Thoracic Outlet Syndrome


Thoracic outlet syndrome (TOS) is the constellation of neurologic and vascular symptoms caused by mechanical compression and entrapment of the subclavian vessels and brachial plexus within a space delimited by the scalene muscle, clavicle and first rib. As these structures pass into the upper extremity they run through three important spaces: the interscalene triangle, the costoclavicular space and the subpectoral space. Compression can occur in any of these spaces secondary to trauma or a structural malformation. A bone abnormality or soft tissue problem usually plays the etiological role. These could be a cervical rib, abnormal first rib, long transverse process of the 7th cervical vertebra or fracture of the clavicle. Soft tissue pathology associated with TOS includes abnormal fibrous bands and ligaments or congenital/acquired alteration of scalenus anterior muscle. In adults more than 90% of TOS cases are neurogenic in origin, with venous compression comprising 5% and arterial compression in 2%. In children arterio-venous ischemic symptoms predominate in 62% with 38% presenting with neurologic symptoms. It is more commonly seen in females. The neurogenic variety of TOS manifests clinically with pain, weakness, cold intolerance, numbness of the hand and occasional loss of muscle at the base of the thumb. The venous TOS manifest with swelling, pain and bluish discoloration of the arm. The arterial TOS shows pain, coldness and paleness of the arm. Pediatric cases presents with neck discomfort, upper limb numbness, weakness and sensory loss. The anatomy of neurogenic TOS is complex and is probably best determine by a combination of plain x-ray, MRI, CT-Scan, duplex scanning,  nerve conduction studies and electromyography. TOS remain a diagnosis of exclusion. Differential diagnosis includes  cervical disk herniation, distal compression neuropathy, syringomyelia, Pancoast tumor and brachial inflammation. Most pediatric patients are managed conservatively correcting posture, exercises and nerve block rather than with surgical intervention. Scalenectomy is suitable for all TOS patients who did not have bony compression. With cervical ribs, the rib is removed after excision the scalenus anterior, medius and minimus muscle. If the transverse process of the 7th cervical vertebra is longer that the first thoracic vertebra, the former should be removed. Surgical complications include brachial plexus injury, pneumothorax, chylous leakage, lymph effusion and hematomas. Postop rehabilitation is imperative.      

References:
1- Vercellio G, Gatti BC, Coletti M, Cipolat L: Thoracic Outlet Syndrome in Paediatrics: Clinical Presentation, Surgical Treatment, and Outcome in a Series of Eight Children. J Pediatr Surg. 38(1): 58-61, 2003
2- Arthur LG, Teich S, Hogan M, Caniano DA, Smead W: Pediatric thoracic outlet syndrome: a disorder with serious vascular complications. J Pediatr Surg 43: 1089-1094, 2008
3- Maru S, Dosluoglu H, Dryjski M, Cherr G, Curl GR, Harris LM: Thoracic outlet syndrome in children and young adults. Eur J Vasc Endovasc Surg. 38(5):560-4, 2009
4- Khan A, Rattihalli RR, Hussain N, Sridhar A: Bilateral thoracic outlet syndrome: An uncommon presentation of a rare condition in children. Ann Indian Acad Neurol. 15(4):323-5, 2012
5- Rehemutula A, Zhang L, Chen L, Chen D, Gu Y: Managing pediatric thoracic outlet syndrome.
Ital J Pediatr.27;41:22. doi: 10.1186/s13052-015-0128-4.
6- Chavhan GB, Batmanabane V, Muthusami P, Towbin AJ, Borschel GH: MRI of thoracic outlet syndrome in children. Pediatr Radiol. 47(10):1222-1234, 2017


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