[Extragenital endometriosis leading to piriformis syndrome].

We report on a 44-year-old woman with a history of sciatica fluctuating with her menstrual cycle and going back over 10 years; ultimately it was present continuously and became disabling. Over the years the patient developed ipsilateral foot-drop, a sensory disorder in the lateral aspect of the lower limb and back of the foot, and atrophy of the gluteus muscle. MRI confirmed the suspicion of extragenital endometriosis, which had caused piriformis syndrome by compression with consequent damage to the sciatic and inferior gluteal nerves. After hormonal therapy had been tried without success, the endometrioma was excised to relieve the pressure on the nerves, and the diagnosis was confirmed histopathologically. The motor deficit remained up to the 15 months since surgery, but the patient is now free of pain.