Just got my mri report. it says multiple (greater than 25) small abnormal t2/flair signal throughout the periventricular deep and subcortical whitemat?

There are a: number of causes of white matter lesions, impossible to make a determination based solely on the fact that they are there. Your doctor needs to correlate the size/distribution/number of lesions in the context of your clinical picture. Various possibilities include demyelinating processes(e.g. MS), vasculitides, and inflammatory/infectious processes(e.g. Lyme disease).