I get numbness on left side of face that lasts a few seconds, then goes away, at least once a day. permanent numbness on chin +lower lip. mra, mri neg?

Sensory neuropathy: You've had evaluation without a diagnosis. That can be worrisome and frustrating, but some of our most confounding problems are in the category of neuropathies -- nerve dysfunctions, which sometimes have no clear underlying cause. Continue to follow up with your neurologist, as this may evolve to a more identifiable syndrome.