Cervical ribs: a cause of distal and cerebral embolism.

The thoracic outlet syndrome occurs when the neurovascular structures are compressed as they traverse the thoracic outlet. Degenerative changes can occur in the subclavian artery and the vessel may become a source of embolism with the risk of acute or chronic upper limb ischaemia. Rarely, distal thromboembolism in the thoracic outlet syndrome may be associated with retrograde flow when there is the added risk of cerebral thromboembolism.