Dandy-Walker Continuum

KEY FACTS

TERMINOLOGY

• Dandy-Walker spectrum (DWS) represents broad spectrum

of cystic posterior fossa (PF) malformations

○ DWS/complex

○ "Classic" DW malformation (DWM)

○ Hypoplastic vermis with rotation (HVR)

○ Persistent embryonic Blake pouch cyst (BPC)

○ Mega cisterna magna (MCM)

IMAGING

• "Classic" DWM

○ Cystic dilatation of 4th ventricle → enlarged PF

○ Vermis hypoplastic, rotated superiorly

• HVR

○ Variable vermian hypoplasia

○ PF/brainstem normal-sized

○ No or small cyst, keyhole-shaped 4th ventricle

• BPC

○ "Open" 4th ventricle communicates with cyst

○ Fastigial recess, primary fissure, PF/brainstem normal

• MCM

○ Enlarged pericerebellar cisterns communicate with basal

subarachnoid spaces

• Occipital bone may appear scalloped/remodeled with all

DWS types (including MCM)

• Routine MR (thin sagittal views crucial)

PATHOLOGY

• Most severe to mildest: DWM with 4th ventriculocele →

classic DWM → HVR → BPC → MCM

• Numerous syndromes associated with DWS

CLINICAL ISSUES

• Marked heterogeneity in genetic, clinical findings

• DWM: 80% diagnosed by 1 year

(Left) Sagittal graphic of

classic Dandy-Walker

malformation shows an

enlarged posterior fossa,

elevated torcular herophili ſt,

superior rotation of

hypoplastic cerebellar vermis

﬇, an overexpanded 4th

ventricle with a thin wall st,

and a dilated ventricle

(hydrocephalus). (Right)

Sagittal T2WI MR DWS shows

a hypoplastic, rotated vermis

﬉, lack of fastigial crease,

and incomplete vermian

lobulation of the posterior

lobules beyond the primary

fissure ﬇. The cyst wall is

faintly seen ﬈.

(Left) Sagittal MRV

demonstrates torcularlambdoid inversion. The

transverse sinuses st angle

upward toward the torcular

﬇, as the cyst has prevented

normal fetal torcular descent.

Note the persistent fetal

occipital sinus ſt. (Right)

Coronal T2WI MR

demonstrates a huge, fluidfilled posterior fossa. Again,

notice that the transverse

sinuses ﬉ are angled upward

toward the torcular herophili

﬈.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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