Cerebral Amyloid Angiopathy

In the Neuro ICU, cerebral amyloid angiopathy (CAA) gets blamed a lot in elderly patients as a cause of their hemorrhagic stroke. Although I am familiar with the disease, I thought I should revisit it.

 CAA is characterized by amyloid beta peptide deposits in the blood vessels of the brain. The deposits weaken the blood vessel wall and makes it prone to bleeding.  It can occur as a sporadic disorder, in association with Alzheimer’s disease or as a familial syndrome. CAA can cause intracerebral hemorrhage, transient neurological symptoms, hemosiderosis, incidental microhemorrhages or cognitive impairment.

 Epidemiology – the incidence is largely age dependent and is uncommon at ages younger than 60-65.


Pathogenesis – The vascular deposits in CAA consist of an amyloid beta-peptide. There has been an APP mutation identified which has been shown to cause AD CAA. Other side effects of the mutated APP is producing an amyloid protein that is unable to be degraded by proteasomes or producing an amyloid protein that has more of a toxic effect on the vascular wall. There is growing evidence from studies that support a link between CAA and the alleles of the Apolipoprotein E gene. Patients who carry the APO epsilon 2 or epsilon 4 allele correlate with a higher risk for CAA. Other factors likely contributing to CAA include pt’s who over express cytokines such as TGF.


Presenting Features – The most common presenting feature of CAA is spontaneous lobar hemorrhage which is located in the cortex and subcortical white matter and sparing of the areas that are affected more by hypertensive hemorrhages such (basal ganglia, thalamus or the pons).  Spontaneous hemorrhage secondary to CAA is more likely to happen in the posterior portion of the brain. A reason for this particular deposition of the amyloid proteins in the posterior circulation is unknown, but may be due to an undiscovered characteristic of the posterior circulation that would decrease the elimination of the beta amyloid deposits. Other clinical manifestations include seizure, headache, hemiplegia and depressed consciousness. Patients may also complain of transient symptoms such  as a recurrent, brief (about 10 minutes) episodes of weakness, numbness or paresthesias.


Diagnostic criteria – CAA should be suspected in patients over the age of 60 who have multiple lobar hemorrhages in the absence of an obvious cause. The true diagnosis can only be definitive with a post-mortem autopsy but there are two approaches to give a probable diagnosis during life such as a gradient-echo MRI and an examination of the tissue (brain biopsy which is rarely done). A gradient-echo MRI will accentuate the signal dropout caused specifically by iron-containing deposits left by old hemorrhages.


Treatment – similar to the treatment of other acute intracerebral hemorrhages by paying attention to the ICP and controlling the blood pressure and surgical hematoma resection.  After diagnosis, patients are to avoid anticoagulation medication such as Warfarin and Aspirin.


Other bits I learned today…

 -Primary Lateral Sclerosis (PLS) is similar to ALS but only involves the upper motor neuron and survival is better than ALS

 - A Jannetta procedure is something that can be done for trigeminal neuralgia. It involves a craniotomy and the removal or separation of various vascular structures, often an ectatic superior cerebellar artery, away from the trigeminal nerve.