Morphometric and Volumetric Characteristics Associated with Surgical Intervention in Chiari I Malformation

Chiari malformation type I (CM-1) is a complex disorder in which tonsillar herniation through the foramen magnum manifests through a wide range of clinical symptoms. Morphometric studies have tied several anatomical aberrancies to the pathophysiology of CM-1, but these findings have yet to make a significant impact on clinical management. Furthermore, tonsillar ectopia does not always manifest with clinical symptoms. We analyzed multidimensional morphometric and volumetric features within the posterior cranial fossa (PCF) of CM-1 patients and correlated these features with the decision to undergo surgical decompression. In our study, CM-1 patients had volumetrically larger tonsils with increased total tonsil length. Within CM-1 patients who underwent surgical decompression, there was a trend for greater length of tonsillar herniation, albeit not statistically significant. On the other hand, CM-1 patients who underwent surgery had significantly more neural tissue within the cross-sectional area of cisterna magna. Our findings suggest that the amount of tissue at the foramen magnum may correlate with CM-1 symptomatology more so than length of tonsillar herniation. The amount of tissue at cisterna magna, its compressibility and density, may be more directly related to CM-1 pathophysiology than the classically utilized definition of tonsillar herniation length. Further study of this phenomenon may lead to elucidated understanding of Chiari pathophysiology and improved diagnostic and prognostic tools.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
01 February 2023