EMGs don't necessarily show TOS. It depends on the skill of the doctor and possibly the underlying cause of the TOS. I don't know why or how my 1st EMG was positive for TOS when it is rather uncommon to have a positive confirmation. My 1st EMG showed problems with the MABC, ulnar nerve, etc. Based on the involvement of different nerves, they can narrow down the site of compression. The doctor who performed my first EMG said I was unusual. He said I was the most "classic" case he has ever seen. He said that most patients present with TOS symptoms but no tests support the suspected problem (TOS). So hang in there!