RESOLVING THORACIC OUTLET SYNDROME (TOS) – PART 1
Updated: May 12
A lot of patients complain about numbness or tingling in their hands when working at the computer, driving their vehicle, or even when waking up in the morning. Many of these same patients also experience tight and restricted neck muscles, have shoulder tension, feel chest tightness, and even pain that can radiate down their arms and hands. Although there are a number of conditions that can present with these same symptoms, one of the commonly found conditions is called Thoracic Outlet Syndrome (TOS).
TOS is an umbrella term that refers to conditions that involve compression of a neurovascular bundle. A neurovascular bundle is a structure that binds together nerves, veins, or arteries with connective tissues, allowing them to travel in tandem through the body. The neurovascular bundle involved in TOS contains the brachial plexus, the subclavian artery and subclavian vein.
ANATOMY OF TOS
In the neck and shoulder regions, the neurovascular bundle travels through the thoracic outlet space. The thoracic outlet space starts at the scalene triangle (a group of three muscles in the neck) and terminates at the pectoralis minor muscle. (1)
Some of the anatomical structures that can potentially cause compression of the neurovascular bundle include:
Scalene Muscles: Entrapment primarily occurs at the anterior and medial scalene, and not as much at the posterior scalene. (7)
Pectoralis Minor Muscle: Many cases of TOS can involve various muscles. In fact, some research is now showing that 75% of TOS cases involve the pectoralis minor muscle.(8) Because the brachial plexus is located just under the pectoralis minor, the compression it causes is primarily neurogenic. (8)
First Rib: The shape of the first rib can be a determining factor in whether or not it is involved in compression. (9)
Ulnar Nerve: The ulnar nerve is made up of the C8/T1 nerve roots. Since the C8/T1 nerve roots are located beside the first rib, they are more susceptible to compression. This is why 70-90% of TOS cases have an ulnar nerve distribution in the 4th and 5th fingers.(9)
TOS presents as one of three different syndromes, either Arterial, Venous or Neurogenic compression of an artery, vein or nerve. Over 90% of all TOS cases involve nerve compression (neurogenic TOS). (9; 19)
Common symptoms of Neurogenic TOS include:
Weakness: This could include weakness and fatigue in the upper extremity.
Headaches: Occipital headaches occur in 76% of patients with TOS. (10; 21)
Shoulder or Arm Pain: Shoulder pain could be a clue that the TOS is neurogenic since shoulder pain is uncommon in arterial or venous TOS. Shoulder and arm pain is seen in 88% of patients with TOS. (21)
Chest Pain: Approximately 72% of patients with TOS experience chest pain. (21)
Altered Sensation in the Hand: Approximately 58% of patients with TOS experience altered sensations (paresthesias) in their hands. (21)
Ulnar Nerve Distribution: Ulnar distribution is more common with TOS than involvement of the median or radial nerves. Over 90% of TOS cases are neurogenic, and 70% to 90% of TOS cases have an ulnar nerve distribution. (9) Distribution would include the medial arm and elbow, following a path to the 4th and 5th fingers. This would include weakness, numbness, and tingling (paresthesias).
Arterial TOS symptoms include decreased blood flow, coldness, and pain. With Venous TOS there may be swelling in the upper extremity, accompanied by increased pain or tingling with activity. In both cases of either Arterial or Venous TOS, shoulder and neck symptoms are uncommon. (11)
CAUSES OF TOS
TOS can be a result of a previous trauma such as motor vehicle accident, a fall, sports injury, previous surgery, poor posture, repetitive arm and shoulder movements, and person-to-person anatomic variations. Many cases can be attributed to myofascial restrictions in the neck (scalene muscles) shoulder, and upper chest (subclavius, pectoralis minor), all of which can lead to nerve entrapment's, muscle imbalances, and dysfunction.
Poor posture is also a common contributing factor. In general, poor posture (anterior posture) often pulls the shoulder forward creating imbalances throughout the chest, upper back, and shoulder girdle. In addition, joint restrictions in the cervical and thoracic spine, between the collarbone (clavicle) and chest bone (sternum), and between the first rib and first thoracic vertebra can all lead to decreased mobility and compensatory movement patterns in the neck, shoulders, and chest-further adding to the development of the TOS syndrome.
The exact cause of TOS is often unknown, and often the symptoms come on slowly and may be of an unknown origin.
EXAMINATION PROCESS FOR TOS
History: This should cover previous traumas, motor vehicle accidents, sports injuries, previous surgeries, work history, etc.
Vitals: It should be noted that, although rare, vascular TOS can cause large differences in the reading of blood pressure between the two arms. These differences can be up to 20 mmHg from right to left side. (22)
Observation: Look for edema, color changes, muscle atrophy, and postural changes.
Neurological Testing: Check Deep Tendon Reflexes, and include muscle testing and sensory examination.
Special Tests: It is important to note that no single test is definitive of TOS, but by using multiple tests in conjunction with each other could lead to a more definitive diagnosis. Here are some of the special tests that we commonly perform at Kinetic Health when we suspect TOS: (click on the name to view a video demonstration)
Pectoral Minor Test: A reduction of symptoms could be an indication of TOS. (12)
Spurling’s Test: This is a good test to differentiate cervical nerve root compression for a patient with TOS. In Spurling’s Test the patient’s head is put into a position of side-bending and extension (closing down the foramina on the same side). If there is nerve root compression, this would increase symptoms on the same side being tested. In a TOS patient, side-bending to the affected side would then relieve symptoms. (13)
Cervical Traction Test: This test can increase symptoms of TOS. The problem is that patients can have both a cervical problem and TOS. If the test can be performed in a way that cervical symptoms can be reduced, without the TOS symptoms being reduced then it may help confirm TOS.
Roo’s Test: Testing for the presence of neural or vascular compromise in the thoracic outlet.
Adson’s Test: This maneuver is often used to diagnose Thoracic Outlet Syndrome.
Costoclavicular Maneuver: This test is for Thoracic Outlet Syndrome caused by compression of the neurovascular bundle between the clavicle and the 1st rib.
Upper Limb Tension Test: Also known as Brachial Plexus Tension Test, it puts stress on the patients neurological structures of the upper body, and allows for evaluation.
Note: For suspected vascular TOS, diagnostic ultrasound is a non-invasive and inexpensive choice for initial imaging. Ultrasound also provides a high sensitivity and specificity. (22)
DIFFERENTIAL DIAGNOSIS (DDx)
It is important to remember that all diagnoses of TOS are a working diagnosis, it is not a diagnosis cast in stone. Especially when you consider that even with a comprehensive physical examination, a diagnosis of TOS often needs to be confirmed by the process of elimination.
Several other syndromes have similar symptoms to TOS and must always be considered. Some of these syndromes, though rare, could also co-exist with TOS. Some of these other conditions are:
Cervical Radiculopathy (nerve root involvement)
Degenerative Disc Disease of the Cervical Spine
Glenohumeral Joint Instability/Shoulder Instability
Malignancies (Pancoast’s Syndrome)
Thoracic Outlet Syndrome can be an extremely painful and debilitating condition. Its resolution requires a thorough physical examination that includes a comprehensive history, orthopedic and neurological testing. It is important to rule out the multiple other syndromes that can have similar symptoms.
In part two of “Resolving Thoracic Outlet Syndrome,” I will discuss recommended treatments and exercise protocols. I will also include demonstration videos for soft-tissue and osseous treatments that we recommend along with examples of specific exercises that we often prescribe to our patients to support their TOS treatments.
Note: References are at the end of Part 2
Do you have Thoracic Outlet Syndrome? If so make an appointment with our incredible team at Kinetic Health in NW Calgary. Just scan the QR code with your phones camera and click the link, or call Kinetic Health at 403-241-3772 to make an appointment today!