Hi. Normally that type of nerve surgery can take 6-8 months to heal and it sounds like they treated his CRPS early on which can put CRPS in remission. Mine is generalized and I also had a nerve injury with surgery but CRPS was not treated til it was too late. During my course of therapy I did meet a guy with the same history as your husband and his also went into remission. (His swelling went away, pain was minimal, good movement, color changes went away, and got off his meds. He was doing well in PT/OT but still had to prevent repetitive movements with that arm. Unfortunately, he was discharged from therapy so I dont know how he is today.
To my understanding remission is when signs and symptoms go away or are controlled (symptoms subside) on medications.
momof4