Cerebral amyloid angiopathy-related inflammation: a case report presenting with a rare variant in SORL1 gene

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a rare clinical entity, characterized by headaches, seizures, rapidly progressive cognitive decline, behavioral changes and magnetic resonance imaging (MRI) findings underlying the autoimmune and inflammatory reaction at the level of CAA-affected vessel. CAA-ri is likely responsive to corticosteroid. MRI shows asymmetric and multifocal white matter hyperintensity (WMH) lesions and multiple cerebral microbleeds. Apolipoprotein E (ApoE) ε4 homozygosity is associated with CAA-ri strongly [Neurology 68(17):1411-1416, 2007, Ann Neurol 73(4):449-458, 2013, J Alzheimers Dis 44(4):1069-1074, 2015]. SORL1 processes a causal involvement in Alzheimer's disease (AD) as a proposed modulator of the amyloid precursor protein (APP). It is unclear whether SORL1 is involved with CAA-ri or not.

A 48-year-old woman suffered from a one-day history of a headache, nausea, and vomiting. Neurological examination revealed normal. We diagnosed this case as probable CAA-ri according to the clinic manifestations and MRI. Gene detection indicated a rare variant in SORL1 and ApoE ε4 homozygosity. When treated with corticosteroid, the patient's clinical symptoms and MRI manifestations were almost relieved. However, when keeping the corticosteroid withdrawal for three months, the patient relapsed with a headache and typical images on MRI emerged. Corticosteroid therapy was effective again. Unfortunately, susceptibility weighted imaging (SWI) showed increased microbleeds. With tapering corticosteroid slowly, no recurrence was found on this patient with four-month follow-up.

A variant of SORL1 may be associated with CAA-ri, recurrence of disease could be detected with MRI by an increased microbleeds. Our case report suggests that corticosteroid therapy might be effective for CAA-ri.