×100 (bottom) H&E staining of specimen revealed tortuous glands lined with simple columnar epithelium with surrounding stroma resembling endometrial tissue with proliferating blood vessels and focal fresh haemorrhages. Lower limb physiotherapy was continued with notable improvement in lower limb motor power to MRC grade 4 at 3 months. In liaison with the gynecological team, she was continued on endometrial suppression therapy with continuous COCPs for three months. Discussions are ongoing on changing to long term GnRH analogues but it is not affordable to the patient as present. She was referred to a genitourinary surgeon due to persistent overflow urinary incontinence. Nerve injury at a previous surgery with resultant neurogenic bladder was the presumed aetiology. She was prescribed bladder training with maintenance of a bladder diary and clean intermittent self-catheterization every 4 h. Results are optimistic thus far.

The Author(s) declare(s) that there is no conflict of interest.