Table 1.

TOS Overview and Classification.

TOS Classification	Predominant Affected Structure	Key Symptoms	Diagnostic Methods
Neurogenic TOS (nTOS)	Brachial plexus	- Neuropathic pain—Sensory loss—Paresthesia of ulnar nerve distribution—Weakness of upper extremity—Neck pain—Occipital headaches—Diminished pulse—Raynaud’s phenomenon—Gilliatt-Sumner hand (severe cases)	- Clinical diagnosis—Physical exam maneuvers (scalene tenderness, neck rotation, head tilt, upper limb tension test, Adson test, EAST)—Imaging (Duplex US, chest and neck radiographs, MRI, CT, EMG)—Neuromuscular blockade of scalene muscles
Venous TOS (vTOS)	Subclavian vein	- Upper limb edema—Pain—Venous distension—Cyanosis—Risk of thrombosis	- Imaging (Duplex US, chest radiograph, CT, MRI venography, catheter-directed venography)
Arterial TOS (aTOS)	Subclavian artery	- Ischemia—Paresthesia—Claudication—Pallor in digits and hand—Absent radial pulse	- Imaging (neck radiographs, CT, MRI/MRA, Duplex US, catheter arteriography)