Clinical and cerebral blood flow studies in patients with intracranial hemorrhage and amyloid angiopathy typical of Alzheimer's disease

Impact of the biological definition of Alzheimer's disease using amyloid, tau and neurodegeneration (ATN): what about the role of vascular changes, inflammation, Lewy body pathology?

BACKGROUND

The NIA-AA research framework proposes a biological definition of Alzheimer's disease, where asymptomatic persons with amyloid deposition would be considered as having this disease prior to symptoms.

DISCUSSION

Notwithstanding the fact that amyloid deposition in isolation is not associated with dementia, even the combined association of amyloid and tau pathology does not inevitably need to dementia over age 65. Other pathological factors may play a leading or an accelerating role in age-associated cognitive decline, including vascular small vessel disease, neuroinflammation and Lewy Body pathology.

CONCLUSION

Research should aim at understanding the interaction between all these factors, rather than focusing on them individually. Hopefully this will lead to a personalized approach to the prevention of brain aging, based on individual biological, genetic and cognitive profiles.

Cerebral amyloid angiopathy-associated intracerebral hemorrhage: pathology and management

Amyloid angiopathy-associated intracerebral hemorrhage (ICH) comprises 12%-15% of lobar ICH in the elderly. This growing population has an increasing incidence of thrombolysis-related hemorrhages, causing the management of hemorrhages associated with cerebral amyloid angiopathy (CAA) to take center stage. A concise reference assimilating the pathology and management of this clinical entity does not exist. Amyloid angiopathy-associated hemorrhages are most often solitary, but the natural history often progresses to include multifocal and recurrent hemorrhages. Compared with other causes of ICH, patients with CAA-associated hemorrhages have a lower mortality rate but an increased risk of recurrence. Unlike hypertensive arteriolar hemorrhages that occur in penetrating subcortical vessels, CAA-associated hemorrhages are superficial in location due to preferential involvement of vessels in the cerebral cortex and meninges. This feature makes CAA-associated hemorrhages easier to access surgically. In this paper, the authors discuss 3 postulates regarding the pathogenesis of amyloid hemorrhages, as well as the established clinicopathological classification of amyloid angiopathy and CAA-associated ICH. Common inheritance patterns of familial CAA with hemorrhagic strokes are discussed along with the role of genetic screening in relatives of patients with CAA. The radiological characteristics of CAA are described with specific attention to CAA-associated microhemorrhages. The detection of these microhemorrhages may have important clinical implications on the administration of anticoagulation and antiplatelet therapy in patients with probable CAA. Poor patient outcome in CAA-associated ICH is associated with dementia, increasing age, hematoma volume and location, initial Glasgow Coma Scale score, and intraventricular extension. The surgical management strategies for amyloid hemorrhages are discussed with a review of published surgical case series and their outcomes with a special attention to postoperative hemorrhage.

Postoperative outcome of cerebral amyloid angiopathy-related lobar intracerebral hemorrhage: case series and systematic review

BACKGROUND

Despite its accessible superficial location, the indication for surgical evacuation in cases of lobar intracerebral hemorrhage (LICH) suspected to be related to cerebral amyloid angiopathy (CAA) is controversial because of advanced patient age and concerns about postoperative hemostasis.

OBJECTIVE

To examine factors associated with postoperative outcome in CAA-related LICH.

METHODS

Review of consecutive patients with pathologically proven CAA who underwent LICH evacuation at Saint Marys Hospital, Rochester, Minnesota, between 1987 and 2006. End points were length of stay and postoperative outcome at discharge and last follow-up using the Glasgow Outcome Scale. We also performed a systematic review of all published studies evaluating the outcome of surgically treated CCA-related LICH published between 1984 and 2010.

RESULTS

We identified 23 patients with CAA-related LICH treated surgically. Favorable outcome (Glasgow Outcome Scale >3) at discharge was noted in 5 patients (22%), and at 6- to 12-month follow-up (n = 15) in 7 patients (47%). Three (13%) died in the hospital, including 1 of 4 patients with postoperative hemorrhage. Intraventricular hemorrhage (IVH) was associated with poor outcome at discharge. Older age (≥75 years), history of hypertension, and degree of preoperative midline shift were associated with more prolonged length of stay. In our systematic review, we identified 14 studies including 278 cases. Overall mortality rate was 25%, and poor postoperative outcome was associated with older age, IVH, and preoperative dementia.

CONCLUSION

Neurosurgical evacuation may be performed with acceptable safety in patients with CAA-related LICH. A systematic literature review indicates that older age, preexistent dementia, and presurgical IVH portend poor postoperative outcome.

Outcome of cerebral amyloid angiopathic brain haemorrhage

BACKGROUND

Abnormal amyloid protein can be deposited in the wall of cerebral arteries leading to fragility and intracerebral haematoma in patients with cerebral amyloid angiopathy. Diagnosis can be done only histologically. The indication of surgically treating intracerebral haemorrhage caused by amyloid angiopathy is controversial. There are studies showing a high mortality and a high rate of recurrent bleeding. Others show almost no recurrent bleeding and a very low mortality and a third party states that even when recurrent intracerebral haemorrhage occurs, re-evacuation should be performed. In the present retrospective study a population of 99 patients suffering from cerebral amyloid angiopathy-related cerebral haemorrhage has been studied, to investigate the surgical outcome.

METHOD

Ninety-nine patients were histologically diagnosed with cerebral amyloid angiopathy in our department from 1991-2004. The outcome has been established by the Glascow Outcome Score.

FINDINGS

It could be shown that intraventricular bleeding and age >75 years increased the mortality after operative evacuation. Recurrent bleeding occurred in 22% of patients. After re-evacuation at least half of the patients survived leading to the suggestion to re-operate a recurrent bleeding since patients have a chance to survive even when the Glascow Outcome Score is 3. The overall mortality in the observed population was 16% and 11% had a very good neurological recovery based on a Glascow Outcome Score of 4-5. The operative outcome in amyloid angiopathy related intracerebral haemorrhage is similar to this of intracerebral haemorrhage induced by other causes like hypertensive bleeding.

CONCLUSIONS

Possible cerebral amyloid angiopathy is no contraindication for evacuation of brain-haematoma, and especially not in patients younger than 75 years old without an intraventricular haemorrhage.

Cerebral vessels in ageing and Alzheimer's disease

The integrity of the cerebral vasculature is crucial to the maintenance of cognitive functions during ageing. Prevailing evidence suggests that cerebrovascular functions decline during normal ageing, with pronounced effects in Alzheimer's disease (AD). The causes of these changes largely remain unknown. While previous studies recorded ageing-related impairments, such as atherosclerosis and loss of innervation in basal surface arteries of the brain, it only recently has been realized that a number of subtle alterations in both the intracranial resistance vessels and the smaller capillaries is apparent in both ageing animals and humans. The dominant changes include alterations in composition of connective tissues and smooth muscle of large vessel walls, thickening of the vascular basement membrane, thinning of the endothelium in some species, loss of endothelial mitochondria and increased pericytes. Some of these attributes appear more affected in AD. Other abnormalities entail profound irregularities in the course of microvessels, unexplained inclusions in the basement membrane and changes in unique proteins and membrane lipids associated with the blood-brain barrier. Brain imaging and permeability studies show no clear functional evidence to support the structural and biochemical anomalies, but it is plausible that focal and transient breach of the blood-brain barrier in ageing, and more notably in AD, occurs. Thus, circumscribed neuronal populations in certain brain regions could become vulnerable. Furthermore, the characteristic deposition of amyloid in vessels in AD may exacerbate the decline in vascular function and promote chronic hypoperfusion. Although not explicit from current studies, it is likely that the brain vasculature is continually modified by growth and repair mechanisms in attempts to maintain perfusion during ageing and disease.