"Sympathectomy is a technique about which we have limited knowledge, applied to disorders about which we have little understanding." Associate Professor Robert Boas, Faculty of Pain Medicine of the Australasian College of Anaesthetists and the Royal College of Anaesthetists

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Sympathectomy altered electroactivity on the heart

The influences on the cardiac autonomic nerve system of the ETS of upper thoracic sympathetic nerve were seen to be of a lesser degree at rest. However, the response to sympathetic stimulation was suppressed after the surgery.
Eur J Cardiothorac Surg 1999;15:194-198
http://ejcts.ctsnetjournals.org/cgi/content/full/15/2/194

These gustatory phenomena were quite different from physiologic gustatory sweating

In a series of 100 bilateral upper dorsal sympathectomies performed for palmar hyperhidrosis, gustatory sweating and other gustatory phenomena were reported by 68 of 93 patients (73%), followed up for an average of 11/2 years. These gustatory phenomena were quite different from physiologic gustatory sweating: a wide range of gustatory stimuli caused a variety of phenomena in varied locations. There was a negative correlation between the incidence of these phenomena and the occurrence of Horner's syndrome after sympathectomy. Analysis of our observations, and of clinical and experimental work of others, leads to the conclusion that gustatory phenomena after upper dorsal sympathectomy are the result of preganglionic sympathetic regeneration or collateral sprouting with aberrant synapses in the superior cervical ganglion.
http://archneur.ama-assn.org/cgi/content/abstract/34/10/619

the PPG signal and the VLF fluctuations of the PPG parameters enable the assessment of the change in sympathetic nervous system activity after sympathectomy

The photoplethysmographic (PPG) signal, which measures cardiac-induced changes in tissue blood volume by light transmission measurements, shows spontaneous fluctuations. In this study, PPG was simultaneously measured in the right and left index fingers of 16 patients undergoing thoracic sympathectomy, and, from each PPG pulse, the amplitude of the pulse (AM) and its maximum (BL) were determined. The parameter AM/BL is proportional to the cardiac-induced blood volume increase, which depends on the arterial wall compliance. AM/BL increased after the thoracic sympathectomy treatment (for male patients, from 2.60±1.49% to 4.81±1.21%), as sympathetic denervation decreases arterial tonus in skin. The very low-frequency (VLF) fluctuations of BL or AM showed high correlation (0.90±0.11 and 0.92±0.07, respectively) between the right and left hands before the thoracic sympathectomy, and a significant decrease in the right-left correlation coefficient (to 0.54±0.22 and 0.76±0.20, respectively) after the operation. The standard deviation of the BL or AM VLF fluctuations also reduced after the treatment, indicating sympathetic mediation of the VLF PPG fluctuations. The study also shows that the analysis of the PPG signal and the VLF fluctuations of the PPG parameters enable the assessment of the change in sympathetic nervous system activity after thoracic sympathectomy.
http://www.springerlink.com/content/w7n21366239753l5/

regional sympathectomy leads to qualitative alterations in localized bone modeling and remodeling

Bone modeling and remodeling are highly regulated processes in the mammalian skeleton. The exact mechanism by which bone can be modeled at a local site with little or no effect at adjacent anatomic sites is unknown. Disruption of the control of modeling within the temporal bone may lead to various bone disease such as otosclerosis, osteogenesis imperfecta, Paget's disease of bone, fibrous dysplasia, or the erosion of bone associated with chronic otitis media. One possible mechanism for such delicate control may be related to the ubiquitous and rich sympathetic innervation of all periosteal surfaces. Previous studies have indicated that regional sympathectomy leads to qualitative alterations in localized bone modeling and remodeling. In this study, unilateral cervical sympathectomy resulted in significant increases in osteoclast surface and osteoclast number within the ipsilateral bulla of experimental animals. The mechanisms by which sympathectomy leads to increased local bone loss is unknown. Potential mechanisms include disinhibition of resorption, secondary to the elimination of periosteal sympathetics, as well as indirect vascular effects.
http://www.ncbi.nlm.nih.gov/pubmed/8723974