Hi and welcome to the Chiari forum.
What other issues have u been having, symptoms along with a CSF obstruction and overcrowding is more important than the length of the herniation...yes, the herniation can be a problem, but it is usually bcuz of the width not the length.
SO ur symptoms r important as to what they r and how they are affecting u.
There are more tests that u should have....a brain MRI w/wo contrast, cervical spine, thoracic and lumbar spine MRI's...they need to rule out a syrinx which can be found newhere in the spine, some Drs only check the cervical spine. U also want to find out if u have overcrowding and a CSF obstruction, Disk issues, sleep apnea, tethered cord, ehlers-danlos, ICP.....
Finding a true chiari specialist to help guide u, is what I would suggest...not all NL and NS's are educated or experienced with how chiari affects us.
We do have a list of the members drs, the list is not a referral, but a means for u to start ur research for the right dr for u.
http://www.medhelp.org/health_pages/Neurological%20Disorders/DOCTORS-LIST-FOR-CHIARI-SYRINGOMYELIA/show/1062?cid=186
"selma"