Twenty-site HDSS mapping after thoracoscopic sympathectomy for primary palmar hyperhidrosis: a secondary complete-case analysis of a multicenter randomized trial.

Objective: To map, using the Hyperhidrosis Disease Severity Scale (HDSS), the preoperative distribution and six-month regional evolution of sweating severity across 20 anatomical sites after dominant-side unilateral versus one-stage bilateral R4 video-assisted thoracoscopic sympathectomy for primary palmar hyperhidrosis. Methods: This was a secondary complete-case, site-level analysis of a prospective multicenter randomized trial. Adults undergoing one-stage bilateral thoracic sympathectomy (BTS) or dominant-side unilateral sympathectomy (UniS) were eligible when baseline and six-month HDSS data were complete for all 20 prespecified sites. HDSS was grouped as 1, 2, or 3-4. Regional outcomes were classified as improvement, stability, or worsening and were stratified by baseline HDSS. Results: Ninety-two patients were included: 36 BTS and 56 UniS. Before surgery, severe sweating was present in 182 of 184 hand-site observations, 168 of 184 foot-site observations, and 75 of 184 axillary-site observations. At six months, improvement was more frequent after BTS than UniS in the hands (88.9% vs 52.7%) and axillae (72.2% vs 29.5%). Worsening was concentrated mainly in abdominal, hemidorsal, and thoracic sites. Among observations that were normal at baseline, progression to HDSS 3-4 occurred in 10.8% after BTS and 7.7% after UniS. Among observations with baseline HDSS 3-4, complete resolution to HDSS 1 occurred in 47.2% after BTS and 21.8% after UniS. Conclusion: Baseline-stratified 20-site HDSS mapping may improve preoperative counseling and postoperative outcome assessment by distinguishing true new-onset compensatory hyperhidrosis from worsening or persistence of pre-existing sweating.