Epidemiology

The incidence of all forms of thoracic outlet syndrome (TOS) is difficult to ascertain and poorly captured in large databases and registries, largely due to wide variations in clinical suspicion and application of sound diagnostic criteria.[32] The incidence is estimated to be between 3 and 80/1000. Neurogenic TOS is the most common form, accounting for over 90% of cases, followed by venous TOS (approximately 5% to 10%), then arterial TOS (approximately 1% to 2%).[33]​ Subclinical symptoms and findings of neurogenic TOS may be seen in a substantial number of office workers.[34] The incidence of venous TOS is also likely under-reported, as investigations pertaining to this condition are often overlooked in assessment of upper extremity deep vein thrombosis.[35][36][37]

Neurogenic TOS

  • Based on clinical referral patterns, the incidence of neurogenic TOS has been estimated to be about 2-3 cases per 100,000 population per year.[36][37]​​

  • Females predominate in most clinical series.[38][39]​​

  • Age ranges from children and adolescents to the elderly, with most cases occurring in people aged 20-50 years.[39]

  • Associated with cervical ribs (partial or complete) in approximately 10% to 20% of patients. Most patients with cervical ribs are asymptomatic throughout the lifespan with only 10% requiring surgical treatment for TOS-related symptoms.[38][39][40][41][42]​​​​

  • Aetiology has changed with changes in workforce and advances of technology. Industrial and manual laborers have been surpassed by accidental causes and repetitive motion injuries related to use of computers and poor posture. Subpopulations such as office workers, motor vehicle accident victims, people injured in the workplace, and athletes have been identified as potentially more prone to developing neurogenic TOS.[5]​​​​​[6][7][8][9][10][11][12][34]​​[43][44]​​[45][46][47]​​​​​​​​[48][49]​​​​

  • Concurrent brachial plexus compression at the scalene triangle and pectoralis minor spaces may be present in approximately 80% to 90% of patients with neurogenic TOS. Nerve compression isolated to the pectoralis minor space occurs in around 5% to 10% of patients.[50][51]

Venous TOS

  • Based on clinical referral patterns, the incidence of venous TOS has been estimated to be about 0.5-1/100,000 population/year.[36][37][52]​​

  • Most often there is a male predominance with a ratio of 2:1, with gender equivalence noted in other series.

  • Tends to affect patients from their teenage years through their 50s.

  • Not associated with cervical ribs.

  • Is frequently related to repetitive exercise, heavy lifting, and overhead motion. These are most often associated with athletic endeavours and may also be associated with physical labour. Occasionally it is associated with congenital and developmental causes.[13][14][53]

Arterial TOS

  • Based on clinical referral patterns, the incidence of arterial TOS has been characterised as rare. From large practices it has been seen as often as 2% to 5% of surgical cases.[18][54][55][56]​​​​​​

  • Women predominate in a ratio of approximately 60:40 to 70:30.

  • Has been reported in a wide age range from teenagers to late 60s.

  • It is associated with presence of congenital bony anomalies (cervical ribs, aberrant first ribs) and orthopaedic injuries (clavicular and first rib fractures), as well as overhead activities (athletes).[19][20][21][22]

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