A 76-year-old man presents with progressive memory impairment and behavioral problems that have developed over the last four years. He has a history of atrial fibrillation and type 2 diabetes mellitus complicated by retinopathy and nephropathy. Except from impairments in multiple cognitive domains, interfering with daily activities, there are no abnormalities on physical and neurological examination.
MRI image of the brain of the patient
B.J.H. Verhaar & E.P. van Poelgeest
The T2*-weighted MRI-image shows cortical superficial siderosis in two locations (see arrows in the image at right), which can be described as linear hypointensities on the gyral surface. Superficial siderosis consists of hemosiderin depositions in the subpial (beneath the pia mater) layers of the brain and spine, and as such thought to result from subarachnoid bleeding.¹ Another characteristic of this MRI is the presence of multiple cerebral microbleeds, which can be recognized as small round or oval hypointensities on a T2*-weighted MRI.²
Both these characteristics, superficial siderosis and cerebral microbleeds, are part of the Boston criteria for the diagnosis of cerebral amyloid angiopathy (CAA).³ CAA is a cerebrovascular disease in which the accumulation of beta-amyloid in the leptomeningeal and cortical vessels causes vascular fragility. As a result, these vessels are prone to bleed resulting in lobar hemorrhage, cerebral microbleeds or superficial siderosis on MRI imaging. For a CAA-diagnosis according to the Boston criteria, a patient must have clinical symptoms, such as lobar or cerebellar bleeding in the absence of hypertension, transient focal neurological symptoms
(“amyloid spells”) or cognitive decline.4,5 For a ‘possible’ or ‘probable’ diagnosis of CAA, a patient older than 55 years must have lobar microbleeds with or without focal or disseminated superficial siderosis.³ The ‘possible’ or ‘probable’ diagnosis can only be confirmed by postmortem pathological examination of the brain. About 30% of non-demented elderly, and the vast majority (~90%) of patients with Alzheimer’s disease appear to have CAA on autopsy.6
CAA exists in sporadic and familial forms. Familial CAA is very rare and often has an earlier age of onset (typically in middle to late middle age). An example of familial CAA is hereditary cerebral hemorrhage with amyloidosis – Dutch type, which is also known as “Katwijkse ziekte”.7
When differentiating between other types of dementia on MRI, you could pay attention to the following characteristics:
- Alzheimer’s disease: hippocampal atrophy, medial temporal lobe atrophy and parietal atrophy;
- Vascular dementia: global atrophy, white matter lesions, lacunes and infarcts in areas needed for cognitive functioning;
- Dementia with Lewy bodies: no specific characteristics on MRI. Therefore, most helpful in distinguishing this diagnosis on MRI is the absence of the specific patterns of other types of dementia. Often reported nonspecific characteristics in Lewy body dementia are a generalized decrease in cerebral volume and an enlargement of the lateral ventricles.8
Figure 2a. T2*-weighted MRI image of a patient with superficial siderosis (arrows) and multiple microbleeds.
Figure 2b Coronal T1-weighted MRI image of a patient with Alzheimer dementia with parietotemporal atrophy and decreased hippocampal volume (white circles). Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 22196
Figure 2c. Axial MRI image (FLAIR) of a patient with vascular dementia with global atrophy and white matter lesions. Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 25641
Figure 2d. Axial MRI image (FLAIR) of a patient with Lewy body dementia with dilatation of sulci in the frontal and parietotemporal regions, decrease in cerebral volume and enlargement of the lateral ventricles. Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 28774.
- Kumar N, Cohen-Gadol AA, Wright RA, Miller GM, Piepgras DG, Ahlskog JE. Superficial siderosis. Neurology. 2006;66(8):1144-1152.
- Cordonnier C. Brain microbleeds. Pract Neurol. 2010;10(2):94-100. doi: 10.1136/jnnp.2010.206086.
- Linn J, Halpin A, Demaerel P, et al. Prevalence of superficial siderosis in patients with cerebral amyloid angiopathy. Neurology. 2010;74(17):1346-1350. doi:
- Greenberg SM, Vonsattel JP, Stakes JW, Gruber M, Finklestein SP. The clinical spectrum of cerebral amyloid angiopathy: Presentations without lobar hemorrhage. Neurology. 1993;43(10):2073-2079.
- Charidimou A, Gang Q, Werring DJ. Sporadic cerebral amyloid angiopathy revisited: Recent insights into pathophysiology and clinical spectrum. J Neurol Neurosurg Psychiatr. 2011:301308.
- Miller-Thomas MM, Sipe AL, Benzinger TL, McConathy J, Connolly S, Schwetye KE. Multimodality review of amyloid-related diseases of the central nervous
system. Radiographics. 2016;36(4):1147-1163.
- van Rooden S, van Opstal AM, Labadie G, et al. Early magnetic resonance imaging and cognitive markers of hereditary cerebral amyloid angiopathy. Stroke.
- Kornienko VN, Pronin IN. Diagnostic neuroradiology. Springer Berlin Heidelberg; 2008:1077. Available here
- Verhaar B, Vernooij MW, Biessels GJ, Muller M. [Risk of vitamin K antagonists in cases of cerebral microbleeds]. Ned Tijdschr Geneeskd. 2018;162(0):D1790. Available here