Comment

This patient fulfils the modified Boston criteria for probable cerebral amyloid angiopathy: age ≥55 years, with multiple haemorrhages restricted to lobar, cortical or subcortical brain regions (cerebellar allowed), focal or disseminated superficial siderosis and no other identified cause of cerebral haemorrhage.

The brain's perivascular spaces are a normal elimination pathway for interstitial fluid and toxic solutes, including amyloid-beta. Dilatation of perivascular spaces on MRI is now recognised as being associated with small vessel disease; associated factors include ageing, diabetes mellitus, hypercholesterolaemia, smoking and hypertension.

Dilatation of the perivascular spaces in the cerebral white matter in cerebral amyloid angiopathy may relate to impaired interstitial fluid drainage due to amyloid deposition in superficial cortical and leptomeningeal or peforating white matter arterioles.2 Their detection on MR scanning may be a promising new marker of cerebral amyloid angiopathy. Hypertensive vasculopathy is more strongly associated with basal ganglia perivascular spaces, whereas in cerebral amyloid angiopathy they are more distributed in the hemisphere white matter.2

Cerebral amyloid angiopathy is an important cause of cognitive decline; clinicians thus need a high index of suspicion in patients with unexplained cognitive impairment. Appropriate blood-sensitive MRI sequences (e.g. gradient echo T2* or susceptibility weighted imaging) should become routine in elderly patients with cognitive impairment, since they can reveal cerebral microbleeds and cortical superficial siderosis as low-signal abnormalities.

In this case, centrum semiovale perivascular spaces prompted us to request further MR scans with blood-sensitive MRI sequences. The imaging findings changed her clinical management, since secondary prevention in cerebral amyloid angiopathy involves antihypertensives and avoidance of antithrombotic medications; disease-modifying treatments including a monoclonal antibody targeting vascular amyloid are also under investigation (see: http://clinicaltrials.gov/ct2/show/NCT01821118).