a lumbar spine MRI, .....testing
for related conditions like
ICP, POTS,tethered cord, ehlers-danlos, sleep apnea...and look at vitamin and mineral levels...vit D, B12, and magnesium and potassium tend to be low for many of us and can cause some of the same symptoms we deal with....
Make sure you get copies of ALL testing including reports.....
And make sure you get a true Chiari specialist...