CSF, Hydrocephalus and Lumbar Puncture Flashcards

1
Q

What is hydrocephalus?

A

A general condition where there is excess CSF within the intracranial space, specifically the intraventricular spaces within the brain

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2
Q

How is CSF produced?

A

Majority produced by choroid plexus that pumps sodium into the subarachnoid space with water following from the blood vessels

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3
Q

Describe the pathway of CSF

A

From the lateral ventricles, CSF travels into the 3rd ventricle then into the cerebral aqueduct and into the fourth ventricle. It then exits the fourth ventricle and flows through the subarachnoid space over and around the brain and spinal cord. It is eventually reabsorbed into the venous system through numerous arachnoid granulations along the dural venous sinuses

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4
Q

What are the two kinds of hydropcephalus?

A

Communicating/non-obstructive

Non-communicating/obstructive

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5
Q

Describe the pathophysiology of communicating hydrocephalus

A

In most cases, CSF production is greater than CSF resorption, and so the ventricular system dilates and ICP rises
Rarely, there is overproduction of CSF and communicating hydrocephalus develops

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6
Q

What are the signs and symptoms of communicating hydrocephalus?

A

In young children, disproportional increase in head circumference compared to the rest of the face and failure to thrive
In those who’s sutures have fused ie older children and up, present with symptoms of increased intracranial pressure: headache, N&V, papilloedema, gait, disturbance, 6th cranial nerve palsy, upgaze difficulty

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7
Q

What are the causes of communicating hydrocephalus?

A

Infection
Subarachnoid haemorrhage
Post-operative
Head trauma

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8
Q

When does non-communicating hydrocephalus occur?

A

Whenever there is any physical obstruction to the normal flow of CSF before it leaves the ventricles

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9
Q

What are the causes of non-communicating hydrocephalus?

A
Aqueductal stenosis
Tumours/masses
Cysts
Infection
Haemorrhage/haematoma
Congenital malformations
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10
Q

What is the first sign of development of hydrocephalus on MRI?

A

Dilation of the temporal horns of the lateral ventricles

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11
Q

What signs of hydrocephalus can be seen on MRI?

A

Dilation of temporal horns of lateral ventricles
Third ventricle becomes ballooned
Lateral ventricle size increases
Peripheral sulci effaced

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12
Q

How is acute hydrocephalus treated?

A

Surgically- placement of external ventricular drain (EVD- catheter passed into lateral ventricle through scalp)
Some patients may have successful weaning off EVD but many will need a shunt inserted

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13
Q

What is the main complication of EVD?

A

High infection risk

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14
Q

How is communicating hydrocephalus treated?

A

Surgical- shunt placement, ventriculo-peritoneal most used

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15
Q

How is non-communicating hydrocephalus treated?

A

Surgical- shunt may be necessary but can be avoided if obstructing lesion is removed
Third ventriculostomy can also be used, often in conjunction with shunt

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16
Q

What are the symptoms of normal pressure hydrocephalus?

A

Urinary incontinence
Gait disturbance
Quickly progressive dementia
(wet, wobbly and wacky)

17
Q

What condition can normal pressure hydrocephalus cause if left untreated?

A

Dementia

18
Q

What investigations can be useful in normal pressure hydrocephalus?

A

Looks like communicating hydrocephalus on CT/MRI

Lumbar puncture- normal opening pressure, symptoms improve with removal of CSF

19
Q

How is normal pressure hydrocephalus treated?

A

Surgically- programmable VP shunt placement

20
Q

What are the indications of lumbar puncture?

A
To obtain CSF for the diagnosis of:
Meningitis
Meningoencephalitis
Subarachnoid haemorrhage
Malignancy
Idiopathic intracranial hypertension
Infusion of drugs or contrast
21
Q

What are the contraindications to lumbar puncture?

A

Unstable patient with cardiovascular or respiratory instability
Localised skin/soft tissue infection over puncture site
Evidence of unstable bleeding disorder
Increased intracranial pressure
Neurologic deterioration can occur if LP done below the level of a complete spinal subarachnoid block
Caution in patient with Chiari malformations

22
Q

At what vertebral level should a lumbar puncture be done?

A

L3-L4 or L4-L5

23
Q

What should the different CSF samples from a lumbar puncture be tested for?

A

Culture and gram stain
Glucose and protein
Cell count and differential

24
Q

What are the complications of lumbar puncture?

A
Headache
Apnea
Back pain
Bleeding or fluid leak around spinal cord
Infection, pain, haematoma
Subarachnoid epidermal cyst
Ocular muscle palsy
Nerve trauma
Brainstem herniation
25
Q

What are the risk factors for a spinal headache as a complication of lumbar puncture?

A
Female
Aged 18-30
Lower BMI
History of headache
Prior spinal headache
26
Q

How is a spinal headache treated?

A

Supine position for at least two hours
Hydration
Caffeine either oral or IV
Epidural blood patch

27
Q

How does brainstem herniation present?

A

Altered mental status
Cranial nerve abnormalities
Cushing triad

28
Q

What is Cushing triad?

A

Bradycardia
Systolic hypertension
Irregular, decreased respirations

29
Q

What steps can be taken if a lumbar puncture fails and collection of CSF sample is critical?

A

Have someone else try- anaesthesia, neurology
Bedside ultrasound for difficult LP
Radiographic guided procedure
Cisterna Magna tap