Hmmm... I'd be interested in that research if you can share it. I've always understood Arnold Chiari malformation to mean that the skull did not grow to full size at birth, which then, over time with build-up of CSF/blood that normally seeps into the suboccipital region, may cause the brain to herniate downward into the spinal canal (only ~10% of people with a type 1 malformation ever become symptomatic). Depending on the type (I have Type 1), symptoms may or may not be present at birth, but, as I understand it, the actual malformed skull always is.
In any case, Chiari definitely shows up on imaging. I would look into other possible causes.
I would be Type 1 if I had it.
genetic mutations (me)
Also, not published but will be soon by a chiropractor I was a patient of:
Lyme disease twists your spine horribly starting at C2 and ending at L5-S1. I have a moderate twist, made worse in my cervical spine by extensive whiplash damage. Traumatic injury from a car accident plus Lyme disease is enough to be suspicious. I’ve never had Tension Headaches in this area before, and while the pain lessens at time, now being not one of them, there has to be another cause than tension headache.