Subjective evaluation

The foundation of an evaluation of patients with suspected NTOS begins with a thorough history including a detailed description of all the patient’s symptoms as well as any factor that affects these symptoms. Patients with NTOS have a history of progressive, subacute or chronic cervical, upper chest, and upper extremity pain. The characteristics of a patient’s pain can vary widely and may be difficult for some patients to describe. There are no specific pain characteristics that are unique to NTOS, and terms such as “sharp,” “dull,” “ache,” or “electric” are frequently used by patients to describe their pain. The location of the patient’s pain also may vary, and no one specific location is required for a diagnosis. The most common areas include the posterior lateral neck and upper trapezius region, the clavicular region, the medial scapular region, the upper pectoral region and axilla. Pain may radiate down an upper extremity that can be generalized or localized to the medial or occasionally the lateral aspect of the upper extremity. Occipital headaches, pain in the face or pain/fullness in the ear are sometimes described. Many patients will describe symptoms of altered sensation, which include paresthesias and/or numbness of the chest, arm, or hand. The symptoms also may be generalized but can localize to the medial or less commonly the lateral upper extremity. Patients may experience motor symptoms such as weakness or fatigue of the upper extremity or decreased coordination for fine motor activity in the hand. Less commonly, patients may exhibit signs of vasomotor instability that include episodic skin discoloration and temperature discrepancy of the upper extremity.

A hallmark of NTOS is the temporal patterns and exacerbating factors. Patients typically experience worsening of symptoms when reaching overhead or repetitive upper extremity movements. In many cases, patients report a history of trauma associated with their symptoms. In a review of the 10-year UCLA Vascular Surgery experience, the clinical team found that more than half of patients reported an antecedent traumatic event, such as a fall onto an outstretched arm or motor vehicle accident. The remaining patients associated their symptoms with work-related activities. It is important when obtaining a history that surgeons assess dominant hand, occupation, hobbies, and activities of daily living. ^, Not only do these data help determine if the presenting symptoms may be attributable to NTOS, but also inform expectations for both patients and their employers in terms of treatment and longitudinal management.

Surgeons should review and document all prior efforts to alleviate symptoms. This includes lifestyle and work modifications (eg, avoidance of certain activities, disability status); physical and occupational therapy; complementary medicine (eg, massage, acupuncture, chiropractic treatments); injections (local anesthetic, steroid or botulinum toxin); prescription and over-the-counter (OTC) analgesia (nonsteroidal anti-inflammatory drugs, opioid, neuropathic medications) or muscle relaxants; psychological or psychiatric treatment; and surgical interventions. In a review of a subset of patients evaluated at our TOS center, almost one-third of patients were managing symptoms with a combination of OTC and prescription medications (Panda and colleagues, unpublished data, 2020). For patients who may proceed to surgery, these data will also help guide immediate postoperative analgesia regimens. Operative reports from prior interventions should be obtained and reviewed for extent of cervical or first rib resection (eg, anterior, posterior, total); operative approach (eg, supraclavicular, transaxillary); use of adjunct procedures (eg, brachial plexus neurolysis); and intraoperative anatomy (eg, presence of ligamentous band). Response to treatment, if any, should be documented in terms of symptomatic improvement. The preceding information will allow the surgeon to appropriately characterize the patient’s symptoms as persistent (eg, no response after treatment) or recurrent (eg, development of symptoms ≥3 months after any prior targeted treatment), and also guide subsequent treatment.

Physical examination and stress maneuvers

Objective evaluation begins with a thorough physical examination. The general appearance of the patient’s posture should be observed in upright and supine positions, with attention given to position of the affected shoulder and asymmetry of the upper extremity. This includes examination of all muscular compartments for bulk and tone, including the ipsilateral hand for evidence of atrophy of the thenar, hypothenar, and interosseous muscles. A careful vascular evaluation follows, including examination for the color and temperature of the skin, swelling, capillary refill, and pulse. A neurologic examination is then performed, first evaluating each dermatome for sensory deficits in light touch, pain and temperature. On motor examination, both active and passive range of motion at each joint are observed. Throughout these steps, the surgeon should evaluate for tenderness to palpation within the thoracic outlet. This simple initial step can assist the surgeon in localizing the pathology to either the scalene triangle or pectoralis minor space.

The physical examination may be followed by a series of provocative and stress maneuvers. The sensitivity of each is relatively high, although with limited specificity and negative predict value. Each are described in detail as follows ^, :

• 1.
  

  One-Minute Elevated Arm Stress Test (EAST) : the EAST is designed to reproduce symptoms through repetitive motion when spaces within the thoracic outlet, specifically the scalene triangle, become narrowed. The patient is seated in a supine position with the arms abducted and externally rotated such that they are in the same plane as the thorax. Both the arms are abducted, and elbows are flexed to 90°. The patient then opens and closes her or his hands each second for 1 minute. The surgeon makes note of the onset and quality of any cervicobrachial pain or distal neurologic disturbance, both of which constitute a positive test.

  
  
• 2.
  

  Upper Limb Tension Test (ULTT) : the ULTT is deigned to reproduce symptoms by placing maximal stretch on the brachial plexus. To do so, the patient is seated in a supine position with the arms abducted and externally rotated such that they are in the same plane as the thorax. The elbows are flexed to 90°. If the patient remains asymptomatic, the elbows are then fully extended, and the hands are pronated. To place additional stretch on the brachial plexus within the thoracic outlet, the patient is instructed to dorsiflex the hands tilt the head away from the affected side. The test is considered positive if at any position (flexion of the elbow, extension of the elbow and dorsiflexion of the wrists, or titling of the head) the patient reports the onset or worsening of cervicobrachial pain.

Imaging

For all patients with suspected NTOS, a chest and cervical spine radiograph should be obtained to evaluate for any bony abnormalities as the source of symptoms, such as a cervical rib or elongated seventh cervical vertebrae transverse process. Our center routinely obtains dedicated computed tomogram angiography or MRI with arterial and venous enhancement and 3-dimensional reconstruction. The results of these studies can assist the surgeon when considering alternative diagnoses (eg, multiple TOS subtypes, musculoskeletal pathology of the cervical spine or shoulder), as well as better delineating the anatomy of the thoracic inlet (eg, scalene musculature, ligamentous bands, subclavius muscle, and scalene muscles). Duplex ultrasonography may obtained in patients with suspected ATOS or VTOS, but others have proposed potential benefits for point-of-care use in NTOS, especially for patients with brachial plexus anatomic variants.

Electrodiagnostic testing

The lack of a definitive or gold-standard physical examination finding or imaging modality has led to a growing number of reports, primarily case-series and observational data, describing the predictive value of electrodiagnostic testing. Electromyography and nerve conduction studies are often normal in patients with NTOS, potentially due to the waxing and waning of symptoms. For these reasons, our center does not routinely obtain electromyography or nerve conduction studies in patients with suspected NTOS unless a concurrent diagnosis is suspected.

Scalene injection

The injection of local analgesia in the scalene musculature is an effective diagnostic and therapeutic test for NTOS, especially when the suspected site of brachial plexopathy is within the scalene triangle. The procedure involves the infiltration of small amount of long-acting local analgesic into the muscle belly of the anterior scalene muscle. The procedure can be completed during a routine clinic visit using a combination of surface landmarks and ultrasonography to ensure localization and minimize adverse events. For patients with challenging anatomy (eg, recurrent NTOS after prior operation, short neck), the test can be performed under fluoroscopy or computed tomography guidance. The underlying mechanism is thought to be due to relaxation and elongation of the anterior scalene muscle, which allows the previously narrow scalene triangle to enlarge, alleviating the compression or irritation of the brachial plexus. For these reasons, studies have demonstrated that symptomatic improvement after a scalene injection test is not only diagnostic of NTOS, but also predictive of treatment effects after surgical decompression through first rib resection and anterior scalenectomy. ^,

Assessment of health-related quality of life

As surgeons strive toward patient-centered care, patient-reported outcome measures (PROMs) have emerged as a key component of the evaluation of patients with NTOS. All patients with suspected NTOS should have the degree of disability associated with their symptoms quantified using a generic or disease-specific instrument. These data can be used not only to better characterize the interference of symptoms on activities of daily living or occupation, but should also serve as key outcomes to follow during longitudinal care.

Although there is no single survey designed and tested specifically for measurement of baseline NTOS symptoms and response to operative or nonoperative treatments, there are generic instruments that have been applied and psychometrically tested in this patient population. The Disability of the Arm, Shoulder, and Hand (DASH) outcome measure is publicly available 30-item survey that quantifies disability associated with upper extremity disorders and response to treatment in a single standardized disability/symptom score. The QuickDASH is a shorter instrument consisting of 11 items of the original 30-item DASH questionnaire that performs similarly, potentially with less perceived burden among patients. Other experienced TOS centers have incorporated the Cervical Brachial Symptom Questionnaire, which uses both questions and a sensory diagram allowing patients to map symptoms to surface anatomy. Because the introduction of PROMs into clinical practice is associated with resources for implementation, a simple TOS disability scale can be incorporated during history-taking, where patients are asked to quantify their disability on a 0 (no disability) to 10 (maximum disability) scale. Each instrument can be used both during baseline evaluation and posttreatment follow-up to quantify persistent or recurrent symptoms.

Multidisciplinary evaluation

Experiences from high-volume TOS centers have informed best practices during the evaluation of patients with NTOS, the cornerstone of which is a multidisciplinary team. At our institution, patients with symptoms of NTOS may be referred to neurologists or surgeons (orthopedic, vascular, or thoracic). During or after the initial visit, we often request formal evaluation by physical therapy, occupational therapy, and diagnostic and interventional radiology for dedicated TOS-protocoled images and image-guided scalene injections, respectively. For patients who are surgical candidates, preprocedural coordination with experienced anesthesiologists allows for adequate perioperative analgesia.