Never heard of this connection either so did a little searching tonight and found these:
1.)Studies on cytomegalovirus and Epstein-Barr virus infection in moyamoya disease. Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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2.)Then I saw this: Q8 Is moyamoya disease infectious? How to prevent it.
A8 The etiology of moyamoya disease is unknown. In 70's and 80', it was believed that the preceding infection (either bacterial or viral) might be related to moyamoya disease. However, this was not proven. Now, it is believed that moyamoya disease is not infectious, thus it is unnecessary to care about it. You should not think that moyamoya disease is infectious and dangerous because it is not so. Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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3.) I also saw several articles, some fairly current, "perhaps" linking the two in a publication called "Current Opinion in Neurology" which requires special access to read the full text.
My

is who the heck knows for sure but, that said, it sure does seem strange to me that if viral infections did have a positive link to MM then wouldn't more neurologists/neurosurgeons (especially those with a lot of MM experience) be doing something about those viral infections?

I would be highly interested to have your doctor tell you, and then please relay that to us, exactly where/what he is reading this all from.
Interesting theory is about all I can say at this point.