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Neurology Y3 > Raised ICP and Hydrocephalus > Flashcards

Raised ICP and Hydrocephalus Flashcards

1
Q

What is ICP (intracranial pressure)?

A

The pressure exerted by the cranium onto the:
- Brain tissue
- CSF
- Intracirculating blood volume

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2
Q

What is the Munro-Kellie doctrine?

A

The sums of volumes of the brain, CSF and intracranial blood is constant. If one of these goes up, one or both of the others goes down.

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3
Q

Immediate compensatory mechanisms for expanding masses?

A
  • Decrease in CSF volume by moving it out of the foramen magnum.
  • Decrease in blood volume by spreading sinuses
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4
Q

Delayed compensatory mechanisms for expanding masses?

A
  • Decrease in extracellular fluid.
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5
Q

What volume of CSF is produced in 24 hours?

A

~500ml

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6
Q

What is the pathway of CSF?

A

Choroid plexus (in lateral ventricles) > ventricular system > subarachnoid space > venous system (arachnoid granulations).

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7
Q

Any obstruction to the CSF pathway will lead to hydrocephalus and increased ICP. True/false?

A

True

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8
Q

Cerebral perfusion pressure equation?

A

CPP = MAP (mean arterial pressure) - ICP (intracranial pressure).

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9
Q

What is Cushing’s triad?

A

It is the bodys response to increased intracranial pressure. It usually indicates a severe lack of oxygen in the brain tissue.

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10
Q

What does Cushing’s triad consist of?

A
  • Bradycardia
  • Irregular respirations
  • Widened pulse pressures (large difference between systolic and diastolic BP).
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11
Q

Autoregulation of cereberal blood flow occurs over a wide range of BP. The CBF remains constant. True/false?

A

True

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12
Q

What is pressure autoregulation?

A

Arterioles dilate or constrict in response to changes in BP or ICP.

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13
Q

What is metabolic autoregulation?

A

Arterioles dilate in response to chemicals e.g. CO2.

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14
Q

Causes of ICP?

A
  • Mass effect e.g. tumour - distorts the surrounding brain.
  • Brain swelling due to e.g. ischaemia, acute liver failure.
  • Increase in central venous pressure e.g. venous sinus thrombosis.
  • Problems with CSF blood flow:
    ~ Obstruction (“obstructive hydrocephalus”) - masses, Chiari syndrome.
    ~ Increased production - choroid plexus papilloma
    ~ Decreased absorption (“communicating hydrocephalus”) i.e. SAH, meningitis, malignant meningeal disease.
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15
Q

Early clinical signs of raised ICP?

A
  • Decreased level of consciousness
  • Headache
  • Changes in vision
  • Nausea and vomiting
  • Papillary dysfunction +/- papilloedema
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16
Q

Late clinical signs of raised ICP?

A
  • Coma
  • Fixed, dilated pupils
  • Bradycardia —- Cushing’s triad
  • Hyperthermia
  • Increased urinary output
  • Hemiplegia (complete paralysis of one side of the body).
17
Q

What is Chiari syndrome?

A

A Chiari malformation is a problem in which a part of the brain (the cerebellum) at the back of the skull bulges through a normal opening in the skull (foramen magnum) where it joins the spinal canal.

18
Q

What is normal pressure hydrocephalus?

A

Normal pressure hydrocephalus (NPH) is an abnormal buildup of cerebrospinal fluid (CSF) in the brain’s ventricles (cavities). It occurs if the normal flow of CSF throughout the brain and spinal cord is blocked in some way.

It is idiopathic and occurs mainly in the elderly. Most likely due to decreased brain elastance.

19
Q

What does Hakim’s triad consist of in Normal Pressure hydrocephalus?

A

Hakim’s triad:
- Abnormal gait (“magnetic” gait) - struggle to lift feet from floor.
- Urinary incontinence
- Dementia

Mnemonic:
“Wet, wacky and wobbly”.

20
Q

Investigations for Normal Pressure Hydrocephalus?

A
  • Lumbar Puncture
  • Lumbar drain test
  • Lumbar infusion studies
21
Q

Management of Normal Pressure Hydrocephalus?

A
  • VP shunt
  • Medium-low or low-pressure valve
22
Q

What is Idiopathic intracranial hypertension (IIH)?

A

Idiopathic intracranial hypertension (IIH) happens when high pressure around the brain causes symptoms like vision changes and headaches.

No detectable cause.

23
Q

Causes of Idiopathic intracranial hypertension (IIH)?

A
  • Typically develops in younger, overweight female patients, many of whom have polycystic ovaries.
  • Probably results from reduced CSF resorption
24
Q

Clinical presentation of Idiopathic intracranial hypertension?

A
  • Headache
  • Double vision, visual blurring
  • Tinnitus
  • Morning nausea + vomiting
  • Papilloedema (in 25%).
25
Q

Idiopathic intracranial hypertension investigations?

A
  • Lumbar puncture
  • CT/MRI head
  • CT ventricles
  • Fundoscopy +/- ophthalmology review
26
Q

Idiopathic intracranial hypertension managament?

A
  • Weight loss
  • Carboanhydrase inhibitors - acetazolamide, toparimate
  • Ventricular atrial/lumbar peritoneal shunt
  • Monitor visual fields and CSF pressure
27
Q

Who is most at risk of normal pressure hydrocephalus?

A

Most commonly in elderly adults and is a recognised cause of dementia.

28
Q

Symptoms of normal pressure hydrocephalus?

A

Classical clinical triad:

Dementia: Often manifests as global cognitive impairment, with attention and memory disturbances.

Magnetic gait: Characterized by difficulty in lifting the feet off the floor, appearing as if they are “stuck.”

Incontinence: Primarily urinary incontinence, but faecal incontinence can also occur.

Useful mnemonic is:

“wet, wacky and wobbly”.

29
Q

Investigation of normal pressure hydrocephalus?

A

CT/MR imaging: These typically show dilated lateral ventricles, although this feature can also be seen in other forms of dementia due to global cortical atrophy.

Lumbar Puncture: Measurement of walking ability and cognitive assessment pre- and post-lumbar puncture can help ascertain which patients could benefit from further surgical management.

30
Q

Management of normal pressure hydrocephalus?

A

Therapeutic lumbar puncture: This procedure can alleviate symptoms and improve cognition and walking ability by removing CSF.

Ventriculoperitoneal shunt: In patients responsive to lumbar puncture, neurosurgery may insert a shunt to permanently redirect the excess CSF from the brain to the abdomen.

Neurology Y3 (40 decks)

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