Hi uc 1228 my name is Meggie. I haven't experienced the de-realization however I would highly recommend a new neurosurgeon. Chiari is usually manageable, you don't have to just live with it. There are surgeries available like decompression to relieve a multitude symptoms (careful who you pick for this one I would highly recommend The Chiari Institute in Great Neck New York) if deemed beneficial, other treatments and medications area also available to minimize symptoms.
I had a syringo-subarachnoid shunt inserted last year and although I was recently told this is not the optimal shunt for a syrinx (syringopleural has the highest success rate) I have had a significant decrease in migraines, less pressure in my neck and head along with slowing the loss of control over my legs. I am on Lyrica for the neuropathic pain, myofascial pain syndrome and accompanying parasthesia which helps immensely. I also recently underwent occipital nerve blocks for my chronic migraines which has helped a great deal and will soon be trying botox for the other areas of my head not numbed by the former.
Please don't suffer in silence as the only one it hurts is you, there is help out there. If you have time the web site for The Chiari Institute is a great resource tool as well as the American Syringomyelia Alliance Project (ASAP) website which offers support as well as the latest medical information all for free.
I hope for you the best.
Meggie