Volume 154, Issue 1 , Pages 113-114, January 2011
Cyclic sciatica associated with contralateral endometrioma: a case report and discussion
Article Outline
Dear Editor,
We report a 31-year old woman with cyclic sciatica topographically associated with a contralateral hemorrhagic cyst of ovarian endometriosis. This false localization sign may be proposed as a new mechanism of cyclic sciatica caused by endometriosis.
The patient was referred with monthly pain in her left thigh, radiating to the dorsal aspect of the foot. Her first child had been delivered by caesarean section because of a breech presentation 6 years ago. Her two other children were also delivered by caesarean section. Eight months after her last operation, she experienced the first sciatic pain in her left thigh during menstruation, which then progressed to cyclic sciatica for 1 year. Pain started on the first or the second day of her menstruation, lasted for 1 week, and resumed in the following cycle after a pain-free interval.
On examination, mild weakness of the anterior tibialis muscle of the left leg and paresthesia in the L4 and L5 dermatones were detected. The Achilles reflex of her left foot was decreased. Electromyography and nerve conduction studies revealed slight axon-loss neuropathy of the left post-ganglionic L4 and L5 nerve roots. As a lumbar root lesion associated with menstruation was strongly suspected, a lumbar spine and a pelvic MRI were conducted by using a 1.5
T MRI system (Siemens, Germany). The lumbar spine MRI showed no sign of a root irritation at L4 and L5 whereas the pelvic MRI performed on the second day of her menstruation demonstrated a cystic mass (2.5cm×5cm×3cm) in the right posterior sacral area (Fig. 1A). The irregular-shaped uterus with a normal homogeneous signal in the myometrium and endometrium (uterine height×uterine body length, 8.0cm×8.0cm) was in contact with the cystic mass on its right side, and compressed the left lower part of the piriform muscle (Fig. 1B). On the sixteenth day of the menstrual cycle, her MRI showed a smaller irregular mass and changes in the internal density consistent with an organizing clot (1cm×1cm×2cm) (Fig. 1D). The uterus, which had shifted asymmetrically during menstruation (Fig. 1B), returned to the midline position after menstruation (Fig. 1C).
Fig. 1.
T2-weighted image (TR: 4000, TE: 105) shows a cystic mass (arrow) with heterogeneous hyperintense signals in the posterior sacral area, pushing the uterus against the sciatic nerve (arrowhead) in the left sciatic notch (A, axial view; B, coronal view) during her menstrual period. After menstruation the cystic mass became an irregular smaller mass (arrow) with hyperintense signals (D, axial view), and the uterus returned to the midline position of pelvic cavity (C, coronal view).
The patient eventually received surgical treatment in attempt to terminate her cyclically intolerable pain and to obtain a definite diagnosis. The surgery revealed a purplish mass with brown-colored content in her right ovary, which was inflamed and in contact with the right side of the uterus. The mass was surgically excised. The pathology report revealed areas of hemorrhage, endometrial glands surrounded by stroma, and absence of lethal cells and scar-like structures. It confirmed typical endometriosis, and excluded the possibility of a hemorrhagic corpus luteum in the cyst. After surgery, she was free from sciatica without any medication such as oral contraceptives in a follow-up period of at least 6 months.
Schlicke first reported a case of endometriosis-induced sciatica in 1946 [1]. Since then, approximately 60 additional cases causing cyclic sciatica have been reported [2]. Almost all the pelvic endometriosis-induced sciatica was related to lesions of the ipsilateral sciatic nerve [2]. Our patient presented the typical clinical features of cyclic sciatica with endometriosis. The only exception is that her endometriosis was located in the contralateral side to the sciatic pain. A possible explanation is that the cystic mass grew in size about 13 times from an irregular shape during the follicular phase (Fig. 1D) to its maximal size during the luteal phase (Fig. 1A). In addition, her uterus seemed larger than the normal size for this stage during menstruation (8cm×8cm vs. 8cm×4.9cm) [3]. Since the pelvic cavity has limited tolerance of the additional pressure of the enlarged endometriosis during the luteal phase, the enlarged uterus was pushed away from the midline about 3cm and compressed the left sciatic notch. The result caused monthly sciatica during menstruation. Another possibility may be the presence of a small endometriotic implant within the ipsilateral sciatic nerve roots, but because the woman recovered from the sciatic pain after surgical removal of her contralateral cystic mass it seems unlikely that her cyclic sciatica was caused by infiltrative endometriosis on the left sciatic nerve.
Conflict of interest statement
None of the authors has any potential conflict of interest.
References
- . Ectopic endometrial tissue in the thigh. JAMA. 1946;132:445–446
- . Evidence for asymmetric distribution of sciatic nerve endometriosis. Obstet Gynecol. 2003;102:383–387
- . The normal uterus on magnetic resonance imaging and variations associated with the hormonal state. Surg Radiol Anat. 1991;13:213–220
PII: S0301-2115(10)00371-4
doi:10.1016/j.ejogrb.2010.07.037
© 2010 Elsevier Ireland Ltd. All rights reserved.
Volume 154, Issue 1 , Pages 113-114, January 2011
