I cannot give you a formal medical opinion over the internet unfortunately, so I cannot tell you whether you can reschedule the surgery or not.
Its important generally to be careful what symptoms you attribute to the Chiari - many times they are asymtpmatic and surgery does not help the symptomsm which are caused by something else. There shoud be evidence of lower brainstem malfunction such as motor or sensory symptoms in the extrmeities, clumsiness, vertigo, swallowing problems. Visual, hearing symptoms, and sleep jerks would be hard to attribute to a Chiari. The fact that a syrinxe is present doe ssuggest that th eChiari is significant.
You will have to weight the risks and benefits with your doctor and come up with teh best surgical or non-surgical plan. What is the current level of your disability and is it worth a surgery?
Good luck
Sue
Thank you.