Low cerebrovascular reserve capacity in long-term follow-up after subarachnoid hemorrhage

BACKGROUND: Intradural arteries formerly in vasospasm after subarachnoid hemorrhage (SAH) show structural changes that result in arterial wall thickening and luminal narrowing. To evaluate if these changes lead to maldistribution of cerebral perfusion and reduced cerebrovascular reserve capacity (CVRC) in surviving patients, a long-term follow-up study of 18 adult patients after SAH was performed. METHODS: Eighteen patients were selected for the study, all had shown vasospasm after an early operation on a ruptured aneurysm, were in good neurological condition (GOS [Glasgow Outcome Score] 4 or 5 ), and had no residual infarcts. A technetium-99m-hexamethyl-propylenamine oxime (HMPAO) single-photon emission computed tomography was performed 15 to 73 months after SAH. To study CVRC, a second investigation after application of acetazolamide was performed 1 week later. RESULTS: Single-photon emission computed tomography showed areas of focally reduced HMPAO uptake predominantly in the hemisphere ipsilateral to the vessels more affected by posthemorrhagic vasospasm. The thalamus and the basal ganglia, the frontal lobe, and the temporal lobe were the regions most frequently showing reduced uptake. The individual change of HMPAO uptake after acetazolamide application ranged from -7% to 44% (mean, 17% +/- 15%). CONCLUSIONS: These results show a remarkable reduction of CVRC compared with findings in healthy individuals. Based on these new findings, further investigations focusing on CVRC in routine SAH follow-up are worth being considered.