Patients with hyperhidrosis have changed grip force, coefficient of friction and safety margin

Objective- To evaluate whether subjects with palmar hyperhidrosis have functional problems with the handgrip caused by the wet slippery surface of palm and fingertips. We used two different dosages of botulinum toxin to explore its impact on sweating and on muscle strength in the hand. Method- Using an object equipped with force sensors we measured the muscle strength and calculated the coefficients of friction and safety margin (SM) in the precision grip before and 2, 4, 6, 8 10-12 weeks and 6 months after treatment of 13 patients with two different doses of botulinum toxin. Sweat evaporation was measured simultaneously. Results- A significant decrease in evaporation and a parallel reduction of grip force in the dominant hand of the patients were observed. The SM used by the patients was significantly lower after the treatment, and increased gradually when sweating reappeared. Conclusions- These measurements showed, for the first time, that hyperhidrosis of the palms may cause an objective perturbation of the hand function which may be partially corrected by botulinum toxin treatment.