i. Symptoms and clinical findings: New cognitive impairment and/or behavioural changes and/or new focal neurological symptoms and/or new headache.

ii. Imaging: Typical findings on cranial MRI—hyperintense, multifocal, round small lesions, at least one of them in the corpus callosum (‘snowball’) in T2 (or FLAIR) weighted sequences.

i. Clinical findings and symptoms not required - BRAO may be silent.

ii. Ophthalmological examination: BRAOs or AWH in fluorescein angiography or characteristic signs of retinal branch ischaemia in funduscopy or SD-OCT.

i. Symptoms and clinical findings: New tinnitus and/or hearing loss and/or peripheral vertigo

ii. Examination of inner ear function: Hearing loss must be supported by an audiogram;§ vestibular vertigo must be supported by specific diagnostics.