Hi...I am so sorry ur neice is going thru so much...chiari is not an easy condition to deal with as there r not many drs that know how to treat it....being in Long Island u have some of the best Chiari Drs right there.....
Chiari is the malformation of the cerebellum part of the skull leaving it too small to contain the cerebellum part of the brain and the tonsils can be forced out and on to the spinal cord and brain stem causing compression and that results in the symptoms u mentioned.Chiari symptoms vary bcuz they also cycle....so u can have a flare depending on the activities she is involved in, or the amount of stress she is dealing with.
Most meds do not help pre op...but I started Topamax post op and do see some help.
U need to have a CINE MRI to determine if ur Niece has a CSF obstruction and overcrowding...odontoid that may be retroflexed.....and u want to rule out related condtitions Like sleep apnea, PTC,tethered cord, Ehlers-Danlos.......
We do have a chiari forum here on MedHelp and it may be a good place to start-
http://www.medhelp.org/forums/Chiari-Malformation/show/257?camp=msc
"selma"