PREVIOUS studies of the Smithwick type of preganglionic thoracic sympathectomy have shown an area of anhidrosis on the ipsilateral side of the face, arm and upper portion of the trunk. The loss of sweating has been pictured as complete. The anhidrosis has usually been determined by the method of electrical skin resistance or by colorimetric methods, such as the starch-iodine test. These methods give similar results.1 In the course of studies with two newer methods, it has been found that the loss of sweating following such an operation is not complete. These methods allow visualization of the function of small numbers of sweat glands and have uniformly shown activity of a small percentage of glands in sympathectomized areas. Evidence is presented that these glands are innervated by preganglionic fibers which arise in the first thoracic root.
For purposes of comparison, both the skin resistance method of Richter2
NETSKY MG. STUDIES ON SWEAT SECRETION IN MAN: Innervation of the Sweat Glands of the Upper Extremity; Newer Methods of Studying Sweating. Arch NeurPsych. 1948;60(3):279–287. doi:10.1001/archneurpsyc.1948.02310030060005
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