Its kind of a "exploding head" syndrome and I have had it. Usually if I have been under stress or have lack of sleep (as in last Jan when my mom died). I described it as "an electric shock between my ears with a loud WHOOSH that actually knocks me off balance". I was under the understanding its a brain stem issue. I told my MS doc and she said she was familiar with it in her patients, but I suspect other types of disorders can cause this too. I saw an episode of "House" where they suspected a young boy of MS who exibited symptoms of "exploding head". I really hated this feeling and I never knew when it was going to hit me. It was very fast and I even think I lost vision for a split second.
I posted here one time asking if anyone else has had it.