Hydrocephalus

Question 1

Types of Hydrocephalus?

Answer 1

1. Increased intracranial pressure -
   A. Communicating (non-obstructive hydrocephalus) - impaired absorption from arachnoid villi. located along the superior sagittal sinus ( site of CSF reabsorption back into into the venous system). This can cause: Subarachnoid/intraventricle hemorrhage, meningitis and congenital absence of arachnoid villi.
   B. Non-communicating ( obstructive hydrocephalus)- obstruction preventing CSF from flowing into the subarachnoid space caused by:
   a. Foramen of Monro obstruction may lead to dilation of one or both lateral ventricles.
   b.Aqueduct of Sylvius obstruction by a number of genetically or acquired lesions (atresia, ependymoma, hemorrhage, tumor) this leads to dilation of both lateral ventricles as well as the third ventricle.
   c. Fourth ventricle obstruction -will lead to dilatation of the aqueduct as well as the lateral and third ventricles (Chiari malformation).
   d.The foramina of Luschka and foramen of Magendie obstruction due to congenital failure of opening (e.g. Dandy-Walker malformation ( cerebellar tumor).

**these are more common seen in children.

2. Normal pressure hydrocephalus -the intracranial constituents become less compliant . A reduction in vascular compliance especially in the superior sagittal sinus has been found . This can initially be countered by increased pulsatile CSF flow through the aqueduct and this is why the intracranial pressure remains normal
   symptoms of this is : WWW: wacky ( demantia), Wiggely ( gait problems ), Wet ( urinary incontinence)
3. Hydrocephalus ex vacuo- occurs when there is damage to the brain caused by stroke or injury, and there may be an actual shrinkage of brain substance. Although there is more CSF than usual, the CSF pressure itself is normal in hydrocephalus ex-vacuo.

** nr 2 & 3 more seen in adult.

Question 2

Cause of Hydrocephalus ?

Answer 2

1. Flow obstruction
2. Reabsorption
3. Excessive CSF production ( Choroid plexus papilloma )

Question 3

Congenital and Acquired etiology of hydrocephalus ?

Answer 3

Congenital- The cranial bones fuse by the end of the third year of life.
For head enlargement to occur, hydrocephalus must occur before then.
1) intraventricular matrix hemorrhages in premature infants,
2) infections,
3) type II Arnold-Chiari malformation,
4) aqueduct atresia and stenosis, and
5) Dandy-Walker malformation.

Acquired (As a consequence of:

1) .CNS infections
2) .Meningitis
3) .brain tumors
4) .head trauma
5) .intracranial hemorrhage (subarachnoid or intraparenchymal)