Outline the advantages and disadvantages of the various techniques used in the diagnosis and monitoring of vasospasm secondary to aneurysmal subarachnoid haemorrhage.
Techniques that have proven or demonstrated potential in the diagnosis and monitoring of
In the conscious patient, may be detected clinically by new focal neurology or a drop in GCS. Advantages: No additional costs and readily available, can be repeated easily, non-invasive (usually), has to be performed at the bedside. Major disadvantage is lack of specificity often necessitating CT/angiography. Also lacks sensitivity, vasospasm can occur without a clinical correlate, early in the disease. Operator dependent.
Conventional 4 vessel DSA angiography:
Remains the gold standard for diagnosis of vasospasm.
May allow therapeutic intervention (angioplasty) at the time.
Disadvantages: invasive, risks of bleeding, embolism, radiation/contrast exposure and transport. Requires skilled interventional radiology, and therefore resource heavy. Risk of stroke (quoted about 1%, but probably a little lower) just from the angio, plus the dissections etc. that occur as well.
Detects vessel narrowing, not necessarily poor flow to distal tissue in all cases (either increased flow rate through narrow vessel or collateral supply. May lead to over treatment.
Transcranial Doppler (TCD):
It is low risk, performed at the bedside, non-invasive and able to be repeated daily enabling trend analysis.
This answer lends itself well to a table format.
Apocryphal notes on the diagnosis and management of SAH are also available.
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.