So why can a ‘short clivus’ be problematic:
It can allow the tip of the odontoid to prod or compress the brainstem, especially if the ligaments have been injured.
So why are low-lying cerebellar tonsils (CT)a problem:
This is a part of your brain that should be 5mm above the opening at the bottom of your skull, to allow free flowing Cerebro-Spinal Fluid (CSF). Low-lying CT can cause a ‘bung’ in the system and contribute to build up of pressure in the head. Over time, this pressure can flatten the pituitary gland, causing a whole range of problems, including weight gain! It may be that you need to get treatment to lose weight!
What is a Retroflexed Odontoid and what difference does it make:
The odontoid is the ‘peg’ part of the C2 bone, if it points backwards towards the spinal canal it is referred to as ‘retroflex’. A normal C2 odontoid points straight up and is less of a threat to the brainstem.
What is the significance of a Pannus:
A normal person, whose head is firm and secure, will not have a pannus. A pannus occurs where there is instability and therefore is a medical ‘sign’ of instability. It’s a pad which the body produces here against the tip of the odontoid, to help safeguard the brainstem from insult and, although it no doubt does help, that help is far from adequate for anything other than very mild instability.
Why does it matter if the posterior arch of C1 encroaches the spinal canal:
The spinal canal needs to be a smooth channel down which the spinal cord and CSF can pass freely, without obstruction. Anything interfering in this smooth passage can alter the fluid dynamics/flow, or impact on the spinal cord. I would also be asking why this is happening, i.e. has your atlas subluxed, or is it unstable ?
What is the anomaly at C4/C5:
There appears to be some change in signal here, where I would expect to see fluid, there is something making an impression on your spinal cord, is it from a disk ? I don’t know but if you look at the line of your spinal cord, it gives this object a ‘body swerve’ if you get my meaning, so it’s obviously aggravating the spinal cord.
Hope some of this is useful, let me know if you need to know anything else.