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Introduction Thoracic Outlet Syndrome (TOS) consists of a group of disorders secondary to compression of neurovascular structures that traverse the thoracic outlet space, is divided into 3 distinct spaces: interscalene triangle, costoclavicular space and subcoracoid (retropectoralis minor space). 1 Within them, we find neurovascular structures such as the brachial plexus, subclavian artery, and subclavian vein. Compression in this region is believed to be secondary to a genetic/anatomical predisposition- such as cervical ribs- combined with repeated stress and trauma, causing a narrowing around the neurovascular structures.2–4 This condition significantly impacts upper limb function and quality of life, more particularly in individuals performing repetitive or overhead arm movements.5 6 Diagnosis of TOS remains challenging due to its overlapping symptomatology with other conditions.2 7 Classification TOS is traditionally classified in three subtypes based on the affected structure: neurogenic (nTOS), venous (vTOS), and arterial (aTOS).rj 90% of reported cases is nTOS.8This subtype tends to appear either at the interscalene triangle or retropectoralis minor space.vTOS usually presents either at the interscalene triangle or costoclavicular space, causing vascular microtrauma leading to potential thrombosis.4 aTOS commonly is seen at the interscalene space leading to potential aneurysmal formation and distal embolization.4 Epidemiology Prevalence is not well known likely due to variations in diagnostic criteria and patient presentation. Recent studies estimate a prevalence of around 1%, 7 particularly more frequent amongst those aged 20 to 50 years, nTOS being the most frequent.7 9 Clinical Presentation By subtype: nTOS is associated with paresthesia, trapezius pain, and weakness in the neck, shoulder, and arm, often exacerbated by upper arm overhead activity. Symptoms radiate into the hand and fingers, with chronic cases presenting with muscle atrophy, although rare, particularly in abductor pollicis brevis, hypothenar muscles and interossei (Gilliat-Summer). 4 5 8 10 Classically, pressure in a painful area triggers neurological symptoms (Positive Tinel’s sign). Special test maneuvers are the One-Minute Elevated Arm Stress Test (EAST) or Upper Limb Tension Test.1 vTOS typically presents with swelling, cyanosis, and a feeling of heaviness in the affected limb. Rarely, deep vein thrombosis may occur (Paget-Schroetter syndrome), particularly in younger, active individuals.8 11 On examination, patients may show features of swelling and plethora in the arm.aTOS manifests classically with pallor, cold sensitivity, reduced pulses, and in severe cases, distal embolic phenomena due to turbulent blood flow or arterial damage.8 12 A combination of Adson’s test with EAST is advised for diagnosis as it holds a combined the specificity of 82%, as Adson’s test specificity alone has been reported as low.5 Symptoms of TOS might be presented as one subtype or a mixture of them in different proportion, history and examination supported by imaging such as CXR, MRI, EMG and US is a key to diagnosis.5 Differential diagnosis is broad and may include: distal entrapment neuropathies, complex regional pain syndrome, rotator cuff pathology or malignancies.Treatment Treatment options have been classified into surgical and conservative.Surgical decompression has been the main treatment option, especially in vascular types of TOS. Aim of surgery is to reduce the tensile load on the region either through first or cervical rib resection, scalenectomy, release fibromuscular bands or pectoralis minor tenotomy, depending on site of pathology. Recently, local anaesthetic injections have been increasingly in use to predict a successful operative outcome.1 4 Non-surgical options include education, changing the profile of physical activity and targeted physical therapy specially when symptoms are more subtle, mainly in different forms of nTOS. More recently, new options have surfaced due to the increasing role of intramuscular and perineural targeted injections with diagnostic and therapeutic function.Physical therapy has shown promising results mainly in nTOS specially by focusing on scapular and glenohumeral stability, but due to wide anatomical and symptomatologic variation results might be limited. Treatment should be continued for at least 6 months before considering more invasive interventions.4 Local anaesthetic injections can be considered as first line treatment for nTOS or after failed physical therapy. Specific targeting with US while injecting local anaesthetic relaxes tensed muscles providing temporal symptomatic relief. A successful injection is defined as a >50% improvement in symptoms 4 hours after with a provocative test.4 Botulinum toxin A (Botox) injections have shown to be a prognostic factor for successful surgery. Botox acts as a chemodenervation agent in the muscle, therefore reducing contraction. Relief is expected to range from 1 to 6 months and reduction of around 50%.1 4 Ultrasound-guided hydrodissection relieves pressure through injecting high volume in the surrounding tissues, opening the space, improving passing neurovascular structures’ ability to glide through the dire passage. Various mixes of fluid have been injected, without consensus so far. Typically, mixtures of dextrose with saline with adjuvants such as LA, steroids and hyaluronidase. While hydrodissection has been increasingly established in various nerve entrapments, it still lacks validation in TOS.4 We present our experience with the management of TOS through a mix of ultrasound hydrodissection with a large volume which contained: 10–20 ml of low concentration LA, 6 mg dexamethasone, 1500 u hyaluronidase, targeted brachial plexus pulsed radiofrequency [set up of 42°C for 5 min, 5 PPS (pulse per second),5 ms pulse width] and 25–100 u Botox injection to interscalene or subclavius muscle depending on individual patient symptomatology.Methods A retrospective observational study was conducted at St George’s Hospital, in London, including 14 patients diagnosed with TOS who had undergone a combination of ultrasound-guided hydrodissection, Botox injection, and local anesthetic administration at least one year prior to data collection.Informed consent was obtained from all participants via telephone follow-up. Patient-reported outcomes were collected, including Visual Analog Scale (VAS) for pain, painDETECT questionnaire for neuropathic pain components, and EQ-5D-5L for quality-of-life assessment. Data on duration of symptomatic relief and percentage of symptom reduction were also recorded and analyzed.Results 14 patients were contacted and 8 (57%) were consented to participate. Among these, 6 patients (75%) reported a significant symptom improvement defined as greater than 50% relief.The duration of symptom relief varied broadly, ranging from 2 weeks up to 6 months, with a mean duration of 2.5 months. 4 patients had undergone surgical intervention; and out of these, 2 (50%) had injection therapy due to postoperative complications. This subgroup exhibited a trend towards shorter duration of symptom relief and reported poorer quality of life, as reflected in lower EQ-5D-5L scores, suggesting a more refractory disease course. Regarding treatment frequency, 60% of patients received only one course, whereas the remainder received multiple injections (two or more), with a noted decline in the magnitude and duration of symptomatic relief upon subsequent injections.Conclusion Our findings support that ultrasound-guided hydrodissection combined with pulsed radiofrequency and botulinum toxin injections offers a promising non-surgical therapeutic option for selected patients with TOS, particularly those with neurogenic symptoms refractory to conservative management. The observed symptom relief, averaging around 2.5 months, underscores the potential utility of these minimally invasive interventions as both diagnostic and therapeutic modalities, consistent with emerging evidence in the literature 4. Patients with previous surgical intervention seemed to have a more challenging clinical course, evidenced by shorter and less robust responses to injection therapy. The results of our short survey highlights the need for individualized treatment planning and further investigation into optimizing the timing and combination of interventions. These initial results are encouraging, and further larger prospective studies are required to establish standardized protocols and to elucidate long-term efficacy.References Foley J, Finlayson H, Travlos A. A review of thoracic outlet syndrome and the possible role of botulinum toxin in the treatment of this syndrome. Toxins 2012 Nov 7;4(11):1223–35.Chang KZ, Likes K, Davis K, Demos J, Freischlag JA. The significance of cervical ribs in thoracic outlet syndrome. J Vasc Surg. 2013;57(3):771–5.Rochkind S, Shemesh M, Graif M, et al. Thoracic outlet syndrome part 2: consensus on the management of neurogenic thoracic outlet syndrome by the European association of neurosurgical societies’ section of peripheral nerve surgery. Neurosurgery 2023;92(1):E1–E10.Capodosal G, Holden D, Maloy W, Schroeder JD. Thoracic outlet syndrome. Current Sports Medicine Reports [Internet] 2024 Sep 1;23(9):303–9.Li N, Dierks G, Vervaeke HE, Jumonville A, Kaye AD, Myrcik D, et al. Thoracic outlet syndrome: a narrative review. J Clin Med. 2021;10(5):962.Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A. Imaging assessment of thoracic outlet syndrome. Radiographics 2006;26(6):1735–50.Serra R, Grande R, Perri P. Epidemiology, diagnosis and treatment of thoracic outlet syndrome: a systematic review. Acta Phlebologica. 2015;16(2):53–63.Dengler NF, Ferraresi S, Rochkind S, Denisova N, Garozzo D, Heinen C, et al. Thoracic outlet syndrome part I: systematic review of the literature and consensus on anatomy, diagnosis, and classification of thoracic outlet syndrome by the European association of neurosurgical societies’ section of peripheral nerve surgery. Neurosurgery 2022 Mar 25;90(6):653–67.Panther EJ, et al. Thoracic outlet syndrome: a review. J Shoulder Elbow Surg. 2022;31(9):e353–e362.Blondin M, et al. Considerations for surgical treatment of neurogenic thoracic outlet syndrome: a meta-analysis of patient-reported outcomes. J Hand Surg Am. 2023;48(7):e511–e520.Winn HR, ed. Brachial plexus nerve entrapments and thoracic outlet syndromes. In: Youmans and Winn Neurological Surgery. 8th ed. Elsevier; 2023.Ferri FF. Thoracic outlet syndrome. In: Ferri’s Clinical Advisor 2024. Elsevier; 2024.