results of sympathectomy deteriorate with time (T.S. Lin & Fang, 1999; Walles et al., 2008). This recurrent postoperative sweating may be due to local nerve regeneration but has not yet been proven (Lee et al., 1999).
http://www.intechopen.com/books/topics-in-thoracic-surgery/surgical-management-of-primary-upper-limb-hyperhidrosis-a-review