CSF, hydrocephalus & lumbar puncture Flashcards by Heo Mun Ho

What is CSF produced by

Choroid plexus

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Is CSF production/resorption metabolically active/passive

Production - active (requires ATP for Na/K ATPase)

Resorption - passive

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How much CSF do we make daily

450-600ml

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At any given moment, there’s how much CSF in the body

150ml

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How much CSF is in the ventricles at any given moment

25ml

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CSF exits the 4th ventricle into the subarachnoid space via what 2 foramen

Formamen of luschka - lateral

Foramen of magendie - medial

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Define hydrocephalus

Excess CSF in the brain

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2 types of hydrocephalus

Communicating (non-obstructive)

Non-communicating (obstructive)

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Describe communicating (non-obstructive) hydrocephalus

CSF pathway open from start to finish, i.e. can travel from choroid plexus to arachnoid villi to be resorbed

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Pathophysiology of communicating hydrocephalus (2)

CSF resorption < production
(under-absorption)

Ventricles dilate –> ICP rises

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In a RARE type of communicating, CSF production > resorption - what condition is this

Choroid plexus papilloma

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Causes of communicating hydrocephalus (4)

Infection
Subarachnoid haemorrhage - blood in subarachnoid space impairs arachnoid granulations so resorption impaired
Post-op
Head trauma

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Describe non-communicating hydrocephalus (obstructive hydrocephalus)

CSF can’t travel freely from start to finish due to a PHYSICAL obstruction

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Causes of non-communicating hydrocephalus (6)

Aqueductal stenosis
Tumours/masses - MOST COMMON
Cysts, e.g. colloid cyst
Infection
Haemorrhage
Congenital malformations

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Symptoms/signs of hydrocephalus

in babies (4)
in children with fused sutures/adults (7)

Babies:
Massive head
Bulging fontanelle
Failure to thrive
Downward looking eyes

Children/adults:
Headache
Nausea
Vomiting
Sleepiness
Gait disturbance (difficulty walking)
Blurry vision
Urinary incontinence

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Investigations of hydrocephalus

CT - shows dilated inferior/ temporal horns of lateral ventricles

MRI

How is the Evans ratio used to diagnose hydrocephalus

Max width of anterior horns of lateral ventricles divided by max width of the skull at the same level

If ratio >30% = indicates ventriculomegaly and potentially hydrocephalus

Treatment of:

communicating hydrocephalus (1)
non-communicating hydrocephalus (3)

Communicating:
Shunt placement

Non-communicating:
Shunt placement
Endoscopic third ventriculostomy
Remove obstructing mass

How does shunt placement work

Shunt is implanted in the brain
. The excess cerebrospinal fluid (CSF) in the brain flows through the shunt to another part of the body, usually the chest or abdo cavity - from here, it’s absorbed into your bloodstream

How does endoscopic third ventriculostomy work

Hole made in the floor of the 3rd ventricle to allow the trapped CSF to bypass cerebral aqueduct and escape to the brain’s surface, where it can be absorbed

Most common type of shunt used for hydrocephalus

Ventriculo-peritoneal

Treatment of acute hydrocephalus

External ventricular drain

What is normal pressure hydrocephalus

Characterised by the clinical features of hydrocephalus (i.e., levodopa-unresponsive gait apraxia +/- urinary incontinence or cognitive impairment), but without significantly elevated CSF pressure

Despite this, the condition responds to a reduction in CSF pressure and/or a CSF diversion procedure

What condition is normal pressure hydrocephalus a reversible cause of

Dementia

Symptoms/signs of normal pressure hydrocephalus (3)

Wet, wobbly, wacky: Urinary incontinence Gait disturbance (unusual walking) Cognitive impairment

Investigations of normal pressure hydrocephalus (3)

CT MRI Lumbar puncture + CSF tap (i.e. lumbar drain) - if LP doesn't improve symptoms

Treatment of normal pressure hydrocephalus (1)

Surgery only if lumbar puncture/ lumbar drain was proven beneficial: Shunt placement - ventriculoperitoneal shunt

Place the wet, wobbly and wacky symptoms in order of which will most likely improve

Gait > incontinence > memory

What vertebral level are LPs performed

Between L3 and L4 | or L4 and L5

What position does the patient have to lie in when doing an LP

Lateral decubitus position - maximally flex spine with chin near chest and knees near chest -usually lying on their left side

Indications of an LP (5)

``` Meningitis Encephalitis Subarachnoid haemorrhage Malignancy Idiopathic intracranial hypertension ```

Contra-indications of an LP (5)

Cardio or resp instability Localised skin infection over puncture site Evidence of unstable bleeding disorder Increased ICP – as you can cause herniation syndrome (HOWEVER, IS NOT A CONTRAINDICATION OF CoH as lumbar puncture would relieve the pressure) Chiari malformation

When doing an LP, will hear 2 pops when inserting spinal needle - what is being punctured in the first and second pop

Ligamentum flavum Then dura mater

Complications of an LP (7)

Post dural puncture headache – MOST COMMON Apnoea – temporary stop of breathing Back pain – maybe disc herniation Bleeding or fluid leak around spinal cord Infection Nerve trauma Brainstem herniation

Management of a post dural puncture headache (4)

Lie flat Hydration Caffeine Epidural blood patch - injecting own blood into the puncture site, clotting factors of the blood patch up the hole

Prevention of a post dural puncture headache (spinal headache) (2)

Using smaller diameter or atraumatic needles | Passing spinal needle parallel to longitudinal fibres of dura

Management of nerve root trauma caused by LP (2)

Remove needle immediately | Steroids

Management of brainstem herniation caused by LP (4)

Remove needle ASAP Raise head of head to improve venous return from brain to heart Mannitol - diuretic Intubate

What properties of CSF can be analysed in CSF analysis (6)

``` Colour Opening pressure Culture + gram stain CSF glucose CSF protein count CSF cell count ```