CSF and Hydrocephalus

Question 1

what are the functions of CSF?

Answer 1

shock absorber for the CNS and may also serve an immunological function analogous to the lymphatic system

Question 2

where is CSF found?

Answer 2

circulates in the subarachnoid space between the arachnoid and dial membranes

Question 3

what does CSF usually look like?

Answer 3

a clear colourless fluid with specific gravity of 1.0007 and a pH of about 7.33-7.35

Question 4

what happens to the protein levels in CSF if there are bacterial or viral infections?

Answer 4

normal= 0.18-0.45 
bacterial= raised (>1)
viral= normal (<1)

Question 5

what happens to the glucose in CSF if there are bacterial or viral infections?

Answer 5

normal= 2.5-3.5
bacterial= <2.2 as bacteria use up the glucose for energy
viral= normal

Question 6

what happens to WCC in CSF if there are bacterial or viral infections?

Answer 6

normal= <3
bacterial= >500
viral= <1000

Question 7

at what rate is CSF produced in adults?

Answer 7

0.3ml/min so 450ml/24 hours which means then in an adult (where average total CSF=150ml), the CSF is turned over 3x a day

Question 8

what happens to the rate of CSF formation when ICP is raised?

Answer 8

when ICP is raised so high that cerebral blood flow is reduced and so CSF production is reduced

Question 9

how does the rate of absorption of CSF relate to pressure?

Answer 9

it is pressure dependent

Question 10

what is a lumbar puncture?

Answer 10

used to get CSF sample and performed with the patient in the lateral recumbent position, only safe with no raised ICP and between L3 and L4 vertebrae

Question 11

what is hydrocephalus?

Answer 11

an abnormal accumulation of CSF within the ventricles of the brain

Question 12

what are the 2 types of aetiologies of hydrocephalus?

Answer 12

subnormal CSF reabsorption or CSF overproduction

Question 13

how does CSF overproduction cause hydrocephalus?

Answer 13

rare, choroid plexus papillomas can cause slightly elevated production of CSF (normally tolerated)

Question 14

how does CSF subnormal CSF reabsorption cause hydrocephalus?

Answer 14

2 subdivisions:
obstructive hydrocephalus (non-communicating)= block proximal to the arachnoid granulations 
communicating hydrocephalus (non-obstructive)= defect in CSF reabsorption by the arachnoid granulations

Question 15

what are the signs and symptoms of hydrocephalus in older children and adults?

Answer 15

increased ICP including papilledema, headache (especially in the morning), vomiting, gait changes, up gaze or abducens palsy

Question 16

what are the signs and symptoms of hydrocephalus in young children whose brain has not fused yet?

Answer 16

abnormalities in head circumference, cranium enlarges at a rate> facial growth, fontanelle full and bulging, irritability, poor head control, upward gaze or abducens palsy

Question 17

what investigations would be performed if hydrocephalus suspected?

Answer 17

ultrasound for children (as sutures not closed) and MRI for adults to show enlarged ventricular system

Question 18

how is communicating hydrocephalus treated?

Answer 18

lumbar puncture and lumbar drain

Question 19

how is obstructive hydrocephalus treated?

Answer 19

external ventricular drain, endoscopic 3rd ventriculostomy but if not suitable for endoscopic procedure then venticulo-peritoneal

Question 20

what are some of the congenital causes of hydrocephalus?

Answer 20

Chiari type 2 malformation and/or myelomeningocele (MM= spina-bifida), Dandy Walker malformation= atresia of foramina of Luschka and Magendie, primary aqueductal stenosis

Question 21

what are some of the acquired causes of hydrocephalus?

Answer 21

communicating= infections, post-hemorrhagic
obstructive= secondary to masses