I read sections of an excellent survey paper last night as well as the Medline Plus entry. In short, a certain type of protein (that is also related to Alzheimer's Disease) builds up on the walls of her brain arteries. Capillaries respond by breaking on the surface of her brain, leading to weird physical sensations. With time a larger break can be expected, which would be a hemorrhagic stroke. There are no lifestyle implications: no eat this, don't eat that, exercise, rest injunctions.
It's clearly early in the understanding of this condition: the only way folks could know about such conditions until recently was postmortem studies. With imaging advancements, observation of the conditions can be done. I gather that awareness has been driven in Alzheimer's research.
I'm grieving a bit: if this is the continued diagnosis, it points to a shorter rather than longer time with Mom. I'm not surprised, and i ponder whether there's some relief. Alzheimer's disease's cognitive decline is a particularly rough memory erasure, whereas ... this is random?
 Charidimou, Andreas, Andre Peeters, Zoe Fox, Simone M. Gregoire, Yves Vandermeeren, Patrice Laloux, Hans R. Jäger, Jean-Claude Baron, and David J. Werring. “Spectrum of Transient Focal Neurological Episodes in Cerebral Amyloid Angiopathy: Multicentre Magnetic Resonance Imaging Cohort Study and Meta-Analysis.” Stroke 43, no. 9 (September 2012): 2324–30. https://doi.org/10.1161/STROKEAHA.112.657759.
 Banerjee, Gargi, Roxana Carare, Charlotte Cordonnier, Steven M Greenberg, Julie A Schneider, Eric E Smith, Mark van Buchem, Jeroen van der Grond, Marcel M Verbeek, and David J Werring. “The Increasing Impact of Cerebral Amyloid Angiopathy: Essential New Insights for Clinical Practice.” Journal of Neurology, Neurosurgery & Psychiatry 88, no. 11 (November 2017): 982–94. https://doi.org/10.1136/jnnp-2016-314697.