ALTERED RESPONSE IN CUTANEOUS SYMPATHETIC OUTFLOW TO MENTAL AND THERMAL STIMULI IN PRIMARY PALMOPLANTAR HYPERHIDROSIS

Skin sympathetic nerve activities (SSNAs) were recorded simultaneously from the tibial and peroneal nerves by microneurography at an ambient temperature of 25 degrees C in five subjects with primary palmoplanta r hyperhidrosis. The resting activity of the tibial SSNA innervating t he sole (glabrous skin) increased moderately (36.5 +/- 1.5 bursts/min) , while mental arithmetic provoked marked responses (1,003.3 +/- 457.4 % compared with the resting level) in the hyperhidrosis group compared with the control normohidrosis group (n = 5, 25.3 +/- 4.2 bursts/min and 142.2 +/- 58.4%, respectively). Differentiation of the tibial SSNA into sudomotor (innervating sweat glands) and vasoconstrictor (innerv ating presphincter of skin vessels) revealed that this SSNA enhancemen t was attributable to not only sudomotor but also vasoconstrictor comp onents during mental arithmetic. in contrast, the responses in the per oneal SSNA (innervating the dorsum pedis, hairy skin) of the hyperhidr osis group were only slightly changed, exhibiting no significant diffe rence from those in the normohidrosis group. Reflex bursts elicited by sound and electric stimulation were normal in amplitude and latency. When the ambient temperature was elevated to 30 degrees C, the tibial SSNAs became more enhanced than did the peroneal SSNAs. The tibial SSN A was markedly enhanced in the hyperhidrosis group (290.0 +/- 78.5%) c ompared with the normohidrosis group (78.3 +/- 25.4%). We conclude tha t the excessive responses in SSNA to the palmar and plantar glabrous s kin to both mental and thermal stimuli may be responsible for the prof use sweating in subjects with primary palmoplantar hyperhidrosis.