A different perspective on cervical X-ray parameters in nTOS: could it play a role in pathophysiology?

Neurogenic Thoracic Outlet Syndrome (nTOS) is characterized by compression of neural structures within the interscalene triangle of the thoracic outlet, with anatomical variations frequently implicated in its etiology. In patients with TOS, spinal nerves pass through a narrow anatomical space as they exit the foramen and traverse the thoracic inlet. The tension of the suprapleural bands extending between the C7 transverse process and the first rib, along with changes in neck position and certain anatomical variations, can lead to compression of the lower trunk. The condition of this anatomical space, where compression occurs, is influenced by the relationship between the lower cervical vertebrae and the first rib. This study aims to determine whether these cervicothoracic angles could lead to lower trunk compression as it passes over the suprapleural membrane. It is hypothesized that this radiological variation may present a higher likelihood of causing compression in TOS patients compared to the normal population. This retrospective study included patients diagnosed with neurogenic TOS who underwent surgery between 2015 and 2023, patients managed with physical therapy without surgery, and a matched control group. The control group consisted of patients presenting to the orthopedic clinic with neck pain but without any pathological findings. Cervical anteroposterior and lateral radiographs were evaluated to measure T1 slope, cervical inclination, the length of the T1 transverse process, and the angle between the T1 transverse process and the T1 vertebral body. We hypothesize that differences in these radiological parameters, often assessed in patients with cervical spondylosis, might contribute to nerve compression at the thoracic outlet. These parameters were compared between groups. Thoracic Outlet Syndrome Index (TOSI) scores and surgical approaches were documented for the operated patients. The study included 52 patients with a mean age of 34.23 ± 11.15 years. Of these, 24 patients were in the TOS group, and 28 were in the control group. Sixteen of the 24 TOS patients underwent surgery, while 8 were managed with physical therapy. Significant differences were observed between the TOS and control groups in cervical inclination and T1 transverse process angle (p = 0.04, p = 0.004). However, no significant relationship was found between T1 slope, T1 transverse process length, and TOS. Cervical inclination was 43 degrees in the TOS group and 48 degrees in the control group. The T1 transverse process angle was 106.5 degrees in the TOS group and 116.5 degrees in the control group. Among the 16 operated patients, 13 (81.25%) underwent a supraclavicular approach, 2 (12.5%) had a combined supraclavicular and pectoralis minor approach, and 1 (6.25%) underwent a pectoralis minor approach. Supraclavicular surgeries included fibrous band excision and anterior and middle scalenectomy. The preoperative and postoperative TOSI scores for the 16 operated patients were 26.2 and 2.23, respectively, with a statistically significant difference (p < 0.001). Increased tension in the fibrous bands over the Sibson-Truffert fascia, exacerbated by poor neck posture, may contribute to lower trunk compression in TOS. The literature supports treatment through excision of these bands via a supraclavicular approach, yielding clinically satisfactory outcomes. In conclusion, demonstrating cervical inclination and T1 transverse process angle preoperatively as indicators of lower trunk compression may predict favorable outcomes with supraclavicular surgery.