The use of ultrasound in the emergency department for the detection of thoracic outlet syndrome: A single case study

Abstract

Introduction

Thoracic outlet syndrome (TOS) refers to a spectrum of syndromes related to the compression of the brachial plexus (neurogenic TOS), subclavian vein or artery in the general region of the thoracic outlet, which is the area just above the first rib and behind the clavicle.

Case report

We report a 27-year-old healthy man who presented to the emergency department with right upper limb pain, tingling and weakness. Point-of-care ultrasonography was performed following a dynamic protocol in the supraclavicular fossa in the right upper limb. A congenital cervical rib, as well as narrowing of the costoclavicular gap, causing vein, artery and spinal roots compression was evidenced. This maneuver reproduced the symptoms, confirming the suspicion of neurogenic TOS.

Discussion

Early diagnosis is important, because the neurogenic compression associated with neurogenic TOS, if prolonged, can lead to muscle weakness and atrophy, being irreversible. Selected patients with neurogenic TOS who have progressive weakness, disabling pain, or who have failed to improve with conservative measures are considered for first rib resection.

Conclusion

Using the dynamic approach during point-of-care ultrasonography examination, in combination with physical examination and cervical radiography, could help identify neurogenic TOS.

Introduction

Thoracic outlet syndrome (TOS) refers to a spectrum of syndromes related to the general region of the thoracic outlet, which is the area just above the first rib and behind the clavicle. This syndrome gives a constellation of signs and symptoms that arise from compression of the brachial plexus (neurogenic—nTOS), subclavian vein (vTOS) or subclavian artery (aTOS). nTOS accounts for more than 95% of the TOS cases, vTOS for 3% and aTOS around 1%.¹ Compression of the brachial plexus leads to pain, paresthesia, numbness and weakness of the upper limb. There may be overlap in symptoms if more than one structure is affected.¹

Ultrasonography is the initial diagnostic test to assess for aTOS or vTOS because it is quick, safe, inexpensive and noninvasive. However, it is often negative or equivocal in nTOS.¹

Case report

A 27-year-old Caucasian man presented to the emergency department (ED) with right upper limb pain, tingling and weakness of the first and second finger, sometimes accompanied with skin color change (pallor), over the course of the previous eight months. He did not report any relevant past medical history and denied previous trauma or injury. The symptoms started to appear gradually a week after he started to work in a restaurant, peeling kebab meat. At that time, he consulted his general physician, and was diagnosed with muscular pain and treated with nonsteroidal anti-inflammatory drugs (ibuprofen 600 mg tid) without clinical improvement. He had no swelling, elbow joint stiffness, redness or temperature increase. He presented to ED when he became unable to work and feared dismissal.

Physical examination revealed right upper limb tenderness on palpation of the supraclavicular fossa, and muscle weakness over the thumb and index finger grip. He had painless passive and active range of motion of his wrists and elbows. It was remarkable that the last degrees of the motion range of the shoulder triggered more pain and weakness. Triceps, biceps and brachioradialis deep tendon reflexes were equal bilaterally. Both radial and ulnar pulses were regular, strong and symmetric. There was no increased local heat over the affected area and skin coloration was normal with no visible wounds.

A cervical radiograph showed a congenital cervical rib (Figure 1(a)). Then, point-of-care ultrasonography (POCUS) was performed on the right upper limb, using a GE VENUE™ R2 ultrasound system and 8–16 MHz linear transducer (GE Healthcare Systems, Chicago, IL, USA).

Figure 1.

(a) Cervical radiograph showing bilateral cervical ribs, more prominent on right side (arrow). (b) The shoulder is elevated and rotated outward with flexion of the elbow. The approximate position of the linear transducer is shown with a white bar. (c) There is an acoustic shadow from the CR and the CL. A: subclavian artery; V: subclavian vein: N: brachial plexus; CR: cervical rib; CL: clavicle.

Then, a dynamic examination was performed: with the head forward, the arm was passively brought into abduction and external rotation to 90° (elbow flexed to 45°) (Figure 1(b)), and then the arm was held for 1 minute in hyperabduction coupled with hyperextension. The transducer was placed in the supraclavicular fossa (Figure 1(b)) and moved to the subclavian triangle, with the patient sitting in a neutral position and following the maneuver. Narrowing of the costoclavicular gap, causing vein, artery and spinal roots compression was detected (Figure 1(c) and Video 1 (available as supplementary material)). This maneuver reproduced the symptoms and confirmed the suspicion. No sign of venous thrombosis or increased arterial blood flow were detected.

nTOS was diagnosed on the basis of these results. Due to the chronicity of his symptoms, he was discharged from the ED with advice on exercises to strengthen the muscles around the shoulder and was referred to the thoracic surgery outpatient clinic. After evaluation, he was placed on a waiting list for elective surgery.

Discussion

Cervical ribs are a predisposing factor for TOS.² They have been associated with symptoms of brachial plexus compression, which include pain, numbness and weakness that are aggravated with any activity that requires elevation or sustained use of the arms or hands.

Standard provocative maneuvers to diagnose nTOS include Adson’s Test (external rotation of upper limb and neck rotation to the affected side), Costoclavicular Test (the patient’s shoulder is pulled down into extension) and Wright Test (hyperabduction of the shoulder and hyperextension of the arm). However, according to previous studies, these tests are prone to false positive results, owing that changes in radial pulse are common during the maneuver, even in the healthy population.^3–5 This could be improved when the patient’s symptoms were considered along with the pulse change.⁶ This fact highlights the need for alternative and reproducible diagnostic methods in this disease.

Ultrasonography is the initial imaging test to evaluate aTOS or vTOS because it is quick, safe, inexpensive and noninvasive. However, diagnostic tests are often negative or equivocal in nTOS¹ although compression of the subclavian vein or artery on ultrasound can support the nTOS diagnosis.³ Moreover, ultrasonography helps to identify individual anatomical variations or nonspecific TOS presentation.⁵

In a retrospective study, Orlando et al.³ found that vessel compression on preoperative duplex ultrasonography with abduction was found in 31% of patients when compared to 8% on the asymptomatic contralateral side.

As in our case, a dynamic test, with provocative maneuvers, can be easily performed to assess the involved vessels and the brachial nerve roots, which reproduced the symptoms. This finding in a patient with a typical clinical history supports the diagnosis of TOS. Ultrasonography can serve as an additional diagnostic modality that can support the suspicion of nTOS in patients presenting with upper limb pain, especially in the ED or in the primary care setting.⁵ Even though magnetic resonance imaging remains the gold standard, POCUS, with its greater availability, non-invasiveness and dynamic component is an excellent but underused diagnostic tool.³

To our knowledge, this dynamic approach during POCUS examination has not been previously described when suspecting nTOS. Early diagnosis is important because the neurogenic compression associated with nTOS, if prolonged, can lead to irreversible muscle weakness and atrophy. Selected patients with nTOS who have progressive weakness, disabling pain, or who have failed to improve with conservative measures are considered for first rib resection.¹

Conclusion

Performing dynamic maneuvers during POCUS examination, in combination with physical examination and cervical radiography, could help identify nTOS.