There are criteria for the length of tonsils beyond the skull in order to officially call it “Chiari”. Some of us do not meet this criteria, yet our CSF flow can still be partially or fully blocked (sometimes called “Chiari Zero”). Most of us benefit from reducing our intracranial pressure with Diamox. This can sometimes even reverse “true” Chiari. References in The Driscoll Theory book. I hope you are like many of us and able to get relief without surgery. Fingers crossed! 🙂