Indications for Surgery and Surgical Options in Chiari Malformation: WFNS Spine Committee Recommendations

Study design: A systematic literature review and consensus using Delphi method. Objectives: This review aims to create recommendations on the surgical indications and approaches to treat Chiari malformation (CM) with or without syringomyelia. Summary of background data: Despite the growing body of knowledge on CM, there are diverse and sometimes contradicting perspectives about surgical indications and procedures in both pediatric and adult populations. Methods: The authors reviewed the literature on CM published from 2011 to 2022. Two consensus conferences were organized by WFNS Spine Committee. The first one was held in Sao Paulo, Brazil on August 2022, and the second one was held in Porto, Portugal on December 2022. Using the Delphi method, a panel of expert spine surgeons and members of the WFNS Spine Committee examined the strength of the literature, elaborated and voted statements about the surgical management of CM. Results: We present 11 consensus statements on the surgical management of CM. Surgery is recommended for patients who have symptoms or if an MRI shows progression in asymptomatic patients. In pediatrics, osteoligamentous decompression only is indicated, whereas adults can have foramen magnum decompression with duroplasty, which is usually sufficient to control the associated syringomyelia. Syrinx drainage is the last option. Arachnoid opening can be performed in patients who have previously failed surgery or if arachnoid morphological anomalies are identified during the initial procedure. Tonsillar shrinkage provides somewhat better clinical efficacy than decompression alone, but at a larger risk of complications. Only patients with concurrent basilar invagination and atlanto-axial instability are advised to undergo atlanto-axial fixation alone. Conclusions: The consensus statements created by a collaborative work provide useful information for surgeons treating CM worldwide to achieve better surgical outcomes and avoid complications.