Chiari Malformation: Diagnosis, Classifications, Natural History, and Conservative Management. World Federation of Neurosurgical Societies Spine Committee Recommendations

Abstract

Study design: A comprehensive search was conducted in PubMed/EMBASE/MEDLINE databases. Inclusion criteria included publications between January 2011 and December 2022 on Chiari malformation (CM) diagnosis classification, natural history, and conservative management.

Objective: This study aims to offer an update on diagnosis classifications, natural history, and conservative management in CM.

Background: CM type 1 involves cerebellar tonsil herniation leading to neurological symptoms. There is controversy regarding its pathophysiology and optimal management, especially for asymptomatic cases. Previous research has focused on surgical outcomes with limited consensus on conservative strategies. Standardized guidelines are needed to enhance clinical decision-making.

Materials and methods: The screening process involved reviewing abstracts, assessing full-text articles, and reviewing references. Eligibility criteria ensured the selection of relevant studies. Data extraction involved recording various variables. Results were discussed and voted on in 2 consensus meetings of the World Federation of Neurosurgical Societies Spine Committee, reaching a consensus using the Delphi method.

Results: A total of 164 abstracts were screened. Ninety-nine articles met the inclusion criteria and were included in the study. Headache, brainstem, and/or cerebellar/brainstem symptoms/signs were confirmed as the main typical neurological hallmarks of CM. Still, an accurate clinical assessment appeared to be the most reliable evaluation model available. Considering classification, the most common form in adults is type 1, whereas type 2 is associated with myelomeningocele and hydrocephalus from childhood. Magnetic resonance imaging is the gold standard to show the extent of tonsillar herniation, overcrowded posterior fossa, or the absence of cisterna magna. Focusing on natural history, for asymptomatic or mildly symptomatic radiologically positive patients conservative management is appropriate. Somatosensory, motor, brainstem auditory evoked potentials and polysomnography could be helpful to guide eventual surgical indication.

Conclusion: Further, higher-quality studies are recommended to establish more substantial evidence and recommendations.

Keywords: Chiari malformation; Chiari malformation classification; Chiari malformation conservative management; Chiari malformation natural history.