Spina bifida occulta in high grade spondylolisthesis.

A 14-year-old boy presented with symptomatic high-grade dysplastic type spondylolisthesis, with a presence of spina bifida occulta, not diagnosed by plain radiographs, but confirmed on preoperative CT and MR. Circumferential fusion with partial reduction of L5/S1 was performed. Awareness of the coexistence of spondylolisthesis and spina bifida by an accurate preoperative planning is paramount to avoid iatrogenic damage to neural elements during surgery.