Yes the gap is definitely wide and I can see that if you’ve injured the ligaments which hold your head on, that your ‘retroflexed odontoid’ will be the ‘pivot point’ and will be pressing into your brainstem when you look down or bend down. The trouble is, you don’t feel any pain at the point where this happens, so you don’t realise what damage is being done, it just generates symptoms – maybe some immediately but they often occur some time later.
Although a low-lying cerebellum can exist without symptoms, depending upon each individuals anatomy and whether or not the CSF is obstructed, when this is combined with cranio-cervical instability, it’s a whole new picture and I believe your trouble is more likely to be hightened by instability. I’d be interested to hear what the consultant says.
see http://prettyill.com/forums/viewthread/712/
This forum topic above talks a little more about the overall possible elements involved and the mechanism, you might find it informative. At approx post 8, there’s a comprehensive summary along with possible methods of treatment and, although it does mention the Zantac and Zyrtec protocol further down, I’d try and keep this to an absolute minimum.