sympathectomy leads to fluctuation of vasoconstriction alternated with vasodilation in an unstable fashion. Following sympathectomy the involved extremity shows regional hyper- and hypothermia

'To quote Nashold, referring to sympathectomy, "Ill- advised surgery may tend to magnify the entire symptom complex"(38). Sympathectomy is aimed at achieving vasodilation. The neurovascular instability (vacillation and instability of vasoconstrictive function), leads to fluctuation of vasoconstriction alternated with vasodilation in an unstable fashion (39). Following sympathectomy the involved extremity shows regional hyper - and hypothermia in contrast, the blood flow and skin temperature on the non- sympathectomized side are significantly lower after exposure to a cold environment (39). This phenomenon may explain the reason for spread of CRPS. In the first four weeks after sympathectomy, the Laser Doppler flow study shows an increased of blood flow and hyperthermia in the extremity (40). Then, after four weeks, the skin temperature and vascular perfusion slowly decrease and a high amplitude vasomotor constriction develops reversing any beneficial effect of surgery (39). According to Bonica , "about a dozen patients with reflex sympathetic dystrophy (RSD) in whom I have carried out preoperative diagnostic sympathetic block with complete pain relief, sympathectomy produced either partial or no relief (40)' Chronic Pain: Reflex Sympathetic Dystrophy : Prevention and ManagementHooshang HooshmandCRC PressINC, 1993 - Medical - 202 pages Eur J Appl Physiol. 2004 Oct;93(1-2):245-51. Epub 2004 Aug 25. Infrared thermography for examination of skin temperature in the dorsal hand of office workers.Gold JE1, Cherniack M, Buchholz B. Author information 1Department of Work Environment, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA. Judith_Gold@uml.edu Reduced blood flow may contribute to the pathophysiology of upper extremity musculoskeletal disorders (UEMSD), such as tendinitis and carpal tunnel syndrome. The study objective was to characterize potential differences in cutaneous temperature, among three groups of office workers assessed by dynamic thermography following a 9-min typing challenge: those with UEMSD, with ( n=6) or without ( n=10) cold hands exacerbated by keyboard use, and control subjects ( n=12). Temperature images of the metacarpal region of the dorsal hand were obtained 1 min before typing, and during three 2-min sample periods [0-2 min (early), 3-5 min (middle), and 8-10 min (late)] after typing. Mean temperature increased from baseline levels immediately after typing by a similar magnitude, 0.7 (0.3) degrees C in controls and 0.6 (0.2) degrees C in UEMSD cases without cold hands, but only by 0.1 (0.3) degrees C in those with cold hands. Using paired t-tests for within group comparisons of mean dorsal temperature between successive imaging periods, three patterns of temperature change were apparent during 10 min following typing. Controls further increased mean temperature by 0.1 degrees C ( t-test, P=0.001) at 3-5 min post-typing before a late temperature decline of -0.3 degrees C ( t-test, P=0.04), while cases without cold hands showed no change from initial post-typing mean temperature rise during middle or late periods. In contrast, subjects with keyboard-induced cold hands had no change from initial post-typing temperature until a decrease at the late period of -0.3 degrees C ( t-test, P=0.06). Infrared thermography appears to distinguish between the three groups of subjects, with keyboard-induced cold hand symptoms presumably due, at least partially, to reduced blood flow. http://www.ncbi.nlm.nih.gov/pubmed/15338221