Prognosis

Neurogenic TOS

Prognosis in neurogenic thoracic outlet syndrome (TOS) is variable. Many patients with neurogenic TOS are successfully treated with physiotherapy alone, focusing on posture correction, stretching, and strengthening. Symptoms may persist despite aggressive physiotherapy and therefore require surgical intervention.

In contemporary thoracic outlet surgery practice, the risks of brachial plexus or phrenic nerve injury, or major vascular complications, are quite low, generally 1% or less.[183][184][185]​​​[186]​ For patients with neurogenic TOS who require surgical intervention, post-operative physiotherapy is paramount, again focusing on posture correction, stretching, and strengthening. Overall, 85% to 90% of patients with neurogenic TOS will describe a substantial improvement in symptoms after recovery from surgery. However, only 10% of patients will describe a complete resolution of symptoms and most patients will still have some degree of pain, numbness, tingling, or a sense of weakness with upper extremity activity. Particularly, for those patients presenting with a Gilliatt-Sumner hand - characterised by pronounced chronic symptoms, long-standing neural damage, and weak hand grip with atrophy - the prognosis is more challenging. Such patients are less likely to be symptom-free after surgical treatment than those with neurogenic TOS and no hand muscle atrophy or electrodiagnostic abnormalities.[30][31]​​​ Neurogenic TOS should therefore be considered a chronic condition requiring long-term management.[186][187]​​​​[188][189]​​​[190]

If patients have recovered well from surgery with a substantial improvement in symptoms for at least 3 months, but at a later point in time begin to experience the same symptoms as prior to surgery, the possibility of recurrent neurogenic TOS must be considered. Conservative measures should be reinstituted to emphasise physiotherapy.[191] If such recurrent symptoms persist despite physiotherapy, reoperation may be indicated. Symptoms can recur from 3 months to 10 years after surgical intervention; however, in most instances, recurrence is observed 1-2 years after operation and may be precipitated by a secondary injury.[154][192][193]​​ When symptoms persist after surgical intervention, if not treated previously it is important to consider nerve compression at the subcoracoid (pectoralis minor) space as an undiagnosed entity that may require follow-up treatment (targeted physiotherapy and/or pectoralis minor tenotomy).[50][194]

Reoperation for persistent or recurrent neurogenic TOS is preferably performed through the supraclavicular approach, although transaxillary approaches have been used and a posterior subscapular approach may have a role in rare cases with proximal lower nerve root involvement at the intraforaminal level.[154][193][195][196][197][198]​​​[199][200]​ Current supraclavicular approaches provide optimal exposure of the nerve roots and entire brachial plexus, thereby reducing the danger of injury to these structures, as well as providing adequate exposure of the subclavian artery and vein. This approach also provides a wider field for easier resection of any bony abnormalities or fibrous bands that may remain and allows extensive neurolysis of the nerve roots and brachial plexus, which are not always accessible through the limited exposure of the transaxillary approach. In some patients, persistence or recurrence of symptoms after initial surgery may be due to undiagnosed neural compression at the subcoracoid (pectoralis minor) space, treatable by pectoralis minor tenotomy.[50][194]

Venous TOS

Prognosis in venous TOS is generally excellent after timely diagnosis, prompt interventional treatment, and appropriate surgical therapy. It is notable that the incidence of arm swelling symptoms and post-thrombotic syndrome is approximately 30% for those who have surgical decompression with a persistent chronic venous occlusion and no vein reconstruction, compared to approximately 60% to 70% in those not having had surgery and treated with long-term anticoagulation alone.[35][91][156]​​​[170]​​​[171][172][201]​​​[202][203]​​​​​​​​ In contrast, the incidence of arm swelling symptoms and post-thrombotic syndrome is only 5% to 10% for patients that have had surgical treatment that achieved adequate decompression and a patent axillary-subclavian vein or bypass.[91][113][172]​​ Despite early success, some patients may develop recurrent subclavian vein stenosis or thrombosis during follow-up, due to progression of unresolved residual venous stenosis or from vein wall scarring after a previous vein repair. Retention of an anterior remnant of the first rib is also a prominent and preventable cause of persistent/recurrent vein compression. Venography and secondary endovascular interventions are often successful, including placement of venous stents if there has been adequate costoclavicular decompression.[167][168]​​​ Reoperations for recurrent venous TOS are also feasible.[204]

Arterial TOS

Prognosis in arterial TOS is largely favourable after appropriate surgical interventions are performed. Thoracic outlet decompression with selective subclavian artery reconstruction has yielded excellent primary patency rates (>90%), secondary patency rates nearly 100%, and durable functional recovery in nearly all patients.​[18][20][55]​​​​​[205][206][207]​​​​​ Patients presenting with acute limb ischaemia and distal thromboembolism may still have chronic vasospasm and potential tissue loss, requiring ongoing medical management.[208]

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