Implications of cortical superficial siderosis in CAA

Imaging of vascular cognitive impairment

Vascular cognitive impairment (VCI) is a major health challenge and represents the second most common cause of dementia. We review the updated imaging classification and imaging findings of different subtypes of VCI. We will focus on the magnetic resonance imaging (MRI) markers of each subtype and highlight the role of advanced MR imaging sequences in the evaluation of these patients. Small vessel dementia appears as white matter hyperintensity, lacunae, microinfarcts, and microbleeds. Large vessel dementia includes strategic infarction and multi-infarction dementias. Hypoperfusion dementia can be seen as watershed infarcts and cortical laminar necrosis. Hemorrhagic dementia results from cerebral amyloid angiopathy and cortical superficial siderosis. Hereditary forms of VCI, caused by gene mutations such as CADASIL, should be suspected when dementia presents in young patients. Mixed dementia is seen in patients with Alzheimer's disease and the coexistence of cerebrovascular disease.

Cortical superficial siderosis and bleeding risk in cerebral amyloid angiopathy: A meta-analysis

OBJECTIVE

To assess the association of cortical superficial siderosis (cSS) presence and extent with future bleeding risk in cerebral amyloid angiopathy (CAA).

METHODS

This was a meta-analysis of clinical cohorts of symptomatic patients with CAA who had T2*-MRI at baseline and clinical follow-up for future intracerebral hemorrhage (ICH). We pooled data in a 2-stage meta-analysis using random effects models. Covariate-adjusted hazard ratios (adjHR) from multivariable Cox proportional hazard models were used.

RESULTS

We included data from 6 eligible studies (n = 1,239). cSS pooled prevalence was 34% (95% confidence interval [CI] 26%-41%; I ² 87.94%; p < 0.001): focal cSS prevalence was 14% (95% CI 12%-16%; I ² 6.75%; p = 0.37), and disseminated cSS prevalence was 20% (95% CI 13%-26%; I ² 90.39%; p < 0.001). During a mean follow-up of 3.1 years (range 1-4 years), 162/1,239 patients experienced a symptomatic ICH-pooled incidence rate 6.9% per year (95% CI 3.9%-9.8% per year; I ² 83%; p < 0.001). ICH incidence rates per year according to cSS status were 3.9% (95% CI 1.7%-6.1%; I ² 70%; p = 0.018) for patients without cSS, 11.1% (95% CI 7%-15.2%; I ² 56.8%; p = 0.074) for cSS presence, 9.1% (95% CI 5.5%-12.8%; I ² 0%; p = 0.994) for focal cSS, and 12.5% (95% CI 5.3%-19.7%; I ² 73.2%; p = 0.011) for disseminated cSS. In adjusted pooled analysis, any cSS presence was independently associated with increased future ICH risk (adjHR 2.14; 95% CI 1.19-3.85; p < 0.0001). Focal cSS was linked with ICH risk (adjHR 2.11; 95% CI 1.31-2.41; p = 0.002), while disseminated cSS conferred the strongest bleeding risk (adjHR 4.28; 95% CI 2.91-6.30; p < 0.0001).

CONCLUSION

In patients with CAA, cSS presence and extent are the most important MRI prognostic risk factors for future ICH, likely useful in treatment planning.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in symptomatic CAA survivors with baseline T2*-MRI, cSS (particularly if disseminated, i.e., affecting >3 sulci) increases the risk of future ICH.