Introduction
Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder marked by amyloid beta-peptide accumulation in the leptomeninges and small-sized cerebral blood vessels. Amyloid deposition causes fragile vessels, which can result in lobar intracerebral hemorrhages (ICH). Cognitive impairments, hemosiderosis, incidental microbleeds, inflammatory leukoencephalopathy, Alzheimer's disease, or transient neurological symptoms may also occur. It can happen in certain familial syndromes or sporadically. A combination of clinical, radiographic, and pathological findings is used to diagnose. However, a postmortem examination of the brain is required for a definitive diagnosis. There are currently no disease-modifying treatments available. The prognosis is determined by the characteristics of the CAA, with worse consequences in patients with large hematomas and older patients.
What Causes Cerebral Amyloid Angiopathy?
The precise cause of cerebral amyloid angiopathy is unknown. CAA is distinguished by the presence of congophilic material (amyloid-beta peptide) in the leptomeninges and small to medium-sized cerebral blood vessels. This deposition weakens vessel walls, increasing their vulnerability to bleeding. Cerebral amyloid angiopathy is classified as sporadic (spontaneous), familial, or iatrogenic.
Familial Cerebral Amyloid Angiopathy:
Familial cerebral amyloid angiopathy refers to a group of extremely rare disorders that are almost always autosomal dominant. Many of these disorders are limited to a few families and differ from spontaneous CAA in that they manifest at a younger age, typically in the middle to late middle years. They may also be a component of multi-system or other central nervous system genetic disorders.
Here are some examples of familial CAA:
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CAA is linked to familial Alzheimer's disease by the Aß peptide and the precursor protein APP (chromosome 21).
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CAA in Down syndrome is a hereditary cerebral hemorrhage accompanied by amyloidosis (Dutch, Flemish, Italian, Piedmont, Iowa, and Arctic types).
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ACys peptide with precursor protein cystatin C (chromosome 20) is an Icelandic-type hereditary cerebral hemorrhage with amyloidosis.
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ATTR peptide with transthyretin precursor protein (chromosome 18) is referred to as meningovascular amyloidosis.
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AGel peptide and the precursor protein gelsolin (chromosome 9) is familial amyloidosis of the Finnish type.
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Gerstmann-Straussler-Scheinker disease is caused by PrPSc peptide and precursor prion protein (chromosome 20).
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ABri peptide in combination with a precursor protein The ABri precursor protein (chromosome 13) is linked to familial British dementia.
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ADan peptide in combination with a precursor protein ADAN (chromosome 13) precursor protein is referred to as familial Danish dementia.
Sporadic Cerebral Amyloid Angiopathy:
The factors that cause amyloid beta-peptide deposition in the elderly patient population are not well understood. Some evidence suggests a connection with apolipoprotein E. (APOE). According to the findings, patients with APOE epsilon 2 or epsilon 4 alleles appear to be at higher risk for cranial hemorrhages than the general population. In most cases (90 %), autopsies of patients with Alzheimer's disease revealed cerebral amyloid angiopathy. This rate remains high (20 to 40 %) in non-demented elderly people.
Iatrogenic Cerebral Amyloid Angiopathy:
Iatrogenic cerebral amyloid angiopathy is a rare but increasingly recognized form of prion disease caused by the transmission of A seeds during surgical procedures such as exposure to cadaveric dura or growth hormone. It is thought to manifest clinically approximately three decades after transmission.
What Are the Symptoms of Cerebral Amyloid Angiopathy?
CAA can result in brain bleeding. The cortex, or outer parts of the brain, are more prone to bleeding than the deep areas. Symptoms arise as a result of brain tissue damage caused by bleeding. Some people experience gradual memory loss. When a CT scan is performed, there are frequent signs that they have had unnoticed bleeding in the brain.
If there is a lot of bleeding, the immediate symptoms look like a stroke. These are some of the symptoms:
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Drowsiness.
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Headache (usually in a specific part of the head).
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Changes in the nervous system can occur suddenly, such as confusion, double vision, delirium, sensation changes, decreased vision, weakness, speech problems, or paralysis.
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Coma or stupor (rarely).
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Vomiting.
If the bleeding is not severe or widespread, the following symptoms may occur:
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Episodes of confusion.
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Intermittent headaches.
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Mental function decline (dementia).
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Weaknesses or strange sensations come and go and affect smaller areas.
How Is Cerebral Amyloid Angiopathy Diagnosed?
CAA is difficult to diagnose without brain tissue. This is typically done after death or when a brain's blood vessels are biopsied. A physical exam may be normal if the bleeding is minor. However, there may be some changes in brain function. The doctor should ask detailed questions regarding the symptoms and medical history. The doctor may suspect CAA based on the symptoms and results of the physical exam and any imaging tests.
The following imaging tests of the head may be performed:
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A CT (computed tomography) or MRI (magnetic resonance imaging) scan will be performed to check for brain bleeding.
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MRA (magnetic resonance angiography) scan to rule out other causes of bleeding and check for large bleeds
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A PET (positron emission tomography) scan will be performed to look for amyloid deposits in the brain.
How Is Cerebral Amyloid Angiopathy Treated?
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There is currently no effective treatment for cerebral amyloid angiopathy. The purpose of treatment is to alleviate symptoms. Rehabilitation may be required in some cases due to weakness or clumsiness. Physical, occupational, or speech therapy may be included.
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Medicines that help to improve memory, such as those used to treat Alzheimer's disease, are sometimes used. In addition, seizures, also known as amyloid spells, can be treated with anti-seizure medications.
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ICH associated with CAA is a common occurrence. Because of this high rate, clinicians usually avoid antiplatelet agents and anticoagulants unless there is a strong indication for anticoagulation.
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Finally, there is limited evidence that immunosuppression can help treat the inflammatory forms of CAA. Pulsed cyclophosphamide or glucocorticoids have been shown in small trials to result in long-term clinical improvement. Other immunosuppressive medications, such as mofetil, mycophenolate, and methotrexate, have also been linked to benefits.
What Is the Prognosis of Cerebral Amyloid Angiopathy?
The prognosis of cerebral amyloid angiopathy varies, but the location and size of the ICH are important factors. Unfavorable outcomes are linked to larger hematoma sizes and the patient's age (above 75 years). Positive ICH outcomes are associated with ventricle sparing and a superficial location. The mortality rate ranges from 10 to 30 %, with patients with increased consciousness and smaller hematomas (50 mL) having the best prognosis. Compared to a hypertensive hemorrhage, CAA has a higher risk of recurrence. According to studies, recurrence rates are around 21%.
CAA is frequently associated with transient and cognitive neurological impairment. Transient neurological symptoms include brief, recurring bouts of numbness, paresthesias, and weakness. The pathogenesis is unknown, but symptoms are typically only transient. Simultaneously, cognitive impairments have revealed decreased cognitive speed and episodic memory loss. Surprisingly, Alzheimer's and CAA frequently coexist. In addition, CAA has also been associated with vascular dementia.
Conclusion
CAA is a type of angiopathy in which amyloid peptides deposit in the walls of small to medium blood vessels in the central nervous system and the meninges. Amyloid deposition causes fragile vessels, which can result in brain bleeds. Presently no cure is available and the condition is managed by symptomatic treatment. If a person has a sudden loss of movement, sensation, vision, or speech, a doctor must be consulted immediately to prevent complications.
