Postgrad Med J                                                                      2003;79:278                                                                                                   doi:10.1136/pmj.79.931.278
A 29 year old man with severe  facial hyperhidrosis underwent an uncomplicated right thoracoscopic  sympathectomy. Before operating                               on his left side, a starch-iodine  preparation was applied to his face in order to demarcate residual  sudomotor function. The                               preparation becomes blue on exposure to  moisture, thereby representing residual sweat gland activity.                            
Figure 1 demonstrates that sympathetic innervation to the face is strictly unilateral, and nerve fibres do not appear to cross                               the midline. This is essentially an iatrogenic variation of the harlequin syndrome,2 which usually results from interruption of post-ganglionic sympathetic fibres secondary to malignant invasion.                            
His facial hyperhidrosis was completely treated once the contralateral sympathectomy was performed.
 
 
