Prevalence of superficial siderosis in patients with cerebral amyloid angiopathy

Abstract

Background: Cerebral amyloid angiopathy (CAA) typically presents with lobar intracerebral macrohemorrhages (ICH) or microbleeds (MBs). Several case reports also found superficial siderosis (SS) in patients with CAA. We aimed to assess the value of SS for the in vivo diagnosis of CAA, and tested whether the inclusion of SS as a criterion alters the sensitivity and specificity of the Boston criteria for CAA-related hemorrhage.

Methods: We retrospectively analyzed the T2*-weighted MRIs of 38 patients with histopathologically proven CAA and of 22 control patients with histopathologically proven non-CAA ICHs regarding the presence of ICHs, MBs, and SS. We compared the sensitivity and specificity of the classic Boston criteria to that of modified criteria, which included SS as a criterion.

Results: ICHs were present in 71% of the patients with CAA, and in all control patients. MBs were found in 47.4% of patients with CAA and in 22.7% of controls. SS was detected in 60.5% of patients with CAA, but in none of the controls. The classic criteria had a sensitivity of 89.5% for CAA-related hemorrhage, while inclusion of SS increased their sensitivity to 94.7% (not significant). On the contrary, the specificity of the Boston criteria was 81.2% both for the classic and for the modified criteria.

Conclusions: Superficial siderosis (SS) occurs with high prevalence in cerebral amyloid angiopathy (CAA) and is rare in non-CAA forms of intracerebral hemorrhages. Thus, we propose that inclusion of SS in the Boston criteria might enhance their sensitivity for CAA-related hemorrhage without loss of specificity.

Figure 1 Flow diagram The retrospective identification of patients with cerebral amyloid angiopathy (CAA) and control patients.

Figure 2 T2*-weighted MRI of 3 different patients with cerebral amyloid angiopathy (CAA) (A, B) A 67-year-old woman with CAA with large left frontal intracerebral hemorrhage (ICH) and focal superficial siderosis in the right and left parietal lobes (arrows). In this patient, 2 microbleeds (MBs) were also present (not shown). (C, D) An 84-year-old woman with CAA with disseminated, bilateral frontal and parietal superficial siderosis (e.g., arrows), in whom no ICHs or MBs were present. (E, F) A 73-year-old woman with CAA with disseminated bilateral superficial siderosis (arrows in E) affecting also the infratentorial compartment (arrows in F). In this patient, 1 infratentorial MB was found (not shown), but no ICHs.