Table 11-3
Sites and Types of Hydrocephalus
SITE TYPE CAUSES AND COMMENTS
Aqueduct of Sylvius—Accounts Stenosis or atresia Congenital (X-linked recessive in small number)
For 33% of hydrocephalus (Volpe, 2001) Insidious onset of symptoms from birth to adulthood
Gliosis Postinflammatory, usually secondary to perinatal
infection or hemorrhage
Prenatal maternal infection(toxoplasmosis)
Obstructive Tumors of 3rd ventricle midbrain
Ependymitis from maternal toxoplasmosis
Congenital aneurysm of Galen vein
Posthemorrhagic Blood from intraventricular hemorrhage in germinal matrix;
most common type of hydrocephalus in preterm infants
4th ventricle or subarachnoid Posthemorrhagic Blood from intraventricular hemorrhage in germinal matrix;
pathway—Intraventricular hemorrhage, most common type of hydrocephalus in preterm infants
postinflammatory conditions, or tumors
4th ventricle and foramen Chiari malformation Accounts for 28%-40% of 4th ventricle obstructions
magnum—Accounts for 50% Type I Neural tube defect with herniation of medulla through
of all hydrocephalus foramen magnum; may be asymptomatic in children;
similar to type II, but milder
Type II More severe defect; downward displacement of brainstem,
4th ventricle, and lower parts of cerebellum through
Foramen magnum with fixed attachment of spinal cord
At site of myelomeningocele
Type III (absence or High cervical or occipitocervical myelomeningocele with
occlusion of ventricles) cervical herniation through body defect
Congenital (Dandy-Walker syndrome) caused by obstruction
of foramina of Luschka and Magendie
Tumors of posterior fossa (e.g., medulloblastoma) causing
pressure on surrounding tissues to produce obstruction
Less often: subdural hematoma, bacterial or granulomatous
meningitis
Arachnoid villi and cisterna Meningitis Bacterial or granulomatous
magna—Obstruction by thick Acute phase: clumping of purulent fluid in drainage channels
arachnoid membrane or meninges Chronic phase: organization of blood and exudate that results
in fibrosis of subarachnoid spaces
Prenatal maternal infections Toxoplasmosis, cytomegalic inclusion disease, mumps
Meningeal malignancy Secondary to leukemia or lymphoma
Arachnoid cyst Located in basal cistern or (uncommon) over cerebral cortex
Tuberculosis, fungal or More common in children ages 2-10 yr old
parasitic infection