<qa>  What is the most common indication for the performance of thoracic sympathectomy?The hyperhidrosis is a relatively common disorder, affecting between 0.6 to 1 of the population. It is characterized by increased sweat in certain areas of the body such as hands, face, feet and armpits. More frequent in young adults and adolescents, mostly females. This is not a serious illness as life threatening, but this situation is very uncomfortable, causing deep embarrassment social relationships and psychological disorders in the carrier, which often isolate themselves socially and acquire habits that conceal their problem. Primary hyperhydrosis is the most common indication for the performance of thoracic sympathectomy. 