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3: Surgery Y3 - Vascular [20] > [4] Thoracic Outlet Syndrome > Flashcards

[4] Thoracic Outlet Syndrome Flashcards

1
Q

What does the term thoracic outlet syndrome refer to?

A

The clinical features that arise from compression of the neurovascular bundle within the thoracic outlet

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2
Q

What can the signs and symptoms of thoracic outlet syndrome be divided into?

A

Neurological (nTOS)
Venous (vTOS)
Arterial (aTOS)

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3
Q

Who does TOS typically occur in?

A

Middle aged individuals

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4
Q

Who is TOS more common in?

A

Women

Muscular individuals

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5
Q

What % of TOS cases are nTOS?

A

95%

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6
Q

What does TOS usually occur in the setting of?

A

Hyperextension injuries, repetitive stress injuries, or external compressing factors

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7
Q

Give an example of repetitive stress injuries that can cause TOS

A

Work-related injuries, particularly when working over the head

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8
Q

Give an example of an external compressing factor that can cause TOS?

A

Poor posture

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9
Q

What can TOS be secondary to?

A

Abnormalities of the 1st rib, anomalous cervical rib, or bands within the thoracic outlet

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10
Q

What mechanisms are most commonly behind thoracic outlet syndrome?

A

Rib anomalies
Muscular abnormalities
Injury

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11
Q

Where do the brachial plexus and subclavian artery pass?

A

Through the scalene triangle

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12
Q

Where does the subclavian vein pass?

A

Anterior to the scalenus anterior

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13
Q

Where can the brachial plexus get compressed?

A

Between the anterior and middle scalene muscles, or against the 1st rib or a cervical rib

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14
Q

What happens when the brachial plexus is compressed?

A

Typically, the lower cord becomes irritated, thus causing symptoms in the ulnar distribution

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15
Q

What can repetitive stress injuries and hyperextension injuries in the neck cause?

A

Acute spasm of the scalene muscle, haemorrhage, or swelling of the scalene muscles

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16
Q

What does acute spasm, haemorrhage, or swelling of the scalene muscles cause?

A

Narrowing of the thoracic outlet

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17
Q

Why can bodybuilders can thoracic outlet syndrome?

A

Due to hypertrophy of the scalene muscles leading to compression

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18
Q

What is the role of cervical ribs in thoracic syndrome?

A

They can predispose patients, especially after hyperextension-flexion (whiplash) injury

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19
Q

What effect can the presence of a costoclavicular ligament have?

A

Can reduce the costoclavicular space, leading to vTOS due to positional venous obstruction

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20
Q

How can TOS arise following clavicular fractures?

A

The healing process from clavicular fractures can cause extra bone formation that compresses neurovascular bundles

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21
Q

Does the absence of a rib anomaly make the diagnosis of arterial thoracic outlet syndrome less likely?

A

Yes

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22
Q

What are the risk factors for thoracic outlet syndrome?

A

Recent trauma
Repetitive motions
Athletes
Anatomical variations

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23
Q

Which athletes are at increased risk of thoracic outlet syndrome?

A

Those who compete in swimming, rowing, weightlifting, or any sport that involves the muscles around the neck and shoulder

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24
Q

Which kind of TOS are athletes at risk of?

A

Venous

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25
Q

What are the clinical features of TOS dependent on?

A

Neurological, arterial, or venous involvement

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26
Q

What may cause worsening of symptoms in TOS?

A

Certain movements, e.g. shoulder abduction or extension

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27
Q

What symptoms can compression of the brachial plexus cause?

A

Paresthesia and motor weakness

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28
Q

What symptoms can venous compression lead to?

A

DVT and extremity swelling

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29
Q

What is DVT and extremity swelling in venous compression known as?

A

Paget-Schrotter syndrome

30
Q

What symptoms can arterial compression lead to?

A

Claudication symptoms or acute limb ischaemia

31
Q

What should be done on examination in thoracic outlet syndrome?

A

Assess for areas of weakness or numbness, for swelling or tenderness, and any features of limb ischaemia

32
Q

What is often present on examination in TOS?

A

Tenderness over scalene muscles

33
Q

What special tests are there for TOS?

A

Adson’s manoeuvre
Roo’s test
Elvey’s test

34
Q

What are the problems for the specific tests for TOS?

A

They have poor sensitivity and specificity

35
Q

How is Adson’s manoeuvre performed?

A

Palpate the radial pulse on the affected side, with the arm initially abducted to 30 degrees. Ask the patient to turn their head and look at the affected sides shoulder, before fully adducting, extending, and laterally rotating the shoulder. Any decrease or loss of pulse is suggestive of TOS

36
Q

How is Roo’s test performed

A

Abduct and externally rotate the shoulder on the affected side to 90 degrees, bend the elbow to 90 degrees, then ask the patient to open and close the hands slowly over a 3 minute period. Worsening symptoms will develop if TOS is present

37
Q

How is Elvey’s test performed?

A

Extend the arm to 90 degrees, with the elbow extended and wrist dorsiflexed, then tilt the patients ear to each shoulder. A loss of the radial pulse or worsening symptoms is suggestive of TOS

38
Q

What are the differential diagnoses of thoracic outlet syndrome?

A
  • Cervical ribs

- Paget-Schrotter syndrome

39
Q

What are cervical ribs?

A

An extra rib that may be present that connects to the cervical spine, which can fuse with the first rib and cause compression

40
Q

What is Paget-Scrotter syndrome?

A

DVT formation in the proximal upper limb veins, typically in the axillary or subclavian veins

41
Q

What initial investigations should be done in suspected thoracic outlet syndrome?

A
  • Routine bloods, including FBC and clotting screen

- Chest radiograph

42
Q

Why is a chest radiograph important in the investigation of thoracic outlet syndrome?

A

To identify potentially bony abnormalities, such as cervical ribs, long transverse cervical processes, or rib/clavicular fracture calluses

43
Q

What % of aTOS patients will have a bony abnormality?

A

90%

44
Q

What common tests are used for the diagnosis of venous or arterial TOS?

A

Initially, a venous and arterial duplex ultrasound

45
Q

What positions should be done using a venous or arterial doppler in the investigation of TOS?

A

With the patient at rest, and the arm in stress positions

46
Q

What investigations may be required for further investigation of venous or arterial TOS?

A

CT imaging or venogram

47
Q

What is a common investigation for nTOS?

A

Nerve conduction studies

48
Q

Why are nerve conduction studies useful in investigating nTOS?

A

As they allow detection of decreased action potential conductance because of nerve compression

49
Q

What can MRI be used for in the investigation of TOS?

A

Detection of cervical ribs and fibrous bands

50
Q

What does the treatment approach of TOS depend on?

A

The type of TOS

51
Q

When is treatment indicated in TOS?

A

Only in symptomatic patients - the presence of a cervical rib or other rib anomalies does not indicate intervention

52
Q

How are most cases of neurogenic TOS managed?

A

Conservatively, with physiotherapy and weight loss

53
Q

When is nTOS not managed conservatively?

A

If there is evidence of progressive neurological weakness or significant pain and paresthesia

54
Q

What can be done if symptoms of nTOS do not improve with physiotherapy alone?

A

In some cases, botulinum toxin A injections into the anterior and middle scalene muscles can be tried in conjunction with physiotherapy

55
Q

What drugs may be required in patients with vTOS?

A

Thrombolysis and anti-coagulation

56
Q

Under what guidance should thrombolysis and anti-coagulation be given in vTOS?

A

Haematology teams

57
Q

What management may be required in long-standing cases of vTOS?

A

Surgical management via venoplasty or venous reconstruction

58
Q

What is required if there is any evidence of aTOS with acute limb ischaemia?

A

Urgent vascular input

59
Q

How can most cases of aTOS be managed?

A

In an elective surgical setting

60
Q

When should surgical procedures be considered in TOS?

A

If conservative measures do not work, or anatomical variations require correction

61
Q

What approaches can be taken to decompression in TOS?

A

Supraclavicular or transaxillary

62
Q

What is done in decompression of TOS?

A

Excision of the first or cervical rib, with release of any restrictive bands and anterior scalene muscle when they impinge on surrounding structures

63
Q

What is the role of physiotherapy in the surgical management of TOS?

A

It is an integral part of recovery after any surgical intervention for TOS

64
Q

What are the complications of TOS surgery?

A

Neurological or vascular damage

Haemothorax, pneumothorax, or chlyothorax

65
Q

Why is chylothorax more likely to occur as a complication to TOS on the left?

A

Because the thoracic duct is within the thoracic outlet on the left, so is at risk of development

66
Q

What can happen if TOS is left untreated?

A

Can lead to further sequelae of the pathology, including permanent nerve damage, aneurysmal dilation of the subclavian artery leading on to embolisation, or loss of limb function

67
Q

What is the prognosis in nTOS?

A

Variable

68
Q

What is the prognosis of vTOS?

A

Largely favourable after appropriate surgical interventions

69
Q

What can happen in some cases, especially nTOS?

A

Symptoms can persist despite aggressive physiotherapy and surgical intervention

70
Q

Can symptoms occur after surgical intervention?

A

Yes, 1 month - 10 years after surgical intervention

3: Surgery Y3 - Vascular [20] (10 decks)

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