Clinical History
A 78-year-old normotensive male patient with temporal and spacial disorientation, unable to find known places and objects.
Imaging Findings
- Admission unenhanced axial CT demonstrated an acute hemorrhage in the left parietal lobe.
- MRI showed diffuse white matter hyperintensity on T2-weighted and T2 FLAIR sequences probably related to diffuse small-vessel disease. Also, T2 FLAIR showed the left parietal lobe hemorrhage.
- Susceptibility weighted imaging (SWI) demonstrated the left parietal lobe haemorrhage but also multiple small focal regions of signal drop out ("black dot") consistent with chronic microhaemorrhages and also linear hypointensities due to superficial haemosiderin deposits (cortical superficial siderosis).
Discussion
- The cerebral amyloid angiopathy (CAA) is an important cause of cerebrovascular disorders in elderly non-hypertensive patients. It is a condition characterised by deposits of beta-amyloid within small cerebral and leptomeningeal vessels. [1]
- The diagnosis is made following the Boston criteria which specify four different diagnostic categories: definite CAA, probable CAA with supporting pathologic evidence, probable CAA, and possible CAA, depending on a combination of clinical, imaging, and histologic data. A “definite” diagnosis of CAA is only made postmortem. In our institution we made the diagnosis of probable CAA. [2]
- Typical radiographic features include cerebral haemorrhage, microhaemorrhages seen with SWI sequences and ischaemic leukoencephalopathy seen on T2 and T2FLAIR sequences.
Cortical superficial siderosis may be seen in up to 60% of patients. [3, 4]
- Microhaemorraghes have a typical peripheral distributions, in comparison to hypertensive microangiopathy that shows a central pattern.
- Pathologic tissue obtained at haematoma evacuation was positive for CAA.
- In conclusion, microhaemorrhages may not be seen on CT. Magnetic resonance imaging (MRI), specially susceptibility weighted imaging (SWI) sequences are the modality of choice to detect small cortical haemorrhages. SWI sequences requires only a few minutes and should be included in routine neuroimaging protocols.
Differential Diagnosis List
Cerebral amyloid angiopathy.
Hypertensive microangiopathy.
Multiple cavernoma syndrome.
Final Diagnosis
Cerebral amyloid angiopathy.