Having thoracic outlet syndrome (TOS), a medical condition characterized by the compression of nerves and blood vessels, can hinder a person’s productivity and ability to hold active professions and lifestyles. It’s estimated TOS occurs in about every 3 to 80 people out of a thousand . But what factors contribute to such a risk? Let’s find out! 1. Age & Sex Young adults between 20 and 40 years old are more prone to having thoracic outlet syndrome.