Type I Chiari malformations are congenital deformities involving cerebellar tonsillar herniation downward through the foramen magnum. Structurally, greater than 5 mm of tonsillar descent in adults and more than 6 mm in children is consistent with type I Chiari malformations. However, the radiographic severity of the tonsillar descent does not always correlate well with the clinical symptomatology. Advanced imaging can help clinically correlate imaging to symptoms. Specifically, cerebrospinal fluid (CSF) flow abnormalities are seen in patients with type I Chiari malformation. Advanced MRI involving cardiac-gated and phase-contrast MRI affords a view of such CSF flow abnormalities.
Key points
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Advanced imaging in type I Chiari malformations currently includes cerebrospinal fluid (CSF) flow imaging, cerebellar tonsillar imaging at the foramen magnum, quantitative posterior fossa biometrics and volumetrics, and spinal cord diffusion tensor imaging.
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Patients with type I Chiari malformations may have increased CSF flow velocities, nonuniform axial plane CSF flow, different anterior and posterior foramen magnum CSF flow, and bidirectional CSF flow.
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Normalization of CSF flow parameters such as decreased maximal flow velocities may be correlated with better surgical outcome.
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Improvement in tonsillar pulsatility seen on cine fast image spin precession imaging is seen postoperatively.
Related posts:
Definitions and Anatomic Considerations in Chiari I Malformation and Associated Syringomyelia
Pathogenesis and Cerebrospinal Fluid Hydrodynamics of the Chiari I Malformation
Prevalence of Chiari I Malformation and Syringomyelia
Surgical History of Sleep Apnea in Pediatric Patients with Chiari Type 1 Malformation
Craniovertebral Junction Instability in the Setting of Chiari I Malformation
Complex Chiari Malformations in Children
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