Cerebral amyloid angiopathy. The Boston criteria.

Clinical History

Normotensive 75-year-old woman presented with abrupt onset of disorientation and difficulty to speak.

Imaging Findings

Normotensive 75-year-old woman presented with abrupt onset of disorientation and difficulty to speak. The magnetic resonance shows a left parietal lobar haemorrhage located at the cortico-subcortical region. The lesion is heterogeneous on T1-Weighted MRI (figure 1) due to different stages of evolution of the haemorrhage. T2-weighted MRI (figure 2) shows the lesion with surrounding edema. On T2-weighted (figure 3)and FLAIR (figure 4) MR images we can see multiple high signal intensity areas (leukoencephalopathy). Axial GRE MR image shows foci of signal loss ("black dot") in cortical-subcortical right parietal lobe (figure 5) and right cerebellum (figure 6). These foci are consistent with chronic microhaemorrhages. The patient underwent cerebral MR angiography (MRA) which demonstrated no evidence of arteriovenous malformation or any pathologic vascular condition.

Discussion

Based on the clinical history (elderly nonhypertensive patient) and the existence of a lobar haemorrhage located at the cortico-subcortical region, multiple high signal intensity areas and foci of signal loss due to microhaemorrhages, we made the diagnosis of “possible” cerebral amyloid angiopathy following the Boston criteria (see Table 1).
Cerebral amyloid angiopathy (CAA) is an important cause of spontaneous cortical-subcortical intracranial haemorrhage (ICH) in the normotensive elderly. CAA is a cerebrovascular disorder characterized by the deposition of ß-amyloid protein in the media and adventitia of small and medium-sized vessels of the cerebral cortex, subcortex, and leptomeninges. CAA should be suggested if lobar haemorrhage is identified with a superficial location and cortical involvement. Haemorrhages that involve the cortex and subcortical white matter within the frontal and parietal lobes are most common. A patient presenting with an acute neurologic deficit or TIA-like symptoms should undergo nonenhanced computed tomography (CT) of the head. Nonenhanced head CT provides crucial information regarding the characteristics of the ICH. If an ICH is present in a cortical-subcortical location suspicious for CAA, the patient should undergo additional evaluation with MR imaging including a gradient-echo (GRE) sequence. GRE is currently the most sensitive MR imaging sequence for detection of the chronic cortical-subcortical microhaemorrhages. Local magnetic field inhomogeneity related to the presence of hemosiderin causes a marked loss of signal at T2*-weighted GRE imaging . These chronic microhaemorrhages can be associated with acute CAA-related ICH, and detection of these chronic microhaemorrhages with GRE imaging increases the probability for CAA. CAA is a vascular disease that is insensitive to detection by MR angiography, conventional angiography, and digital subtraction angiography. Regardless of the size, CAA-related ICH exhibits a distinctive cortical-subcortical distribution that generally spares the deep white matter, basal ganglia, and brainstem. A single large cortical-subcortical ICH in a patient presenting with an acute neurologic deficit is
not entirely specific for a diagnosis of CAA. In the differential diagnosis we must consider that ICH is most commonly caused by hypertension, trauma, bleeding diatheses, illicit drug use (mostly amphetamines and cocaine), and vascular malformations. Other
causes include haemorrhagic tumors, ruptured
aneurysms, and vasculitis. Hypertension is the most common cause of
nontraumatic haemorrhage in adults. In contrast
to the typical cortical-subcortical location of
CAA-related haemorrhage, hypertensive haemorrhages,
both large and small, most commonly occur
in the deep gray matter, such as the basal ganglia
or thalami, or the brainstem. The presence of cortical microhaemorrhages lends specificity in patients presenting with acute ICH, but there are other causes than CAA of multifocal “black dots” , such as traumatic diffuse axonal injury, haemorrhagic metastases and CADASIL. In conclusion, when atrophy and leukoencephalopathy are seen in conjunction with acute or chronic ICH in a cortical-subcortical location and cortical microhaemorrhages, the diagnostic specificity for CAA is increased.

Differential Diagnosis List

Final Diagnosis

"Possible" CAA (based on The Boston criteria).

URL:	https://www.eurorad.org/case/6554
DOI:	10.1594/EURORAD/CASE.6554
ISSN:	1563-4086