Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder that tends to manifest in normotensive elderly patients. It is common and most often presents clinically as an intracerebral haemorrhage 1. It is usually not associated with systemic amyloidosis.
CAA can be found on screening gradient imaging in up to 16% of asymptomatic elderly patients 4. Autopsy studies have found a prevalence of approximately 5-9% in patients between 60 and 69 years, and 43-58% in patients over the age of 90 4.
Symptomatic clinical presentation is usually with an intracerebral haemorrhage, found in 40% of autopsy proven cases of CAA 1. This is often in the form of microhaemorrhages. Of all patients with cerebral haemorrhage, CAA is found in 4-10% of cases 2. Vessel damage can also result in ischaemic leukoencephalopathy 1.
Occasionally mass like lesions have been reported 3 (not to be confused with cerebral amyloidosis seen in patients with systemic amyloidosis).
The Boston criteria 7are a combination of clinical, radiographic and pathological criteria which are used to assess the probability of CAA.
CAA is characterised by the deposition of ß-amyloidin the media and adventitia of small and medium sized arteries of the cerebral cortex and leptomeninges 4. This is associated with with associated fibrinoid degeneration, and microaneurysm formation 1. Amyloid is an eosinophylic, insoluble protein, located in the extra-cellular space, and stains with Congo red yielding apple green birefringence when viewed with polarized light 3. It is important to note that amyloid deposition is also encountered in other clinical scenarios including spongiform encephalitis 1:
- pathological of CAA changes are seen in ~80% of those with Alzheimer's disease 5
- ~40% of those with CAA have Alzheimer's dementia type symptoms
Findings reflect the various manifestations of the disease.
- not seen on CT
- small focal regions of signal drop out best seen on T2* sequences (gradient echo, echo-planar, SWI) as regions of blooming
- may be difficult to see on conventional T1 and T2 sequences 4
- tend to be subcortical (grey-white matter junction) rather than basal ganglia (c.f. hypertensive microhaemorrhages) 4
- cerebral haemorrhage
- diffuse low density of the white matter
- diffuse white matter hyperintensity on T2 weighted scans 1,6
- focal mass 3
- low density on CT with mass effect (differential diagnosis : glioma)
- low signal
- high signal
- evidence of haemorrhage not necessary
Neurodegenerative diseases are legion and their classification just as protean. A useful approach is to divide them according to underlying pathological process, although even using this schema, there is much overlap and thus resulting confusion.
- progressive supranuclear palsy (PSP)
fronto-temporal lobar degeneration (FTLD)
- behavioural variant fronto-temporal dementia (bvFTLD)
- language variant fronto-temporal dementia (lvFTLD), (aka primary progressive aphasia (PPA)
- corticobasal degeneration
- typical / classical Alzheimer's disease
- variant (e.g. posterior cortical atrophy)
- cerebral amyloid angiopathy (CAA)
- transthyretine-associated cerebral amyloidoses
- human prion diseases (not always included as neurodegenerative)
- neuronal intranuclear hyaline inclusion disease (NIHID)
- Alzheimer disease
- spinocerebellar ataxias
- Huntington disease
- hereditary spastic paraplegia
- amyotrophic lateral sclerosis (ALS)
- 1. Caulo M, Tampieri D, Brassard R et-al. Cerebral amyloid angiopathy presenting as nonhemorrhagic diffuse encephalopathy: neuropathologic and neuroradiologic manifestations in one case. AJNR Am J Neuroradiol. 22 (6): 1072-6. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 2. Mandybur TI, Bates SR. Fatal massive intracerebral hemorrhage complicating cerebral amyloid angiopathy. Arch. Neurol. 1978;35 (4): 246-8. Arch. Neurol. (link) - Pubmed citation
- 3. Osumi AK, Tien RD, Felsberg GJ et-al. Cerebral amyloid angiopathy presenting as a brain mass. AJNR Am J Neuroradiol. 1995;16 (4): 911-5. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 4. Walker DA, Broderick DF, Kotsenas AL et-al. Routine use of gradient-echo MRI to screen for cerebral amyloid angiopathy in elderly patients. AJR Am J Roentgenol. 2004;182 (6): 1547-50. AJR Am J Roentgenol (full text) - Pubmed citation
- 5. Haacke EM, Delproposto ZS, Chaturvedi S et-al. Imaging cerebral amyloid angiopathy with susceptibility-weighted imaging. AJNR Am J Neuroradiol. 2007;28 (2): 316-7. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 6. Loes DJ, Biller J, Yuh WT et-al. Leukoencephalopathy in cerebral amyloid angiopathy: MR imaging in four cases. AJNR Am J Neuroradiol. 1990;11 (3): 485-8. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 7. Chao CP, Kotsenas AL, Broderick DF. Cerebral amyloid angiopathy: CT and MR imaging findings. Radiographics. 26 (5): 1517-31. doi:10.1148/rg.265055090 - Pubmed citation
- 8. Osborn A, Blaser S, Salzman K. Encyclopedia of Diagnostic Imaging. AMIRSYS. (2008) ISBN:0721629059. Read it at Google Books - Find it at Amazon
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Cerebral amyloid angiopathy (CAA)||✗|
|Cerebral amyloid microangiopathy||✗|