Perfusion-weighted MRI in cerebral amyloid angiopathy-related transient focal neurological episodes.

Introduction: Sporadic cerebral amyloid angiopathy (CAA) is a common age-related cerebral small vessel disease characterized by progressive ß-amyloid deposition in the walls of small cortical arteries, arterioles, and capillaries in the cerebral cortex and overlying leptomeninges. CAA-related transient focal neurological episodes (CAA-TFNEs) represent a challenging clinical feature interesting from a pathophysiological point of view.

Case Report: Here we present two cases of CAA-TFNEs in which we performed functional imaging with perfusion-weighted imaging MR and brain 18 F-FDG PET. In both cases, we found a topographic relationship between the involved cortical areas and the clinical expression of CAA-TFNEs. Cortical superficial siderosis in the first case and a convexity subarachnoid hemorrhage in the second case were found in the contralateral rolandic area corresponding to the clinical symptoms. The same areas showed a reduction of rCBV and rCBF on perfusion-weighted MR and were also associated in one case with hypometabolism on 18 F-FDG PET.

Discussion: These new findings strengthen the hypothesis that CAA involves the superficial leptomeningeal arteries but also the short penetrating arterioles reaching different depths in the cortex generating hypoperfusion and altered vascular reactivity and consequently reduced neuronal activity.

Conclusion: Understanding CAA-TFNEs is pivotal because they carry a very high risk of subsequent lobar intracerebral hemorrhage but are frequently misdiagnosed as TIAs and treated with antithrombotics enhancing the bleeding risk associated with CAA.