Tissue at risk concept for endovascular treatment of severe vasospasm after aneurysmal subarachnoid haemorrhage

Objective: To report a case of severe vasospasm after subarachnoid haemorrhage (SAH) where "tissue at risk'' was identified by magnetic resonance imaging (MRI), and to demonstrate the haemodynamic consequences with either resolution of the perfusion-diffusion mismatch by balloon angioplasty or evolution of an infarct. Methods: A 45 year old women with SAH underwent surgical treatment of a ruptured middle cerebral artery (MCA) aneurysm. On day 3 she became obtunded and developed a right hemiparesis. Diffusion weighted (DWI) and perfusion weighted (PWI) imaging were done before and after transluminal balloon angioplasty (TBA) of multi-focal proximal vasospasm. Results: The initial MRI revealed no DWI lesion but PWI showed a severe perfusion deficit of 6.7 to 16.4 seconds in the complete left MCA territory. Digital subtraction angiography confirmed severe segmental narrowing of left C1 and M1. The spastic segments were successfully dilated by TBA. Follow up MRI showed that the PWI-DWI mismatch resolved in the anterior and middle MCA territory with no tissue infarction, whereas in the terminal dorsal MCA territory a severe mismatch remained and cerebral infarction evolved. Conclusions: PWI/DWI can identify tissue at risk for infarction in severe vasospasm following SAH. This may allow selection of patients for angioplasty and the monitoring of treatment effects.