Abstract

Background: Thoracic outlet syndrome (TOS) is a debilitating neurologic condition that is commonly encountered in routine neurosurgical practice. It causes severe pain, paresthesias, and weakness in the affected limb and can negatively impact patients’ quality of life. Classically, TOS is caused by compression of the neurovascular bundle in the thoracic outlet region, often by soft tissue or bony anomalies. A relationship to cervicothoracic scoliosis has not been previously reported. The purpose of this case series is to report on the clinical and radiographic findings, surgical interventions, and clinical outcomes in patients with TOS and concurrent cervicothoracic scoliosis. We hypothesize that the abnormal cervicothoracic curvature may contribute to compression within the thoracic outlet.

Methods: Patients who presented to the senior author’s clinic and had both cervicothoracic scoliosis and TOS were identified, and a retrospective chart review was performed. A review of the electronic medical records was used to collect clinical information and outcomes data. The study is a retrospective case series of patients who presented to the senior author’s clinic and underwent surgical intervention by the senior author at a university hospital. Ten patients were identified as having symptoms consistent with TOS and were also found to have coexisting cervicothoracic scoliosis. We report on the preoperative physiology measures, such as imaging and electrodiagnostic findings, and postoperative self-reported symptoms and functional measures.

Results: Ten patients who presented to the clinic for evaluation of symptoms consistent with TOS were also noted to have mild-to-moderate cervicothoracic scoliosis. Eight of these patients underwent surgical intervention for their TOS, including anterior scalenectomy, pectoralis minor release, first rib resection, or a combination of the three procedures. Four patients underwent bilateral procedures. At 3 months, all patients (100%) had improvement in their numeric rating scale, and at 1 year, this dropped to 83%.

Conclusion: It is well-known that bony abnormalities, such as the presence of a cervical rib or elongated C7 transverse process, can lead to the development of TOS; however, a relationship to scoliosis, which similarly may deform the thoracic outlet region has not been reported. The relationship between these two conditions merits ongoing clinical evaluation.

Keywords: Cervicothoracic scoliosis, Neurogenic thoracic outlet syndrome, Scoliosis, Spinal deformity, Thoracic outlet syndrome, Vascular thoracic outlet syndrome

INTRODUCTION

Thoracic outlet syndrome (TOS) is a well-described clinical syndrome characterized by pain, numbness, paresthesias, and weakness in the upper limbs. This constellation of symptoms is caused by compression of the brachial plexus and/or the subclavian vessels in the anatomical region known as the thoracic outlet.[ 8 , 2 , 3 , 5 , 6 ] Several well-known anatomic anomalies in this region may be responsible for symptoms, including the presence of cervical ribs, elongated C7 transverse processes, abnormal origin or insertion of the scalene muscles, scalene hypertrophy, fascial bands, and/ or abnormal vessels.[ 2 ] It is conceivable that other structural abnormalities of the thoracic outlet region could similarly result in symptoms consistent with TOS, although such an association between TOS and cervicothoracic scoliosis has not yet been described. Herein, we present a series of ten patients presenting with unilateral or bilateral TOS that occurred in conjunction with cervicothoracic scoliosis managed both operatively and nonoperatively. We did not separate the patients into vascular and neurogenic TOS, as in our experience, most patients have a component of both.

MATERIALS AND METHODS

Patients who presented to the senior author’s neurosurgery clinic and had both cervicothoracic scoliosis and TOS were identified and included in the series. A retrospective chart review was performed. A review of the electronic medical records was used to collect patient demographics, clinical information, and outcomes data. We use the numeric rating scale (NRS) for patient-reported upper extremity pain (0 representing no/minimal symptoms; 10 representing the most severe symptoms) at preoperative as well as 3-month and 12-month postoperative intervals. The degree of cervicothoracic scoliosis was assessed using the standard Cobb angle. Data collection within the scope of this study was approved by the Institutional Review Board and was granted a waiver of informed consent due to its retrospective nature.

RESULTS

We identified a total of ten patients that met inclusion criteria for the study. Patients ranged in age from 17 to 55 years old (average 35), with seven females and three males. The average scoliotic curvature by Cobb angle was 17°. Three patients were symptomatic on the concave side only (30%), two were symptomatic on the convex side only (20%), and five were symptomatic on both (50%). Of the five patients with bilateral symptoms, 4 (80%) were more symptomatic on the concave side. Out of the five common diagnostic studies commonly utilized (Electrodiagnostics [EDX], magnetic resonance imaging [MRI], magnetic resonance angiogram [MRA], computed tomography [CT]/X-ray, and Doppler ultrasonography), all patients had abnormalities on at least one of these studies. Dopplers were abnormal most commonly, with abnormalities seen in 8 patients (80%). Of these ten individuals, surgical decompression was performed on 8 patients (80%); four of these were bilateral (50%), for a total of 12 limbs, with two patients being managed without surgical decompression (20%). Surgical techniques included anterior scalenectomy, most commonly, and/or pectoralis minor release. No deformity correction was attempted in any of the patients. Table 1 presents a full summary of patient characteristics.

Table 1:

Patient demographic and clinical characteristics.

Representative cases

Case #1

Clinical presentation

A 17-year-old male presented to the neurosurgery clinic for evaluation of 1 year of progressive symptoms of burning pain, numbness, and tingling in his right upper limb. The pain began soon after he had started swimming, but he denied any direct trauma to the arm. He reported a burning pain along his right scapula, as well as intermittent burning and tingling extending into the right arm, predominantly in a C8-T1 distribution. His symptoms were significantly exacerbated by extending his arms above his head, driving, and swimming, and his overall NRS pain score was 7 on the right. Physical examination showed the subtle weakness of the hand’s intrinsic muscles with a medical research council grade of 4/5 and, more proximally, 5/5. The sensation was diminished to light touch, most noticeably in the C8 distribution and to a lesser degree in C6 and C7. Thoracic outlet maneuvers, including Adson’s and Wright’s tests, resulted in the loss of radial pulse on the right. Roos’s test reproduced his symptoms. The examination was consistent with a clinical diagnosis of TOS, and therefore, additional TOS workup was pursued.

Diagnostic workup

CT of the cervical spine demonstrated a Klippel-Feil malformation of T1–T3, with fusion of the vertebral bodies, right facets, and right transverse processes from T1 to T3 and of the spinous processes from T2 to T3. In addition, there was hypoplasia of the right side of these vertebral bodies, resulting in an upper thoracic levoscoliosis measuring approximately 32° [ Figures 1a and b ]. The scoliosis resulted in a narrowing between the first rib and the C7 transverse process, raising concern for possible impingement of the exiting C8 nerve root on the right. EDX were unremarkable [ Figure 1c ].

Figure 1:

(a) Cervical X-ray and (b) thoracic and (c) cervical computed tomography scans from Case #1 demonstrating Klippel-Feil abnormality with fusion of T1–T3, narrowing between the right C7 transverse process and first rib, and 32° scoliotic curvature. Note the narrow space between the C7 transverse process and the first rib on the right side (arrow) compared to the left.

The patient was then lost to follow-up before completing the remainder of the diagnostic workup. Six years later, he presented again to the clinic for evaluation of the same symptoms. Doppler pulse volume recordings showed normal arterial waveforms in the right upper limb with all arm positions. Interestingly, there was diminished waveform with two maneuvers on the asymptomatic left side. MRI of the brachial plexus revealed impingement of the C8 nerve root as it passed posterior to the anterior scalene, as well as of the T1 nerve root as it passed through a narrowed first intercostal space. Both findings appeared to be related to the thoracic scoliotic curvature.

Examination at the time of re-presentation was similar to 6 years prior. Additionally, there was noted to be a Tinel sign in the supraclavicular region, as well as a positive scratch collapse test[ 1 ] in this region. He was subsequently referred for a steroid injection to the anterior scalene muscle. Follow-up showed that the patient had significant improvement in his pain following the steroid injection that was sustained for 3–4 weeks.

Surgery and postoperative course

The patient underwent an uncomplicated anterior scalenectomy for decompression of the brachial plexus with our standard technique through a supraclavicular incision.

Postoperatively, he recovered well. He was seen back in the clinic for a 6-week postoperative follow-up and reported significant improvement in the pain, numbness, and tingling he had been experiencing. And was overall very happy with the outcome of the surgery (NRS pain score 0 at 1-year follow-up). He later underwent anterior scalenectomy on the left side for similar symptoms with complete resolution of his pain.

Case #2

Clinical presentation

A 30-year-old male presented to the neurosurgery clinic after a referral from Plastic Surgery for evaluation of TOS. His symptoms started approximately a year before presentation with right volar forearm, wrist, and hand numbness, tingling, and pain that then progressed to involve his left hand, as well. Symptoms worsened with the arms overhead. Physical examination revealed subtle weakness of the right hand, with 4+/5 strength in abductor pollicis brevis and 4/5 strength in abductor digiti minimi. He was also noted to have decreased sensation to light touch over the 4^th and 5^th digits on the right. He had positive thoracic outlet provocative maneuvers, with radial pulse dropout bilaterally, right greater than left. Roos’s test was positive bilaterally. Scratch collapse test was positive in the supraclavicular region bilaterally.

Diagnostic workup

EDX performed shortly after symptom onset was unremarkable. On vascular ultrasound, there was evidence of arterial impingement bilaterally with two arm maneuvers on the right and three on the left. MRA of the chest did not reveal any evidence of subclavian artery impingement on the right with arms abducted but did show mild deformity on the left. The MRI revealed mild effacement of the fat surrounding the brachial plexus within the costoclavicular space with arm abduction. No evidence of a cervical rib was seen on the CT of the cervical spine, but approximately 20° levoconvex cervicothoracic scoliosis was identified.

Initial nonoperative management and later operative course

He was referred for physical therapy, as well as botulinum toxin injection to the bilateral anterior and middle scalene muscles, which provided significant improvement in his symptoms for approximately 8 weeks following these injections. However, after this original period of relief, he experienced a recurrence in his symptoms bilaterally, worse on the right. He elected to proceed with the right, followed by left anterior scalenectomies a few months apart and experienced resolution of his symptoms with only intermittent hand numbness.

Case #3

Clinical presentation

A 42-year-old female presented to the neurosurgery clinic with pain on the right side of her neck, tingling and numbness in bilateral hands, and intermittent red/purple discoloration of the right hand.

Physical examination was significant for numbness in the right thumb but 5/5 strength throughout the bilateral upper limbs. She had a positive scratch collapse test over the supraclavicular region bilaterally and tenderness to percussion at the supraclavicular area on the right. Thoracic outlet maneuvers were diffusely positive, right more pronounced than the left.

Diagnostic workup

Imaging showed 22° levoconvex cervicothoracic scoliosis with the apex at T2. EDX were negative. Doppler vascular studies were negative for arterial and venous impingement. MRA’s chest showed compression of the right subclavian vein with arms above her head [ Figure 2 ].

Figure 2:

The cervical X-ray from case #3 (a) shows a 22° levoconvex scoliotic deformity. (b) The magnetic resonance imaging was performed with arms up and demonstrated narrowing of the subclavian vein with the arm above the head (red arrow).

She underwent botulinum toxin injection to the right anterior scalene muscle and demonstrated a good, though temporary, clinical response, so surgical decompression was offered.

Surgery and postoperative course

She underwent right anterior scalenectomy and had significant improvement in symptoms after surgery.

Two years later, she developed worsening symptoms in both arms and hands. She reported that both hands felt limp and heavy. Re-evaluation revealed a positive scratch collapse test and Tinel’s sign of the right pectoralis minor. Once again, EDX were negative, but vascular studies showed arterial impingement with two thoracic outlet maneuvers bilaterally. She then underwent a right pectoralis minor injection, which provided moderate relief of her symptoms for several days. She recently underwent a right pectoralis minor release and will be seen in the clinic for her postoperative follow-up soon.

DISCUSSION

TOS is a disorder that arises from compression of the neurovascular bundle that traverses the thoracic outlet region.[ 8 , 2 , 3 , 5 , 6 ] Anatomically, the thoracic outlet is defined as the space between the supraclavicular fossa and the axilla and between the clavicle and first rib.[ 5 ] Compression in this region can occur in three main locations – the interscalene triangle (between the anterior and middle scalene muscles), the costoclavicular space (between the clavicle, first rib, and upper scapula), and the subcoracoid space (between the pectoralis minor, 2^nd–4^th ribs, and coracoid process).[ 8 , 5 ] The structures in the neurovascular bundle that traverse this region include the brachial plexus, subclavian artery and vein, and axillary artery and vein.[ 8 , 5 ] TOS was first described by Peet et al. in 1956.[ 9 ] The clinical syndrome is characterized by pain, paresthesias, weakness, and/or pallor of the affected extremity.[ 8 , 3 , 5 , 6 ] Extreme cases can present with the classic Gilliatt-Sumner’s hand. In contrast to cervical radiculopathy, the symptoms associated with TOS typically involve multiple dermatomes and muscle groups.

Classically, TOS is caused by compression of the brachial plexus (especially the lower trunk) and/or the associated vascular structures by the anterior and middle scalene muscles.[ 8 , 2 , 3 , 5 , 6 ] Variations in scalene anatomy or the presence of an accessory scalene muscle (found in 30– 50% of patients with TOS[ 5 ]) can also contribute to the development of symptoms. Variations in bony anatomy are also known to contribute to the development of this clinical picture. These osseous abnormalities include the presence of a cervical rib or elongated C7 transverse processes.[ 8 , 5 , 6 ] According to one study, approximately 70% are related to soft-tissue etiologies, with the remaining 30% related to bony abnormalities.[ 8 ] A number of cases are also related to trauma, either acutely or related to scarring and/or fibrosis many years later.[ 8 , 6 ]

We present a series of ten cases of concurrent TOS and cervicothoracic scoliosis. This is a relationship that has not been previously described in the literature. As described above, it is well established that certain bony irregularities, such as a cervical rib, can cause impingement of the neurovascular structures in the thoracic outlet region, and removal of such ribs often provides symptomatic benefit to patients who suffer from this syndrome. While this small case series does not prove causality, it is reasonable to hypothesize that other bony abnormalities that similarly cause deformation of the thoracic outlet region, in this case, cervicothoracic scoliosis, could result in compression of the neurovascular structures in that region, leading to the clinical manifestations of TOS. Based on the available literature, the rate of adolescent idiopathic scoliosis in the general population is 0.47–5.2%, approximately half of which has a primary thoracic curve.[ 4 , 7 ] Based on the total number of TOS cases we see, the incidence of scoliosis is higher in patients with TOS (10%) than in the general population. Although it could be coincidental, this may signify that a causative effect can be in play here. That being said, most patients who needed surgery responded well to our standard anterior scalenectomy approach, and none required deformity correction. In this series, 7/10 patients were symptomatic (or more symptomatic if bilateral symptoms were present) on the concave side of the scoliosis. Scoliosis could alter the bony anatomy by shortening the distance between the transverse processes and the first rib [ Figure 1c ], possibly causing nerve compression. It could also alter the anatomy of the scalene muscles by stretching and increasing the tension on the convex side or shortening and hypertrophy on the concave side. It’s possible that scoliosis itself does not cause TOS but the secondary changes in the scalene muscles, which explains patients developing symptoms only later in life and the good response to scalene injections and scalenectomy surgery without having to subject the patient to a big deformity correction surgery. This relationship warrants further investigation, as it could have potential implications for workup and treatment strategies for TOS in the future.

CONCLUSION

TOS is a common disorder that can have a significant impact on patients’ quality of life, so it is critical to understand the underlying pathologic abnormalities that contribute to its development. While the exact relationship between cervicothoracic scoliosis and the development of TOS has not yet been fully elucidated, it is an important diagnostic consideration in the workup of patients with suspected TOS and warrants ongoing investigation.

Ethical approval:

The research/study was approved by the Institutional Review Board at the University of Wisconsin-Madison Institutional Review Board, number 2013–1411, dated January 13, 2014.

Declaration of patient consent:

Patient’s consent not required as patient’s identity is not disclosed or compromised.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

References

1. Cheng CJ, Mackinnon-Patterson B, Beck JL, Mackinnon SE. Scratch collapse test for evaluation of carpal and cubital tunnel syndrome. J Hand Surg Am. 2008. 33: 1518-24

2. Hanna A, Bodden LO, Siebiger GR. Neurogenic thoracic outlet syndrome caused by vascular compression of the brachial plexus: A report of two cases. J Brachial Plex Peripher Nerve Inj. 2018. 13: e1-3

3. Klaassen Z, Sorenson E, Tubbs RS, Arya R, Meloy P, Shah R. Thoracic outlet syndrome: A neurological and vascular disorder. Clin Anat. 2014. 27: 724-32

4. Konieczny MR, Senyurt H, Krauspe R. Epidemiology of adolescent idiopathic scoliosis. J Child Orthop. 2013. 7: 3-9

5. Kuhn JE, Lebus V GF, Bible JE. Thoracic outlet syndrome. J Am Acad Orthop Surg. 2015. 23: 222-32

6. Laulan J, Fouquet B, Rodaix C, Jauffret P, Roquelaure Y, Descatha A. Thoracic outlet syndrome: Definition, aetiological factors, diagnosis, management and occupational impact. J Occup Rehabil. 2011. 21: 366-73

7. Lenke LG, Betz RR, Harms J, Bridwell KH, Clements DH, Lowe TG. Adolescent idiopathic scoliosis: A new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am. 2001. 83: 1169-81

8. Li N, Dierks G, Vervaeke HE, Jumonville A, Kaye AD, Myrcik D. Thoracic outlet syndrome: A narrative review. J Clin Med. 2021. 10: 962

9. Peet RM, Henriksen JD, Anderson TP, Martin GM. Thoracic-outlet syndrome: Evaluation of a therapeutic exercise program. Proc Staff Meet Mayo Clin. 1956. 31: 281-7