[4] PMS is often caused by injury to the neck, excessive stretching of the shoulder, or certain sports that involve overhead throwing.
[1] Confirmation of the diagnosis can be done by blocking the pectoralis minor muscle or injecting botulinium.
[5] First-line treatment for patients with PMS but without TOS is self-stretching of the pectoralis minor muscle.
[6] Other treatments include injection of botulinium, or surgery that cuts the pectoralis minor tendon.
[7][8][2] For patients with PMS but without TOS, one study found that surgery resulted in a good or excellent outcome in 90 percent of cases.