Every once in a while, there's a post here on TM about air leaking through someone's nose while playing the trumpet. This is something called "stress velopharyngeal insufficiency". For some, it is an occasionally problem. But for others, as in the story below, it can be a more persistent issue. For those in the latter category, the video also talks about a potential new treatment option.
Operation to ovation for Minn. oboist - KMSP-TV