Dandy-Walker Phenotype with Brainstem Involvement: 2 Distinct Subgroups with Different Prognosis.

Area of Science:

• Neurology
• Developmental Biology
• Medical Imaging

Background:

• Dandy-Walker phenotype diagnosis relies on specific imaging features.
• Significant variability in associated malformations exists, particularly in the brainstem.
• Brainstem involvement can have profound implications for patient prognosis.

Purpose of the Study:

• To detail brainstem dysgenesis in a large cohort of Dandy-Walker phenotype patients.
• To define subtypes of brainstem involvement and their clinical impact.
• To investigate the association between brainstem malformations and clinical outcomes.

Main Methods:

• Retrospective review of MR imaging and clinical records from 329 Dandy-Walker phenotype patients.
• Detailed analysis of 73 subjects with co-occurring brainstem malformations.
• Comparison of posterior fossa measurements and clinical data across patient subgroups.

Main Results:

• Two major forms of brainstem involvement were identified: mild (78%) and severe (22%).
• Mild form primarily involved anteroposterior disproportions (e.g., pontine hypoplasia).
• Severe form showed tegmental dysplasia with folding, bumps, or clefts, associated with ventriculomegaly, callosal/gray matter malformations, cysts, bulbar dysfunction, seizures, and increased mortality.

Conclusions:

• Brainstem malformations in Dandy-Walker phenotype are classifiable into mild and severe forms.
• The severe form, though less common, exhibits distinct imaging features.
• Severe brainstem malformations correlate with a more severe clinical presentation and increased mortality.