I had a supine mri cervical spine done and was reported as normal. i have symptoms of cervical instability and i measured cxa of 127 degrees, grabb oakes 8.9mm and harris measurement of 12.7mm, no chiari malformation. could 'normal' report be wrong?

The numbers are not normal with MRI taken at a supine position and they are probably consistent with your condition, cervical instability; however, you should talk to the doctor who ordered the MRI or the radiologist who was reading the images.

The measurements that you have made are only valid on cervical x-rays in a neutral position. Furthermore, cervical MRI scans frequently do not include the occipital cervical junction and axial images routinely start at C2 and extend distally. It would not be unusual for a cervical MRI scan to be read as normal and miss instability at the occipital cervical junction.