Symptomatic spinal arachnoid cyst with spastic diplegia secondary to cerebral palsy: illustrative case.

backgroundSelective dorsal rhizotomy (SDR) can improve the spastic gait of carefully selected patients with cerebral palsy. Spinal arachnoid cysts are a rare pathology that can also cause spastic gait secondary to spinal cord compression. OBSERVATIONS: The authors present an interesting case of a child with cerebral palsy and spastic diplegia. He was evaluated by a multidisciplinary team and determined to be a good candidate for SDR. Preoperative evaluation included magnetic resonance imaging (MRI) of the spine, which identified an arachnoid cyst causing spinal cord compression. The cyst was surgically fenestrated, which provided some gait improvement. After recovering from cyst fenestration surgery, the patient underwent SDR providing further gait improvement. LESSONS: SDR can be beneficial for some patients with spastic diplegia. Most guidelines do not include spinal MRI in the preoperative evaluation for SDR. However, spinal MRI can be beneficial for surgical planning by localizing the level of the conus. It may also identify additional spinal pathology that is contributing to the patient's spasticity. In rare cases, such as this one, patients may benefit from staged surgery to address structural causes of spastic gait prior to proceeding with SDR.