Communicating hydrocephalus – extra ventricular obstruction
Noncommunicating hydrocephalus – intra ventricular obstruction
Ventriculomegaly – lack of brain parenchyma (atrophy or lack of development)
Surgical intervention – role in cases where there is imbalance in CSF production and absorption
CSF formed by choroid plexus and drained mostly by brain and spinal cord, to lesser extent by arachnoid granulations
Net CSF flow in direction of third to fourth ventricle, influenced by cerebrovascular pulsations
Neonates and infants
Post hemorrhagic and post infectious, aqueduct stenosis, gliosis, Chiari II, Dandy-Walker malformation, vein of Galen malformation
Progressive macrocephaly
Frontal bossing
Calvarial thinning
Tense, bulging anterior fontanelle
Sutural diastases
Enlarged scalp veins
Sunsetting eyes with failure of upward gaze
Lateral rectus palsy
Leg spasticity (due to stretching of corticospinal tracts)
Older children
Posterior fossa neoplasms, aqueduct stenosis
Early morning headache
Nausea, vomiting
Papilledema
Leg spasticity
Cranial palsies
Altered consciousness
Intra ventricular obstruction
Temporal horns dilated disproportionate to lateral ventricular dilatation
Enlarged anterior and posterior recesses of third ventricle
Inferior convexity of floor of third ventricle
Transependymal edema
Bulging of fontanelles
Sulcal spaces, major fissures and basal cisterns small or obliterated
Widening of radius of frontal horn with decrease in its angle with midline plane
Erosion of dorsum sella
Copper-beaten skull
Extra ventricular obstruction
Could be totally normal in imaging
Mild sulcal or ventricular prominence
Hemorrhage and protein debris in infection and malignancy
Impaired venous drainage and venous hypertension
Diffuse arteriopathies
The 0-2 years conundrum
Variable rates of growth of skull and the developing brain can mimic hydrocephalus in the first 2 years of brain development
Documentation of serial growth of head circumference and serial change in size of ventricles will offer more confidence in diagnosing hydrocephalus
11 – 20 years
It is normal for the scans to reveal thin ventricles and tight sulci in this age. It is perfectly normal and should not be misinterpreted as cerebral edema
The basal cisterns will be of normal dimensions in all normal patients
Mechanical obstruction
Narrowest parts of the ventricular system prone for mechanical obstruction
Foramina of Monro
Cerebral aqueduct
Fourth ventricular outflow foramina
Foramina of Monro
Superior extension of suprasellar tumors, arachnoid cysts, colloid cysts
Giant cell astrocytoma in tuberous sclerosis
Cerebral aqueduct
Tectal plate gliomas
Superior extension of midline posterior fossa tumors, brain stem astrocytomas
Inferior extension of pineal region tumors
Basal cisterns can get obstructed by diverticula arising from atria of dilated lateral ventricles. Distinguish this from arachnoid cysts by demonstrating continuity of these diverticula with the ventricular system
Infections and tumors show hyperdense exudates in basal cisterns, subarachnoid space and pial enhancement
Aqueduct stenosis
Most common cause in children
Present anytime from birth to adulthood
Developmental or acquired
Often due to infection or intraventricular hemorrhage
Dilated lateral and third ventricles
Normal fourth ventricle
No tectal plate tumor
Site of narrowing – proximal at level of superior colliculi in intercollicular sulcus
Congenital webs are seen in distal aqueduct
CSF overproduction
Choroid plexus papilloma
Apart from excess production, these tumors exert mass effect at trigone of lateral ventricle or the foramen of Monro, also induce hemorrhage within the ventricle
Spinal cord screening
Recommended in all cases of extra ventricular obstruction to rule out spinal cord neoplasms
Chiari II malformation
Presents early in life
Craniocervical junction obstruction
Displaced fourth ventricular outlet foramina adds to obstruction
Poor CSF absorption capability of spinal cord
Shunt malfunction
Occpital headaches at night
Fourth ventricle is no longer slit like. Looks normal or dilated
Raised intracranial venous pressure
Jugular outflow obstruction in craniosynostoses
Venous thrombosis
Vein of Galen aneurysm
Dural arteriovenous shunts
CSF drainage techniques
External ventricular drainage
Ventriculoperitoneal shunt
Ventriculoatrial shunt
Third ventriculostomy
Shunt infection
1-5% incidence
Higher in infants
Signs of ventriculitis: hyper dense ependyma on CT, ependymal enhancement, debris in ventricles. Can also lead to cerebrates
