The anterior rami of the spinal nerves between the C4 and T2 innervate the skin of the upper limb

The area of skin supplied by one spinal nerve is known as dermatome. A knowledge of segmental innervation of the skin enables one to determine the level of injury to the spinal cord. It is also essential in the conduction and interpretation of the physical examination of a patient.
A lesion of a spinal nerve manifests itself as a motor or sensory disturbance along it's distribution.

Human Anatomy:Volume I: Upper Limb And Thorax, 2008

The T1 and T2 segments innervate the head and neck; T2 through T6 segments, the upper extremities and thoracic viscera

Basic neurosciences with clinical applications
By Eduardo E. Benarroch, Elsevier Health Sciences, 2006

discrepancies in denervation of the SNS

Surgical extirpation of portions of the sympathetic nervous system frequently fails to produce precisely that permanent peripheral denervation which is to be expected from text-book diagrams of the anatomical arrangement of the system.
The discrepancies are not uncommon even when the surgical technique is above suspiciion. They can in part, of course, be attributed to variations in the detailed anatomy of the sympathetic trunks or in the pattern of distribution of the branches and communications of these trunks. Such atypical arrangements in the autonomic nervous system are frequent. Thus, for example, during careful dissection of the cadaver, with all the relationships exposed, the correct identification of a particular paravertebral sympathetic ganglion can be very difficult; in the depths of a surgical incision, it is often impossible. But, even when the possibility of the usual anatomical anomalies of the sympathetic nervous system has been excluded, persistence of autonomic activity in unexpected areas may, and in certain regions always does, follow operative removal of parts of the system which should have caused complete sympathetic paralysis in the are or region concerned.
Intermediate sympathetic ganglia, J. D. Boyd, Univ. of Cambridge

• Oxford Journals
• Medicine
• British Medical Bulletin, Vol. 13 No. 3
  

Primer on the autonomic nervous system

Hyperthermia, heat intolerance, heat prostration and heat stroke may occur with widespread failure of thermoregulatory sweating, whereas local skin trophic changes occur with chronic postganglionic sudomotor neuropathy.

Primer on the autonomic nervous system, By David Robertson, Academic Press, 2004

more liable to develop reflex bronchospasm under light levels of anesthesia after ETS

Thus, patients with essential hyperhidrosis who have undergone bilateral thoracic sympathectomy, may be more liable to develop reflex bronchospasm under light levels of anesthesia.
CAN J ANESTH 2005 52:9

depletion of brain noradrenaline levels caueses a disturbance in cerebral microvasculatur tone

Chemical sympathectomy with six-hydroxydopamine leads to marked noradrenaline denervation in the nucleus ceruleus-innervated areas (Jonnson 1983) and to a decrease in noradrenaline levels measured in the cerebral cortex (Onesti et al. 1989).
Rats were subjected to chemical sympathectomy by stereotactic injection of 6-hydroxydopamine into the lateral ventricle. A hypertensive condition at a mean arterial pressure of about 160mm Hg was maintained for 1 hour by intravenous phenylephedrine. Compared with a control group CBF increased, cerebral autoregulation was impaired and specific gravity of the cerebral tissue revealed cerebral oedema. It was suggested that depletion of brain noradrenaline levels caueses a disturbance in cerebral microvasculatur tone and renders the cerebral blood vessels more vulnerable to hypertension (Kobayashi et al. 1991).

Topics in Neuroanaesthesia and Intensive Care

Experimental and Clinical Studies upon Cerebral Circulation, Metabolism and Intracranial Pressure

Cold, Georg E., Dahl, Bent L. 2002, XIV, 416 p., Hardcover ISBN: 978-3-540-41871-9

Effect of adrenalectomy or sympathectomy on spinal cord blood flow

We conclude that adrenalectomy near-totally ablates the hypothermia-associated increase in RSCBF measured in intact rats and that abdominal sympathectomy totally ablates it. This evidence complements morphological evidence for adrenergic innervation of the spinal cord vasculature.

http://ajpheart.physiology.org/cgi/content/abstract/260/3/H827
Am J Physiol Heart Circ Physiol 260: H827-H831, 1991;

Alterations in cytokine and antibody production following chemical sympathectomy

The Journal of Immunology, Vol 155, Issue 10 4613-4620, Copyright © 1995 by American Association of Immunologists

acinar degranulation following sympathectomy

Chronic bilateral postganglionic sympathectomy (4-6 weeks duration) caused a drastic reduction in the capacity of the gland to secrete saliva in response to parasympathetic stimulation, reaching only one-third of that from normal animals. The initial output of amylase was greater than in normal animals but the total output was similar. The control unstimulated sympathectomized glands appeared similar morphologically to normal resting glands. However, on the parasympathetically stimulated side, besides the usual amount of acinar degranulation, there was also a conspicuous development of acinar vacuolation, not seen in the other groups of animals.
September 1, 1988 The Journal of Physiology, 403, 105-116.

Elective treatment for sweaty palms is classified as psychosurgery

ETS can alter many bodily functions, including sweating , heart rate , heart stroke volume , blood
pressure , thyroid , baroreflex , lung volume , pupil dilation, skin temperature, goose bumps and
other aspects of the autonomic nervous system . It can diminish the body's physical reaction to
exercise and/or strong emotion, and thus is considered psychiatric surgery. In rare cases sexual
function or digestion may be modified as well.
LVHyperhidrosis.com
Aury Nagy MD

Catecholamine sensitivity of cat leg vessels after sympathectomy

Am J Physiol 212: 466-471, 1967;