Ataxia -Numbness- MRI says "No Stroke"

I am having episodes of Ataxia in the mornings lasting a few hours, have numbess on right side of my tongue, mild headache, feels like a cap is sitting on my head and nothing is there. I had an MRI today, no contrast and it was normal.  I am being scheduled for a MRA.  What will this show that will benefit and what could be happeing.  Very confused as the Ataxia is severe in the mornings and gets better during the day. Can some one help explaing what the MRA may show that the MRI didn't? Thank you