What Does White Matter Lesions On The Brain Found On A MRI Mean?

The lesions could indicate any number of things so a consult with your neurologist would be the best thing because they would be privy to your medical history and can prescribe test that might help pinpoint the problem.  I, also, have numerous diffused white matter lesions on my brain.  I had a recent fall and took a hit to the back of my head and had several childhood illnesses that might have resulted in viral encephalopathy.  I do not fit the MS profile.
Who knows?

I had a stroke 2 years ago. There were white lesions on MRI. I have had another MRI that shows more white lesions, buy no new strokes. Dr. Wants a spinal tap to check for MS. I forgot to tell him I have been bitten many times with ticks recently. Later I found out Lyme disease can cause white brain lesions. Should I call him back before the Spinal tap. Will it check for Lyme disease in spinal tap?

The brain has left hemisphere and right hemisphere. Both these parts contain gray matter and white matter. The white matter are not lesions of any disease. They are part of the brain. The lesions of migraine can be on the whit matter of brain.