CSF

Question 1

Describe cerebrospinal fluid (CSF)

Answer 1

Surrounds the brain and spinal cord and may function as a shock absorber for the CNS
Also has immunological function analogous to lymphatic system
Normally clear and colourless, gravity of 1.007 and pH 7.33-7.35

Question 2

Where does the CSF circulate?

Answer 2

Within the subarachnoid space between arachnoid and pial membranes

Question 3

Describe the production of CSF

Answer 3

Produced by choroid plexuses located in both lateral ventricles and in the 4th ventricle
Rest of intracranial production occurs in interstitial space
Small amount by ependymal lining of ventricles and in spine by dura of nerve root sleeves

Question 4

How much CSF is produced?

Answer 4

0.3ml/min - average CSF volume of body is 150ml
Is turned over 3 times a day

Question 5

How is CSF absorbed?

Answer 5

Primarily by arachnoid villi (granulations) that extend into dural venous sinuses
Other sites include - choroid plexuses and lymphatics
Rate of absorption is pressure dependant

Question 6

Describe the circulation of CSF

Answer 6

From lateral ventricles, 3rd ventricle, cerebral aqueduct and then 4th ventricle
Then into central canal for subarachnoid space through foramen of Luschka and Magendie
Foramen of Monro between lateral and 3rd ventricle

Question 7

What is the normal constituents of CSF?

Answer 7

Pressure between 5-20
Low protein
Glucose 2.5-3.5
Gram stain normal
Glucose 0.6
Low WCC
No RBCs

Question 8

Describe a lumbar puncture

Answer 8

Patient in lateral recumbent position
Line connecting posterior superior iliac crest will intersect midline at L4 spinous process
Spinal needle enters subarachnoid space below spinal cord

Question 9

What is hydrocephalus?

Answer 9

An abnormal accumulation of cerebrospinal fluid within the ventricles of the brain
Prevalence 0.9-1.8/1000 births

Question 10

What are the 2 main functional subdivisions of hydrocephalus?

Answer 10

Obstructive and communicating

Question 11

Describe obstructive hydrocephalus

Answer 11

Block proximal to arachnoid granulations
On CT or MRI can see enlargement of ventricles proximal to block

Question 12

Describe communicating hydrocephalus

Answer 12

Defect in CSF reabsorption by the AG
CSF over production is rare and some choroid plexus papilloma

Question 13

What are some congenital causes for hydrocephalus?

Answer 13

Chiara type 2 malformation/ myelomeningocele
Primary aqueduct stenosis
Dandy Walker malformation

Question 14

What is Danny Walker malformation?

Answer 14

Atresia of foramina of Luschka and Magendie

Question 15

What are some acquired causes for hydrocephalus?

Answer 15

Infectious (most common cause of communicating HCP), post-haemorrhagic and secondary to masses - non neoplastic and neoplastic

Question 16

What is Chiari type 2 malformation?

Answer 16

Spina Bifta

Question 17

What does the posterior fossa tumour compress?

Answer 17

4th ventricle and temporal horns of lateral ventricle

Question 18

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

Answer 18

Those of increased ICP - papilledema, headache with nausea and vomiting, gait changes, upgaze or abducent palsy
Slowly enlarging ventricles can be asymptomatic

Question 19

What are the signs and symptoms of hydrocephalus in young children?

Answer 19

Abnormalities in head circumference, irritability and poor head control, nausea, vomiting, fontanelle full and bulging, enlargement of skull veins, upwards gaze palsy, abducent palsy and irregular breathing

Question 20

What investigation is used for babies with hydrocephalus?

Answer 20

US

Question 21

What investigations are used for hydrocephalus in older children and young adults?

Answer 21

CT and MRI

Question 22

What is the treatment for hydrocephalus?

Answer 22

Communicating HCP - lumbar puncture, lumbar drain and ventriculo-peritoneal shunt
Obstructing - external ventricular drain and endoscopic third ventriculostomy

Question 23

How does a EVD work?

Answer 23

External ventricular drain
Ventricular catheter in frontal horn
Drain fluid at pressure
Common for subarachnoid haemorrhage and severe hydrocephalus