VP05.21: A case of piriformis syndrome in extragenital endometriosis

Piriformis syndrome is a rare entrapment neuropathy involving the sciatic nerve in its relation with the piriformis muscle. We report on a female patient, age 47, with a history of abnormal uterine bleeding, dysmenorrhea and intermenstrual pelvic pain associated with sciatica pain going back at least 10 years. Initial gynecological examination suggested adenomyosis. After unsuccessful medical treatment with continuous desogestrel and mefenamic acid, laparoscopic hysterectomy and bilateral salpingectomy were performed. Surgery findings suggested severe pelvic endometriosis which was confirmed by histopathological conclusions. Against medical advice, the patient suspended hormonal therapy for the first 6 months after surgery, followed by a progressive increase in unspecific pelvic pain. In the following months, despite medical treatment with dienogest and nonsteroidal anti-inflammatory drugs, left lower limb symptoms (such as pain radiating into the buttock and hamstring, muscle stiffness and decrease in muscular strength) became prominent. Magnetic resonance described two cystic lesions with 7 and 12 millimetres adjacent to the medial part of the left piriformis muscle suggestive of extragenital endometriosis lesions. The patient was prescribed pregabalin treatment in increasing dosages with clinical improvement of left lower limb pain-related symptoms. Piriformis syndrome can be a rare form of extragenital endometriosis in which diagnosis can be challenging. Clinical evaluation of patients with endometriosis should prompt strenuous investigation of any symptoms in spite of how unrelated they may initially seem.