Iatrogenic Spinal Deformity Following Spinal Intradural Arachnoid Cyst Fenestration Despite Minimal Access With Laminoplasty and Endoscopy in a Pediatric Patient.

Spinal intradural arachnoid cysts (SAC) are non-neoplastic lesions that can cause spinal cord compression and present with myelopathy, radiculopathy, and/or back pain. Because these cysts typically span multiple levels, endoscopy could be a useful tool to avoid wide exposure. We present an 8-year-old patient with a history of gait imbalance and urinary incontinence who was found to have a SAC spanning C7 to T6 causing spinal cord compression. An osteoplastic laminoplasty was performed from T4 to T7 followed by ultrasonic verification of intracystic septations, dural opening, and cyst fenestration. A flexible endoscope was then introduced into the cystic cavity to guide complete rostral and caudal decompression of the arachnoid cyst. At six months follow-up, the patient was able to ambulate independently, but his urinary incontinence remained unchanged. Despite the combination of ultrasound and neuroendoscopy to minimize exposure, our patient suffered from worsening kyphosis from 36 degrees preoperative to 55 degrees postoperative and worsening scoliosis from 17 to 39 degrees which required treatment with a thoracolumbar sacral orthosis. Preoperative imaging demonstrated a reverse S-shaped scoliosis with the apex at T6 and T7 which were the levels included in the laminoplasty. This illustrates the need for careful preoperative risk stratification to avoid this postoperative complication.