Pathologic processes leading to cerebral hemorrhage in amyloid angiopathy

Plaque formation and the intraneuronal accumulation of β-amyloid in Alzheimer's disease

Amyloid plaques and neurofibrillary tangles (NFTs) in the brain are the neuropathological hallmarks of Alzheimer's disease (AD). Amyloid plaques are composed of β-amyloid peptides (Aβ), while NFTs contain hyperphosphorylated tau proteins. Patients with familial AD who have mutations in the amyloid precursor protein (APP) gene have either increased production of Aβ or generate more aggregation-prone forms of Aβ. The findings of familial AD mutations in the APP gene suggest that Aβ plays a central role in the pathophysiology of AD. Aβ42, composed of 42 amino acid residues, aggregates readily and is considered to form amyloid plaque. However, the processes of plaque formation are still not well known. It is generally thought that Aβ is secreted into the extracellular space and aggregates to form amyloid plaques. Aβ as extracellular aggregates and amyloid plaques are thought to be toxic to the surrounding neurons. The intraneuronal accumulation of Aβ has more recently been demonstrated and is reported to be involved in synaptic dysfunction, cognitive impairment, and the formation of amyloid plaques in AD. We herein provide an overview of the process of the intraneuronal accumulation of Aβ and plaque formation, and discuss its implications for the pathology, early diagnosis, and therapy of AD.

Subcortical hematoma caused by cerebral amyloid angiopathy: does the first evidence of hemorrhage occur in the subarachnoid space?

Six autopsy cases of subcortical hematoma caused by CAA were examined to elucidate the primary site of hemorrhage. Immunohistochemistry for amyloid beta-protein (A beta) revealed extensive CAA in the intrasulcal meningeal vessels rather than in the cerebral cortical vessels. All of the examined cases had multiple hematomas in the subarachnoid space, mainly in the cerebral sulci, as well as intracerebral hematomas. Each intracerebral hematoma was connected to the subarachnoid hematomas at the depth of cerebral sulci or through the lateral side of the cortex. There was no debris of the cerebral cortical tissue in the subarachnoid hematomas. In case 2, another solitary subarachnoid hematoma, which was not connected to any intracerebral hematoma, was seen. In all of these subarachnoid hematomas, many ruptured A beta-immunopositive arteries were observed. These ruptured arteries did not accompany any debris of the brain tissue, some of them were large in diameter (250-300 microm), and several of them were far from the cerebral cortex. Therefore, it was considered that they were not cortical arteries but meningeal arteries. Within the cerebral cortex, there were only a few ruptured arteries associated with small hemorrhages. There were no ruptured vessels within the intracerebral hematomas. There was a strong suggestion that all of the subarachnoid hematomas, including the solitary one in case 2, originated from the rupture of the meningeal arteries. The present study indicates that in some cases of subcortical hematoma caused by CAA, the primary hemorrhage occurs in the subarachnoid space, in particular the cerebral sulci, because of rupture of multiple meningeal arteries. Infarction occurs subsequently in the cortex around the hematoma, the hematoma penetrates into the brain parenchyma, and finally, a subcortical hematoma is formed.

Cerebral amyloid angiopathy: an overview

Cerebral amyloid angiopathy (CAA) is characterized by amyloid deposition in cortical and leptomeningeal vessels. Several cerebrovascular amyloid proteins (amyloid beta-protein (Abeta), cystatin C (ACys), prion protein (AScr), transthyretin (ATTR), gelsolin (AGel), and ABri (or A-WD)) have been identified, leading to the classification of several types of CAA. Sporadic CAA of Abeta type is commonly found in elderly individuals and patients with Alzheimer's disease. Cerebral amyloid angiopathy is an important cause of cerebrovascular disorders including lobar cerebral hemorrhage, leukoencephalopathy, and small cortical hemorrhage and infarction. We review the clinicopathological and molecular aspects of CAA and discuss the pathogenesis of CAA with future perspectives.

Postoperative outcome of 37 patients with lobar intracerebral hemorrhage related to cerebral amyloid angiopathy

BACKGROUND AND PURPOSE

Several recent studies have suggested that neurosurgical procedures are not contraindicated in patients with cerebral amyloid angiopathy (CAA). The purpose of this study was to elucidate the clinical factors influencing the outcome of patients with CAA-related intracerebral hemorrhage (ICH) treated surgically.

METHODS

A total of 50 neurosurgical procedures (42 intracerebral hematoma evacuations, 4 ventriculoperitoneal shunts, 3 ventricular drainages, and 1 brain biopsy) were performed in 37 patients with CAA-related ICH. To ascertain the clinical factors that may influence their postoperative outcome, their clinical data (demographics, medical history, recurrent lobar hemorrhage, radiographic characteristics, multiple lobar hemorrhage, surgical details, and postoperative hemorrhage) were examined retrospectively and subjected to multivariate analysis.

RESULTS

Twenty patients (54%) had a good outcome, and only 4 (11%) died. Parietal hematomas, advanced age (>/=75 years), and intraventricular hemorrhages had significant adverse influence on the postoperative outcome. Clinically significant postoperative hemorrhage requiring evacuation occurred after 2 (5%) of 42 intracerebral hematoma evacuations. Postoperative hemorrhage did not have significant adverse influence on the outcome.

CONCLUSIONS

Neurosurgery can be performed relatively safely in patients with CAA-related ICH, and their postoperative outcome is better than that reported previously. Surgical treatment should be considered for such patients aged <75 years without a parietal hematoma and intraventricular hemorrhage.