Dandy-Walker

• progressive cystic enlargement of 4th ventricle causes upward displacement of tentorium, torcula, transverse sinus, and downward displacement, causing enlargement of posterior fossa -> on exam, see prominent occiput
• causes blockage of foramen of Magendie and Luschka
• associated hydrocephalus is almost universal, and may be present at birth or appear later in life
• may have associated agenesis of cerebellar vermis or corpus callosum

Clinical

• variable, depends on progression of hydrocephalus
• may present at birth or later; 60% show signs of hydrocephalus and increased ICP by age 2
• if symptomatic, there is often an unusually prominent bulging occiput
• if less than 1 year of age, transillumination of skull effectively demonstrates the posterior fossa cyst, and also prominent scalp veins
• ataxia, nystagmus, CN deficits may occur

Hydrocephalus

• divergent strabismus
• abducens nerve paresis
• impaired up gaze
• if severe, sun setting sign
   

neuro: developmental delay, persistence of early infantile automatisms, spasticity and hyperreflexia of lower extremities