Cerebral Amyloid Angiopathy

Synonyms

6

Overview

Cerebral amyloid angiopathy (CAA) is a neurological condition in which amyloid protein is deposited onto the walls of the arteries of the brain (and less frequently, veins). Although CAA often does not cause symptoms, it may cause bleeding into the brain (hemorrhagic stroke), dementia, or neurologic episodes in some patients. The majority of CAA cases occur in individuals who do not have a family history.

It is not associated with systemic amyloidosis. CAA has been recognized as one of the morphologic hallmarks of Alzheimer disease (AD), but it is also often found in the brains of elderly patients who are neurologically healthy. While often asymptomatic, CAA may lead to dementia, intracranial hemorrhage (ICH), or transient neurologic events. ICH is the most recognized result of CAA. Most affected individuals die within a decade after signs and symptoms first appear, although some people with the disease have survived longer.

There are many different types of hereditary cerebral amyloid angiopathy. The different types are distinguished by their genetic cause and the signs and symptoms that occur. The various types of hereditary cerebral amyloid angiopathy are named after the regions where they were first diagnosed.

The Dutch type of hereditary cerebral amyloid angiopathy is the most common form. Stroke is frequently the first sign of the Dutch type and is fatal in about one third of people who have this condition. Survivors often develop dementia and have recurrent strokes. About half of individuals with the Dutch type who have one or more strokes will have recurrent seizures (epilepsy).

People with the Flemish and Italian types of hereditary cerebral amyloid angiopathy are prone to recurrent strokes and dementia. Individuals with the Piedmont type may have one or more strokes and typically experience impaired movements, numbness or tingling (paresthesias), confusion, or dementia.

The first sign of the Icelandic type of hereditary cerebral amyloid angiopathy is typically a stroke followed by dementia. Strokes associated with the Icelandic type usually occur earlier than the other types, with individuals typically experiencing their first stroke in their twenties or thirties.

Strokes are rare in people with the Arctic type of hereditary cerebral amyloid angiopathy, in which the first sign is usually memory loss that then progresses to severe dementia. Strokes are also uncommon in individuals with the Iowa type. This type is characterized by memory loss, problems with vocabulary and the production of speech, personality changes, and involuntary muscle twitches (myoclonus).
Two types of hereditary cerebral amyloid angiopathy, known as familial British dementia and familial Danish dementia, are characterized by dementia and movement problems. Strokes are uncommon in these types. People with the Danish type may also have clouding of the lens of the eyes (cataracts) or deafness.

 

Symptoms

Approximately 87% of individuals with hereditary cerebral hemorrhage with amyloidosis - Dutch type have intracranial hemorrhage (bleeding in the brain) and 13% have infarcts (stroke). The first stroke usually occurs between the ages of 45 and 65 years, and is not caused by hypertension or hemorrhagic diathesis (bleeding tendency). Nausea, vomiting, progressive headache, focal neurological signs (double or decreased vision, speech difficulties, confusion, delirium, weakness or paralysis, sensation changes or loss of sensation, progressive intellectual deterioration and memory disturbance) and impairment of consciousness are the most frequent signs and symptoms. Psychiatric abnormalities, including dementia are also common, with some patients developing dementia without intracranial hemorrhage.

Causes

The clinical symptoms of hereditary cerebral hemorrhage with amyloidosis - Dutch type are caused by the build-up of a protein called amyloid within the arterial walls of the brain. This protein build-up causes bleeding into the brain. The symptoms occur because bleeding in the brain harms brain tissue.

Hereditary cerebral hemorrhage with amyloidosis-Dutch type is an autosomal dominant disorder with complete penetrance (all individuals who inherit the mutated gene will develop the condition). The likely genetic defect is in the amyloid protein precursor protein (APP) gene on chromosome 

Mutations in the APP gene are the most common cause of hereditary cerebral amyloid angiopathy. APP gene mutations cause the Dutch, Italian, Arctic, Iowa, Flemish, and Piedmont types of this condition. Mutations in the CST3 gene cause the Icelandic type. Familial British and Danish dementia are caused by mutations in the ITM2B gene.

  • Most cases of cerebral amyloid angiopathy are sporadic, although genetic predispositions exist (eg, ApoE subtypes confer different risk profiles).
  • Most cases of CAA-related ICH are spontaneous, but they may be related to vessel wall injury by atherosclerosis and hypertension. The risk of intracranial bleeding following head trauma and neurosurgical procedures is increased in patients with CAA. Some evidence suggests that CAA has a role in a substantial proportion of anticoagulant- and thrombolytic-related hemorrhages.
  • Hereditary forms of CAA are due to specific gene mutations.

Diagnosis

Susceptibility weighted imaging has been proposed as a tool for identifying CAA-related microhemorrhages.[17] Biopsies also play a role in diagnosing the condition.

Types:
It is usually associated with amyloid beta.

However, there are other types:

  • the "Icelandic type" is associated with Cystatin C
  • the "British type" is associated with ITM2B

Research is currently being conducted to determine if there is a link between cerebral amyloid angiopathy and ingestion of excessive quantities of aluminum.

Treatment

There is no known effective treatment for hereditary cerebral hemorrhage with amyloidosis - Dutch type. Treatment is supportive and based on the control of symptoms. In some cases, rehabilitation is needed for weakness or clumsiness. This can include physical, occupational, or speech therapy. Occasionally, some patients are good candidates for medications that can help improve memory. The management of intracranial hemorrhage (ICH) related to hereditary cerebral hemorrhage with amyloidosis - Dutch type is identical to the standard management of ICH. The main objectives include reversing anticoagulation, managing intracranial pressure, and preventing complications.

  • Cerebral amyloid angiopathy (CAA) is largely untreatable at this time
  • The management of CAA-related intracranial hemorrhage (ICH) is identical to the standard management of ICH. Pay special attention to reversing anticoagulation, managing intracranial pressure, and preventing complications.
  • If coexisting vasculitis is found on angiography and brain biopsy, long-term treatment (up to 1 y) with steroids and cyclophosphamide is indicated.

Resources

  • NIH
  • Genetics Home Reference