I have a chiari 1 malformation, and an arachnoid cyst, how do i know if i am a candidate for surgery?

See a neurosurgeon: A well trained neurosurgeon can evaluate you, correlate your symptoms with the MRI appearance of the chiari, and decide whether surgery would be safe and effective to relieve your symptoms. Not all chiari malformations need surgery.

Depends on symptoms: If the chiari 1 is symptomatic, then surgical treatment should be considered. The same goes for the arachnoid cyst - where exactly is it and is it causing symptoms? Both conditions can be "incidental-omas" and need no treatment.

See a neurosurgeon: Depending on the location of the arachnoid cyst and the degree of cerebellar tonsilar ectopia from your chiari, you may well be a surgical candidate. Posterior fossa arachnoid cysts are a common cause of secondary chiari malformations(if the cyst is large enough to create increased pressure, it can push the bottom of the cerebellum through the foramen magnum, causing the chiari). See neurosurgeo.