A discussion of these techniques was expected from the candidates in Question 2 from the second paper of 2013, Question 5 from the first paper of 2013 and Question 8 from the first paper of 2008. Generally speaking, the college wants the candidates to discuss the advantages and disadvantages of the various techniques.

Techniques used to monitor for vasospasm
Technique Advantages Disadvantages
Clinical examination
  • Cheap
  • Available at the bedside
  • Easily sequentialised
  • Inaccurate
  • Operator-dependent
  • Many episodes of vasospasm are not associated with physical signs
DSA
  • Gold standard
  • Offers a means of treating the vasospasm
  • May overtreat by picking up narrowing which is not associated with a decreased flow
  • Radiation exposure
  • Contrast exposure
  • Need for transport
  • Need for skilled personnel
  • invasive
  • 1% risk of stroke or dissection
CTA
  • Reasonable sensitivity and specificity
  • Non-invasive
  • Radiation exposure
  • Contrast exposure
  • Need for transport
  • Need for skilled personnel
  • Frustrated by the presence of coils and clips (artifact is generated)

Transcranial Doppler
  • High (100%) specificity;
  • non invasive
  • Easily sequentialised
  • Operator-dependent
  • Mediocre sensitivity
EEG
  • Highly sensitive and specific
  • Can pick up features of ischaemia and vasospasm earlier than the development of obvious signs or radiological features
  • Non invasive
  • Requires skilled operator and interpreter; may not be available
  • Ideally, EEG monitoring should be continuous.
SPECT
  • potentially very useful in detecting ischaemia and cerebral hypoperfusion
  • Not validated, and mainly a tool of research

References

Oh's Intensive Care manual

Chapter   51   (pp. 568)  Acute  cerebrovascular  complications by Bernard  Riley  and  Thearina  de  Beer

Marshall, Scott A., Paul Nyquist, and Wendy C. Ziai. "The role of transcranial Doppler ultrasonography in the diagnosis and management of vasospasm after aneurysmal subarachnoid hemorrhage." Neurosurgery Clinics of North America21.2 (2010): 291-303.

Greenberg, E. D., et al. "Diagnostic accuracy of CT angiography and CT perfusion for cerebral vasospasm: a meta-analysis." American Journal of Neuroradiology 31.10 (2010): 1853-1860.

Sloan, M. A., et al. "Sensitivity and specificity of transcranial Doppler ultrasonography in the diagnosis of vasospasm following subarachnoid hemorrhage." Neurology 39.11 (1989): 1514-1514.

Rivierez, M., et al. "Value of electroencephalogram in prediction and diagnosis of vasospasm after intracranial aneurysm rupture." Acta neurochirurgica 110.1-2 (1991): 17-23.