033. The Diagnostic Value of Separate SPINE Imaging for Syrinx Detection in the Pre-Operative Assessment of Chiari I Malformations

Authors: Cody Lee Nesvick, MD

Chiari I malformations are associated with cervicothoracic syringomyelia, which may influence the decision for treatment with suboccipital decompression. Children often undergo separate SPINE imaging after diagnosis of Chiari by brain magnetic resonance imaging (MRI), but the yield and utility of this SPINE imaging for occult syrinx detection has not been investigated.Methods: To determine the utility of dedicated SPINE imaging in the pre-operative workup of Chiari I malformations, we retrospectively reviewed the charts of all patients aged 18 and under who underwent suboccipital craniectomy for Chiari decompression, with or without syrinx, at a single institution over a 20-year period. Patients with Chiari II, secondary Chiari malformations and craniosynostosis were excluded. Pre-operative MRI and associated anesthesia event data were collected.
One hundred forty-six children underwent Chiari decompression over the study period. Of these, 83 patients (56.8%) underwent brain MRI only as part of the initial imaging workup. Fifty-seven of these patients (68.7%) underwent separate MR imaging of the SPINE at a later date to assess for syrinx. Twenty-five of these patients (43.9%) underwent general anesthesia for adjunct imaging requiring either endotracheal intubation or laryngeal mask airway (LMA) for airway protection. Eight patients who underwent adjunct SPINE imaging (14.0%) were found to have syrinx, including six patients (10.5%) with cervicothoracic syrinx which demonstrated reduction after decompression and were considered pathophysiological. The remaining two patients were found to have thoracic syrinx that did not change after decompression and thus were considered unrelated to the Chiari malformation.
In the setting of Chiari I malformation, separate spine imaging detected a pathophysiological syrinx in about ten percent of cases but often required an additional general anesthesia exposure. The risks, benefits and costs of spine imaging should be considered on a personalized basis when working up Chiari malformations in children.