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Free Content Complex Chiari Malformation: What the Neurosurgeon Needs to Know

Chiari malformation type 1 is a frequently encountered but incompletely understood morphologic variant that may present with headache and lower cranial nerve symptoms. The main surgical treatment for Chiari malformation type 1 is suboccipital decompression. Further research has identified a subset of patients with Chiari malformation type 1 with radiographic findings that predispose to suboptimal outcomes from suboccipital decompression alone. This disease process has come to be referred to as complex Chiari malformation. Here, we discuss imaging findings of complex Chiari malformation, identify craniovertebral metrics used to stratify patients, and propose a reporting structure to assist our neurosurgical colleagues in the selection of appropriate treatment.

Learning Objective: To understand imaging findings and radiographic metrics associated with Complex Chiari malformation and their implication on surgical management

Keywords: AAI = atlantoaxial instability; ADI = atlantodental interval; BAI = basion-axis interval; BI = basilar invagination; CCI = craniocervical instability; CCM = complex Chiari malformation; CDP = clivodental pivot; CM1 = Chiari malformation type 1; CVJ = craniovertebral junction; CXA = clivo-axial angle; OCF = occipitocervical fusion; SOD = suboccipital decompression; VBSC = ventral brainstem compression; VCMD = ventral cervicomedullary dura; pB-C2 = perpendicular basion-C2 line (Grabb line)

Document Type: Research Article

Publication date: January 1, 2022

More about this publication?
  • Neurographics is the peer-reviewed, quarterly educational journal of the American Society of Neuroradiology. The journal includes review articles as well as high-yield case reports that have been solicited from society meetings including the annual ASNR meeting as well as the American Society of Spine Radiology, the American Society of Pediatric Neuroradiology, the American Society of Functional Neuroradiology, and the American Society of Head and Neck Radiology meetings. Unsolicited educational review articles and case reports are also accepted for review at the discretion of the Editor-in-Chief. Submissions focusing on a pictorial approach to educational objectives are highly encouraged. The journal is open access and available online. CME credit is offered for reading review articles and completing quiz-based self-assessment activities through the ASNR Education Connection portal.

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