Hydrocephalus Flashcards
What is CSF
clear fluid found in ventricles and subarachnoid space
How much CSF will ventricles normally contain?
25 ml in each
What cells produce CSF?
- modified ependymal cells
- which form the choroid plexus
- can also arise from interstitial fluid
What are the constituents of CSF?
- very similar biochemistry to blood
- far fewer proteins or WBC
- increased Mg
- decreased Ca
Where is the choroid plexus located?
- lateral ventricles
- not in third or fourth
What drug can reduce CSF production?
- acetazolamide (carbonic anhydrase inhibitor)
- remifentanil
- noradrenaline
What can increase CSF production?
- volatile anaesthesic agenst
- NO
- hypercapnoea (CO2 retention)
What is the function of CSF?
- provides buoyancy to lighten weight of brain
- protects from acc/dec injuries
- removes waste from brain
- forms pressure buffer to reduce brains impact on ICP
Where does CSF drain after the fourth ventricle?
- cisterns then through arachnoid granulations into dural venous sinuses
- carried in venous blood and recycled
How does flow of CSF depend on pressure?
- raised ICP means increased flow of CSF
- raised venous pressure can get back flow from venous sinsuses
What is Hydrocephalus?
increase in CSF in the head which results in increased ICP
When is hydrocephalus most common?
- birth (often treated before birth)
- patients with Spina Bifida
What can hydrocephalus result in if untreated?
neurological deficits and cognitive disorders
What are the causes of hydrocephalus?
- Communicating blockage
- Non-communicating blockage
- Congenital
- Acquired
What is the difference between communicating and non-communicating blockages?
Communicating - blockage to CSF resorption in arachnoid granulations/overproduction
Non-communicating - blockage within pathway
What are examples of congenital and acquired causes of hydrocephalus?
Congenital - spina bifida or aqueduct stenosis
Acquired - infection, tumour or subarachnoid haemorrhage
How does hydrocephalus present in infants?
- macrocrania (larger skull)
- recurrent vomiting
- abnormal cry
- recurrent apneoa
- bradycardia
- sunsetting eyes/gaze (late sign)
How does hydrocephalus present in children/adults?
- headache
- vomiting
- confusion
- diplopia/CN palsy (usually CN6)
- ataxia/dementia
- bradycardia/hypertension
What investigations should be done for hydrocephalus?
- fundoscopy check for papilloedema
- CT or MRI of brain
What does each colour on a CT scan if brain show?
white = bone Grey = brain tissue black = CSF
What other problems can present on a brain CT that looks like hydrocephalus?
- Scan can show enlarged ventricles that look like hydrocephalus which can just be due to the brains atrophy as we age
- idiopathic intracranial hypertension (seen in young, obese females)
What problem can occur when shunt used to treat hydrocephalus in infants?
- shunt can become blocked
- but CT scan can still show reduction in ventricle size as ventricles lose their compliance
How is hydrocephalus treated?
- Ventricular shunt
- Endoscopic Third Ventriculostomy (ETV)
What is a ventricular shunt?
catheter which is put into drain CSF from ventricles either out the body or to another area in the body outside the head (usually abdomen)
What are the locations ventricular shunts can drain into?
- External drain (drains out body)
- Peritoneum
- Atria
- Pleural space
How does ETV work and what should you be cautious of?
- pass an endoscope in through lateral ventricles and drain CSF
- must be careful to not damage basilar artery
What is the most common cause of posterior fossa stroke?
cardiac emboli
blockage of what blood vessel will cause posterior fossa stroke?
basilar
What is the treatment for supratentorial infarction?
- brain will swell
- to reduce pressure can remove part of the skull to allow brain to swell
