Clinical Diagnosis of Neurogenic TOS
Many doctors find a challenge in making the clinical diagnosis of neurogenic TOS. Patients with neurogenic TOS may have a broad range of symptoms that are non-specific. For many doctors without experience diagnosing TOS, this collection of non-specific symptoms will appear confusing and hard to explain. At the same time, an experienced TOS specialist will recognize a familiar pattern of symptoms occurring together. It is important to remember that no clinical sign is highly specific or accurate. Instead, when a doctor makes the clinical diagnosis of neurogenic TOS, he or she should perform imaging tests to confirm or rule out the diagnosis.
Clinical Diagnosis of Neurogenic TOS
The clinical evaluation of a patient with suspected TOS consists of an accurate and detailed medical history, and a specialized physical examination.
In general, a doctor evaluates a patient by taking a medical history. In detail, the medical history starts with the ‘presenting complaint’ or chief complaint. The chief complaint comprises the primary symptom causing the patient to find a doctor. After hearing the patient’s chief complaint, a doctor gathers details by taking a history of present illness. Typically, the following details make up the history of present illness:
History of Present Illness
Site: Where does it hurt?
Onset: Was the onset sudden, gradual or intermittent?
Character: Is the pain sharp or dull? Focal or diffuse?
Radiation: Does the pain stay in one place, or does it radiate to another area from the initial site of pain?
Associations: Are there other symptoms besides pain, such as numbness, tingling or coldness?
Time course: Is the pain always present? Does it get worse at certain times? Does it increase suddenly or gradually?
Exacerbating/relieving factors: What positions or activities make the pain better or worse?
Severity: How does the pain rank compared to other pain? What number is the pain on a 1 to 10 scale?
TOS History of Present Illness
Moreover, an experienced TOS specialist will zero in on details that are specific to neurogenic TOS:
Site: Which side of the arm hurts? Which fingers hurt, and which sides of these fingers? Is there pain in one or both arms?
Onset: Did the pain arise immediately, or after a delay? Was the onset gradual, sudden, or intermittent?
Character: Is the pain aching, sharp, deep, or diffuse/poorly-localized?
Radiation: Does the pain move down the arm or up to the neck? Does it go to the fingertips? Does it spread to both sides of the body?
Associations: Headaches? Chest pain? Back pain? Dizziness? Imbalance walking?
Time course: Does the pain go away overnight, or over the weekend? Is the pain worse in the morning, or at night? Is the pain constant, or does it wax and wane?
Exacerbating/relieving factors: Does the pain worsen when brushing your hair or using a hair dryer? Is it worse when driving a car, using a phone, or working at a computer?
Severity: How does the pain affect your lifestyle? What things do you avoid or do differently because of pain?
Besides a detailed and specific TOS history of present illness, a TOS specialist would investigate possible causative factors of TOS. Specifically, any history of overuse, trauma, and occupational or recreational stressors could contribute to the development of TOS. Additionally, an experienced TOS specialist would fully explore the time course of symptoms.
For example, many TOS patients are able to define a specific traumatic episode that created immediate symptoms. Notably, many TOS patients have suffered a neck injury in a motor vehicle accident. Frequently, a TOS patient will relate a work-related injury, while others describe a recreational injury. In particular, some TOS patients note sudden onset of symptoms after activities like mountain climbing or weightlifting.
Nonetheless, while post-traumatic neurogenic TOS frequently develops with a sudden onset, some patients have a delayed or gradual onset.
In contrast, patients who develop neurogenic TOS from overuse frequently are unable to define a specific event or time where they first experienced symptoms. These patients often describe a pattern of symptoms that were so mild as to be of little concern. Yet over time, the symptoms worsened and persisted to the point that they impacted the patient’s lifestyle. These patients often relate a history of mild symptoms occurring only after long episodes of overuse, either recreational or occupational. After a period of rest, or following work, the symptoms would spontaneously resolve. Sooner or later, if the inciting activity continued, symptoms would persist after work, or overnight. Even at this point, patients frequently would note relief over weekends. However, even these respites would fade, and symptoms would persist from that point forward.
Following the history of present illness, a TOS specialist would expand other elements of the patient’s overall medical history that are pertinent to neurogenic TOS:
Past Medical History
Has the patient ever broken the collarbone or ribs? Has the patient had surgery to the cervical spine, neck, chest, or shoulder? What drugs has the patient taken in the past, or is currently using? What treatments has the patient previously tried for TOS, such as physical therapy or acupuncture?
Is the patient’s work sedentary or active? Does the patient use a computer? Is there lifting involved in work, particularly with the arms forward or overhead?
What sports does the patient participate in? Do these involve use of the arms overhead? Does the patient use computers, phones or tablets on a regular basis?
What position does the patient sleep? Does the patient carry young children?
It is important to realize that the standard neurological examination is insufficient for the diagnosis of neurogenic TOS. When a patient presents to a physician with arm and neck pain, the physician would perform a standard neurologic examination. Unfortunately, this examination would be unlikely to rule in or rule out neurogenic TOS.
For this reason, doctors must be familiar with the specialized physical examination tests that can demonstrate findings of neurogenic TOS. After performing a standard neurological examination, a TOS specialist performs a series of specialized provocative TOS tests. These tests are intended to demonstrate compression of blood vessels or nerves, or tension on nerves, in the thoracic outlet.
The diagnosis of TOS has evolved over a long period of time. TOS was first described in 1818. Since then, experts have studied the anatomy and causes of TOS. Many of these experts have devised provocative in attempts to diagnose TOS quickly and accurately. Notably, most of these tests have been based on changes in blood flow, rather than nerve compression or tension. At the same time, most patients with TOS have neurogenic TOS, making tests of blood flow quite limited for diagnosis. More recent peer-reviewed evaluation of these provocative these tests has proven that they have limited sensitivity, specificity, or accuracy.
It should be noted that compression of arteries or veins is not equivalent to compression of nerves. Before the invention of modern medical imaging, doctors could not distinguish compression of blood vessels or nerves in any patient. However, experts used tests of vascular compression as proxies for nerve compression, since they had no better test. Obviously, we now have better tools to distinguish compression of blood vessels and nerves. Unfortunately, some clinicians still use tests of blood flow in patients with nerve compression.
Experienced TOS specialists realized that they needed to improve the clinical evaluation of nerve compression. Fortunately, these specialists have developed clinical tests to evaluate nerve compression. Knowledgeable TOS specialists have added these tests to their diagnostic tool box. It is important to realize that these tests are better than tests of blood flow for diagnosing neurogenic TOS. However, they are not highly accurate, and do not distinguish the underlying anatomic causes of neurogenic TOS. Instead, they provide a solid basis for suggesting the diagnosis of TOS in a patient with a suitable clinical presentation and corresponding signs and symptoms. Finally, while tests of blood flow may overlap those for nerve compression, TOS specialists understand how to distinguish their results.
These tests are called ‘provocative’ tests. To explain, the examining physician moves the patient’s arms or neck into specific positions during each test. These positions temporarily increase compression of blood vessels or nerves in order to reproduce the patient’s symptoms and signs.
The patient assumes a sitting position, with arms at the side. The patient turns his head towards the affected side, extends his neck (bends his neck backwards), and takes and holds a deep inspiration. The physician monitors the patient’s radial pulse at the wrist. If the pulse diminishes or disappears, or if the patient’s symptoms are reproduced, Adson’s test is positive.
A variant of Adson’s test is the reverse Adson’s test, where the procedure is performed in identical manner, but with the patient’s head turned away from the affected side.
With the patient sitting, the examiner puts his or her fingers on the radial pulse at the wrist. After the pulse is localized, the examiner puts downward traction on the arm, rotates the arm in the outward direction, and moves the arm back and away by about 45 degrees. In some descriptions, the patient turns their head to the opposite side during the test. The Halstead maneuver is considered positive if the radial pulse decreases or disappears. Presumably, the maneuver causes compression of the subclavian artery in some people. In theory, compression of the artery correlates with compression of the brachial plexus. However, peer-reviewed medical articles do not support this theory. Also, in our imaging experience, compression of the artery occurs in isolation in some patients, but with compression of the brachial plexus in other patients. The degree of brachial plexus compression in this setting ranges from none to severe. Therefore, like all physical examination tests that rely on the radial pulse, the Halstead maneuver should not be considered diagnostic of neurogenic TOS.
Wright Test (Hyperabduction Maneuver)
The patient is positioned sitting or supine (lying on her back). The examiner lifts the patient’s arm overhead to an angle greater than 90 degrees at the shoulder, with the elbow straight or bent less than 45 degrees, while monitoring the patient’s radial pulse. A decreased or absent radial pulse, or reproduction of the patient’s symptoms, is a positive test, and is thought to be caused by narrowing of the costoclavicular interval.
Novak and McKinnon have adapted this test by keeping the elbow extended and the wrist in neutral as not to provoke cubital tunnel syndrome (entrapment of the ulnar nerve at the elbow) or carpal tunnel syndrome (entrapment of the median nerve at the wrist).
The patient can be sitting or standing for the Roos’ test. The patient holds their arm in the “stick ‘em up” position, with the shoulders raised 90 degrees, the elbows bent 90 degrees, and the hands above the head, with palms facing forward and the head and neck in neutral position. The patient then opens and closes their hands for three minutes. A positive test occurs when the patient’s symptoms are reproduced within three minutes.
The test was conceived by Dr. David Roos, a pioneering surgeon in the 1970’s who catalogued many of the soft tissue abnormalities of the thoracic outlet in patients with TOS. The Roos’ test is also known as the EAST test (Elevated Arm Stress Test) or Abduction External Rotation Test (AER Test).
Costoclavicular Test (Eden Test)
The patient is sitting, and assumes a ‘military’ posture, with the back straight and the shoulders pushed backward and downward. The physician may help depress the shoulder on the side being examined, while monitoring the radial pulse at the wrist. If this pulse decreases or disappears, or if the patient’s symptoms are reproduced, the test is positive. A positive test is assumed to be due to narrowing at the costoclavicular interval, causing compression of the subclavian artery or brachial plexus.
This is also known as pressure provocation testing. Tapping with the examiner’s finger over the nerves may produce a tingling sensation within the distribution of the nerve. The test is performed over the common entrapment sites in the upper extremity as the carpal tunnel, the median nerve in the forearm, the cubital tunnel, and the brachial plexus in the infra- and supraclavicular fossa. This test tends to be positive in later stages of chronic nerve compression.
Upper Limb Neural Tension Test
Butler (1) describes tension testing utilizing upper limb nerve tension tests, with emphasis on the upper limb nerve tension test 3 (ULTT 3), which is more sensitive for ulnar nerve irritation. These tension tests involve the increase of tension of nerves, through stretching by means of positioning joints in predetermined positions, to tension nerves from cervical nerve roots to the peripheral nerves in the fingers. The tests are considered positive when reproduction of symptoms is obtained or range of motion is limited. Butler also recommends performance of the slump test in longsitting and sitting to investigate the spinal canal components for adverse neural tension. He also suggests that the possibility of double or multiple crush syndromes should be investigated, as well as the contribution of the sympathetic nervous system to the symptoms presented.
Most patients with neurogenic TOS have neck and arm pain. A doctor will attempt to rule out narrowing of the cervical spine as the cause of these symptoms. Many doctors will perform Spurling’s test for this purpose. Spurling’s test can suggest entrapment of the nerve roots as they exit the spinal canal. It should be remembered that most patients with neurogenic TOS are young and otherwise healthy. Thus, these patients are unlikely to have chronic degenerative changes or narrowing of the cervical spine. For this reason tests of the cervical spine should be performed, but are most often negative.