Case Presentation: An 85-year-old female presented to the ED with a chief concern of altered mental status from her previous baseline cognitive status a few hours prior. The patient’s medical history was significant for dementia, type 2 diabetes mellitus, and hypothyroidism. Initial exam revealed a confused but cooperative patient, A&Ox2 (self and time), discoloration of the skin on the dorsal side of the foot and well-demarcated erythema with significant overlying scale bilaterally with no other notable findings. The patient was hypertensive upon arrival 167/64, respiratory rate 18 and oxygen saturation 95% on room air. BMP was without acute abnormalities and no clear signs of infection were noted. Patient experienced urinary incontinence and gross hematuria and CT abdomen/pelvis revealed bladder distension for which a bladder scan was performed and demonstrated 1L of urine. CT chest revealed no pulmonary consolidation or edema and no pleural effusion. CT head without contrast revealed changes of advancing chronological age without evidence of acute abnormality identified. MRI of the brain demonstrated multiple small foci of remote hemosiderin deposition involving the bilateral cerebral hemispheres with superimposed small regions of superficial siderosis suspected involving the parasagittal and posterolateral left frontal lobe. Additional findings included abnormal hyperintense regions of parenchymal edema predominantly involving the subcortical white matter of multiple brain lobes, findings reflecting manifestation of underlying CAA-ri. The patient completed a 5-day course of IV methylprednisolone with plans for a steroid taper outpatient. The patient was also treated with IV cefazolin for possible non-purulent cellulitis. Following these measures, the patient returned to her cognitive baseline per family and was discharged to follow up with neurology outpatient.
Discussion: CAA-ri is a subtype of CAA theorized to be an autoimmune response caused by anti-amyloid beta (Aβ) antibodies in the CSF of patients with cerebral amyloid plaques (1). It often presents as a rapidly progressing dementia, rather than with hemorrhagic stroke as patients with CAA without related inflammation typically do (2). These patients are important to identify as treatment with high-dose corticosteroids has been shown to eliminate symptoms in up to 55% of patients (3). Historically, a brain biopsy was needed to confirm the diagnosis of CAA-ri, but in recent years, guidelines for diagnosis via MRI have been shown to be highly reliable (4). This patient’s advanced age makes her an uncommon presentation of CAA-ri as the average age of onset is 67 years. Her lack of seizure and headache, each of which are reported in 32% of cases is also unique(3).
Conclusions: New guidelines have made CAA-ri a much easier diagnosis to make which may broaden the demographics of patients who are diagnosed with CAA-ri (4). It is important to recognize CAA-ri as a potential cause of acute AMS and confusion, particularly in patients with underlying dementia or Alzheimer’s Disease, as symptoms can be successfully managed with corticosteroids.
