Venous Compressive Disorders.

Venous compressive disorders are a heterogenous group of vascular syndromes characterized by extrinsic venous compression that can lead to complications of venous hypertension or venous thrombosis. Endovascular damage secondary to deep venous thrombosis (DVT) can result in post-thrombotic syndrome (PTS), a potentially debilitating condition that can be associated with significant morbidity in the pediatric population. Here we discuss 4 venous compressive disorders: iliac vein compression (May-Thurner syndrome [MTS]); subclavian vein compression at the venous thoracic inlet (Paget-Schroetter syndrome); left renal vein compression (nutcracker syndrome); and popliteal vein compression (popliteal entrapment syndrome) with a focus on clinical evaluation and diagnostic methods. Where endovascular therapy is appropriate, specific procedural considerations including procedure indications, equipment, procedural steps, technical challenges, complications, clinical follow-up and expected outcomes are discussed.

Surgical outcomes for occluded venous thoracic outlet syndrome following transaxillary first rib resection.

OBJECTIVE: Surgical decompression via transaxillary first rib resection (TFRR) is often performed in patients presenting with venous thoracic outlet syndrome (VTOS). We aimed to evaluate the outcomes of TFRR based on chronicity of completely occluded axillosubclavian veins in VTOS. METHODS: We performed a retrospective institutional review of all patients who underwent TFRR for VTOS and had a completely occluded axillosubclavian vein between 2003 and 2022. Patients were categorized into three groups based on the time of inciting VTOS event to TFRR acuity of their venous occlusion: <4 weeks, 4 to 12 weeks, and >12 weeks. We evaluated the association of TFRR timing with 1-year outcomes, including patency and symptomatic improvement. We used the χ2 test to compare baseline characteristics and postoperative outcomes. RESULTS: Overall, 103 patients underwent TFRR for VTOS with a completely occluded axillosubclavian vein (median age, 30.0 years; 42.7% female; 8.8% non-White), of whom 28 had occlusion at <4 weeks, 36 had occlusion at 4 to 12 weeks, and 39 had occlusion at >12 weeks. Postoperative venogram performed 2 to 3 weeks after TFRR demonstrated that 78.6% in the <4 weeks group, 72.2% in the 4- to 12-weeks group, and 61.5% in the >12 weeks group had some degree of recanalization (P = .76). Postoperative balloon angioplasty was successfully performed in 60 patients with stenosed or occluded axillosubclavian vein at the time of postoperative venogram. At the 10- to 14-month follow-up, 79.2% of the <4 weeks group, 73.3% of the 4- to 12-weeks group, and 73.3% of the >12 weeks group had patent axillosubclavian veins based on duplex ultrasound examination (P = .86). Among patients who underwent postoperative balloon angioplasty, 80.0%, 85.0% and 100% in the <4 weeks, 4- to 12-weeks, and >12 weeks groups respectively demonstrated patency at 10 to 14 months (P = .31). Symptomatic improvement was reported in 95.7% in the <4 weeks group, 96.7% in the 4- to 12-weeks group, and 93.5% in the >12 weeks group (P = .84). CONCLUSIONS: TFRR offers excellent postoperative outcomes for patients with symptomatic VTOS, even in cases of completely occluded axillosubclavian veins, regardless of the chronicity of the occlusion. By 14 months, 95.2% of patients experienced symptomatic improvement, and 75% attained venous patency.

Novel Reconstruction of Complex Central Venous Occlusion Using Supraclavicular Stent Graft in Hemodialysis Patients.

BACKGROUND: Subclavian vein and brachiocephalic vein occlusions are challenging problems in dialysis patients with ipsilateral upper extremity (UE) vascular access or in need of one. HeRO grafts (Hemodialysis Reliable Outflow, Merit Medical Systems, Inc, South Jordan, UT) have been used to manage such occlusions but patients with chronic hypotension treated with HeRO graft may have threatened patency. We describe an alternative technique using a supraclavicular stent graft to reconstruct the venous outflow, evaluate outcomes of this procedure, and discuss its role in complex hemodialysis patients. METHODS: From January 2019 to January 2020, we performed open surgical and endovascular dialysis access procedures in 297 patients. Eight patients (2.7%) with failing or failed access and subclavian and or brachiocephalic vein occlusion were treated with supraclavicular stent graft placement. Mean age was 52 years, ranging from 32 to 70. Five patients had failed access and were dialyzed using catheters (two femoral). Three patients with failing fistulas had severe arm edema. Two patients had recurrent HeRO graft thrombosis. We performed a retrospective review of these 8 patients and evaluated access patency and complications. RESULTS: Technical success and access function were 100% in all patients. One patient developed ischemic neuropathy and underwent proximalization of the arterial inflow with improvement. Already-existing fistulas were used for dialysis the day after the procedure and new grafts within 2-4 weeks. Arm edema resolved within one week after the procedure. Median follow-up was 254.5 days, range 24-408 days, with primary patency rate of 87.5% and secondary patency rate of 100%. Only one patient has required reintervention. Postoperative evaluation with ultrasound has revealed patent stent graft in the area of the subcutaneous cervical tunnel over the clavicle. CONCLUSIONS: Supraclavicular stent graft placement to a central vein can be used successfully to reconstruct venous outflow in hemodialysis patients with complex central vein occlusions. A supraclavicular extra-anatomic path can be used safely and effectively to place new UE vascular access or salvage threatened access in this challenging patient population.

Paget-Schroetter Syndrome: a case report of diagnosis, treatment, and outcome in a healthy 18-year-old athletic swimmer.

Paget-Schroetter Syndrome is a rare condition in the spectrum of deep vein thromboses involving spontaneous upper extremity venous thrombosis in the axillary-subclavian vein. The syndrome usually occurs in young, healthy individuals and is a progressive, anatomic manifestation of venous thoracic outlet syndrome. Thrombosis is secondary to repetitive overuse of the arm, leading to compression, microtrauma, and local inflammation of the particularly vulnerable subclavian vein in the thoracic outlet at the junction of the first rib and clavicle. The condition is often misdiagnosed because of its rarity and can lead to significant disability and morbidity if treatment is delayed. In this case report, Paget-Schroetter Syndrome, causing significant pain and dysfunction, is presented in an 18 year-old female freestyle-swimmer that was successfully treated with anticoagulation, thrombolysis, thoracic outlet decompression and first rib resection, scalenectomy, venolysis, and venoplasty. Early suspicion of this condition can lead to prompt diagnosis, and subsequent aggressive interventional treatment with catheter-directed thrombolysis and thoracic outlet decompression, in addition to anticoagulation, demonstrated success in achieving complete resolution of symptoms in this case.

Transposition of external jugular to proximal internal jugular vein for relief of venous thoracic outlet syndrome and maintenance of arteriovenous fistula access for chronic hemodialysis: A new approach.

We are reporting a case of venous thoracic outlet syndrome with recurrent subclavian vein thrombosis in the setting of an ipsilateral brachiocephalic arteriovenous fistula for hemodialysis that was malfunctioning due to the central vein obstruction. The patient also had a concomitant external jugular vein origin stenosis. Given her body habitus and aversion to recovery after traditional first rib resection, we elected for an alternative treatment with an external jugular vein to internal jugular vein transposition with balloon angioplasty of the stenosed external jugular origin segment. The goal of this was to provide simultaneous relief of her outlet obstruction symptoms and salvage her dialysis access with a less invasive technique.

Outcomes of venous bypass combined with thoracic outlet decompression for treatment of upper extremity central venous occlusion.

BACKGROUND: Upper extremity central venous stenosis results from a variety of environmental and anatomic conditions, including venous thoracic outlet syndrome, the presence of device leads or catheters, and the turbulence created by the presence of arteriovenous fistulas or grafts. In cases of total occlusion, especially at the bony costoclavicular junction, options for endovascular treatment and open venous reconstruction are limited and bypass grafting may be needed. We describe our experience with venous bypass combined with thoracic outlet decompression in a cohort of symptomatic patients with subclavian vein occlusion. METHODS: A prospectively collected database of patients was queried for patients treated for central venous obstructive disease with venous bypass in the setting of both symptomatic venous thoracic outlet syndrome and ipsilateral arteriovenous access from July 2012 to December 2017. All but one patient presented with arm swelling and had either failed to respond to or were unsuitable for endovenous therapy. One patient desired elective removal of a venous stent because of pain and anxiety. Operative procedures were performed at the discretion of the operating surgeon. RESULTS: Fourteen patients (eight men; average age, 42 years) underwent open thoracic outlet decompression with first rib resection (n = 11) or claviculectomy (n = 4). Indication for treatment was dialysis-associated venous outlet obstruction in five, effort thrombosis (Paget-Schroetter syndrome) in seven, presence of a venous implantable cardioverter-defibrillator lead in one, and patent but painful venous stent in situ with significant anxiety. Nine patients required first interspace sternotomy for exposure of the proximal subclavian vein. One patient with acute Paget-Schroetter syndrome had been treated with preoperative thrombolysis without resolution; all others were chronically occluded. Bypass conduit was jugular vein in one, bovine carotid artery graft in two, paneled great saphenous vein in two, femoral vein in eight, and polytetrafluoroethylene in one. Mean operative time was 187 (±45) minutes, with mean estimated blood loss of 379 (±209) mL. There were two early graft thromboses that were revised with jugular venous turndown and femoral vein bypass, respectively. All patients experienced immediate symptom relief. Morbidity included two graft thromboses, two instances of wound dehiscence, two operative site hematomas, non-ST elevation myocardial infarction, vein harvest site infection, polytetrafluoroethylene graft infection, and phrenic nerve injury. At a mean follow-up of 357 (±303) days, primary assisted patency and secondary patency for the entire cohort were 71.4% and 85.7%, respectively, with 100% primary assisted patency among those with femoral vein conduit. At last follow-up, 13 of the 14 living patients (93%) remained symptom free. CONCLUSIONS: In our experience, venous bypass combined with thoracic outlet decompression achieves symptomatic relief in approximately 90% of patients with symptomatic upper extremity central venous occlusion, with morbidity limited to the perioperative period.

Medial claviculectomy for the treatment of recalcitrant central venous stenosis of hemodialysis patients.

OBJECTIVE: Outflow tract stenosis is the leading cause of hemodialysis access loss. Many lesions are highly resistant to endovascular treatment, necessitating open surgical intervention. We present our experience using medial claviculectomy for treatment of recalcitrant lesions at the thoracic outlet. METHODS: We retrospectively reviewed patients who underwent medial claviculectomy for dialysis-associated venous thoracic outlet syndrome at our institution between February 2013 and February 2018. Data collection included demographics, past medical history, access history, subsequent procedures, preoperative and postoperative brachial volume flows, and access use. RESULTS: We performed 25 medial claviculectomies in 25 patients with central venous stenosis. Four patients underwent concomitant central venous bypass and were excluded from this study. Twelve accesses were created at our institution; of these, the average access age was 41.6 months (±26.7 months). All patients previously underwent multiple angioplasty attempts to treat outflow stenosis and continued to have residual symptoms and poor fistula function. Medial claviculectomy with venolysis and angioplasty were performed to treat residual outflow stenosis at the level of the subclavian vein. Twenty-one patients had residual stenosis requiring angioplasty. Six patients had subclavian rupture requiring stent graft placement. All patients reported symptom improvement and immediate use of the fistula after medial claviculectomy. Nineteen (76%) patients reported complete resolution of symptoms after the procedure. Ultimately, eight (32%) ipsilateral arteriovenous accesses were lost, and six (24%) patients died in follow-up with patent, functional fistulas. Median length of follow-up was 17 months (interquartile range, 5-28 months). The 18-month primary patency and secondary patency with regard to subclavian vein interventions were 28% (95% confidence interval, 13.8%-56.1%) and 84% (95% confidence interval, 69.7%-100%), respectively. One patient required ligation for high-output cardiac failure. One patient had contralateral brachiocephalic jailing, which was corrected with kissing brachiocephalic stents. CONCLUSIONS: Medial claviculectomy is an effective treatment of recalcitrant central venous stenosis of the thoracic outlet. Balloon angioplasty or stent or stent graft placement is often necessary after extrinsic compression is alleviated and demonstrates acceptable secondary patency rates.

Surgical and endovascular central venous reconstruction combined with thoracic outlet decompression in highly symptomatic patients.

BACKGROUND: Subclavian vein stenosis or occlusion at the thoracic outlet is a problem associated with certain anatomic and environmental stresses (venous thoracic outlet syndrome [VTOS]), the presence of central venous catheters, and the high flows associated with arteriovenous (AV) access in the limb. We describe our experience with open and endovascular techniques for restoring patency in highly symptomatic patients. METHODS: A prospectively collected database of patients was queried for patients treated for central venous obstructive disease in the setting of highly symptomatic VTOS and ipsilateral AV access from October 2011 to August 2016. RESULTS: During the study period, 54 procedures were performed in 53 patients (68% male; mean age, 50.1 years). Indications for operation were venous outflow obstruction in patients with conventional VTOS (n = 19) or costoclavicular junction stenosis associated with ipsilateral dialysis access (n = 34). All patients had significant symptoms of swelling or pain. Eight patients underwent on-table pharmacomechanical thrombolysis for acute occlusion. All patients underwent costoclavicular junction decompression, 48 by infraclavicular first rib resection and 5 by claviculectomy; 6 patients underwent sternoclavicular rotation (Molina procedure) in addition to rib resection for further exposure. Surgical reconstruction of the vein was employed in 18 patients (33%); 9 underwent interposition grafting, 1 had jugular turndown, and 8 had patch angioplasty. The one patient undergoing two procedures suffered acute occlusion after patch repair followed by jugular turndown. Four patients underwent surgical reconstruction after thrombolysis. Endovascular procedures were performed in 36 patients (67%); 23 underwent venous angioplasty alone, and 13, all with hemodialysis access-associated stenosis, underwent stenting. Mean operative time was 135 (±63.5) minutes, and mean estimated blood loss was 238 (±261) mL. Median length of stay was 4 days. Perioperative complications were noted in 14 (26.4%) patients, including wound complications (n = 6), cardiac complications (n = 4), reocclusion (n = 3), and hemothorax requiring chest tube placement (n = 1) in a patient undergoing on-table thrombolysis. Mean follow-up was 13.6 (0.6-58.5) months. Initial clinical symptom relief was experienced in 100% of patients at the time of hospital discharge. During follow-up, 5 (9.4%) patients developed recurrent symptoms, 6 (11.3%) had reocclusion of the central system, and 16 (30.2%) required reintervention for restenosis, all but 2 in patients with ipsilateral hemodialysis access. Mean time to reintervention was 134 (±285) days. CONCLUSIONS: Given our decision-making threshold, both open and endovascular procedures are associated with relatively low morbidity and high efficacy for treatment of central venous occlusion in both symptomatic VTOS and AV access-associated subclavian vein disease. Restenosis is common in patients with a patent ipsilateral hemodialysis access.

Triple lead cephalic versus subclavian vein approach in cardiac resynchronization therapy device implantation.

Cardiac resynchronization therapy (CRT) device implantation is associated with severe complications including pneumo- and hemothorax. Data on a sole cephalic vein approach (sCV), potentially preventing these complications, are limited. The aim of our study was to compare a sole cSV with a subclavian vein approach (SV) in CRT implantations with respect to feasibility and safety. We performed a prospective cohort study enrolling twenty-four consecutive de-novo CRT implantations (group A) using a sCV at two centers. Fifty-four age-matched CRT patients implanted via the SV served (group B) as reference. Procedural success rate and complications were recorded during a follow-up of 4 weeks. All CRTs could be implanted in group A, with 91.7% using cephalic access alone. In group B, CRT implantation was successfully performed in 96.3%. Procedure and fluoroscopy duration were similar for both groups (sCV vs. SV: 119 ± 45 vs. 106 ± 31 minutes, 17 ± 9 vs 14 ± 9 minutes). Radiation dosage was higher in sCV group vs. SV (2984 ± 2370 vs. 1580 ± 1316 cGy*cm2; p = 0.001). There was no case of a pneumothorax in group of sCV, while two cases were observed using SV. Overall complication rate was similar (sCV: 13.0% vs. SV: 12.5%). de-novo CRT implantation using a triple cephalic vein approach is feasible. Procedure duration and complication rates were similar, while radiation dosage was higher in the sCV compared to the SV approach. Despite its feasibility in the clinical routine, controlled prospective studies with longer follow-up are required to elucidate a potential benefit with respect to lead longevity.

Respiratory changes in subclavian vein diameters predicts fluid responsiveness in intensive care patients: a pilot study.

The present pilot study investigated whether respiratory variation in subclavian vein (SCV) diameters correlates with fluid responsiveness in mechanically ventilated patients. Monocentric, prospective clinical study on fluid responsiveness in adult sedated, mechanically ventilated ICU patient, monitored with the PiCCO™ system (Pulsion Medical System, Germany), and requiring a fluid challenge (FC). A 10-min fluid bolus of 500 mL of 0.9% saline was administered. Cardiac output (CO) and dynamic parameters [stroke volume variation (SVV) and pulse pressure variation (PPV)] measured by transpulmonary thermodilution and pulse contour analysis (PiCCO™) as well as classical hemodynamic parameters were recorded at baseline and after FC. Fluid responsiveness was described as an increase in CO of ≥ 15%. Ultrasound measurements obtained in the subclavian long-axis view were used to calculate the SCVvariability index. A cut-off value for SCV variation for the prediction of fluid responsiveness was determined using receiver operating curve (ROC) analysis. Nine of 20 FCs (45%) induced an increase in CO of ≥ 15%. At baseline, the SCVvariability index was greater in responders than in non-responders (34.0 ± 21.4 vs. 9.0 ± 5.5; p = 0.0005). Diagnostic performance for the SCVvariability index revealed a cut-off value of 14 with a sensitivity of 100% [Confidence interval (CI) 95% (90; 100)] and a specificity of 82% [CI 95% (48; 98)] for the prediction of fluid responsiveness. Other parameters, such as SVV and PPV, could not predict fluid responsiveness. The correlation coefficient between CO variation and the SCVvariability index was 0.73 (p < 0.001). The SCVvariability index was a reliable, non-invasive parameter for the prediction of fluid responsiveness at the bedside of mechanically ventilated, critically ill patients in this pilot study.

Vasoconstrictive responses of the cephalic vein during first-time cardiac implantable electronic device placement.

BACKGROUND: During cardiac implantable electronic device (CIED) implantation procedures cardiac leads have been mostly introduced transvenously. The associated injury to the selected vessel and adjacent tissues may induce reflex vasoconstriction. The aim of the study was to assess the incidence of cephalic vein (CV) vasoconstriction during first-time CIED implantation. MATERIALS AND METHODS: Of the 146 evaluated first-time CIED implantation procedures conducted in our centre in 2016, we selected those during which CV vasoconstriction was recorded. We focused on the stage of the procedure involving CV cutdown and/or axillary vein (AV)/subclavian vein (SV) puncture for lead insertion. Only cases documented via venography were considered. RESULTS: Vasoconstriction was observed in 11 patients (5 females and 6 males, mean age 59.0 ± 21.2 years). The presence of this phenomenon affected the stage of CIED implantation involving cardiac lead insertion to the venous system, in severe cases, requiring a change of approach from CV cutdown to AV/SV puncture. The extent of vasoconstriction front propagation was limited to the nearest valves. Histological examinations of collected CV samples revealed an altered spatial arrangement of myocytes in the tunica media at the level of leaflet attachment. CONCLUSIONS: Cephalic vein vasoconstriction is a rare phenomenon associated with accessing the venous system during first-time CIED implantation. The propagation of CV constriction was limited by the location of the nearest valves.

Paget-Schroetter Syndrome Resulting from Thoracic Outlet Syndrome and KAATSU Training.

A 29-year-old woman who worked as a KAATSU (a type of body exercise that involves blood flow restriction) instructor visited our emergency room with a chief complaint of swelling and left upper limb pain. Chest computed tomography (CT) showed non-uniform contrast images corresponding to the site from the left axillary vein to the left subclavian vein; vascular ultrasonography of the upper limb revealed a thrombotic obstruction at the same site, leading to a diagnosis of Paget-Schroetter syndrome (PSS). We herein report our experience with a case of PSS derived from thoracic outlet syndrome (TOS), in a patient who was a KAATSU instructor.

Radiologists need to be aware of secondary central venous stenosis in patients with SAPHO syndrome.

OBJECTIVES: We aimed to define central venous stenosis (CVS) caused by sternocostoclavicular hyperostosis as a feature of synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome on routine contrast-enhanced computed tomography (CT) images. The relationship between SAPHO syndrome and CVS without venous thrombosis caused by anterior chest wall compression has not been investigated. Therefore, the present study evaluated CVS in patients with SAPHO syndrome at our hospital. METHODS: We retrospectively reviewed contrast-enhanced CT images of ten patients with suspected or diagnosed SAPHO syndrome between January 2007 and November 2015. The patients were assessed by contrast-enhanced CT using 16-, 64- or 128-detector row scanners. Two radiologists independently assessed the presence of CVS or obstruction and SAPHO syndrome in a retrospective review of CT images. RESULTS: Six of the ten patients had findings of CVS with SAPHO syndrome. The mean diameter and patency rate at the site of CVS were 1.88 mm and 27.2%, respectively. Stenosis was more significant in terms of the mean diameter of CVS sites than of stenotic sites that crossed the anteroposterior vein (p < 0.05). CONCLUSIONS: Radiologists who routinely assess contrast-enhanced CT images should be aware that sternocostoclavicular hyperostosis with SAPHO syndrome could cause secondary CVS. KEY POINTS: • SAPHO syndrome can cause central venous stenosis. • Radiologists should consider central venous stenosis in patients with SAPHO syndrome. • Early diagnosis of central venous stenosis due to SAPHO syndrome is challenging.

Thrombosis in an Internal Jugular Vein and an Upper Limb Deep Vein Treated with Edoxaban.

A 45-year-old man complained of swelling of the left side of his neck and left upper limb. Ultrasonography and enhanced computed tomography (CT) revealed thrombosis of the left internal jugular, subclavian, and brachiocephalic vein. Based on various examinations, the patient was diagnosed with idiopathic venous thrombosis early in his clinical course. There were no findings to suggest malignancy or abnormal coagulability. However, two months after the start of treatment, the patient was diagnosed with gastric cancer. Despite the presence of Trousseau syndrome, treatment with edoxaban (an oral anticoagulant), reduced the swelling dramatically without any bleeding complications.

Significance of Blunted Venous Waveforms Seen on Upper Extremity Ultrasound.

BACKGROUND: Current guidelines recommend vascular mapping ultrasound (US) prior to arteriovenous fistula creation. Blunted venous waveforms (BVWs) suggest central venous stenosis; however, this relationship and one between BVWs and the presence of a central venous catheter (CVC) remain unclear. METHODS: All patients who received upper extremity vascular mapping US between January 2013 and October 2014 at a single institution were retrospectively reviewed. Patient demographics, comorbidities, US results, pacemaker history, and CVC status were collected. Waveforms were assessed at the proximal subclavian vein/distal axillary vein and interpreted by radiologists. Patients were determined to have central venous stenosis (CVS) if detected by venography within 6 months of US. RESULTS: There were 342 patients, of which 165 (48%) had a current CVC and 29 (8.5%) had BVW of at least 1 arm. Right-sided BVW were associated with a history of a prior ipsilateral CVC (odds ratio [OR] = 4.5, 95% confidence interval [CI] = 1.6-12.6, P = 0.009). Of the 342 patients, 69 (20%) had a venogram within 6 months. Seventeen (25%) of the 69 patients had CVS, with 7 involving the left subclavian vein, 8 the right subclavian vein, and 3 the superior vena cava (one patient had tandem stenoses). A BVW on the left side was not associated with any CVS. A BVW on the right side was associated with an ipsilateral CVS (OR = 5.8, 95% CI = 1.2-27.4, P = 0.04). This association persisted in the setting of a prior CVC (relative risk = 1.3, 95% CI = 0.9-2, P = 0.01). CONCLUSIONS: There are associations between right-sided BVW and an ipsilateral subclavian vein stenosis. We recommend that hemodialysis access planning includes venography to rule out central vein stenosis in patients with BVW, especially if right-sided and in the setting of a prior CVC.

The thoracic outlet syndromes: Part 2. The arterial, venous, neurovascular, and disputed thoracic outlet syndromes.

The thoracic outlet syndromes (TOSs) are a group of etiologically and clinically distinct disorders with 1 feature in common: compression of 1 or more neurovascular elements as they traverse the thoracic outlet. The medical literature reflects 5 TOSs: arterial; venous; traumatic neurovascular; true neurogenic; and disputed. Of these, the first 4 demonstrate all of the features expected of a syndrome, whereas disputed TOS does not, causing many experts to doubt its existence altogether. Thus, some categorize disputed TOSs as cervicoscapular pain syndrome rather than as a type of TOS. To better understand these disorders, their distinctions, and the reasoning underlying the categorical change of disputed TOS from a form of TOS to a cervicoscapular pain syndrome, a thorough understanding of the pertinent anatomy, pathology, pathophysiology, and electrodiagnostic manifestations of these pathophysiologies is required. This review of the TOSs is provided in 2 parts. In part 1 we covered general information pertinent to all 5 TOSs and reviewed true neurogenic TOS in detail. In part 2, we review the arterial, venous, traumatic neurovascular, and disputed forms of TOS. Muscle Nerve 56: 663-673, 2017.