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.
www.ubcmj.com/pdf/ubcmj_2_1_2010_24-29.pdf

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.

http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0442.1967.tb00255.x/abstract

Monday, January 11, 2010

Importance of bilateral sympathetic innervation on cerebral blood flow autoregulation in the thalamus

Brain Res. 1987 Jun 16;413(2):297-301.

Effects of bilateral sympathetic innervation on the regulation of cerebral blood flow to the thalamus were examined in spontaneously hypertensive rats (SHR). The superior cervical ganglion was removed on one side or bilaterally, and blood flow in the thalamus was repeatedly measured with a hydrogen clearance technique during a stepwise increase in arterial pressure. Sympathectomy on one side neither had effects on the pressure-flow relationship nor on the blood pressure levels of upper limits of autoregulation in the ipsilateral thalamus. In contrast, bilateral sympathetic denervation impaired the autoregulatory function in the thalamus and the upper limits were significantly lower than those in intact rats: 206 +/- 8 vs 226 +/- 10 mm Hg, respectively (P less than 0.02).
PMID: 3607478 [PubMed - indexed for MEDLINE]

effect of electric stimulation of the sympathetic cord in the upper thoracic level on the middle cerebral artery blood flow

Source: CEREBROVASCULAR DISEASES Volume: 2 Issue: 6 Pages: 359-364 Published: NOV-DEC
1992
Times Cited: 20 References: 41
Abstract: The effect of electric stimulation of the sympathetic cord in the upper thoracic level on the middle cerebral artery blood flow veloCitY (V(MCA)) in humans was examined using transcranial Doppler sonography monitoring during surgery for palmar hyperhidrosis.
Sympathetic stimulation resulted in marked and rapid increases Of V(MCA). The responses were preceded by prompt increases of mean arterial blood pressure (MABP) and heart rate (HR).
Division of the sympathetic cord cranially or caudally to the stimulation site partially reduced the V(MCA), MABP and HR responses. Both these operations reduced sympathetic pathways to the heart as reflected by a decrease in HR and MABP. The integrity of the sympathetic pathway from the stimulation site through the superior cervical ganglion and the carotid plexus was not a prerequisite for a V(MCA) response. Our data suggest that the V(MCA) increase mainly results from stimulation of the heart and the cardiovascular system, resulting in marked increases of blood
pressure and heart rate.

Obviously, it is not simply a compensatory hyperhidrosis transposition from postoperative reduction

In contrast, it is of particular interest to find that patients with cerebroischemic syndrome who received thoracic sympathectomy rarely developed substantial postsympathectomy compensatory hyperhidrosis (PCH). The etiology of PCH is still unclear. Obviously, it is not simply a compensatory hyperhidrosis transposition from postoperative reduction of palmar sweating. Based on our observations, we postulated two possible mechanisms. The first of these mechanisms is denervation hypersensitivity of the surgically injured distal sympathetic stump. This could explain why CH may appear soon after sympathectomy, but is not found in patients who undergo local excision of axillary sweat glands or undergo local treatment. Another mechanism is regeneration of preganglionic fibers or collateral sprouting of sympathetic fibers from the proximal stump of the sympathetic trunk. This could explain the long-term existence of PCH.
Ann Thorac Surg 2001;72:667-668

Receptor hypersensitivity is a common problem after significant sympathetic injury, including clammy hands, erythema, and allodynia. When sympathetic nerves regenerate, they may establish aberrant connections to sensory receptors, muscles, or other sympathetics receptors; this may lead to an over-response or abnormal response.
http://wiki.cns.org/wiki/index.php/Injury,_Sympathetic_Nerve