6: Hydrocephalus Flashcards
What is the normal CSF pressure in the subarachnoid space?
10 mmHg
Anyone with a CSF pressure greater than ___ mmHg should be suspected of having hydrocephalus.
15 mmHg
How much circulating CSF does a typical adult have at any one time?
How much CSF do you produce per day?
1600ml circulating at any one time
500ml produced per day
CSF production (increases / decreases) as you get older.
decreases
What happens if you remove too much CSF during a lumbar puncture?
Tonsilar herniation
Cushing’s response - hypertension, bradycardia, irregular breathing
What causes increased CSF pressure?
Blockage of ventricles
Overproduction of CSF
Impaired CSF absorption
Which drug decreases CSF production?
Acetazolamide
Which structures absorb CSF from the cranial cavity?
Arachnoid granulations
ICP affects CSF (production / absorption).
CSF absorption only, inverse relationship
What are the functions of CSF?
Maintenance of homeostasis e.g nutrition, ions
Keeps the brain buoyant - reduces pressure exerted on skull
What is a Chiari malformation?
What disease does it cause?
Congenital OR acquired tonsilar herniation of cerebellum and brainstem through the foramen magnum and into the spinal canal
Syringomyelia
What is syringomyelia?
Which malformation can cause it?
Abnormal fluid-filled cavity/ies within the spinal cord
Chiari malformation
How can syringomyelia cause hydrocephalus?
Impaired CSF flow from spinal cord to brain due to compression of central canal by syrinxes
CSF builds up and ICP increases
What is the physical presentation of hydrocephalus in children?
Abnormally large head
Thin, shiny scalp with visible veins
Bulging fontanelles
Sunset eyes
What eye sign can be seen in children with hydrocephalus?
“Sunset” eyes
Downward gaze with area of sclera visible between upper eyelid and iris
Which structure in the brain is compressed to cause a sunset gaze?
Tectal plate
What are the neuro symptoms of paediatric hydrocephalus?
Sensory and motor problems
Behavioural changes - sleeping, feeding, irritability
Vomiting
Why can hydrocephalus cause visual loss?
Increased CSF volume
=> Increased ICP
=> Pressure on meninges surrounding CN II
=> Papilloedema
=> Visual loss
Acquired hydrocephalus tends to be a ___ disease.
resolving
Which acute brain disease causes acquired hydrocephalus?
Why?
Subarachnoid haemorrhage
Arachnoid granulations are blocked with blood and can’t absorb CSF properly
Which tube can be fitted to drain CSF from the ventricles of a patient with hydrocephalus?
Ventriculoperitoneal shunt
Valves only open if ICP is too high, avoiding excessive draining of CSF
Why are shunts avoided in hydrocephalus involving tumours?
Tumour may be disseminated into peritoneal cavity
What is craniosynostosis?
Inappropriate fusion of cranial bones caused by rapid head size changes
What are the signs and symptoms of a blocked shunt in patients with hydrocephalus?
N&V
Headache
Blurred vision
“Sunsetting” - lack of upgaze
pretty much the same as hydrocephalus
