Long Island Thoracic Outlet Syndrome
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Legal Analysis

How Car Accidents Cause Thoracic Outlet Syndrome

The thoracic outlet is a narrow anatomical space bounded by the clavicle anteriorly, the first rib inferiorly, and the anterior and middle scalene muscles posteriorly. Through this confined space pass the brachial plexus nerve roots (C5\u2013T1) supplying the arm and hand, the subclavian artery supplying blood to the upper extremity, and the subclavian vein returning blood from the arm. When this space is narrowed by trauma, muscle spasm, or bony displacement, the result is compression of one or more of these structures \u2014 a condition known as thoracic outlet syndrome.

Whiplash and the scalene mechanism is the most common car accident pathway to neurogenic TOS. In a rear-end collision, the hyperextension phase forces the cervical spine posteriorly, stretching and then reflexively contracting the anterior scalene muscles. The subsequent hyperflexion rebound places additional eccentric load on the scalenes. This acute muscle injury initiates a spasm-fibrosis cycle: the scalene muscles become hypertonic and shortened, progressively narrowing the thoracic outlet and increasing pressure on the brachial plexus roots passing between the anterior and middle scalene muscles. The compression targets the lower trunk of the brachial plexus (C8 and T1 nerve roots), which is anatomically closest to the first rib \u2014 producing the characteristic neurogenic TOS pattern of numbness and weakness in the ring and small fingers, medial forearm, and hand.

Seatbelt injury across the clavicle is a second important TOS mechanism. In frontal collisions, the seatbelt shoulder strap \u2014 which crosses the clavicle and chest \u2014 applies sudden, high-force deceleration loading to the clavicle and surrounding structures. This can fracture the clavicle directly or produce periosteal injury and subsequent callus formation that narrows the costoclavicular space (the space between the clavicle and the first rib). For arterial TOS, the subclavian artery runs through the costoclavicular space and is particularly vulnerable to this mechanism; for venous TOS, the subclavian vein is similarly positioned. For a full discussion of the car accident mechanisms that produce thoracic injury, see our car accident lawyer page.

Cervical rib as a risk factor deserves specific attention. A cervical rib is an anomalous rib arising from the 7th cervical vertebra, present as an anatomical variant in approximately 0.5 to 1% of the general population. Most people with a cervical rib are asymptomatic throughout their lives. However, a cervical rib substantially narrows the thoracic outlet and creates a predisposition to TOS: the brachial plexus and subclavian artery must course over the cervical rib and its fibrous band as they exit the thoracic outlet, creating a fulcrum over which the neurovascular bundle is stretched and compressed. A car accident that causes scalene spasm or first rib displacement in a person with an asymptomatic cervical rib may be the precipitating event that converts a pre-existing anatomical anomaly into symptomatic TOS. Under New York’s eggshell plaintiff doctrine, the defendant who causes the accident is fully liable for the TOS that results, including the fact that the plaintiff’s cervical rib predisposed them to the condition.

The Three Types of Thoracic Outlet Syndrome

TOS is classified into three forms based on which neurovascular structure is compressed. Each has distinct clinical features, diagnostic criteria, and treatment pathways with direct implications for the personal injury claim.

Neurogenic TOS (approximately 95% of all TOS cases) results from compression of the brachial plexus \u2014 specifically the lower trunk (C8\u2013T1 nerve roots) \u2014 between the hypertonic scalene muscles and the first rib. Symptoms follow the C8\u2013T1 dermatomal and myotomal distribution: numbness and tingling in the ring and small fingers and the medial forearm; weakness in intrinsic hand muscles (hypothenar muscles, interossei, and the thenar muscles innervated by the ulnar nerve); and in some patients, Raynaud’s-like symptoms (episodic color changes, coolness, and pallor of the fingers) reflecting sympathetic nerve involvement. Pain typically radiates from the neck and shoulder down the arm in an ulnar pattern and is provoked or worsened by overhead arm positions. Neurogenic TOS diagnosis is clinical: provocative tests \u2014 the Adson test (pulse diminution with neck rotation and deep inspiration), the Wright hyperabduction test (pulse diminution with shoulder abduction to 180 degrees), and the Roos stress test or elevated arm stress test (EAST, reproducing symptoms with arms elevated for 3 minutes) \u2014 combined with cervical X-ray for cervical rib and the clinical pattern of C8\u2013T1 symptoms constitute the diagnostic standard of care.

Arterial TOS (less than 1% of TOS cases) results from subclavian artery compression between the clavicle and the first rib, often associated with a cervical rib or bony anomaly that creates arterial compression at the thoracic outlet. Symptoms include diminished or absent radial pulse in specific arm positions, pallor, coldness, and pain in the hand and forearm. In severe or chronic cases, subclavian artery thrombosis, embolization to the digital arteries, or aneurysm formation may occur, producing ischemia of the hand or fingers. Arterial TOS is objectively confirmed by CTA or MRA angiography showing subclavian artery stenosis, occlusion, or aneurysm. Treatment requires urgent vascular surgical intervention \u2014 typically first rib resection combined with arterial repair or bypass. Arterial TOS is the least controversial of the three forms because objective vascular imaging provides unambiguous confirmation of the diagnosis.

Venous TOS (approximately 4\u20135% of TOS cases) results from subclavian vein compression or thrombosis at the thoracic outlet. The classic presentation is Paget-Schroetter syndrome \u2014 acute axillosubclavian vein thrombosis (DVT) presenting as sudden arm swelling, cyanosis, and pain in a young, active patient. In car accident cases, the mechanism is seatbelt injury across the clavicle producing direct venous compression or injury, or the scalene and muscular trauma of whiplash producing venous compression at the costoclavicular junction. Venous TOS is confirmed by duplex ultrasound, venography, or CT venography showing subclavian vein compression or thrombosis. Acute treatment involves thrombolytic therapy and anticoagulation, followed by surgical first rib resection to decompress the thoracic outlet and prevent recurrence. Long-term complications include post-thrombotic syndrome with persistent arm swelling, pain, and functional limitation.

Diagnosing TOS After a Car Accident: Tests and Imaging

The diagnostic pathway for TOS following a car accident depends on the clinical form suspected and the results of provocative testing. Understanding these diagnostic steps is essential for both obtaining the correct medical care and building the legal claim.

Adson’s test is performed by palpating the radial pulse while the patient rotates the head toward the affected side and takes a deep breath while the arm is slightly abducted and extended. A positive test is diminution or obliteration of the radial pulse with symptom reproduction, suggesting anterior scalene compression of the subclavian artery (and by proximity, the brachial plexus). Adson’s test has limited specificity when used alone but remains a component of the TOS clinical examination.

Wright hyperabduction test involves palpating the radial pulse while passively abducting and externally rotating the shoulder to 90 degrees and then 180 degrees (the overhead position). Pulse diminution or symptom reproduction at this position suggests subclavian artery compression under the pectoralis minor tendon at the coracoid process (a variant of TOS sometimes called pectoralis minor syndrome) or at the costoclavicular junction.

Roos test (Elevated Arm Stress Test, EAST) is considered the most sensitive clinical provocative test for neurogenic TOS. The patient holds both arms in the "stick-up" position (elbows at shoulder height, hands elevated, shoulders externally rotated) and opens and closes the hands slowly for 3 minutes. Reproduction of the patient’s arm and hand numbness, tingling, heaviness, or weakness is a positive result. Inability to maintain the position for 3 minutes due to progressive symptoms is also a positive finding. The Roos test is the most clinically meaningful of the provocative tests because it directly reproduces the patient’s functional complaint in a controlled, observable manner.

Cervical X-ray for cervical rib should be obtained in all suspected TOS cases. Standard AP and lateral cervical X-rays will demonstrate a cervical rib or elongated C7 transverse process if present, providing the anatomical basis for the compression and establishing why the patient was predisposed to TOS.

Nerve conduction studies and the normal EMG issue is the central diagnostic controversy in neurogenic TOS. Standard EMG/NCV studies assess peripheral nerve conduction (ulnar nerve, median nerve, medial antebrachial cutaneous nerve) and are frequently normal in neurogenic TOS because the compression at the thoracic outlet is proximal to the points measured by routine electrodiagnostic studies. Some specialized centers perform ulnar F-wave studies or somatosensory evoked potentials to assess proximal conduction, but these studies are not universally positive. The thoracic surgery and vascular surgery literature is clear that normal EMG does not exclude neurogenic TOS and is not required for surgical diagnosis or treatment. This is the key point that must be communicated to a jury: the treating thoracic surgeon, who performs first rib resection regularly and knows the anatomy of the thoracic outlet directly, diagnoses neurogenic TOS on clinical grounds, and their clinical opinion is the standard of care \u2014 not the opinion of a neurologist who has performed a one-time electrodiagnostic study.

Botulinum toxin injection into the scalene is both a diagnostic and therapeutic tool. Injection of botulinum toxin A into the anterior scalene muscle under ultrasound or CT guidance temporarily paralyzes the muscle, relieving the compressive force on the brachial plexus. If the patient experiences significant, reproducible relief of arm and hand symptoms following the injection, this is objective evidence that scalene spasm is the mechanism of brachial plexus compression \u2014 confirming the neurogenic TOS diagnosis. The injection response is documented in the surgeon’s records and is one of the most effective pieces of objective evidence in a neurogenic TOS personal injury case.

New York Law: §5102(d) Threshold and TOS Claims

New York Insurance Law §5102(d) requires that a plaintiff prove their injuries satisfy one of nine enumerated serious injury categories to recover non-economic damages (pain and suffering) from the at-fault driver. For TOS car accident claims, three categories are most applicable.

Permanent consequential limitation of use of a body organ or member is the most compelling threshold theory for surgically treated TOS. First rib resection or scalenectomy represents definitive surgical intervention that permanently alters the anatomy of the thoracic outlet. Patients who undergo first rib resection retain permanent anatomical changes (absence of the first rib), and many have persistent post-surgical limitations in shoulder and arm function, grip strength, and overhead reach. The treating thoracic surgeon’s permanence opinion \u2014 that the plaintiff has reached maximum medical improvement with permanent upper extremity functional limitations attributable to the TOS and its surgical treatment \u2014 satisfies this category.

Significant limitation of use of a body function or system is the primary threshold theory for non-surgical neurogenic TOS. Because neurogenic TOS compromises the function of the upper extremity \u2014 producing grip weakness, inability to maintain overhead arm positions, difficulty with fine motor tasks, and sensory loss in the hand \u2014 the functional limitation documented by the treating thoracic surgeon on successive examinations can constitute the objective evidence required under Toure v. Avis Rent A Car (2002). The surgeon must document specific, measurable functional deficits: grip dynamometry showing reduced grip strength compared to the contralateral hand, documented inability to maintain the Roos test position for the prescribed duration, and clinical findings consistent with C8\u2013T1 distribution impairment. These findings, documented at multiple examinations, form the evidentiary foundation of the significant limitation claim.

The 90/180-day category is available for TOS patients whose functional limitations during the first 180 days after the accident are severe enough to constitute inability to perform substantially all of their usual and customary daily activities for at least 90 of those days. TOS symptoms \u2014 arm numbness, hand weakness, inability to type, inability to drive, inability to perform overhead work \u2014 can satisfy this standard when contemporaneously documented. Employer records showing absence from work, treating surgeon’s visit notes documenting specific functional restrictions, and the plaintiff’s daily symptom log are the building blocks of the 90/180 claim.

Damages in TOS cases include the full range of economic and non-economic losses. Economic damages include: no-fault medical expenses up to $50,000; TOS surgical costs ($20,000\u2013$80,000 or more for complex vascular reconstruction); post-surgical physical therapy; lost wages during treatment and surgical recovery; and vocational loss for plaintiffs whose TOS permanently restricts them from their pre-accident occupation. Non-economic damages include past and future pain and suffering, loss of enjoyment of life, and psychological impact of chronic upper extremity dysfunction. TOS cases involving first rib resection in working-age plaintiffs with vocational restrictions routinely produce results in the range of $300,000 to $1,000,000 or more when all elements of the damages case are properly assembled.