***UPDATE - February 25, 2019***
Wifey had 4th MRI about a month ago. Our surgeon at Keck USC reviewed last Friday. Slight growth of about 1mm of all three dimensions but surgeon's review with us said this is normal and not to be concerned at this time. So, 5th MRI will be done end of this year unless, of course, she develops ringing in ear, loss of balance, further loss of hearing.
So, hope this information helps. Best wishes to all you good people.