The amount of compensatory sweating depends on the patient, the damage that the white rami communicans incurs, and the amount of cell body reorganization in the spinal cord after surgery.
Other potential complications include inadequate resection of the ganglia, gustatory sweating, pneumothorax, cardiac dysfunction, post-operative pain, and finally Horner’s syndrome secondary to resection of the stellate ganglion.

After severing the cervical sympathetic trunk, the cells of the cervical sympathetic ganglion undergo transneuronic degeneration
After severing the sympathetic trunk, the cells of its origin undergo complete disintegration within a year.

Spinal cord infarction occurring during thoraco-lumbar sympathectomy
J Neurol Neurosurg Psychiatry 1963;26:418-421 doi:10.1136/jnnp.26.5.418

Saturday, November 3, 2012

Chronic pain can occur after peripheral nerve injury, infection, or inflammation - sympathectomy is a nerve injury

Blocking sympathetic function, whether by surgical sympathectomy, systemic phentol- amine, or systemic guanethidine, relieves partial nerve injury-induced neuropathic pain in laboratory animal models as well as humans (8, 35, 146, 239, 278). Indeed, sympathectomy does not just relieve pathological pain in the body region ipsilateral to the CRPS-initiating event; rather, it also relieves pain arising from anatomically impossible mirror-image sites, that is, the identical body region contralateral to the initiating event (278). Thus sympathetectomy must somehow quiet the contralateral spread of spinal cord hyperexcitability underlying mirror- image pain.
Alterations in sympathetic fibers rapidly follow pe- ripheral nerve injury. This occurs as sprouting of sympa- thetic fibers, creating aberrant communication pathways from the new sympathetic terminals to sensory neurons (35). Sympathetic sprouting has been documented in the region of peripheral terminal fields of sensory neurons (262), at the site of nerve trauma (57), and within the dorsal root ganglia (DRG) containing cell bodies of sen- sory neurons (248, 343). Each of these sites develops spontaneous activity and sensitivity for catecholamines and sympathetic activation (8, 53).
The clearest evidence that immune activation partic- ipates in sympathetic sprouting comes from studies of the DRG. DRG cells receive signals that peripheral nerve injury has occurred via retrograde axonal transport from the trauma site. These retrogradely transported signals trigger sympathetic nerve sprouting into DRG (205, 308). As a result of nerve damage-induced retrogradely trans- ported signals, glial cells within the DRG (called satellite cells) proliferate (248) and become activated (343); mac- rophages are recruited to the DRG as well (63, 176). In turn, the activated satellite glial cells (and, presumably, the macrophages) release proinflammatory cytokines and a variety of growth factors into the extracellular fluid of the DRG (206, 246–248, 258, 277, 308, 358). These sub- stances stimulate and direct the growth of sympathetic fibers, which form basket-like terminals around the satel- lite cells that, in turn, surround neuronal cell bodies (247, 248, 343). For discussion of satellite cell functions, see section IIIA.
Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado
Physiol Rev
82: 981–1011, 2002; 10.1152/physrev.00011.2002.

A randomized placebo-controlled trial of oxybuty... [J Vasc Surg. 2012] - PubMed - NCBI

A randomized placebo-controlled trial of oxybuty... [J Vasc Surg. 2012] - PubMed - NCBI: "Palmar and axillary hyperhidrosis improved in >70% of the patients, and 47.8% of those presented great improvement. Plantar hyperhidrosis improved in >90% of the patients. Most patients (65.2%) showed improvements in their quality of life. The side effects were minor, with dry mouth being the most frequent (47.8%).
Treatment of palmar and axillary hyperhidrosis with oxybutynin is a good initial alternative for treatment given that it presents good results and improves quality of life."

bilateral sympathectomy may cause bowel, bladder, or sexual dysfunction

If regional sympathetic blockade provides relief, surgical sympathectomy can be considered. Initial pain relief may be significant, but symptoms tend to recur over the next 2 to 5 years.[53] This is believed to occur owing to incomplete surgical removal of all sympathetic innervation to the extremity. Collateral reinnervation can occur, but bilateral sympathectomy may cause bowel, bladder, or sexual dysfunction.[14]

It is possible to disrupt the sympathetic chain ganglion by treatments other than surgery. Ablation with radiofrequency devices and caustic chemicals (such as alcohol) have been described, but the region of necrosis may expand beyond the ganglion and long-term results are unknown.[59,][69] As such, surgical sympathectomy is considered strictly as a last resort.  
Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes By Frank R. Noyes, MD