Case 15 - Intracranial aneurysm

Question 1

where are cerebral aneurysms typically located, what is the hunt hess classification?

Answer 1

cerebral aneurysm

• bifurcations near circle of Willis
• risk of rupture is increased with increasing size

Hunt-Hess classification

• devised to grade risk of mortaility with sub-arachonid hemorrhage (SAH)
• Grade 0 - unruptured
• Grade 1 - minimal h/a
• grade 2 - mod-severe h/a
• Grade 3 - drowsiness, confusion, mild focal deficit
• grade 4 - stupor, hemiparesis, moribund

Question 2

what are the most serious complications after subarachnoid hemorrhage from ruptured aneurysm?

Answer 2

1) rebleeding
* most common in 24-48 hrs after insult
2) cerebral vasospasm

• most common day 3-15 after insult
• vasospasm leads to cerebral infarction

Question 3

what are surgical options for SAH 2/2 ruptured aneurysm?

Answer 3

craniotomy with clipping vs endovascular coiling

• dependent on location, size of aneurysm, neck size

Question 4

what additional monitors are indiciated for patients undergoing intracranial aneurysm clipping?

Answer 4

1) arterial line preinduction

• monitor BP with induction and intubation
  
  • avoid sympathetic stimulation during induction and intubation -> inc risk of rupture of aneurysm
  • transmural pressure = MAP - ICP
• beat to beat monitoring
• blood gas sampling/lab sampling

2) electrophysiologic monitoring

• clipping may involve direct aneurysm clipping (induced hypotension) or
• temporary occlusion of feeding arterial supply to aneurysm (induced HTN for collateral flow required)
• both Risk Cerebral ischemia, therefore monitor for this
  
  • EEG - place over regions at risk
  • SSEP
  • MEPs - highly sensitive to ischemia

Question 5

How is MAP controlled during aneurysm clipping surgery?

Answer 5

pre-induction arterial line

1) aneurysmal dissection

• reduce BP as risk of aneurysm rupture is great during surgical manipulation of tissue adjoining the aneurysmal sac
• if there is rupture -> Need to decrease BP to facilitate surgical visualizatoin and control of bleed. Use propofol or adenosine

2) direct aneurysm clip placement or #3
* induced hypotension to facilitate direct clip placement
3) temporary occlusion of feeding vessels
* induced HTN required for collateral blood flow

Question 6

what is cerebral vasospasm, how is it treated?

Answer 6

cerebral vasospasm

• seen day 3-15 after insult
• arterial narrowing and decreased flow -> cerebral ischemia
• mech = vasospasm 2/2 blood degredation products in subarachnoid space
• RF = large subarachnoid hemorrhage (more exposed blood)

Tx:

• prevent = nimodipine
• Triple H
  
  • HTN
  • hypervolemia
  • hemodilution to Hct of 30%
    
    • maintain adequate CaO2 + decrease viscosity of blood (increase blood flow)
• angioplasty + balloon dilation
• endovascular injection of papaverine or verpamil

Question 7

how is aneurysm rupture during aneurysm clipping managed?

Answer 7

• induction + intubation
  
  • avoid sympathetic stimulation -> inc risk of rupture
  • Transmural pressure = MAP - ICP
• during aneurysmal dissection
  
  • induced hypotension
  • high risk of rupture with surgical manipulation around aneurysmal area

Intra-op rupture of aneurysm

• immedietly decrease BP with propofol or adensoine
• helps facilitate surgical visualization and control of ruptured aneurysm
• adenosine -> temporary circulatory arrest -> leads to a temporary bloodless field

Clipping

• direct permanent clip of aneurysmal neck = induced hypotension to decrease risk of rupture (do not want to increase transmural pressure)
• temporary clip of feeding vessels to allow permanent clip of aneurysmal neck = induced HTN to help collateral flow