P035 Cyclical sciatica: a case of extra-pelvic endometriosis

<h3>Background and Aims</h3> Sciatic endometriosis is an infrequent extra-pelvic manifestation of endometriosis that can mimic radiculopathy, leading to diagnostic delay and unnecessary treatments. We present a case highlighting the clinical clues and diagnostic pathway to raise awareness among pain specialists. <h3>Methods</h3> A 43-year-old woman was referred to our pain clinic with a 3-year history of insidious, radicular-type pain radiating from the left buttock to the foot (VAS 9/10), accompanied by paraesthesias and cyclical worsening during menstruation. Suspected piriformis syndrome and disc herniation led to unsuccessful physiotherapy and a non-relieving diagnostic injection. Examination revealed antalgic gait, left foot dorsiflexion weakness (3/5), positive straight-leg-raise, and piriformis tenderness. Lumbar MRI and EMG did not reveal any abnormalities. With no lumbar pathology to explain the radicular symptoms, pelvic and lumbosacral plexus MRI were performed, revealing endometriotic lesions compressing the sciatic nerve. Diagnosis was confirmed through consultation with gynaecology. <h3>Results</h3> Pharmacological treatment with gabapentin and paracetamol-codeine reduced pain to VAS 7/10. Fluoroscopy-guided pulsed radiofrequency of the dorsal root ganglia at L4, L5, and S1, the roots that converge to form the sciatic nerve, further decreased pain to VAS 2/10. Laparoscopic excision was performed 8 weeks later. At three-month follow-up, the patient was pain-free with normal gait and dorsiflexion. <h3>Conclusions</h3> Cyclical sciatic or gluteal pain unresponsive to conventional lumbar or piriformis interventions should prompt consideration of sciatic endometriosis. Detailed menstrual history, targeted pelvic/plexus imaging, and early multidisciplinary referral are crucial for timely diagnosis. Awareness of this entity can prevent prolonged patient suffering and guide effective combinational pain and surgical therapies.