Pediatric moderate-/high-grade spondylolisthesis surgery complication

Moderate- to high-grade spondylolisthesis is a difficult pathology to treat, with complications not infrequently associated with injury to the L5 root. Attention to detail with preoperative planning and surgical technique can minimize the risk of complication in these surgeries. We present here a rare complication, conus medullaris syndrome, due to the delayed diagnosis of a compressive arachnoid cyst in the lumbar spine. The symptoms evolved rapidly over the first postoperative day, though diagnosis was delayed due to the obscure diagnosis and the massive cyst occupying the entire lumbar canal. Patients with high-grade spondylolisthesis may have risk factors for the presence of arachnoid cysts. Surgeons should be aware of the signs associated with this concomitant pathology, as this may further reduce the risk of catastrophic complications.