It looks as if your odontoid is retroflexed slightly. Also the disks in your neck are degenerating. I suspect the your odointiod is pressing against the bottom of your brain called basilar invagnation (sp?) Your tonsils are low lying. I suspect high pressure as it looks like too much fluid in your cisterns which would cause chiari symptoms. Also do you have EDS? If so your results would be drastically different if you had an upright MRI.