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Neurology > Hydrocephalus > Flashcards

Hydrocephalus Flashcards

1
Q

What is normal intracranial pressure?

A

7-15mmHg

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2
Q

Where in the brain is CSF produced?

A

Choroid plexus - 500ml/day

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3
Q

State three compensatory mechanisms for maintenance of intracranial pressure

A
  • decrease in CSF volume through foramen magnum
  • decrease in blood volume through sinuses
  • decrease in extracellular fluid
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4
Q

State the equation for cerebral perfusion pressure

A

MAP - ICP = CPP

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5
Q

What should CPP normally be?

A

MAP - ICP = CPP
90 - 10 = 80
Anything above 70 is normal

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6
Q

What happens to ICP in pain or injury? How does this impact CPP?

A

ICP increases in response to pain or injury, hypotension often occurs in trauma so as a result CPP falls

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7
Q

State the equation for cerebral blood flow

A

CBF = CPP/vascular resistance

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8
Q

Over what range of blood pressure does CBF remain constant?

A

50-150mmHg

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9
Q

Name three autoregulatory mechanisms which maintain CBF

A
  • pressure (BP/ICP changes cause dilation/constriction)
  • metabolic (chemical stimuli cause dilation)
  • carbon dioxide (acts as a potent vasodilator)
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10
Q

State the causes of increased ICP

A
  • mass effect
  • brain swelling
  • increased venous pressure (can be physiological)
  • obstruction (chiari syndrome)
  • increased production (choroid plexus papilloma)
  • decreased absorption (SAH/meningitis)
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11
Q 
For the following age groups state the normal ICP
adults 
newborn 
kids 
older kids
A

Adults 7-15mmHg
Newborn 1.5-6mmHg but can be less than 0
Young kids 3-7mmHg
Older children 10-16mmHg

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12
Q

What are the early signs/symptoms of increased ICP?

A
  • Loss of consciousness
  • headache due to fluid on brain
  • papillary dysfunction/papilloedema
  • visual changes and upgaze abnormality
  • nausea and vomiting
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13
Q

What are the late signs/symptoms of increased ICP?

A
  • coma
  • fixed, dilated pupils
  • hemiplegia
  • bradycardia (Cushings triad)
  • hyperthermia
  • increased urinary output (very late brainstem death)
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14
Q

What are the two main types of hydrocephalus?

A

Communicating

Non-communicating

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15
Q

What is the difference between communicating and non-communicating hydrocephalus?

A

Communicating - enlargement of 3rd and 4th ventricle

Non-communicating - aqueductal stenosis

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16
Q

What is the goal of increased ICP management?

A

Maintain CPP and prevent ischaemia/compression

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17
Q

What non-medical interventions help in raised ICP?

A

Maintain head in midline - 30-45 degrees
Avoid gagging, coughing, loosen tubes/collars
Decrease environmental stimuli
Maintain normothermia, fluid and electrolytes, normocarbia

18
Q

Describe the medical management for increased ICP

A

Diuretics - hypertonic saline requires lower volumes
Barbiturate coma
Antiepileptics to avoid seizures which may further increase ICP

19
Q

What surgical treatment can be used in increased ICP?

A

Bifrontal decompression
Remove mass lesion
CSF diversion

20
Q

Describe a VP shunt

A

Ventriculoperitoneal shunt goes from the right ventricle (non-dominant side) and travels under the skin behind the ear to the peritoneum where it drains and is absorbed back into the venous system.

21
Q

Name some alternative drainage sites

A
  • pleura (risk of pleural effusion)

- SVC (directly into the heart)

22
Q

What causes normal pressure hydrocephalus?

A

Idiopathic disease of the elderly

23
Q

State the typical symptoms of normal pressure hydrocephalus

A

Hakim’s triad

  • abnormal gait
  • urinary incontinence
  • dementia
24
Q

What will MRI of normal pressure hydrocephalus show?

A

Enlarged 3rd and 4th ventricles out of proportion to the cortical sulcal enlargement

25
Q

How is normal pressure hydrocephalus investigated?

A

LP
LP drain test
LP infusion studies

26
Q

What is the treatment for normal pressure hydrocephalus?

A

VP shunt with appropriate pressure valve

27
Q

What is thought to cause idiopathic intracranial hypertension?

A

Unknown - CSF imbalance, hormones, venous pressure (stenosis) may be involved

28
Q

Who typically gets idiopathic intracranial hypertension?

A

Overweight western women of child bearing age

29
Q

What condition is IIH associated with?

A

PCOS

30
Q

State the signs and symptoms of IIH

A
  • headache
  • double vision/blurred vision
  • tinnitus
  • radicular pain
  • papilloedema
31
Q

How is IIH investigated?

A 
LP 
CT/MR head 
CT venogram 
Fundoscopy/ophthalmology review 
Must rule out other pathologies
32
Q

How is IIH treated?

A

Weight loss
Carbonanhydrase inhibitors - acetazolamide and topiramate
Diuretics
CSF diversion
Interventional radiology (venous sinus plasty/stenting)
Optic Nerve Sheath Fenestration

33
Q

What is the problem with venous stenting?

A

It is permanent and cannot be removed and 50% go on to need a shunt

34
Q

What is acetazolamide used for?

A

Raised ICP but also altitude sickness among other diseases

35
Q

Where do coloid cysts arise from?

A

99% foramen of munro - usually asymptomatic but can cause obstruction or hydrocephalus

36
Q

What is Cushing’s triad?

A

Decreased HR
Increased BP
Irregular respiration

37
Q

Describe the compensation of CPP when ICP increases

A

MAP - ICP = CPP

CPP increases so therefore MAP increases by vasoconstriction to reduce CPP

38
Q

Name the congenital causes of hydrocephalus

A

Aqueductal stenosis

  • chiari malformation
  • spina bifida
  • Dandy walkers syndrome
39
Q

What malformation occurs in Chiari I?

A

Caudal displacement of cerebellar tonsils

40
Q

What malformation occurs in Chiari II?

A

Central displacement of cerebellum and medulla

Herniation of the fourth ventricle

41
Q

How will chiari I present?

A

Headache, downbeat nystagmus, central cord symptoms (teenage years)

42
Q

How will chiari II present?

A

Severe brainstem dysfunction in infants and weakness that may progress to quadriplegia

Neurology (29 decks)

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