Fedele, L., Bianchi, S., Raffaelli, R., Zanconato, G., & Zanette, G. (1999). Phantom endometriosis of the sciatic nerve. Fertility and Sterility, 72(4), 727-729. https://doi.org/10.1016/s0015-0282(99)00305-2
Fedele L, Bianchi S, Raffaelli R, Zanconato G, Zanette G. Phantom endometriosis of the sciatic nerve. Fertil Steril. 1999;72(4):727-729. doi:10.1016/s0015-0282(99)00305-2
Fedele, Luigi, et al. "Phantom endometriosis of the sciatic nerve." Fertility and Sterility, vol. 72, no. 4, 1999, pp. 727-729.
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Sciatic nerve endometriosis may go undetected on CT and MRI
Sciatic nerve endometriosis may go undetected on CT and MRI, a three-patient case report suggests. All three women had cyclic sciatica, pelvic endometriosis and nerve damage on testing. Pain eased clearly in all three on a GnRH agonist, a drug that lowers ovarian hormones, and claudication improved partly.
Study at a glance, case report of three women: Sciatic nerve endometriosis may go undetected on CT and MRI. Source: Fedele L et al., 1999, PMID 10521118.
Key Findings
Three women, aged 36, 32 and 37, had cyclic sciatica and proven pelvic endometriosis (stages I, IV and III). Each had electromyographic evidence of sciatic nerve damage.
CT and MRI findings were negative in all three women, including MRI performed in different phases of the menstrual cycle.
Each woman received monthly leuprolide acetate, a GnRH agonist, with daily transdermal estradiol. Pain eased clearly in all three, with partial improvement in claudication.
At 12 months, electromyography showed good reinnervation (restored nerve supply to muscle) in the first woman and slight reinnervation in the third. The second had not yet had the planned electromyography.
The two women diagnosed after 3 years and 8 years of symptoms had substantial reductions in motor function despite clear improvement in pain. The second woman was diagnosed after 3 months.
Interpretation
This case report follows three women with cyclic sciatica and proven pelvic endometriosis, seen at an academic referral center. The diagnosis rested on cyclic symptoms, proven pelvic endometriosis, electromyography, exclusion of other causes and response to treatment. No lesion was located on imaging. The authors presume that the lesions were too small for imaging to resolve. They propose that response to the GnRH agonist may confirm the diagnosis. Two women with delayed diagnoses had substantial reductions in motor function despite pain relief, which the authors say implies that the disease tends to progress. The women chose medical treatment to keep their reproductive function. The findings support further study of this diagnostic approach in larger groups of women with cyclic sciatica.
RRM Context
Restorative reproductive medicine looks for the cause of cyclic pain. Here the timing of symptoms was one basis for all three diagnoses. A GnRH agonist is a suppressive medication that reduces ovarian activity, and the authors read relief on it as supporting their diagnosis. Earlier cases, the authors report, were mostly treated with surgical ablation, usually plus removal of the ovaries or radiation to destroy them. Excision is the surgical standard in restorative endometriosis care.
Our editorial summary of this paper, not the article's abstract.
Abstract
Objective
To assess the efficacy and diagnostic value of GnRH agonist (GnRH-a) therapy in cases of hidden sciatic nerve endometriosis.
Design
Case report.
Setting
Academic tertiary referral center for endometriosis treatment.
Patients
Three patients with cyclic, catamenial sciatica associated with pelvic endometriosis who had electromyographic evidence of sciatic nerve damage but negative computed tomography and magnetic resonance imaging findings.
Interventions
Monthly administration of the GnRH-a leuprolide acetate plus daily transdermal E2 (25 microg).
Main Outcome Measures
Relief of pain symptoms and improvement in motor function.
Results
All three patients had clear decreases in pain and partial amelioration of claudication.
Conclusions
Endometriosis of the sciatic nerve may be hard to diagnose with the use of current imaging techniques but may be proved by clinical response to GnRH analogue treatment and may be more frequent than previously thought.
