Diffusion tensor imaging assessment of microstructural brainstem integrity in Chiari malformation Type I.

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Chiari malformation Type I (CM-I) diagnosis relies on cerebellar tonsillar herniation, which doesn't always correlate with symptoms.
• Neurological deficits in CM-I are thought to stem from brainstem compression.
• Conventional MRI may not detect subtle brain microstructural changes.

Purpose of the Study:

• To investigate structural and microstructural neuroimaging metrics for distinguishing CM-I patients from controls.
• To assess brainstem microstructural integrity using diffusion tensor imaging (DTI).

Main Methods:

• Eight CM-I patients and 16 controls underwent MRI, including T1-weighted and diffusion tensor imaging.
• Image postprocessing involved coregistration using 3D Slicer software.
• Fractional anisotropy (FA) was calculated in anterior and posterior lower brainstem compartments.

Main Results:

• No significant differences in posterior fossa or fourth ventricle volumes between groups.
• Significantly higher FA in the anterior brainstem compartment in CM-I patients preoperatively (p = 0.001).
• FA values normalized post-decompressive surgery, except in CM-I patients with syrinx.

Conclusions:

• Microstructural alterations, indicated by elevated lower brainstem FA, are reliably associated with CM-I diagnosis.
• FA normalization after surgery suggests DTI's potential as an adjunct diagnostic tool for CM-I.
• Further validation studies are needed to confirm the significance of DTI in assessing brainstem integrity in CM-I.