We tested the hypothesis that palmar hyperhidrotics have more active sweat glands in their palm than normal palmar sweating individuals. In order to estimate the number of active sweat glands in the palm, we performed iontophoresis of pilocarpine in the hypothenar eminence of hyperhidrotic and normal individuals, and we compared the number of sweat gland traces on imprints, taken with an ameliorated technique. We found no statistically significant difference in the density of sweat glands on the hypothenar eminence of hyperhidrotic and normal individuals. We concluded that palmar hyperhidrosis cannot be attributed to higher density of active sweat glands of the palm of hyperhidrotics.
Key words: Sweat glands, hyperhidrosis, palmar sweating, iontophoresis.
The greater skin conductance activity at the distal, relative to the medial, phalanx has been attributed by Freedman et al. (1994) to the greater density of sweat glands at the distal, relative to the medial, site. They suggested that there is a positive relationship between sweat glands count and skin conductance activity. Although this relationship holds for different areas within the palm, it could be supposed that differences in palmar sweating between hyperhidrotic and normal individuals are caused by differences in the density of their palmar sweat glands.
In previous works, we have demonstrated that palmar sweating does not directly participate in thermoregulation (Kerassidis, 1994), and that palmar hyperhidrosis cannot be attributed to hematological abnormality, electrolytic or glucose imbalance, thyroid gland dysfunction, neurological abnormality, over-functioning of the sympathetic nervous fibers passing through T2,3 ganglia, or over-reactivity to startling stimulation (Kerassidis, Charistou, Kohiadakis, Tzagournissakis & Bitzaraki, 1997). In the present study we investigate the simple hypothesis that palmar hyperhidrosis is caused by a higher density of active sweat glands of the palms of hyperhidrotics.
It is well known that the penetration of pilocarpine (agonist of acetylcholine) around the secretory portion of the sweat gland causes sweat secretion (Sato, Kang, Saga & Sato, 1989). Researchers (Morris, Dische & Mott, 1992) have used hydrophobic mould silicone to trace the points from which the sweat is secreted in the skin surface. This method is inappropriate for hyperhidrotics, because excessive sweating can destroy the tracing ability of silicone. Other researchers (Kennedy, Sakuta, Sutherland & Goets, 1984; Altomare et al., 1992; Ryder et al., 1988) have spread alcohol iodine and starch powder that turns black in the presence of sweat and have estimated the number of active sweat glands from a photograph. But this method also is inappropriate for hyperhidrotics, because of the quick painting caused by excessive sweating, that could make the treated area muddy. Obviously, we had to modify the tracing methods in order to estimate with a satisfactory precision the active sweat glands in the palm of hyperhidrotics. We achieved that, in a very simple way, by taking imprints of the active sweat glands of the testing area (painted with alcohol iodine) in a simple paper which contained polysaccharides. We observed the quality of these imprints through a transparent glass, at the time the traces were printed. This way, we could remove the palm before traces become muddy and we could take more than one imprints, in order to avoid bad traces and artifacts.
Participants The individuals of this test had participated to our previous work on pathophysiology of palmar hyperhidrosis (Kerassidis et al., 1997). From the beginning of that work, we had used a gravimetric confirmation method, in order to judge the participants’ estimation of the degree of their palmar sweating. All participants of the present work were undoubtedly well defined as hyperhidrotic or normal, not only because of this gravimetric test, but also because the tasks of the previous work confirmed that. Twenty-four individuals participated in our test: 12 hyperhidrotics in the palms, 7 females and 5 males (mean age 30 years old), and 12 normal palmar sweating individuals, 7 females and 5 males (mean age 26 years old).
Materials A 3×5 cm sheet of blotting paper was soaked in 4% w/v pilocarpine chloride in benzalkonium chloride (Alkon-Courreur, Sterile ophthalmic solution) and applied to the test area of the palmar skin. Two 2×3 cm gauze pads soaked in sterile normal saline served as conductive materials. One was placed over the blotting paper, on the hypothenar eminence of the left palm and the other on the exterior side of the palm of the same hand. Two 1.5×2.5 cm copper pieces served as electrodes. The electrodes were placed over the gauze pads so that the positive electrode was over the pilocarpine. A current of 1 mA was applied for 5 min. We used 3 batteries (9V each one), connected in series, to form an electric source. The regulation of current at the value of 1 mA (provided that the individuals did not present the same value of palmar resistance due to the different thickness and wetting of stratum cormeum) was accomplished by a potentiometer connected in series with palmar resistance. Alcohol iodine was used for printing on the paper sweat spots, produced on the points of skin porus where sweat was secreted from sweat glands. Counting of the spots was accomplished via the Microcomputer Imaging Device (MCID, Imaging Research INC) from a photostat in a transparent membrane.
Procedure After a 5 min iontophoresis of pilocarpine in the hypothenar eminence of the left palm of the individual, the palm was dried, painted with alcohol iodine and dried again. At this time the palm was placed on a paper sheet, which was firmly placed on a sloping glass, so that the testing area was laid over the paper. The experimenter looked carefully at the opposite side of the glass so that she could watch spots appearing on the paper caused by the sweat coming out of the pores of the testing area. When it was estimated that the sweat spots were clearly distinguished, the subject was asked to remove carefully its palm from the paper sheet. This procedure of taking an imprint of the testing area on the paper sheet was repeated again. Four imprints of the testing area were taken for each subject (see Fig.). Then, the paper sheets were clearly photocopied on transparent membranes. (The photostats were additionally necessary because fainting of the imprints on the papers would happen a few weeks later.)
The time between the placement of the palm on the paper and its removal was different for each individual. In order to see if there were sweat glands that might not have produced sweat till the removal of the palm (because they might have been less activated), we occasionally left the palm on the paper sheet, for longer time than what we estimated as necessary. Many sweat traces were joined this way and the imprint became muddy, but no increase in the number of spots was observed.
Data analysis The counting of the spots was accomplished via the Microcomputer Imaging Device. The technician had not the information to whom the imprint belonged. The device could count the spots in any selected area. We measured and compared areas of any magnitude, but the comparisons on 1 cm2 area of hypothenar eminence with the higher density of spots for all individuals (near the sulcus, indicated by the arrow in Fig.), can give all the necessary information. The differences to the density of spots of this area (and the very adjacent) between the 4 imprints of the same individual were small (0-5%) and the higher measured value was selected for the statistical analysis. We compared the number of spots (active sweat glands) in the count area of hypothenar eminence, by a two factor (sex and hyperhidrosis) Analysis of Variance (ANOVA).
The mean values and standard deviations of the number of active sweat glands in the count area of hypothenar eminence are shown in the Table. The two factor ANOVA revealed no statistically significant difference between hyperhidrotic and normal individuals (F=1.7, P<.20). Females presented a higher number of active sweat glands on the count area (425 s.g./ cm2) than males (383 s.g./ cm2), but the difference was not statistically significant (F=3.1, P<0.09). The correlation coefficient between age and number of sweat glands count was also insignificant (r=0.079), probably because of the narrow range of the ages of participants.
At first, we have to mention that our imprint technique on a simple paper was proved to be a good method for recording from hyperhidrotic palm. In addition, this method is an amelioration of the already existing ones, because of its simplicity and inexpensiveness. The researcher can take, for these reasons, more than one imprint and be ascertained that the recording has not been falsified by artifacts. Besides, the possibility of artifacts to slip into the imprints is almost negligible, in opposition to the blind methods of silicone or of photograph which demand perfect taking (correct lighting and distance estimation, focus on a small area, absolute immobility of the hand etc.) and an absolutely faultless development.We tested the hypothesis that hyperhidrotics in palms have a higher density of active palmar sweat glands. We found no statistically significant difference in the density of active sweat glands on the higher density area of 1 cm2 of hypothenar eminence of hyperhidrotic and normal individuals.The hypothenar eminence is the area that touches the paper when an individual writes. It is well known that hyperhidrotics sweat so much in this area that usually need to use a napkin for writing. In the first test of our previous work (mentioned in the methods section) we found that the mean weight of sweat of hyperhidrotic palm was 6-7 times more than that of normal individuals. If this difference was due to higher density of palmar active sweat glands, hyperhidrotics may have 6-7 times higher density compared to normal individuals. Our finding suggests that the difference in palmar sweating between hyperhidrotic and normal individuals cannot be attributed to the difference of sweat gland density. We consider this conclusion as a contribution to the investigation of what kind of error or benefit lies behind palmar hyperhidrosis.
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Table Mean values and standard deviations (in parentheses) of the number of active sweat glands on an area 1 cm2 of the hypothenar eminence of the palm. Hyperhidrotics Normal Total Female 420 (62) 429 (57) 425
Male 356 (11) 410 (78) 383
Total 393 (57) 421 (64)