Mobile schwannoma of the cauda equina incarcerated following caudal migration after trauma--case report.

A 56-year-old man presented with a very rare case of mobile schwannoma of the cauda equina incarcerated following caudal migration after trauma, manifesting as attack of severe back pain and bilateral sciatica which developed just after a fall. Magnetic resonance imaging demonstrated a large intradural tumor at the L4-5 level with redundant nerve roots below that. Two days before the surgery, his pain unexpectedly lessened without additional treatment. Computed tomography showed that the tumor had migrated cranially and was now located at the L3-4 level. These findings suggest that the severe symptoms were caused by incarceration of a mobile tumor at the L4-5 level following the trauma. The tumor was successfully removed using minimally invasive procedures with guidance provided by the intraoperative myelography. The patient was relieved from pain postoperatively. The histological diagnosis was schwannoma. This case suggests that intraoperative myelography is a useful method for guiding the removal of mobile tumors.