The main observation of our study was that the functional abnormality detected in the small airway of patients who underwent bilateral dorsal sympathectomy to treat primary hyperhidrosis is still present 3 years after surgery, although the patients remain clinically asymptomatic.
Studies to date evaluate alterations in lung function at 1, 3, and 6 months after sympathectomy. Only 1 recent study provides data 1 year after surgery. Ponce González et al10 studied a group of 37 patients who underwent forced spirometry before surgery, and at 3 months and 1 year after surgery. They observed a decrease in FVC, FEV1, and FEF25%-75% at 3 months, although FVC returned to baseline values at 12 months, whereas FEV1 and FEF25%-75% remained significantly low (-2.8% and -11.2%, respectively). These findings are consistent with ours, and corroborate the persistence of minimal bronchial obstruction 3 years after surgery. This appears to be associated with the influence of the sympathetic nervous system on bronchomotor tone.
As previously mentioned, the airway is innervated mainly by the parasympathetic nervous system. Sympathetic innervation, although scant, indirectly affects motor tone and could have caused the mild residual obstructive pattern after surgery. Despite the doubtful role of the sympathetic nervous system in the lung, a series of physiologic studies show the effect of sympathetic nervous activity after bilateral dorsal sympathectomy.11,12 The first was by Noppen and Vincken4, who compared the results of lung function studies (spirometry, diffusion, and lung volumes using plethysmography) in 7 patients before dorsal sympathectomy performed using VATS, at 6 weeks, and at 6 months (previous studies had been performed using invasive techniques [thoracotomy]). A statistically significant decrease was observed in FEV1, FEF25%-75%, and total lung capacity 6 weeks after surgery. At 6 months, the authors again evaluated the 35 patients and found that total lung capacity had returned to normal values, whereas FEF25%-75% remained low. They attributed the permanent decrease in FEF25%-75% to the sympathetic denervation produced by surgery, and stressed that, in patients with primary hyperhidrosis, bronchomotor tone is influenced by the sympathetic nervous system. This contrasts with the common opinion that motor tone in the airway is not affected by this system. Both the study by Ponce González et al,10 who evaluated their patients at 1 year, and our study, in which we evaluated patients at 3 years, show that persistence of the decrease in FEF25%-75% over time is related more to sympatholysis of the ganglia than to VATS.
