CSF and hydrocephalus Flashcards
what is hydrocephalus
excess CSF within the intracranial space and, specifically, the intraventricular spaces within the brain
causing dilation of the ventricles, and a wide range of symptoms.
where and how is CSF produced
produced in the choroid plexus in the brain
metabolically active process (require ATP)
sodium is pumped into the subarachnoid space and water follows from the blood vessels
where are choroid plexus located
lateral ventricles (temporal horn roofs, floor of bodies)
posterior 3rd ventricle roof
caudal 4th ventricle roof
how much CSF if produced per day
450-600 cc
how much CSF is present at any one time
~150cc
~25 within brain ventricles
what is the usual relationship between CSF production and resorption
normally production = resorption
exists in a delicate balance
what is the pathway of the CSF out of the ventricles
- lateral ventricles
- foramen of monro
- 3rd ventricle
- cerebral aqueduct
- 4th ventricle
- formina of luschka/magendie
- subarachnoid space around brain/spinal cord
where is CSF resorbed
resorbed into the venous blood system at arachnoid granulations along the dural venous sinuses
how do the arachnoid granulations resorb CSF
contain villi which function as pressure dependent one way valves
a passive process driven by the pressure gradient between the intracranial space (ICP) and veneer system (CVP)
what are the two main types of hydrocephalus
communicating (CoH)
- non-obstructive
non-communicating (NCH)
- obstructive
why is CoH known as non-obstructive hydrocephalus
CSF pathway open from start to finish
- from choroid plexus to arachnoid villi
why is NCH known as obstructive hydrocephalus
CSF can’t travel freely from start to finish
what are the two types of problem that cause CoH
- problem is in CSF resorption - i.e. can’t keep pace with CSF production
doesn’t need to be a large insult as balance very sensitive
- ventricular system dilates uniformly, ICP rises
- overproduction of CSF - disrupts balance
rare but can be caused by choroid plexus papillomas
what are the signs and symptoms of CoH in young children with unfused cranial sutures
disproportional increase in head circumference compared to the rest of the face/body
failure to thrive
what are the signs and symptoms of CoH in children with fused sutures/adults
symptoms of increased intracranial pressure;
- headaches
- nausea, vomiting
- papilloedema
- gait disturbance
- 6th cranial nerve palsy
- upgaze difficulty
what can cause CoH
infection - eg bacterial meningitis
subarachnoid haemorrhage - blood and blood breakdown products cause scarring of arachnoid granulations
post operative
head trauma
how can CoH present
GRADUAL - from a “gentle” disruption of the balance between CSF production and resorption over time
ACUTE - due to large insult that causes acute disruption of the balance - CSF resorption suddenly reduced
- medical emergency as neurological decline very rapid
what type of problem causes NCH
ANY physical obstruction to the normal flow of CSF BEFORE it leaves the ventricles
what are the causes of NCH
aqueductal stenosis
tumours/cancers/masses
cysts
infection
haemorrhage/haematoma
congenital malformations/conditions
how can NCH present
GRADUAL - processes (ie masses) developing over a long period of time - cause gradual symptoms
ACUTE - e.g. intraventricular bleed can cause acute obstruction - rapid mental status decline
what are the radiographical findings that can help diagnose hydrocephalus
- dilation of the temporal horns of the lateral ventricles
- ballooned 3rd ventricle
- periphral sulci effaced (not seen)
what is the treatment for hydrocephalus
surgical:
acute - external ventricular drain (EVD)
permanent shunt if EVD cannot be successfully weaned
removal of obstructing lesion
what is an EVD and what are the associated risks
a catheter passed through the scale and skull into the lateral ventricle
drains CSF to a collection system at the bedside
high infection risk
what is the mainstay treatment for CoH
permanent shunt
- ventriculo-peritoneal (VP) - most common
- lumbar-peritoneal (LP) - but can cause over drainage
- ventriculo-atrial (VA) - if peritoneal failure
what is the mainstay treatment for NCH
shunt placement
removal of obstructing lesion
third ventriculostomy
what is third ventriculostomy
performed in conjunction with VP shunt
hole is surgically opened in floor of 3rd ventricle - CSF flows into interpeduncular cistern and pre-pontine space (bypasses cerebral aqueduct)
what must you keep in mind when taking a history from a patient with a headache and a VP shunt
headache NOT automatically caused by shunt malfunction/infection
BUT can be the cause as 40% shunts fail in the first year
how can a VP shunt fail
Mechanical failure from occlusion/disconnection,
migration,
overdrainage/underdrainage,
infection,
skin erosion
what is normal pressure hydrocephalus (NPH)
hydrocephalus where ICP remains normal but CoH seen on CT/MRI
one of the rare and preventable/reversible causes of dementia
under diagnosis can lead to a diagnosis of alzheimers or age-related dementia
what is the classic triad presentation of NPH
Hakim/Adams triad
+ wet, wobbly, wacky
- urinary incontinence
- gait disturbance - wide stance, short shuffling steps
- quickly progressing dementia
how can NHP be diagnosed
CT/MRI - shows CoH
Lumbar puncture - normal opening pressure
gait assessment
MMSE - mini mental state examination
symptoms improve with CSF removal
good history taking and time with patients family
what is the treatment for NPH
programmable VP shunt placement first choice
LP shunts ted to overdrain and are difficult to assess and revise
what is the prognosis for NPH
outcome better if symptoms present for a shorter period of time
least likely symptom to improve is dementia
order of symptom improvement
gait>incontinence>memory
