The diagnosis of Thoracic Outlet Syndrome (TOS) typically involves a combination of specialized clinical tests, along with various imaging and electrophysiological studies. These investigations may include X-rays, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and electromyography (EMG). Due to the diverse and often vague nature of its symptoms and findings, TOS can be a challenging diagnosis, and delays may occur even with thorough examination and investigation.