Palmar Hyperhidrosis: Neural Pathway Involved In Thoracic Sympathetic Control On Palmar Sweat Glands And Rational Selection Of Surgical Approach For Sympathectomy

Objective: The present study aims to unmask the neuralpathway involved in the control of palmar sweat gland bythoracic sympathetic nervous system, so as to offer anatomicalevidence for endoscopic thoracic sympathicotomy. In addition,based on the outcomes of long-term post-operative follow ups,rational selection of the most appropriate surgical approach toconduct individualized sympathectomy in the treatment ofplamar hyperhidrosis was also discussed.Methods:(1) The technique of HRP (Horseradish Peroxidase)retrograde tracing was employed to locate the sympatheticpostganglionic neurons innervating pad skins of15rats’forelimbs.(2)The structures of sympathetic trunks in50patients with palmar hyperhidrosis (bilateral sides) and60normal controls (unilateral side) were observed and comparedunder thoracoscope. Nuclear fast red-fast green myelin sheathstaining was performed on20strings of Type I,18strings ofType II and14strings of Type III Kuntz nerves, as so toevaluate the ratios of myelinated to unmyelinated nerve f ibers.In addition, electron-microscopic observation was conducted on9strings of Type I,8strings of Type II and5strings of Type IIIKuntz f ibers to characterize their ultra-structural features.(3) 996PH patients who received endoscopic thoracicsympathicotomy more than3years ago were invited toparticipate in a long-term fol low-up survey. The809respondedpatients were divided into4groups, i.e. Group R2-4(n=162),resection of nerves extending through R2-4; Group R3(n=374),resection of nerves or accessory nerves (Kuntz nerve) extendingthrough R3; Group R3-4(n=138), resection of nerves oraccessory nerves extending through R3-4; and Group R4(n=135), resection of nerves or accessory nerves extendingthrough R4. The inter-group differences were studied from4different aspects, i.e. the in tra-operative hand temperatureprof iles, the post-operative therapeutic outcomes for palmarhyperhidrosis and the concomitant facial/axil lary/plantarhyperhidrosis, the incidence of compensatory hyperhidrosis andthe post-operative satisfaction.Results:(1) In the15rats, the sympathetic postganglionicneurons innervating forelimb pad skins were mainly located inthe middle cervical ganglia (23.5%), he cervicothoracic ganglia(72.9%) and T3ganglia (2.8%).(2) The probability ofpresenting at least one type of Kuntz nerves on the surfaces ofT2-T4rib within unilateral chest cavity was as fol low:81%inthe patients with palmar hyperhidrosis (81/100) and35%in thenormal controls (21/60). This difference was statistical lysignif icant. The f indings of nuclear fast red-fast green myelinsheath staining revealed the ratios myelinated to unmyelinatednerve f ibers were as fol low:78.2%in Type I f ibers,93.7%inType II f ibers and92.6%in Type III f ibers. The results ofelectron-microscopic ultrastructu ral observation showed that Type I Kuntz nerves were dominated by myelinated f ibers whileType II and III Kuntz nerves were dominated by unmyelinatedf ibers.(3) Of the996PH patients who received endoscopicthoracic sympathectomy more th an3years ago,809respondedto the survey. The obtained therapeutic effect rate for palmarhyperhidrosis was100%. The incidence of relapsed palmarhyperhidrosis during long-term follow up was1.48%. The effectrates for facial, axillary and plantar hyperhidrosis were63.2%,68.7%and32.9%, respectively. Moderate-to-severecompensatory hyperhidrosis was the major factor leading topatients’ unsatisfactory or even regretful feeling after receivingthe surgery. The incidences of moderate-to-severecompensatory hyperhidrosis in Group R2-4, R3, R3-4and R4were19.7%,9.8%,13.1%and4.2%, respectively. Both theinter-group and the pair-wise differences were sta tisticallysignificant (P<0.05). The patients in Group R2-4claimed thelowest satisfaction level.Conclusions:(1) The sympathetic postganglionic neuronsinnervating palmar skin are mainly located in either middlecervical or cervicothoracic ganglia, and thus it is unnecessary toremove the ganglia when applying sympathectomy in thetreatment of palmar hyperhidrosis.(2) In the treatment ofpalmar hyperhidrosis, sympathetic innervation of the hand maynot necessarily be blocked. Cutting off the lower ganglia is ableto reduce the incidence of post-operati ve compensatoryhyperhidrosis. However, resection of nerves extending throughR4needs to be more cautious; patient’s pre-operativerequirement on the hand dryness, as wel l as the intra-operative variation in hand temperature and patient’s anatomicalcharacteristics should all be taken into consideration.