Hydrocephalus Flashcards
Where is CSF produced?
Choroid plexuses
What is the rate of CSF production?
0.3ml/min
Where is CSF reabsorbed?
Arachnoid villi (granulations) that extend into dural venous sinuses
What are the constituents of normal CSF?
5-20cmH2O
Normal appearance
0.18-0.45g/L protein
2.5-3.5mmol/L glucose
Normal gram stain
<3 WCC
What are the constituents of bacterial CSF?
> 30cmH2O
Turbid appearance
1g/L protein
<2.2mmol/l glucose
Positive gram stain
5000 WCC
What are the constituents of viral CSF?
Normal pressure
Clear appearance
<1g/L protein
Normal glucose
Normal gram stain
<1000 WCC
What is hydrocephalus?
Abnormal accumulation of CSF in ventricles of the brain
What are the subdivisions of the hydrocephalus?
- Obstructive hydrocephalus (non -communicating)
- Communicating hydrocephalus
What is obstructive hydrocephalus?
A block proximal to the arachnoid granulations
Enlargement of ventricles proximal to block
What is communicating hydrocephalus?
Defect in CSF absorption by the arachnoid granulations
What are the congenital causes of hydrocephalus?
Myelomeningocele
Primary aqueductal stenosis
Dandy Walker malformation
Why does myelomeningocele cause hydrocephalus?
Causes the brain to be positioned further down into the upper spinal column than normal, which is called an Arnold Chiari II malformation.
This causes the normal flow of fluid out of the brain to be obstructed
Why does primary aqueductal stenosis cause hydrocephalus?
Blockage of cerebral aqueduct means third ventricle can’t drain into 4th ventricle
Why does Dandy walker malformation cause hydrocephalus?
Vermis does not fully form so 4th ventricle and posterior fossa fill with CSF
What are the acquired causes of hydrocephalus?
Infectious
Post-haemorrhagic
Neoplastic/non-neoplastic masses
