My 2 cents
I suffer from mild vertigo I can usually keep it under control.
however I was on a night dive on a small wreck, I had dived the site several times before, I was used to the area I knew where I was and all was going well until I lost my budy and the virtigo kicked in and I started to panic I couldn't tell up from down and my boyancy control started to go a bit strange.
Next thing I know my reg had been kicked out of my mouth and my training kicked in I calmed down recovered my mouthpiece located my buddy (who decided to ascend a few meters that's why they disappeared.) and continued with the dive.
Basically training and practice is the best policy.
Since then I don't really seem to get the virtigo anymore (although I'm not telling my friend as he's the one that always has to go up ladders).