He retired in 2012 after suffering post-concussion syndrome from three notable head injuries .
Robertson won a silver medal in snowboard cross at the 2010 Winter Olympics in Vancouver and was considered somewhat of an unknown and surprise medalist .
Robertson retired in 2012 after suffering post-concussion syndrome from three notable head injuries .
Robertson won a silver medal in snowboard cross at the 2010 Winter Olympics in Vancouver and was considered somewhat of an unknown and surprise medalist .