Does sound like a major size, huh? First off, I'd wanna know, thumb length or thumb width? Secondly, whose thumb are we measuring?

Seriously. The actual size of the herniation is not as important as the signifigance of the block of CSF (cerebral spinal fluid), in Chiari DX's. Some people have thin very elongated cerebral tonsils, so even though there is extreme herniation, there is very little to no blockage to the CSF flow itself.... while in others there is very slight to no herniation, but the tonsils are "thicker" and therefore block the fluid flow severly. Other people have absolutely no heriation of the tonsils but major symptoms due to over crowding of the hindbrain its self and the resultant blockage of CSF flow (Chiari0).

So it isnt the actual amount of herniation as much as the symptoms, rate of progression and the degree to which a person is experiancing them at, that most NS's use as a guideline to whether surgery is required.

Hope this helps honey!!!

God Bless you and yours!!!!!

Dawn