Summary: A 70-year-old male presents with a history of increasing headaches and confusion.
Cerebral amyloid angiopathy
There is confluent T2/FLAIR signal abnormality within the right temporal, parietal, occipital, and posterior
frontal lobe with a smaller focus in the left middle temporal lobe. There is
associated mass effect with effacement of the adjacent cerebral sulci and mild
right to left midline shift. Postcontrast images demonstrate no abnormal
enhancement. Select images from a gradient-echo image demonstrate numerous foci
of low-signal susceptibility artifact in the right temporal lobe.
Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder characterized by β-amyloid deposition within the
media and adventitia of small- and medium-sized vessels of the cerebral
hemispheres. Cases are generally sporadic, but hereditary forms may occur.
Sporadic cases are much more common in the elderly. With age, the prevalence of
CAA increases to approximately 75% of patients older than age 90.
Many patients with CAA are asymptomatic, but those who present acutely have a
stroke-like clinical presentation secondary to intracranial hemorrhage.
Alternatively, patients who present with chronic symptoms tend to have a
clinical picture of dementia. CAA is also frequently associated with Alzheimer
dementia with approximately 40% of CAA patients with dementia showing changes of
Alzheimer dementia at autopsy, and 90% of patients with Alzheimer dementia
demonstrating changes of CAA at autopsy. The natural history of CAA is
recurrent hemorrhages and progressive cognitive decline.
Definitive diagnosis of CAA requires histologic analysis, which is impractical as most
cases do not demonstrate a lesion, which is amenable to biopsy. Therefore,
familiarity with the imaging features of CAA is important to ensuring an
accurate diagnosis and proper treatment. As patients usually present with
stroke-like symptoms, computed tomography (CT) is the imaging evaluation of
choice to determine the presence or absence of hemorrhage. If intracranial
hemorrhage is present in a cortical-subcortical location suspicious for CAA, magnetic
resonance imaging (MRI) should be obtained, including a gradient echo sequence.
Gradient echo images should demonstrate foci of signal loss in a
cortical-subcortical distribution, which correlates with hemosiderin deposition
from chronic microhemorrhages. The microhemorrhages occur in the same anatomic
distribution as β-amyloid deposition within the vessels. Microhemorrhages are
less common in the brainstem, cerebellum, and deep gray nuclei. In addition,
most cases will also show significant cerebral atrophy.
Much less common morphologic varieties of CAA include a mass-like lesion termed an
amyloidoma and a leukoencephalopathic form with diffuse white matter
involvement as seen in the patient in this case. The amyloidoma form
demonstrates a strongly enhancing mass with minimal mass effect, while the
leukoencephalopathic form demonstrates confluent white matter hyperintensities
on T2/FLAIR images. Both forms usually also demonstrate classic
cortical-subcortical microhemorrhages, which serve as a clue to the diagnosis. Patients
who demonstrate a subacute worsening of symptoms may have an inflammatory
subtype of the leukoencephalopathic form with increased surrounding vasogenic
edema. This subtype has termed cerebral amyloid inflammatory vasculopathy and
is responsive to steroids. The differential for confluent white-matter signal abnormality is
long, including demyelination, ischemia, infarction, infection, and edema, so CAA
should be considered in cases associated with cortical-subcortical hemorrhages
and a history of dementia.
As there is currently no treatment, which has been shown to halt or reverse β-amyloid deposition, care is instead
focused on minimizing the risk of hemorrhage, including possible
discontinuation of anticoagulation, which has been shown to increase the risk
of intracranial hemorrhage in patients with CAA. In the small subset of
patients who have an acute inflammatory form, such as this patient, steroids
are often effective. This patient was treated with steroids and showed
significant improvement clinically as well as on follow-up imaging.
- Chao CP, Kotsenas AL,
Broderick DF, et al. Cerebral amyloid angiopathy: CT and MR imaging findings.
- Kinnecom C, Lev MH, Wendell L, et al. Course of cerebral amyloid angiopathy-related
inflammation. Neurology. 2007;68:1411-1416.
- Eng JA, Frosch MP, Choi K, et al. Clinical manifestations of cerebral amyloid angiopathy-related
inflammation. Ann Neurol. 2004;55:250-256.