The Brachial Plexus and Thoracic Outlet Syndrome The brachial plexus of nerves and

Understanding Signs and Symptoms the subclavian/axillary artery and

By Joseph E. Muscolino, DC vein comprise a neurovascular

bundle that is often compressed

in the lower neck/upper thoracic 1 Thoracic outlet syndrome is the name given region, causing a condition known to a set of neurovascular compression syndromes that affect the brachial plexus of as thoracic outlet syndrome (TOS). nerves and/or the subclavian/axillary artery and vein where they outlet from the thorax into the upper extremity. Note the presence There are actually four different forms of a cervical rib on the model’s left side. of TOS, each named for the region where Images courtesy Joseph E. Muscolino. the compression occurs (Image 1). One Illustrations by Giovanni Rimasti. Photography is called anterior scalene syndrome because by Yanik Chauvin and Joseph E. Muscolino. the neurovascular contents are entrapped and compressed between the anterior and middle scalene muscles. The second is called costoclavicular syndrome because the Middle scalene C5 entrapment/compression occurs between C6 Anterior scalene the first rib (cost is Latin for “rib”) and C7 C3 the clavicle. The third is called pectoralis Brachial plexus C8 trunks T1 minor syndrome because the entrapment/ compression occurs between the pectoralis

C6 minor and the rib cage. The fourth type Cervical rib of TOS occurs due to the presence of a

Subclavian genetic anomaly that creates what is called artery a cervical rib, which is a formation of bone

Musculocutaneous nerve off the seventh cervical vertebra (C7). Median nerve The first three types of TOS—anterior Ulnar nerve scalene, costoclavicular, and pectoralis minor syndromes—are caused by soft- tissue postural dysfunction and will 1st rib Axillary nerve respond well to manual and movement Radial nerve Subclavius therapy care. Therefore, the emphasis for anyone in the field of bodywork should Brachial plexus be placed on these forms of TOS. The cords fourth type—cervical rib TOS—being due to a relatively rare bony anomaly (which occurs in approximately 1–2 percent of Axillary artery and vein the population) is not readily treatable with manual and movement therapy and is therefore of less importance to bodyworkers. Pectoralis minor

60 massage & bodywork november/december 2017 Brachial Plexus Tree

2 This image is an anatomically correct, yet artistic, rendering of the brachial plexus of nerves, providing a visual touchstone for learning the structures. Leaves represent the muscles innervated by the branches of the brachial plexus; “½” indicates that muscle is innervated by two different nerve branches. Please see Tables 2 and 3 for a listing of the muscles corresponding to the abbreviations used in this image. Cervical Rib: “True” Thoracic Outlet Syndrome? Interestingly, the cervical rib version of TOS is often referred to in medical literature as true TOS, which implies that the other forms of TOS are in some way false. Terming cervical rib TOS as “true” occurs because of the undue emphasis the medical establishment places on skeletal structure, as well as the lack of importance it places on soft-tissue dysfunction (the cause of the other three types of TOS). But it should be stated that all four forms of TOS can cause the signs and symptoms of TOS and, therefore, are all “true” forms of TOS.

SIGNS AND SYMPTOMS OF TOS hand. Most often, upper extremity nerve Arterial Symptoms A full awareness of the signs and symptoms compression is experienced in the hand. Arterial blood is delivered to the upper of TOS cannot be understood without Compression of a sensory neuron can extremity via the subclavian artery, which, a somewhat in-depth knowledge of the cause irritation of the neuron, creating as it travels distally, becomes the axillary brachial plexus; however, the major concepts aberrant sensory impulses resulting in artery, then the brachial artery, and then can be addressed and understood. Before increased sensation, termed hyperesthesia. divides into the radial and ulnar arteries, moving forward with this discussion, it is Examples include hypersensitivity to which enter the hand. The various types worth noting that symptoms, by definition, touch, a feeling of tingling even when of TOS can potentially compress the are subjective in that they must be reported no stimulus is being applied to the skin, subclavian artery or axillary artery pathway by the client. For example, only the client or burning or shooting pain. When the of arterial delivery into the upper extremity. can state if they are experiencing pain. compression is greater, it can begin to This would decrease the delivery of Signs, on the other hand, are objective obstruct axonal flow within the sensory oxygenated arterial blood to all the tissues in that they can be measured by the neuron, resulting in diminished ability of and cells of the upper extremity, distal to therapist. For example, the strength of the neuron to carry impulses. This, in turn, the point of compression. In light-skinned the client’s pulse is a sign that can be results in diminished sensation, termed individuals, the skin’s pallor might become felt and reported by the therapist. hypesthesia. This is often experienced as cyanotic (bluish) and is often noticed in pins and needles, instead of a full sensation the hand. Decreased arterial flow can be Neural Symptoms of touch, when pressure is applied to the objectively measured by feeling for the Almost all peripheral spinal nerves are skin. If the axonal flow is entirely blocked, strength of the client’s radial pulse at the mixed in that they carry both sensory and numbness can result. Any altered sensation, wrist (it should be emphasized that it is motor neurons (the only exception is the whether it is hyperesthesia or hypesthesia, the strength of the pulse, not the rate C1 nerve root, which is only sensory). In can be termed paresthesia. Because of the pulse, that is assessed). As we will this sense, they can be likened to two- paresthesia, is by definition, something see later in this article, palpating for the lane north-south highways comprising the client feels, it is a subjective symptom strength of the radial pulse is the primary a northbound lane that carries sensory and must be reported by the client. means by which TOS is assessed. information gathered in the periphery Given that motor neurons are up to the central nervous system, and responsible for directing muscle contraction, Venous Symptoms a southbound lane that carries motor compression of a motor neuron would Venous blood is drained from the upper information down from the central affect muscle function. If the motor neuron extremity by veins that are similarly named nervous system to the periphery. TOS is irritated and creates aberrant nerve to the arteries. TOS can compress the usually involves peripheral nerve impulses, then muscle twitching (termed subclavian and/or axillary vein, which compression; therefore, the two major fasciculation) can occur. If the compression is would result in decreased venous return types of neural signs/symptoms result greater, then obstruction of the axonal flow and cause pooling of fluid—in other from sensory compression and motor could result in the inability of the neuron words, swelling—in the extremities. As compression. And, given that the brachial to direct its muscle fibers to contract. This with neural and arterial compression, this plexus of nerves travel to/from the upper would result in weakness, and, perhaps in will usually be noticed in the hands. extremity, these signs and symptoms time, atrophy of the associated musculature. would manifest in the upper extremity—in ORTHOPEDIC ASSESSMENT OF TOS other words, the arm, forearm, and/or Given that there are three different forms of soft-tissue dysfunctional TOS, there are also three different orthopedic assessment tests. I like to describe the fundamental concept of

62 massage & bodywork november/december 2017 3A Orthopedic assessment tests for TOS. 3A: Adson’s test for anterior scalene syndrome. 3B: Eden’s test for costoclavicular syndrome. 3C: Wright’s test for pectoralis minor syndrome. 3D: Alternate Wright’s test position for pectoralis minor syndrome.

3C 3D 3B

on the brachial plexus of nerves (or the to both anterior scalene syndrome and subclavian/axillary artery or vein). a cervical rib. Cervical ribs can often be Therefore, our orthopedic assessment palpated, but definitive assessment of a tests for these conditions involve increasing cervical rib would be made by X-ray. the physical stress on the structures involved. For whom would we perform these Eden’s Test TOS orthopedic assessment tests? Most Eden’s test for costoclavicular syndrome often, it would be for any client who presents is performed by asking the client to with upper extremity paresthesia or motor assume a posture that stresses the body by dysfunction. The most common symptom decreasing the costoclavicular space. This of TOS is tingling or numbness in the hand. is accomplished by asking the client to The three orthopedic assessment tests for push their chest out and pull their shoulder TOS are Adson’s, Eden’s, and Wright’s. girdles back, as if standing at attention in front of a commanding military officer orthopedic assessment as “stress and assess.” Adson’s Test (Image 3B). This pushes the first rib If we believe a structure is unhealthy and Adson’s test for anterior scalene syndrome anteriorly against the clavicle as the clavicle causing the client to experience the signs or places a tension stress on the scalene is pulled posteriorly against the first rib. symptoms of a condition, then the goal of musculature by stretching it, thereby pulling our assessment test is to increase the stress it taut and hard against the neurovascular Wright’s Test on that structure to see if it reproduces or contents. Given that the anterior/middle Wright’s test for pectoralis minor syndrome increases the client’s characteristic pattern scalenes are flexors of the neck in the sagittal stresses the pectoralis minor by stretching of signs and symptoms. To do this, we need plane, lateral flexors in the frontal plane, it. Because the pectoralis minor is a to understand the underlying mechanics and contralateral rotators in the transverse protractor and depressor of the scapula, of the condition we are assessing. With plane, they would be stretched by asking the client’s scapula is brought back into anterior scalene syndrome, the underlying the client to move the neck into extension, retraction and elevation, using the client’s mechanism is tight anterior/middle lateral flexion to the opposite side, and arm as the contact (Image 3C). This tautens scalene musculature; with costoclavicular rotation to the same side (Image 3A). and hardens the pectoralis minor, as it is syndrome, the underlying mechanism It should be noted that if the pulled posteriorly against the neurovascular is a decreased costoclavicular space client is experiencing TOS due to the contents. There is an alternative position between the clavicle and first rib; and with presence of a cervical rib, then because for Wright’s test that involves stretching pectoralis minor syndrome, the underlying the compression caused by the cervical and tethering the brachial plexus of nerves mechanism is a tight pectoralis minor. rib occurs at the scalene musculature, around the pectoralis minor by simply Each of these cases results in compression Adson’s test would usually show positive. bringing the arm into abduction with Therefore, Adson’s test assesses TOS due the elbow joint flexed to approximately

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