Scalenus Syndrome: A Literature Review

Scalenus syndrome is often diagnosed as thoracic outlet syndrome (TOS). We performed literature searching reporting scalenus syndrome and we narratively describe the finding in this review. Scalenus syndrome is a unique clinical entity and commonly occurred. This syndrome can be classified into neurogenic TOS (nTOS) on the interscalene triangle, which also related to myofascial pain syndrome. There are three factors that contribute to scalenus syndrome, which are congenital anomaly, trauma, traumatic myositis, and hypertrophy of scalenus anterior muscle. The symptoms of scalenus syndrome can be divided into two types, which are neurologic and vascular symptoms. The neurologic manifestation can originate from the somatic and sympathetic nervous system. There is microscopic evidence of inflammation, hypertrophy, degeneration, and fibrosis of scalenus anterior muscle in scalenus syndrome cases. Scalenus syndrome can be treated surgically or conservatively. Non-surgical or conservative treatment can be applied to mild scalenus syndrome, especially nTOS, in the initial phase. Surgical management should be performed in persistent symptoms of nTOS or involving subclavian artery manifesting as arterial TOS (aTOS). Scalenus syndrome has quite similar clinical manifestation as nTOS and aTOS. However, this clinical syndrome should be considered as different entity because of different pathophysiology compared to TOS. Scalenus syndrome is caused by dynamic pathology of anterior scalenus muscle.

Modern Diagnosis and Surgical Management of Thoracic Outlet Syndrome: A Comprehensive Review

Conventionally TOS has been thought to represent a group of diverse disorders that result in compression of the neurovascular bundle exiting the thoracic outlet. Until recently, TOS classification has been based on symptoms, rather than the underlying pathology, with the subgroups consisting of neurogenic (NTOS), venous (VTOS or PSS), and arterial (ATOS). Neurogenic TOS accounts for over 95% of the cases, followed by venous (3–5%) and arterial (1–2%). Neurogenic TOS (NTOS) has been further divided into True NTOS (TNTOS) and Disputed NTOS (DNTOS), with DNTOS reportedly representing 95–99% of all neurogenic cases. In order to decrease confusion and to improve therapeutic results with TOS, the disease should be classified based on the underlying pathologic entity. Acquired and traumatic abnormalities of the clavicle and first rib should be classified separately. Clearly after the more common and objectively supported diagnoses of conditions that result in neurovascular symptoms of the upper extremity, such as cervical spine disease, carpal tunnel disease, and nerve entrapment syndromes, have been ruled out, there remains a group of patients who are suspected of having TOS. In these patients, rather than the more usual classification such as arterial, venous, or neurogenic, the more accurate approach from a diagnostic and therapeutic approach is to classify them as: Cervical Rib Disease: Patients with cervical rib syndrome (CRS) can have complications relating to compression of the subclavian artery (previously referred to as ATOS) and the brachial plexus(previously referred to as True NTOS) secondary to a well-formed cervical rib, or to an incompletely formed first rib, fibrous band associated with a rudimentary cervical rib, or a giant transverse process of C7. Thoracic Outlet Disease or “Subclavian Vein Compression Syndrome”: In these patients an abnormal first rib at its junction with the sternum results in compression of the subclavian vein at the subclavian-innominate junction. Compression of the vein results in venous hypertension in the upper extremity and resultant neurologic symptoms. With prolonged compression of the subclavian-innominate junction, the vein clots giving rise to Paget–Schroetter syndrome. Therefore, patients who have been previously classified as Disputed Neurogenic and Venous TOS represent a variable symptomatic presentation of the same pathologic entity, which affects the subclavian vein. Presently MRA of the thoracic outlet with arm maneuvers is the test of choice in patients suspected of having TOS. This test shows the abnormal bony tubercle on the first rib with extrinsic compression of the subclavian innominate junction, which is exacerbated with elevation of the arm above the shoulder. Robotic resection of the medial aspect of the first rib along with disarticulation of the costo-sternal joint has the best reported results to date.

The use of ultrasound in the emergency department for the detection of thoracic outlet syndrome: A single case study

Introduction Thoracic outlet syndrome (TOS) refers to a spectrum of syndromes related to the compression of the brachial plexus (neurogenic TOS), subclavian vein or artery in the general region of the thoracic outlet, which is the area just above the first rib and behind the clavicle. Case report We report a 27-year-old healthy man who presented to the emergency department with right upper limb pain, tingling and weakness. Point-of-care ultrasonography was performed following a dynamic protocol in the supraclavicular fossa in the right upper limb. A congenital cervical rib, as well as narrowing of the costoclavicular gap, causing vein, artery and spinal roots compression was evidenced. This maneuver reproduced the symptoms, confirming the suspicion of neurogenic TOS. Discussion Early diagnosis is important, because the neurogenic compression associated with neurogenic TOS, if prolonged, can lead to muscle weakness and atrophy, being irreversible. Selected patients with neurogenic TOS who have progressive weakness, disabling pain, or who have failed to improve with conservative measures are considered for first rib resection. Conclusion Using the dynamic approach during point-of-care ultrasonography examination, in combination with physical examination and cervical radiography, could help identify neurogenic TOS.