Raised ICP and Hydrocephalus

Question 1

ICP Physiology

Answer 1

• Cerebral blood flow controlled by regulating cerebral perfusion and cerebral vascular resistance
• Chemoregulation
  
  • pCO² (rising - vasodilation, falling - vasoconstriction)
  • pO² (falling - vasodilation)
  • Extrecellular pH (rising - vasoconstricton, falling - vasodilation)
  • Metabolic byproducts (rising - vasodilation, falling - vasoconstriction)
• Autoregulation
  
  • BP (rising - vasoconstricton, falling - vasodilation)
  • ICP (rising - vasodilation)
• Majority of CSF produced by the choroid plexus in adults
• CSF volume in adults around 150mls - 50:50 = intracranial:spinal
• Rate 0.3mls/min or 450mls per day
• CSF provides buoyancy, protection, reservoir, excretion of metabolic waste and transit route for pineal secretions to pituitary gland

Question 2

How does the brain cope when things go wrong?

Answer 2

• Reduce volume of CSF - flows into spinal canal
• Reduce cerebral blood volume
• Reduce extracellular fluid volume
• Skull expands (only in babies and infants)
  
  • Fontanelle becomes swollen
  • Skull sutures can become splayed

Question 3

Symptoms of raised ICP in adults and older children

Answer 3

• Headache
• Disturbed sleep
• Nausea and vomiting
• Blurred vision
• Drowsiness/coma
• Delayed development
• Decreased GCS
• Papilloedema
• Focal neurological symptoms due to mass lesion
• Focal neurological deficit

Question 4

Symptoms of raised ICP in babies and infants

Answer 4

• Bigger head
• Poor feeding
• Poor sleeper
• Drowsiness/coma
• Failure to thrive
• Delayed development
• Increasing OFC
• Bulging fontanelle
• Papilloedema
• Decreased GCS
• Focal neurological symptoms
• Focal neurological deficit

Question 5

Investigation of raised ICP

Answer 5

• US

Question 6

Management of raised ICP

Answer 6

• Treat the cause:
  
  • Remove the tumour
  • Evacuate the haematoma
  • Treat the hydrocephalus
• Non-surgical
  
  • Steroids
  • Mannitol
  • Controlled ventilation
  • Sedation

Question 7

Definition of hydrocephalus

Answer 7

• Disruption of normal CSF hydrodynamics within the CNS
  
  • Accumulation of CSF within the centricular system of the brain
  • Due to obstruction to CSF flow and absorption rather than overproduction of CSF
• Classification
  
  • Fuctional
    
    • Obstructive or non-communicating (not safe to LP)
    • Communicating (safe to LP)
  • Aetiological
    
    • Congenital
      
      • Chiari malformation or spina bifida
      • Aqueductal stenosis (x-linked)
      • Dandy Walker complex
      • Congenital arachnoid cysts
      • Atresia of the foramen of munro
    • Acquired
      
      • Haemorrhage
      • Infection
      • Traumatic head injury
      • Tumour

Question 8

Presentation of hydrocephalus in older children and adults

Answer 8

• Headache
• Nausea and vomiting
• Double or blurred vision
• Drowsiness or decreased consciousness
• Developmental delay
• Decreased GCS
• Papilloedema
• 6th nerve palsy
• Parinaud’s syndrome

Question 9

Treatment of hydrocephalus

Answer 9

• Eliminate the obstruction (i.e. remove tumour)
• Divert flow of CSF
  
  • Extraventricular drain
  • Endoscopic third ventriculosotomy
  • Shunt
• Reduce the production of CSF
  
  • Choroid plexectomy