Thoracic outlet syndrome for thoracic surgeons

Estimation of the prevalence of isolated inter-scalene compression from simultaneous arterial and venous photoplethysmography in patients referred for suspected thoracic outlet syndrome

Objective.In patients with suspected thoracic outlet syndrome (TOS), diagnosing inter-scalene compression could lead to minimally invasive treatments. During photo-plethysmography, completing a 30 s 90° abduction, external rotation ('surrender' position) by addition of a 15 s 90° antepulsion 'prayer' position, allows quantitative bilateral analysis of both arterial (A-PPG) and venous (V-PPG) results. We aimed at determining the proportion of isolated arterial compression with photo-plethysmography in TOS-suspected patients.Approach.We studied 116 subjects recruited over 4 months (43.3 ± 11.8 years old, 69% females). Fingertip A-PPG and forearm V-PPG were recorded on both sides at 125 Hz and 4 Hz respectively. A-PPG was converted to PPG amplitude and expressed as percentage of resting amplitude (% rest). V-PPG was expressed as percentage of the maximal value (% max) observed during the 'Surrender-Prayer' maneuver. Impairment of arterial inflow during the surrender (As+) or prayer (Ap+) phases were defined as a pulse-amplitude either <5% rest, or <25% rest. Incomplete venous emptying during the surrender (Vs+) or prayer (Vp+) phases were defined as V-PPG values either <70% max, or <87% max.Main results.Of the 16 possible associations of encodings, As - Vs - Ap - Vp- was the most frequent observation assumed to be a normal response. Isolated arterial inflow without venous outflow (As + Vs-) impairment in the surrender position was observed in 10.3% (95%CI: 6.7%-15.0%) to 15.1% (95%CI: 10.7%-20.4%) of limbs.Significance.Simultaneous A-PPG and V-PPG can discriminate arterial from venous compression and then potentially inter-scalene from other levels of compressions. As such, it opens new perspectives in evaluation and treatment of TOS.

Traumatic arterial thoracic outlet syndrome after multiple rib fractures not including the first rib in Korea: a case report

Arterial thoracic outlet syndrome (TOS) resulting from thoracic trauma is an exceedingly rare condition, typically caused by a fracture of the first rib or clavicle. In this report, the author presents a case of traumatic arterial TOS precipitated by multiple left rib fractures, notably excluding the first rib, following a fall from a 2-m high stepladder. The patient was treated successfully with first rib resection via a transaxillary approach, and the postoperative course was uneventful. The literature includes no known reports of traumatic arterial TOS in patients with multiple fractures that spare the first rib, making this the first documented case of its kind. In this instance, the patient sustained fractures to the fourth and fifth ribs. The TOS was likely not a direct result of the multiple rib fractures, which were located some distance from the thoracic outlet. Rather, it is hypothesized that the trauma from these fractures caused a soft tissue injury within the thoracic outlet, which ultimately led to the development of TOS.

Thoracic outlet syndrome in women

Thoracic outlet syndrome (TOS) is observed more frequently in women, although the exact causes of this sex disparity remain unclear. By investigating the three types of TOS-arterial, neurogenic, and venous-regarding symptoms, diagnosis, and treatment, this article aims to shed light on the current understanding of TOS, focusing on its variations in women.

A Literature Review of Methods of Perioperative Pain Management in Thoracic Outlet Decompression

OBJECTIVES

Post-operative pain control in thoracic outlet decompression (TOD) is difficult due to the complex innervation of the anatomical region. Poor post-operative pain control has been associated with worse patient experiences and prolonged inpatient stays. This study aims to identify evidence-based peri-operative analgesic strategies for thoracic outlet decompression.

METHODS

MEDLINE and Embase searches were performed to identify literature assessing peri-operative pain control methods in patients undergoing TOD. Studies were limited to the English language and within 10 years of publication. Abstracts were screened for relevance by two reviewers and identified review articles on thoracic outlet decompression were also included for critical appraisal.

RESULTS

The primary literature search yielded 124 studies whose abstracts were screened resulting in a total of 16 studies being included for full review and critical appraisal. This included 1 randomised control trial, 7 retrospective cohort studies, 1 case series study, 2 case report study and 5 review articles. Studies utilised a baseline of multimodal oral analgesics with their main investigative focus centred on the use of different methods of peripheral nerve blockade.

CONCLUSION

There is only 1 published randomised controlled trial study investigating postoperative analgesic modalities in thoracic outlet decompression. This deficit of evidence was reflected in the high variation of pain management strategies employed in the published literature. Evidence should be sought to assess the relative efficacy of the various pain management strategies.

Congenital, Acquired, and Trauma-Related Risk Factors for Thoracic Outlet Syndrome-Review of the Literature

Thoracic outlet syndrome is a group of disorders that affect the upper extremity and neck, resulting in compression of the neurovascular bundle that exits the thoracic outlet. Depending on the type of compressed structure, the arterial, venous, and neurogenic forms of TOS are distinguished. In some populations, e.g., in certain groups of athletes, some sources report incidence rates as high as about 80 cases per 1000 people, while in the general population, it is equal to 2-4 per 1000. Although the pathogenesis of this condition appears relatively simple, there are a very large number of overlapping risk factors that drive such a high incidence in certain risk groups. Undoubtedly, a thorough knowledge of them and their etiology is essential to estimate the risk of TOS or make a quick and accurate diagnosis.

General Overview and Diagnostic (Imaging) Techniques for Neurogenic Thoracic Outlet Syndrome

Thoracic outlet syndrome is an uncommon and controversial syndrome. Three different diagnoses can be made based on the compressed structure, arterial TOS, venous TOS, and neurogenic TOS, though combinations do exist as well. Diagnosing NTOS is difficult since no specific objective diagnostic modalities exist. This has resulted in a lot of controversy in recent decades. NTOS remains a clinical diagnosis and is mostly diagnosed based on the exclusion of an extensive list of differential diagnoses. To guide the diagnosis and treatment of TOS, a group of experts published the reporting standards for TOS in 2016. However, a consensus was not reached regarding a blueprint for a daily care pathway in this document. Therefore, we constructed a care pathway based on the reporting standards for both the diagnosis and treatment of NTOS patients. This care pathway includes a multidisciplinary approach in which different diagnostic tests and additional imaging techniques are combined to diagnose NTOS or guide patients in their treatment for differential diagnoses. The aim of the present work is to discuss and explain the diagnostic part of this care pathway.

Upper arm versus forearm transcutaneous oximetry during upper limb abduction in patients with suspected thoracic outlet syndrome

Context: Thoracic outlet syndrome (TOS) is common among athletes and should be considered as being of arterial origin only if patients have “clinical symptoms due to documented symptomatic ischemia.” We previously reported that upper limb ischemia can be documented with DROPm (minimal value of limb changes minus chest changes) from transcutaneous oximetry (TcpO2) in TOS.

Purpose: We aimed to test the hypothesised that forearm (F-) DROPm would better detect symptoms associated with arterial compression during abduction than upper arm (U-) DROPm, and that the thresholds would differ.

Methods: We studied 175 patients (retrospective analysis of a cross-sectional acquired database) with simultaneous F-TcpO2 and U-TcpO2 recordings on both upper limbs, and considered tests to be positive (CS+) when upper limb symptoms were associated with ipsilateral arterial compression on either ultrasound or angiography. We determined the threshold and diagnostic performance with a receiver operating characteristic (ROC) curve analysis and calculation of the area under the ROC curve (AUROC) for absolute resting TcpO2 and DROPm values to detect CS+. For all tests, a two-tailed p &lt; 0.05 was considered indicative of statistical significance.

Results: In the 350 upper-limbs, while resting U-TcpO2 and resting F-TcpO2 were not predictive of CS + results, the AUROCs were 0.68 ± 0.03 vs. 0.69 ± 0.03 (both p &lt; 0.01), with the thresholds being −7.5 vs. −14.5 mmHg for the detection of CS + results for U-DROPm vs. F-DROPm respectively.

Conclusion: In patients with suspected TOS, TcpO2 can be used for detecting upper limb arterial compression and/or symptoms during arm abduction, provided that different thresholds are used for U-DROPm and F-DROPm.

Clinical Trial Registration:ClinicalTrials.gov, identifier NCT04376177.

Quantitative analysis of venous outflow with photo-plethysmography in patients with suspected thoracic outlet syndrome

Background

Venous compression is the second most frequent form of thoracic outlet syndrome (TOS). Although venous photo-plethysmography (PPG) has been largely used to estimate the consequences of chronic thromboses (Paget Schroetter syndrome), systematic direct quantitative recording of hemodynamic consequences of positional venous outflow impairment in patients with suspected TOS has never been reported.

Objective

We hypothesized that moving the arms forward (prayer: “Pra” position) while keeping the hands elevated after a surrender/candlestick position (Ca) would allow quantification of 100% upper limb venous emptying (PPGmax) and quantitative evaluation of the emptying observed at the end of the preceding abduction period (End-Ca-PPG), expressed in %PPGmax.

Materials and methods

We measured V-PPG in 424 patients referred for suspected TOS (age 40.9 years old, 68.3% females) and retrieved the results of ultrasound investigation at the venous level. We used receiver operating characteristics curves (ROC) to determine the optimal V-PPG values to be used to predict the presence of a venous compression on ultrasound imaging. Results are reported as a median (25/75 centiles). Statistical significance was based on a two-tailed p &lt; 0.05.

Results

An End-Ca-PPG value of 87% PPGmax at the end of the “Ca” period is the optimal point to detect an ultrasound-confirmed positional venous compression (area under ROC: 0.589 ± 0.024; p &lt; 0.001). This threshold results in 60.9% sensitivity, 47.6% specificity, 27.3% positive predictive value, 79.0% negative predictive value, and 50.8% overall accuracy.

Conclusion

V-PPG is not aimed at detecting the presence of a venous compression due to collateral veins potentially normalizing outflow despite subclavicular vein compression during abduction, but we believe that it could be used to strengthen the responsibility of venous compression in upper limb symptoms in TOS-suspected patients, with the possibility of non-invasive, bilateral, recordable measurements of forearm volume that become quantitative with the Ca-Pra maneuver.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT04376177].

Relationship Between Inflow Impairment and Skin Oxygen Availability to the Upper Limb During Standardized Arm Abduction in Patients With Suspected Thoracic Outlet Syndrome

Objective

Thoracic outlet syndrome (TOS) should be considered of arterial origin only if patients have clinical symptoms that are the result of documented symptomatic ischemia. Simultaneous recording of inflow impairment and forearm ischemia in patients with suspected TOS has never been reported to date. We hypothesized that ischemia would occur in cases of severely impaired inflow, resulting in a non-linear relationship between changes in pulse amplitude (PA) and the estimation of ischemia during provocative attitudinal upper limb positioning.

Design

Prospective single center interventional study.

Material

Fifty-five patients with suspected thoracic outlet syndrome.

Methods

We measured the minimal decrease from rest of transcutaneous oximetry pressure (DROPm) as an estimation of oxygen deficit and arterial pulse photo-plethysmography to measure pulse amplitude changes from rest (PA-change) on both arms during the candlestick phase of a “Ca + Pra” maneuver. “Ca + Pra” is a modified Roos test allowing the estimation of maximal PA-change during the “Pra” phase. We compared the DROPm values between deciles of PA-changes with ANOVA. We then analyzed the relationship between mean PA-change and mean DROPm of each decile with linear and second-degree polynomial (non-linear) models. Results are reported as median [25/75 centiles]. Statistical significance was p < 0.05.

Results

DROPm values ranged −11.5 [−22.9/−7.2] and − 12.3 [−23.3/−7.4] mmHg and PA-change ranged 36.4 [4.6/63.8]% and 38.4 [−2.0/62.1]% in the right and left forearms, respectively. The coefficient of determination between median DROPm and median PA-change was r² = 0.922 with a second-degree polynomial fitting, but only r² = 0.847 with a linear approach.

Conclusion

Oxygen availability was decreased in cases of severe but not moderate attitudinal inflow impairments. Undertaking simultaneous A-PPG and forearm oximetry during the “Ca + Pra” maneuver is an interesting approach for providing objective proof of ischemia in patients with symptoms of TOS suspected of arterial origin.

Digital Biomarkers for the Objective Assessment of Disability in Neurogenic Thoracic Outlet Syndrome

Neurogenic thoracic outlet syndrome (nTOS) is a musculoskeletal disorder in which compression of the brachial plexus between the scalene muscles of the neck and the first rib results in disabling upper extremity pain and paresthesia. Currently there are no objective metrics for assessing the disability of nTOS or for monitoring response to its therapy. We aimed to develop digital biomarkers of upper extremity motor capacity that could objectively measure the disability of nTOS using an upper arm inertial sensor and a 20-s upper extremity task that provokes nTOS symptoms. We found that digital biomarkers of slowness, power, and rigidity statistically differentiated the affected extremities of patients with nTOS from their contralateral extremities (n = 16) and from the extremities of healthy controls (n = 13); speed and power had the highest effect sizes. Digital biomarkers representing slowness, power, and rigidity correlated with patient-reported outcomes collected with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and the visual analog scale of pain (VAS); speed had the highest correlation. Digital biomarkers of exhaustion correlated with failure of physical therapy in treating nTOS; and digital biomarkers of slowness, power, and exhaustion correlated with favorable response to nTOS surgery. In conclusion, sensor-derived digital biomarkers can objectively assess the impairment of motor capacity resultant from nTOS, and correlate with patient-reported symptoms and response to therapy.

Improvement of disability in neurogenic thoracic outlet syndrome by robotic first rib resection

BACKGROUND

Robotic transthoracic first rib resection (R-FRR) has advantages over traditional approaches however its impact on post-operative nTOS outcomes is unknown. Our primary objective was to determine improvement of patient-reported outcome measures (PROMs) of pain and disability following R-FRR in neurogenic thoracic outlet syndrome (nTOS). Our secondary objective was to compare improvement of patient-reported pain between R-FRR and supraclavicular FRR (SC-FRR) in nTOS.

METHODS

We queried a prospectively-maintained, single surgeon, single institution database for nTOS patients undergoing R-FRR or SC-FRR with available pre-operative and post-operative PROMs. PROMs included the Disability of the Arm, Hand, and Shoulder (DASH) questionnaire and Visual Analog Scale (VAS) for pain.

RESULTS

Cohort 1 included 37 patients undergoing 40 R-FRRs and was comprised of 32 females, aged 36 years on average. Pre-operative VAS and DASH (6.0 and 64.2, respectively) improved significantly at the first (2.8 and 35.0, P<0.001 for both) and second post-operative visits (1.4 and 30.2, P<0.01 for both) which occurred at 2.6 and 15.3 weeks, respectively. Cohort 2 included 57 R-FRR performed in 53 patients, and 35 SC-FRRs performed in 34 patients. R-FRR and SC-FRR groups did not significantly differ in sex, age, hand dominance, TOS laterality, or pre-operative VAS. At first post-operative visit (2.4 weeks), R-FRR was associated with lower VAS scores (P=0.023) and greater VAS improvement than SC-FRR (53% and 27% decrease, respectively, P=0.008).

CONCLUSIONS

R-FRR results in significant improvement in disability and pain in nTOS and may have a greater impact on patient-reported pain than SC-FRR in the early postoperative period.

Arterial Digital Pulse Photoplethysmography in Patients with Suspected Thoracic Outlet Syndrome: A Study of the "Ca+Pra" Maneuver

The level of pulse amplitude (PA) change in arterial digital pulse plethysmography (A-PPG) that should be used to diagnose thoracic outlet syndrome (TOS) is debated. We hypothesized that a modification of the Roos test (by moving the arms forward, mimicking a prayer position (“Pra”)) releasing an eventual compression that occurs in the surrender/candlestick position (“Ca”) would facilitate interpretation of A-PPG results. In 52 subjects, we determined the optimal PA change from rest to predict compression at imaging (ultrasonography +/− angiography) with receiver operating characteristics (ROC). “Pra”-PA was set as 100%, and PA was expressed in normalized amplitude (NA) units. Imaging found arterial compression in 23 upper limbs. The area under ROC was 0.765 ± 0.065 (p < 0.0001), resulting in a 91.4% sensitivity and a 60.9% specificity for an increase of fewer than 3 NA from rest during “Ca”, while results were 17.4% and 98.8%, respectively, for the 75% PA decrease previously proposed in the literature. A-PPG during a “Ca+Pra” test provides demonstrable proof of inflow impairment and increases the sensitivity of A-PPG for the detection of arterial compression as determined by imaging. The absence of an increase in PA during the “Ca” phase of the “Ca+Pra” maneuver should be considered indicative of arterial inflow impairment.

Surgical Technique: Minimally Invasive First-Rib Resection

Minimally invasive surgical approaches to the treatment of thoracic outlet syndrome (TOS) will become increasingly common as more surgeons gain experience in thoracoscopic and robotic technique. Robotic surgery may be more technically advantageous because of improved visualization and maneuverability of wristed instruments. Longer-term outcome data are necessary to definitively establish the equivalency or superiority of minimally invasive TOS compared with open surgery in the treatment of TOS.

Safety of robotic first rib resection for thoracic outlet syndrome

OBJECTIVES

Robotic first rib resection (R-FRR) is an emerging approach in the field of thoracic outlet syndrome (TOS) that has technical advantages over traditional open approaches, including superior exposure of the first rib and freedom from retracting neurovascular structures. We set out to define the safety of R-FRR and compare it with that of the conventional supraclavicular approach (SC-FRR).

METHODS

We queried a prospectively maintained, single-surgeon, single-institution database for all FRR operations performed for neurogenic TOS and venous TOS. Preoperative, intraoperative, and complications were compared between approaches.

RESULTS

Seventy-two R-FRRs and 51 SC-FRRs were performed in 66 and 50 patients, respectively. These groups were not significantly different in age, body mass index, sex, type of TOS, or preoperative use of opioids. Length of procedure and hospital stay were not different between groups. Postoperative inpatient self-reported pain (visual analog scale score 4.7 vs 5.2; P = .049) and administered morphine milligram equivalents (37.5 vs 81.1 MME, P < .001) were significantly lower in R-FRR than SC-FRR. Brachial plexus palsy was less frequent after R-FRR than SC-FRR (1% vs 18%, P = .002) and resolved by 4 months in call cases. All cases were sensory palsies with the exception of 2 motor palsies, which were both in the SC-FRR group. In multivariable analyses, R-FRR was independently associated with less frequent total complications than SC-FRR (P = .002; odds ratio, 0.08; 95% confidence interval, 0.02-0.39).

CONCLUSIONS

R-FRR provides outstanding exposure of the first rib and eliminates retraction of the brachial plexus and its consequences.

Traditional medicine treatment for thoracic outlet syndrome: A protocol for systematic review of randomized controlled trials

BACKGROUND

Diagnosis of thoracic outlet syndrome (TOS) is challenging; however, proper evaluation and treatment ensure relief from symptoms in most patients. A comprehensive approach to treatment is important, considering the multifactorial etiology of TOS. The objective of this systematic review is to describe the methods for evaluating the effectiveness and safety of acupuncture-based traditional medicine treatments for TOS.

METHODS

A total of 13 databases will be searched, from their inception to the present date, for studies that have investigated the treatment of TOS. Databases that will be included are MEDLINE, Embase, AMED, Cochrane Library, CINAHL, and 4 Korean, 2 Chinese, and 2 Japanese databases.We will include randomized controlled trials (RCTs) assessing acupuncture-based traditional medicine for the treatment of any type of TOS. All RCTs on traditional medicine with any form of acupuncture will be eligible for inclusion. The methodologic quality of the RCTs will be analyzed using the Cochrane Collaboration tool to assess the risk of bias, and the confidence in the cumulative evidence will be assessed using the grading of recommendations assessment, development, and evaluation instrument.

ETHICS AND DISSEMINATION

The results of this systematic review will be published in a peer-reviewed journal and disseminated both electronically and in print. The review will be updated to inform and guide health care practices.

TRIAL REGISTRATION NUMBER

PROSPERO 2020 CRD42020164869.

Cervical Rib Synostosis to the First Rib: A Rare Anatomic Variation

BACKGROUND

Congenital anatomic variations exist in human anatomy, which create both diagnostic and treatment challenges. Understanding the osteologic and radiographic anatomy of supernumerary ribs arising from the cervical spine and recognizing the morphologic variations thereof is of great importance to clinicians, radiologists, and surgeons alike.

CASE DESCRIPTION

This case study describes osteologic morphology and radiologic characteristics of a rare anatomic variant of a cervical rib (CR): a unilateral, right-sided CR synostosis to the first thoracic rib of a 50-year-old South African man of African ancestry. The characteristic features included increased angulation, widening of the body, and shortening of the length of the right-sided first thoracic rib. The synostosis of the CR shaft was at the level of the angle of the first thoracic rib. The widest aspect of the first thoracic rib was close to the site of fusion, namely the angle, with the mediolateral length approximately 34.51 mm. This is in contrast to the contralateral first thoracic rib measuring, at its widest, 26.39 mm. The CR was located approximately 3.34 mm superiorly to the first thoracic rib at the cervical articular facet. The CR presented with a well-defined head, which is small and rounded with the inclusion of an articular facet. Thereafter, it presented with a short neck, just over half the length of the inferiorly placed first thoracic rib, and a similar sized articulating facet at the tubercle. The appearance of the trabecular bone pattern on radiographs is in keeping with the contralateral left first rib, although altered in accordance with the gross osteologic appearance described earlier. Furthermore, the radiographs highlight an elliptical lucent-zone within the trabecular bone demonstrating decreased density centrally with a thin rim of sclerotic cortical bone peripherally. This is consistent with classical rib architecture in cross-section representing the CR shaft site of fusion to the first thoracic rib. The CR synostosis to the first thoracic rib represents a novel complex, termed by the authors as a cervicothoracic rib complex.

CONCLUSION

The present report refers to the osteologic and radiographic description and comparison of a unilateral, right-sided CR synostosis to a first thoracic rib. The clinical implications of CRs may consist of neurologic, vascular complications, and functional deficits of the involved limb associated with thoracic outlet syndrome (TOS). A CR synostosis to the first thoracic rib represents an associated increased risk of vascular injury, with poorer operative outcomes associated with TOS. This case study is of particular importance to vascular surgeons and neurosurgeons involved with surgical planning and intervention strategies relating to CRs and TOS.

Thoracic Outlet Syndrome: A Comprehensive Review of Pathophysiology, Diagnosis, and Treatment

Thoracic outlet syndrome, a group of diverse disorders, is a collection of symptoms in the shoulder and upper extremity area that results in pain, numbness, and tingling. Identification of thoracic outlet syndrome is complex and a thorough clinical examination in addition to appropriate clinical testing can aide in diagnosis. Practitioners must consider the pathology of thoracic outlet syndrome in their differential diagnosis for shoulder and upper extremity pain symptoms so that patients are directed appropriately to timely therapeutic interventions. Patients with a definitive etiology who have failed conservative management are ideal candidates for surgical correction. This manuscript will discuss thoracic outlet syndrome, occurrence, physical presentation, clinical implications, diagnosis, and management.

Microvascular Response to the Roos Test Has Excellent Feasibility and Good Reliability in Patients With Suspected Thoracic Outlet Syndrome

Background: Exercise oximetry allows operator-independent recordings of microvascular blood flow impairments during exercise and can be used during upper arm provocative maneuvers.

Objective: To study the test-retest reliability of upper-limb oximetry during the Roos test in patients with suspected thoracic outlet syndrome (TOS).

Materials and Methods: Forty-two patients (28 men, 14 women; mean age: 40.8 years) were examined via transcutaneous oxygen pressure (TcpO2) recordings during two consecutive Roos tests in the standing position. The minimal decrease from rest of oxygen pressure (DROPmin) value was recorded after each maneuver was performed on both arms. The area under the receiver operating characteristic (ROC) curve defined the DROPmin diagnostic performance in the presence of symptoms during the tests. The Mann–Whitney U-test was used to compare the DROPmin in the symptomatic vs. asymptomatic arms. The test-retest reliability was analyzed with Bland-Altman representations. The results are presented as means ± standard deviations (SD) or medians [25–75 percentiles].

Results: The symptoms by history were different from the symptoms expressed during the Roos maneuvers in one-third of the patients. The DROPmin measurements were −19 [−36; −7] mmHg and −8 [−16; −5] mmHg in the symptomatic (n = 108) and asymptomatic (n = 60) arms, respectively. When TOS observed on ultrasound imaging was the endpoint, the area under the ROC curve (AUC) was 0.725 ± 0.058, with an optimal cutoff point of −15 mmHg. This value provided 67% sensitivity and 78% specificity for the presence TOS via ultrasound. When symptoms occurring during the test represented the endpoint, the AUC was 0.698 ± 0.04, with a cutoff point of −10 mmHg. This provided 62% sensitivity and 66% specificity for the presence of pain in the ipsilateral arm during the test. The test-retest reliability of DROPmin proved to be good but not perfect, partly because of unreliability of the provocation maneuvers.

Conclusion: To the best of our knowledge, this study is the first to investigate microvascular responses during the Roos maneuver in patients with suspected TOS. The presence of symptoms was significantly associated with ischemia. TcpO2 facilitated the recording of both macrovascular and microvascular responses to the Roos test. The Roos maneuver should probably be performed at least twice in patients with suspected TOS.