Pichler, Michael

Introduction: Cortical superficial siderosis (cSS) refers to deposition of blood breakdown products along the cerebral cortex, causing characteristic staining patterns seen with iron-sensitive MRI techniques. Cortical superficial siderosis is a relatively rare disorder, but has been linked to cerebral amyloid angiopathy and Alzheimer’s disease. The objective of this study was to determine the frequency and natural history of cSS in the general elderly population. Methods: MRI scans from the Mayo Clinic Study of Aging (MCSA), an ongoing population-based study of elderly residents in Olmsted County, Minnesota, were reviewed by neuroradiologists. Participants with cSS were identified based on linear pattern of hypointensity on gradient recalled echo imaging consistent with cSS. Exclusion criteria were: 1) MRI findings not consistent with cSS or 2) alternative explanation for MRI findings (such as aneurysmal subarachnoid hemorrhage, intracranial surgery, or trauma). Additional data abstracted included extent of cSS, presence of cerebral microbleeds, and clinical outcome. Results: Eleven out of 1,441 participants had MRI scans showing cSS (0.8%). When stratified by age, the frequency was 0.4% in those 50 to 70 years old and 1.1% in those over 70 years old. Six participants had only focal involvement of cSS (restricted to three or fewer sulci) and five had disseminated involvement (affecting more than three sulci). Microbleeds were seen in four of five (80%) participants with disseminated cSS, but none with focal cSS. Five participants (2 focal, 3 disseminated cSS) had follow up MRI scans, with an average follow up of 25 months. There was no further hemorrhage in those with focal cSS. However, all three participants with disseminated cSS experienced additional hemorrhage: one with new microbleeds, one with new microbleeds and lobar hemorrhage, and one with sulcal subarachnoid hemorrhage and lobar hemorrhage. Conclusion: Although rare, cSS may be encountered in the general elderly population. Extent of involvement of cSS and concomitant microbleeds may be important risk factors for progression of disease and intracerebral hemorrhage. The clinical significance of focal cSS occurring in the absence of microbleeds requires further investigation.

Background and Purpose— Superficial siderosis (SS) is characterized by hemosiderin deposition in the superficial layers of the central nervous system and can be seen during postmortem examination or with iron-sensitive magnetic resonance imaging techniques. The distribution of SS may predict the probable underlying cause. This study aimed to report the prevalence and natural history of SS in a population-based study. Methods— Brain magnetic resonance imaging scans from the MCSA (Mayo Clinic Study of Aging), a population-based study of residents 50 to 89 years of age in Olmsted County, Minnesota, were reviewed. Participants with imaging consistent with SS were identified from 2011 through 2016. An inverse probability weighting approach was used to convert our observed frequencies to population prevalence of SS. Additional data abstracted included amyloid positron emission tomography, Apolipoprotein E genotype, coexisting cerebral microbleeds, and extent of SS. Results— A total of 1412 participants had eligible magnetic resonance imaging scans. Two participants had infratentorial SS, restricted to the posterior fossa. Thirteen participants had cortical SS involving the cerebral convexities (7 focal and 6 disseminated). Only 3 of the participants with cortical SS (23%) also had cerebral microbleeds. The population prevalence of SS was 0.21% (95% confidence interval, 0–0.45) in those 50 to 69 years old and 1.43% (confidence interval, 0.53–2.34) in those over 69 years old. Apolipoprotein E ε2 allele was more common in those with SS (57.1% versus 15.0%; P <0.001). Compared with participants without SS, those with SS were also more likely to have a positive amyloid positron emission tomographic scan (76.9% versus 29.8%; P <0.001). Conclusions— SS may be encountered in the general elderly population. The association with increased amyloid burden and Apolipoprotein E ε2 genotype supports cerebral amyloid angiopathy as the most common mechanism. Longitudinal follow-up is needed to evaluate the risk of subsequent hemorrhage in cases of incidentally discovered SS.