Phantom endometriosis of the sciatic nerve

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. Patient(s): 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. Intervention(s): Monthly administration of the GnRH-a leuprolide acetate plus daily transdermal E₂ (25 μg). Main Outcome Measure(s): Relief of pain symptoms and improvement in motor function. Result(s): All three patients had clear decreases in pain and partial amelioration of claudication. Conclusion(s): 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.