Thoracic Spinal Arachnoid Cyst in a Patient With Cerebral Palsy: Clinical Evaluation and Technical Note

Spinal arachnoid cysts (SACs) are uncommon lesions that may lead to neurological decline due to spinal cord compression. They are particularly rare in the pediatric population and even more so among patients with cerebral palsy (CP). We present a case of a four-year-old female with CP undergoing evaluation for spasticity in the context of potential candidacy for selective dorsal rhizotomy. Imaging revealed a dorsal thoracic SAC extending from the level of T4 to T9, causing significant spinal cord compression. Given that differentiating spasticity-associated symptoms attributable to CP versus the arachnoid cyst was difficult, surgical intervention was pursued prior to rhizotomy consideration. The patient underwent a two-level thoracic laminectomy, consisting of a total laminectomy at T6 and a partial laminectomy involving the superior aspect of T7, with endoscopic-assisted cyst fenestration. Her postoperative course was uneventful, and follow-up myelography confirmed reestablished cerebrospinal fluid (CSF) flow and spinal cord decompression. This case highlights the importance of thorough evaluation when managing spasticity in pediatric patients with CP, as well as the utility of flexible endoscopic-assisted fenestration as a minimally invasive treatment option for SACs.