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62 m a s s a g e & b o d y w o r k n o v e m b e r / d e c e m b e r 2 0 1 7 SIGNS AND SYMPTOMS OF TOS A full awareness of the signs and symptoms of TOS cannot be understood without a somewhat in-depth knowledge of the brachial plexus; however, the major concepts can be addressed and understood. Before moving forward with this discussion, it is worth noting that symptoms, by definition, are subjective in that they must be reported by the client. For example, only the client can state if they are experiencing pain. Signs, on the other hand, are objective in that they can be measured by the therapist. For example, the strength of the client's pulse is a sign that can be felt and reported by the therapist. Neural Symptoms Almost all peripheral spinal nerves are mixed in that they carry both sensory and motor neurons (the only exception is the C1 nerve root, which is only sensory). In this sense, they can be likened to two- lane north-south highways comprising a northbound lane that carries sensory information gathered in the periphery up to the central nervous system, and a southbound lane that carries motor information down from the central nervous system to the periphery. TOS usually involves peripheral nerve compression; therefore, the two major types of neural signs/symptoms result from sensory compression and motor compression. And, given that the brachial plexus of nerves travel to/from the upper extremity, these signs and symptoms would manifest in the upper extremity—in other words, the arm, forearm, and/or hand. Most often, upper extremity nerve compression is experienced in the hand. Compression of a sensory neuron can cause irritation of the neuron, creating aberrant sensory impulses resulting in increased sensation, termed hyperesthesia. Examples include hypersensitivity to touch, a feeling of tingling even when no stimulus is being applied to the skin, or burning or shooting pain. When the compression is greater, it can begin to obstruct axonal flow within the sensory neuron, resulting in diminished ability of the neuron to carry impulses. This, in turn, results in diminished sensation, termed hypesthesia. This is often experienced as pins and needles, instead of a full sensation of touch, when pressure is applied to the skin. If the axonal flow is entirely blocked, numbness can result. Any altered sensation, whether it is hyperesthesia or hypesthesia, can be termed paresthesia. Because paresthesia, is by definition, something the client feels, it is a subjective symptom and must be reported by the client. Given that motor neurons are responsible for directing muscle contraction, compression of a motor neuron would affect muscle function. If the motor neuron is irritated and creates aberrant nerve impulses, then muscle twitching (termed fasciculation) can occur. If the compression is greater, then obstruction of the axonal flow could result in the inability of the neuron to direct its muscle fibers to contract. This would result in weakness, and, perhaps in time, atrophy of the associated musculature. Arterial Symptoms Arterial blood is delivered to the upper extremity via the subclavian artery, which, as it travels distally, becomes the axillary artery, then the brachial artery, and then divides into the radial and ulnar arteries, which enter the hand. The various types of TOS can potentially compress the subclavian artery or axillary artery pathway of arterial delivery into the upper extremity. This would decrease the delivery of oxygenated arterial blood to all the tissues and cells of the upper extremity, distal to the point of compression. In light-skinned individuals, the skin's pallor might become cyanotic (bluish) and is often noticed in the hand. Decreased arterial flow can be objectively measured by feeling for the strength of the client's radial pulse at the wrist (it should be emphasized that it is the strength of the pulse, not the rate of the pulse, that is assessed). As we will see later in this article, palpating for the strength of the radial pulse is the primary means by which TOS is assessed. Venous Symptoms Venous blood is drained from the upper extremity by veins that are similarly named to the arteries. TOS can compress the subclavian and/or axillary vein, which would result in decreased venous return and cause pooling of fluid—in other words, swelling—in the extremities. As with neural and arterial compression, this will usually be noticed in the hands. ORTHOPEDIC ASSESSMENT OF TOS 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 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.