hello there! this condition CRPS/causalgia/RSD is mostly post traumatic or surgical.and approximately 5 % of people after these traumatic episodes get it. its because of imbalance between sympathetic(flight,fight, fright) responses and parasympathetic responses(rest and digest) of autonomic nervous system. and immobilityincreases this 5 % odds to 20 percent.so regualar physiotherapy helps.how old are you? average age affected is 30-60 with 49 mean. kids have better prognosis than adults. lets discuss some treatment options. a person can be benifited only if diagnosed early and do prophylaxises to avoid hemiplegic strokes and colles fractures( wrist fracture) all that leads to immobility because immobilization increases the trouble and once fibrotic stages are reached no help then, so the best remedy is prophylaxis and physiotherapy excercises on regular basis. now medicines like sympatholytic agents help. like GABA analogs( gabapentin) cl channel inhibitors like BACLOFEN (better administered intrathecally. inside spinal cord) anti inflammtory medications like corticosteroids and calcitonins help too. along with oral bisphosphonates but only in early phases. sympathetic nerve blockages are also done to relieve pain.average 4 to 5 blocks are required to relieve symptoms permanently. thoracic or lumbar sympathectomies can be done, chemical sympathectomies are done too by injecting phenols and alcohols to ablate the sympathetic chain and relieve the symptoms. newer technologies like spinal cord stimulation are also tried and are proving useful too. here is th elist of drugs you can use from pick one from each class.there are 3 1- sympatholytics Clonidine (Catapres),Guanethidine (Ismelin),Phenoxybenzamine (Dibenzyline),Prazosin (Minipress) 2-Anti inflammatory Prednisone (Deltasone, Meticorten, Orasone) 3.Endocrine Agents. Calcitonin (Miacalcin, Osteocalcin) with oral bisphosphonates. keep follow ups. do regular excercise. avoid immobility. recognise symptoms early and have early management and you will be fine, if the disease progressed for some reason stiffness will occur and persistent pain will be the result and i have seen may patients commiting suicide from that. so you need to have an eye on symptoms and do as i told you to from A to Z . and hope you will be fine. now Mirtazapine is just an antidepressant and has nothing to do with the disease except for some psychological relief by relieving depression etc. but it would be like hiding the head in the sand to avoid trouble, and you need to fight it. hope i was of some help cheers Dr Khan