Spectrum of transient focal neurological episodes in cerebral amyloid angiopathy: multicentre magnetic resonance imaging cohort study and meta-analysis.

BACKGROUND AND PURPOSE Transient focal neurological episodes (TFNE) are recognized in cerebral amyloid angiopathy (CAA) and may herald a high risk of intracerebral hemorrhage (ICH). We aimed to determine their prevalence, clinical neuroimaging spectrum, and future ICH risk. METHODS This was a multicenter retrospective cohort study of 172 CAA patients. Clinical, imaging, and follow-up data were collected. We classified TFNE into: predominantly positive symptoms ("aura-like" spreading paraesthesias/positive visual phenomena or limb jerking) and predominantly negative symptoms ("transient ischemic attack-like" sudden-onset limb weakness, dysphasia, or visual loss). We pooled our results with all published cases identified in a systematic review. RESULTS In our multicenter cohort, 25 patients (14.5%; 95% confidence interval, 9.6%-20.7%) had TFNE. Positive and negative symptoms were equally common (52% vs 48%, respectively). The commonest neuroimaging features were leukoaraiosis (84%), lobar ICH (76%), multiple lobar cerebral microbleeds (58%), and superficial cortical siderosis/convexity subarachnoid hemorrhage (54%). The CAA patients with TFNE more often had superficial cortical siderosis/convexity subarachnoid hemorrhage (but not other magnetic resonance imaging features) compared with those without TFNE (50% vs 19%; P=0.001). Over a median period of 14 months, 50% of TFNE patients had symptomatic lobar ICH. The meta-analysis showed a risk of symptomatic ICH after TFNE of 24.5% (95% confidence interval, 15.8%-36.9%) at 8 weeks, related neither to clinical features nor to previous symptomatic ICH. CONCLUSIONS TFNE are common in CAA, include both positive and negative neurological symptoms, and may be caused by superficial cortical siderosis/convexity subarachnoid hemorrhage. TFNE predict a high early risk of symptomatic ICH (which may be amenable to prevention). Blood-sensitive magnetic resonance imaging sequences are important in the investigation of such episodes.