Primary pelvic hydatid cyst - An unusual cause of sciatica and foot drop

Study Design. A case report of primary pelvic hydatid cyst causing sciatica and foot drop. Objective. To document the occurrence of primary pelvic hydatid cyst as one of the hidden causes of lower limb weakness and foot drop, and to recommend inclusion of the pelvic cavity when assessing sciatica and foot drop. Summary of Background Data. It is common to see foot drop caused by peripheral lesions around the knee or disc herniation in the lumbar spine, but if these sites were excluded, the pelvic cavity must be examined for hidden disease that may explain the cause of foot drop and sciatica. Methods, The authors involved in the care and management of this patient were interviewed and all medical records, radiologic investigations, and related literature were reviewed. Results. After exclusion of spinal and peripheral causes of foot drop, computed tomography of the pelvis showed a well-localized cystic swelling in the right side of the pelvis over the lumbosacral plexus roots. Surgical excision of the cyst resulted in partial recovery of the foot drop at 3 years of follow-up. Conclusion. Primary pelvic hydatid cyst rarely causes pressure on the lumbosacral plexus. This was a case of hydatid cyst in the pelvis causing sciatica and foot drop, and it indicates the pelvis as a hidden source of sciatica and foot drop. After surgical excision followed by 4 months' mebendazole therapy, there was no evidence of recurrence on long-term follow-up.