short and complete course on thoracic outlet syndrome, from introduction to etiologies, classification, clinical presentation, work-up, treatment, differential diagnosis and prognosis and complications
3. INTRODUCTION
Thoracic outlet syndrome (TOS) manifests when pressures in the
thoracic outlet increase to the point of impinging vessels or nerves.
Thoracic outlet syndrome (TOS) is a nonspecific diagnosis
representing many conditions that involve the compression of the
neurovascular structures that pass through the thoracic outlet.
TOS presents in a vague and nondescript way.
The first rib, scalene muscles, and the clavicle comprise the thoracic
outlet.
Patients present with a wide range of symptoms, from minor
complaints to debilitating manifestations.
4. INTRODUCTION
Neurogenic thoracic outlet
syndrome account for over 90% of
all cases.
TOS is more prevalent in females
and those with poor muscle
development, poor posture, or
both.
Its estimated incidence is anywhere
between 3 to 80 cases per 1000
population.
5. ETIOLOGIES
The main cause of TOS is neck trauma.
Other causes include:
Poor neck positioning and repetitive movements over a long period, from erroneous
exercises.
Thoracic ribs or space-occupying lesions such as the, including tumors or cysts.
Fibrous muscular bands from overuse, or in muscular athletes
Trapezius muscle deficiency, it can cause the shoulder to depress, which can cause the
outlet to diminish, thus increasing the pressure.
Presence of ectopic cervical ribs and prominent C7 transverse processes (large cervical rib
fused to the first rib)
Fracture of the clavicle.
6. CLASSIFICATION
TOS can be subdivided into 3 types, depending on the organ affected.
Neurogenic Thoracic Outlet Syndrome:
Neurogenic is the most common type of TOS.
It occurs when abnormal portions of bony or soft tissue in the lower neck region compress or
irritate the nerves of the brachial plexus.
Venous Thoracic Outlet Syndrome:
This condition occurs when major veins in the lower neck and upper chest are damaged.
The vein becomes scarred or narrowed because of the compression and thrombosis may
develop further jeopardizing veinous return.
Arterial Thoracic Outlet Syndrome:
The least common but most serious type of TOS is Arterial Thoracic Outlet.
Compression of the artery may yield to an emboli.
7. CLINICAL PRESENTATION
Nebulous pain is one of the most common complaints amongst all etiologies.
Neurogenic thoracic outlet syndrome
Similar to the other versions of TOS, vague pain is a common symptom.
Atrophy of the intrinsic muscles of the hand can also occur, as well as weakness in the
hand and neurologic sensory deficits.
Venous obstruction
can present with upper extremity swelling, venous distention, and pain ranging from
the hand to the forearm.
Upper extremity deep venous thromboses (DVTs) may occur.
The arterial variant of thoracic outlet syndrome can appear with
Color changes in the upper extremity and diminished pulses which may only appear in
certain positions in which pressure increases.
8. CLINICAL PRESENTATION
The physical exam, in a patient with suspected TOS, is crucial to confirming the diagnosis.
Symmetry and range of motion of both arms should be tested initially.
Spurling’s test in which the patient’s head is extended and laterally flexed with the examiner
providing axial compression.
This test should reproduce radicular pain.
In a patient with suspected arterial compression due to TOS, the Adson maneuver should be
performed.
This test involves extending and slightly abducting the shoulder.
The patient extends their neck and turns it toward the examiner’s shoulder while the examiner
palpates the radial pulse.
The pulse should diminish if arterial compromise is present.
9. CLINICAL PRESENTATION
A neurological exam focused on the upper extremity is necessary to evaluate
for nerve compression.
Gilliatt-Sumner hand is a finding in which the abductor pollicis brevis and the
hypothenar muscles become atrophied due to the nerve compression.
The roos stress test can help to test for any variant of TOS.
In this test, the patient abducts and externally rotates their shoulders with the elbow at a
ninety-degree angle.
The patient will then open and close their hand.
Fatigue or reproduction of symptoms is a positive result.
10. PARACLINICAL INVESTIGATIONS
The first step is a basic chest x-ray or cervical spine x-ray: can give the examiner crucial
information about the patient’s anatomy, which is likely the culprit of the malady.
Angiography can be helpful; however, it remains controversial, as it’s often positional and
challenging to reproduce on command, making this an obstacle in this diagnostic approach.
Venous dopplers are useful to help detect compression of the subclavian vein or other veins
in the thoracic outlet syndrome.
Electrodiagnostic studies (EMS) are a classic diagnostic mode to diagnose neurogenic TOS.
EMS has issues with neurogenic TOS often being transient;
If positive can give a confirmatory diagnosis.
A positive result is considered a reduction of less than 85 m/s, and an overall velocity of less than 60
m/s is regarded as an indication for surgery.
11. TREATMENT
Can be conservative or surgical.
It is common practice, and most physicians recommend, to attempt
conservative management initially, except for patients with severe
compression causing debilitating symptoms.
Conservative management consists of lifestyle modifications, physical therapy
(PT), and rehabilitation.
Lifestyle modifications are crucial to treat and prevent future relapses.
Postural correction is a common adjustment that can relieve patients’
symptoms.
Physical therapy is a mainstay as first-line treatment for patients suffering
from TOS
12. TREATMENT
Surgical intervention is a controversial method of treatment.
In patients with a severe compromise of the vasculature of atrophy
of intrinsic muscles of the hand, surgery is the recommended
approach.
However, without credible and substantial evidence that TOS is the
culprit, surgery is not recommended.
Due to the nonspecific and vague nature of the symptoms, the
majority of cases do not have this evidence.
13. DIFFERENTIAL DIAGNOSIS
Due to the vague nature of the symptoms of
thoracic outlet syndrome, many injuries and
nondescript pain disorders are common
differentials for TOS.
One commonly confused disorder is pectoralis
minor syndrome.
Pectoralis minor syndrome (PMS) presents with
pain in the anterior chest wall, trapezius muscle,
and over the scapula but also correlates with arm
and hand pain or paresthesia.
PMS is caused by compression of nerves by the
pectoralis minor muscle and not in the thoracic
outlet.
Main differential diagnoses for thoracic
outlet syndrome. Daniels et al, 2017
14. PROGNOSIS AND COMPLICATIONS
Overall, the prognosis is excellent in patients with thoracic outlet syndrome.
Patients who undergo conservative therapy have their symptoms resolve in
about 90% of cases.
Most of these individuals do not have relapses especially if conservative means
are followed.
Due to the benign nature of most treatment modalities and the insidious nature
of the condition, TOS does not correlate with high rates of complications.
Ischemic change could manifest if a vascular compromise occurs.
Venous gangrene and potentially even phlegmasia cerulea dolens can arise in
severe cases.
Most of the complications arise from surgical intervention (iatrogenic nerve
injury, pneumothorax, bleeding complications), which is why most physicians
recommend conservative therapy.
15. IN FINE
Thoracic outlet syndrome occur when there’s obstruction of brachial plexus
structures in the thoracic outlet.
It can affect: nerves, veins and artery.
The clinical presentation is often vague and depends of the structure
affected.
The confirmatory test is the electromyogram though when negative doesn’t
ruleout the TOS.
Conservative management is the most advisable therapteutic regimen as it
presents less side effects.
Beware of Pectoralis minor syndrome which is a common differential
diagnosis.
