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MR Criteria

Aplasia or marked hypoplasia of the cerebellar vermis

“Umbrella” or ”bat wing” shaped fourth ventricle

Stretched/Thickened superior cerebellar peduncles with deep interpeduncular fossa creates “molar tooth” appearance.

Absence of the cerebellar vermis

cerebellar hemispheres apposing each other in the midline

4th ventricle

triangular shape mid 4th

`batwing‘/’umbrella’ appearance at the level of upper pons.

Superior cerebellar peduncles

nearly horizontal

extend anteriorly towards the mid-brain.

Stretched thickened superior cerebellar peduncles and relatively deep interpeduncular fossa create “molar tooth” appearance

Midbrain small in AP diameter -- no decussation of the SCPs.

Autosomal Recessive inheritance

Clinical syndrome

congenital ataxia

hyperpnea-apnea

abnormal eye movements

mental retardation.