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CHAPTER 25
tomy produces only hypohidrosis below the level of the lesion. In the oblongata, most
sweat fibres travel through an area occupied by the lateral reticulo-spinal tract.
Spinal cord
Within the spinal cord the supranuclear sudomotor fibres pass through the posterior
aspect of the antero-lateral tract very close to the lateral pyramidal tract and the border
zone of the intermedio-lateral horns, where the segmental synapse with the ganglion
cells of the grey matter takes place. Unilateral cordotomy of the antero-lateral tract only
results in ipsilateral hypohidrosis below the level of the lesion if the dorso-medial part
of the antero-lateral tract is severed. Experience has shown that cordotomies at the
level of C2-C3 may spare sudomotor fibres, with the result that only those fibres are
interrupted which innervate distinct areas only, such as trunk and leg dermatomes, as
shown in Fig. 127 of a patient who had a cordotomy carried out by Foerster on the
left side below C2 because of intractable hyperpathic pain, following neuroma formation
in his right hand resulting from an ulnar nerve injury. The thermoregulatory sweat test
showed hypohidrosis over the left side of the face, trunk and leg, while the sudomotor
function of the left shoulder and left arm was spared (Guttmann & List, 1928). This
FIG. 128.
