Background: Superficial siderosis (SS) is a rare finding on T2*-weighted magnetic resonance imaging (MRI), regarded as a radiological marker of cerebral amyloid angiopathy (CAA). The present study investigates with 7.0-tesla MRI the prevalence of SS and its underlying pathological substrate in a consecutive series of post-mortem brains of elderly patients with various neurodegenerative and cerebrovascular lesions.
Materials and methods: The prevalence of SS and associated lesions was screened using 7.0-tesla MRI and their neuropathological correlates in 120 post-mortem brains of patients with various neurodegenerative and cerebrovascular diseases.
Results: Eighty-three separate zones of SS were detected in 45 brains (37.5%), including 25 areas of disseminated SS (dSS) and 58 areas of focal SS (fSS), restricted to less than 3 sulci. dSS was spatially related to sequels of 14 lobar haematomas and 11 cerebral infarcts, while fSS was connected to 19 microbleeds and 39 micro-infarcts (p < 0.001). Comparison of the 15 CAA to the 30 non-CAA brains showed that dSS was due to an old lobar haematoma in 53% of the former group compared to 3% of the latter group (p = 0.003). fSS was due to a microbleed in 7% of the CAA brains and to 40% of the non-CAA brains (p = 0.03).
Conclusions: SS is associated with both haemorrhagic and ischaemic underlying lesions. It is frequently observed on T2*-weighted 7.0-tesla MRI, and two types of SS may be described. Clinicians should keep in mind that SS may be found in other settings than CAA.