A brief history of amyloid angiopathy as a cause of hemorrhagic strokeAlthough the deposition of amyloid protein in the brain was originally described in 1907, it took scientists several decades to realize that this slow progressive condition could be the cause of intracerebral hemorrhage (ICH). Back in the early 20th century, it was shown that amyloid deposits were present in the brains of people who had developed dementia toward the end of their lives, giving rise to the hypothesis that amyloid deposits were associated with dementia. Beginning in the 1960s, though, several reports were also published showing amyloid deposits in the brains of elderly people who had died from intracerebral hemorrhage (ICH). As more of these reports were published, it became clear that amyloid deposition was strongly associated with both dementia and some forms of ICH. Over time, the condition came to be known as amyloid angiopathy.
Why does amyloid angiopathy cause bleeding in the brain?Amyloid deposits tend to accumulate inside the walls of arteries in the brain, causing them to deteriorate over time until they break down and bleed. Very often, bleeding is localized to tiny areas called “petechial hemorrhages,” but when amyloid angiopathy leads to a large bleed, it can be life threatening.
One of the hallmarks of ICH caused by amyloid angiopathy, is that it occurs typically in areas near the surface of the brain, in a distribution typically referred to as “lobar."
Who gets amyloid angiopathy?The risk factors for developing amyloid angiopathy are far from obvious. The only clear risk factor at this time appears to be age, as amyloid deposits are commonly found in people who are older than 55. An association between some forms of the apolipoprotein E gene and amyloid angiopathy has also been reported, but as of late 2008, the meaning of this association remains speculative.
How is amyloid angiopathy diagnosedThe most reliable method used to diagnose amyloid angiopathy is a brain biopsy. Because a biopsy is a surgical procedure that carries a certain risk of bleeding and/or infection, biopsies are not performed unless they are absolutely necessary. Fortunately, physicians can now make a presumptive diagnosis of amyloid angiopathy using a form of MRI called "the gradient echo" (GRE), which is a very efficient test for bleeding in the brain regardless of whether the bleeding is small or large or whether it took place hours or years before. The characteristic appearance of amyloid angiopathy on GRE is commonly referred to as “cortical cerebral microbleeding."
What are the symptoms of amyloid angiopathy?The symptoms of amyloid angiopathy vary depending on how much bleeding is caused by the damaged blood vessels. When bleeding is small, there may be no symptoms at all. In some cases, the symptoms can be vague, causing a progressive loss of memory or a mild deficit in brain function, such as blurry vision. When bleeding is large, though, there can be major neurological symptoms that include hemiparesis, hemiplegia, loss of consciousness, seizures, coma and even death.
How is amyloid angiopathy treated?Once bleeding in the brain has occurred, the treatment of ICH due to amyloid angiopathy is no different from the treatment of ICH due to any other cause. First, if bleeding causes increased intracerebral pressure (ICP), from swelling or mass effect, doctors may need to perform emergent surgery or implement other measures to relieve the ICP. Doctors also treat patients with antiseizure medicines in order to prevent seizures. If bleeding is small but significant enough to cause stroke symptoms, doctors monitor patients for one or more days in the intensive care unit until they become stable.
At the present time, there is little that can be done to reverse amyloid protein deposition. People who are diagnosed with this disorder, however, should maintain normal blood pressure and avoid blood thinners, such as aspirin or plavix, as these can increase their risk of bleeding in the brain.
Fazekas F, Kleinert R, Roob G, Kleinert G, Kapeller P, Schmidt R, Hartung HP. Histopathologic analysis of foci of signal loss on gradient-echo T2*-weighted MR images in patients with spontaneous intracerebral hemorrhage: evidence of microangiopathy-related microbleeds. AJNR Am J Neuroradiol. 1999; 20: 637–642
Smith EE, Eichler F. Cerebral amyloid angiopathy and lobar intracerebral hemorrhage. Arch Neurol. 2006 Jan;63(1):148-51.
Steven M. Greenberg, MD, PhD; Megan E. Briggs, BA; Bradley T. Hyman, MD, PhD; George J. Kokoris, MD, PhD; Constantino Takis, MD; Daniel S. Kanter, MD; Carlos S. Kase, MD Michael S. Pessin, MD; Apolipoprotein E 4 Is Associated With the Presence and Earlier Onset of Hemorrhage in Cerebral Amyloid Angiopathy Stroke. 1996;27:1333-1337