Can Thoracic Outlet Syndrome Cause Dizziness or POTS?

What Is Thoracic Outlet Syndrome?

The thoracic outlet is the tight passage at the base of your neck, behind the neck muscles and under the collarbone and first rib. Nerves and blood vessels bound for the arm pass between the scalene muscles of the neck, over the first rib and under the collarbone. Thoracic outlet syndrome (TOS) is the name for a range of conditions where the brachial plexus (the nerve bundle that runs the arm), the subclavian artery or the subclavian vein gets compressed on the way through (Simpson, 2025).

TOS is grouped by which structure is squeezed. It's neurogenic when the nerves are compressed, venous when it's the vein and arterial when it's the artery (Simpson, 2025; Panther, 2022). Neurogenic TOS is the most common subtype (Lim, 2021).

The usual squeeze points are the scalene muscles and the first rib. Neck trauma or repeated work stress can scar the scalenes or shift a cervical rib (an extra rib some people are born with) so it presses on the nerves (Panther, 2022). In a cadaver study, the nerves showed tissue changes of compression where the anterior scalene and the first rib meet them, and the authors point out that nerve compression in TOS has been documented less well than vessel compression (Tiongco, 2023). On the vessel side, an 8-patient imaging series showed the subclavian artery narrowed between the collarbone and first rib in some cases and blocked over an abnormal first rib in others (Utukuru, 2026).

Our team describes the outlet as the space behind the neck muscles, under the collarbone and first rib, and sees posture and tight muscles as common contributors. Higher up, the same neck muscles can affect blood flow to the brain, which is a separate squeeze from the one at the outlet.

Can Thoracic Outlet Syndrome Make You Dizzy?

It can, and every published example our team found is a case report or case series. That's enough to show it happens and too little to say how often.

The strongest lead involves the vein. A 2025 case series of people with persistent oscillating vertigo found compression at 1 or more points along the veins draining the head and neck, and one of those points was the subclavian vein at the thoracic outlet. Relieving the obstructions, which included thoracic outlet decompression for some patients, significantly relieved the vertigo, even when only one side was decompressed (Cha, 2025). The abstract doesn't say how many patients had compression at the outlet itself, and our team describes oscillating vertigo as a different sensation from the lightheadedness many people with POTS feel on standing.

The artery side shows up in rare, serious cases. A previously healthy 22-year-old with TOS had his left subclavian artery blocked where it crossed an abnormal first rib, and an embolism blocked his basilar artery, which supplies the back of the brain. The authors concluded that TOS from a first rib anomaly may cause stroke (Yamaguchi, 2008). A separate case report links a cervical rib to a stroke in the same back-of-the-brain territory (Paliwal, 2014). The Yamaguchi report describes a single patient with a stroke rather than everyday dizziness.

The standard arm-raise test for TOS can also bring on lightheadedness. At the Johns Hopkins Chronic Fatigue Clinic, 64 people with ME/CFS or idiopathic chronic fatigue did the elevated arm stress test (EAST). During the test, 41% reported whole-body symptoms, most often lightheadedness (19%) and generalized fatigue (11%) (Edwards, 2025). The group was defined by chronic fatigue rather than a TOS diagnosis.

Arm down Arm raised

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Put together, the published record shows that outlet compression can produce dizziness in some cases, and nothing yet shows how often. When dizziness is the main complaint, the inner ear and balance system deserve a look too, and the types of vestibular dysfunction show how those problems differ.

Is Thoracic Outlet Syndrome Linked to POTS?

No published study our team found has tested TOS as a cause of POTS. A PubMed search for TOS together with POTS came back empty, and the most relevant Europe PMC titles weren't about it, so any link between the 2 is still a question for testing.

The broader category of vascular compression has more behind it. A 2026 review reports that retrospective studies, case series and clinical observations suggest vascular compression syndromes may be common in people with dysautonomia, particularly POTS, and often go unrecognized. It adds that surgical decompression or venous stenting may improve orthostatic intolerance in selected patients, though high-quality prospective data remain limited (Davis, 2026). That review covers compression in the head and neck, abdomen, pelvis and legs, and its summary doesn't name the thoracic outlet.

Our team's position is that every POTS workup should look for blood vessels that are mechanically compressed, and that's the place to start. The clinic sees subclavian compression in a lot of its POTS patients, and it also looks for compression in the back of the neck and around the carotid arteries. Our team says whiplash and sports impacts, such as hockey hits, can set this up.

In the clinic's model, a narrowed subclavian, carotid or vertebral artery can change how much blood the heart moves, and the heart rate climbs to compensate. Our team reads that fast heart rate as a rescue for brain blood flow: POTS is the rescue working, and orthostatic hypotension is the rescue failing. No study our team found has tested that chain for TOS, so it stays the clinic's working model.

The outlet is one stretch of a longer route, so the clinic checks the whole route, including the neck and the carotid and vertebral arteries, instead of the outlet alone. The neck side is covered in can craniocervical instability cause POTS and how neck problems affect the brain. A drop in upright brain blood flow without a fast heart rate is closer to OCHOS.

Question	What's published	Study type
What is TOS?	Compression of the brachial plexus, subclavian artery or subclavian vein at the outlet, in neurogenic, venous and arterial forms (Simpson, 2025; Panther, 2022)	Reviews
Can it cause vertigo?	Vertigo tied to compressed head and neck veins, the subclavian vein at the outlet among them; relieved by decompression combined with other treatments (Cha, 2025)	Case series
Can it cause stroke?	Basilar artery occlusion in one patient with a first rib anomaly (Yamaguchi, 2008); a cervical rib linked to a vertebrobasilar stroke (Paliwal, 2014)	Case reports
Does the arm-raise test cause lightheadedness?	19% of 64 chronic fatigue patients (Edwards, 2025)	Retrospective cohort
Is vascular compression common in POTS?	Possibly, from retrospective and case data; TOS isn't named (Davis, 2026)	Narrative review
Does TOS cause POTS?	No study found	None

What Signs Point to Compression at the Outlet?

Our team looks for a cluster of clues that point to the outlet instead of the brain or the neck.

Finger tingling and a weak grip point to the nerves, and cold hands that change with arm position point to the vessels. Pinched nerve roots higher in the neck can cause similar arm symptoms, so the exam has to tell the 2 apart.

How Is Thoracic Outlet Syndrome Tested?

TOS is diagnosed from the history, exam maneuvers and imaging. A 2022 review holds that the diagnosis needs evidence of a physical problem that can be corrected, and shouldn't be given just because other causes were ruled out (Panther, 2022).

For neurogenic TOS, a 2026 review lists the medical history, a systematic physical exam, supporting tests, a diagnostic muscle block and ruling out other diseases. The same review notes that neurogenic TOS may be underdiagnosed, and that the consensus frameworks used to diagnose it lack robust outside validation (Li, 2026).

Imaging supports the diagnosis by showing which structure is compressed, where and why, while the clinical exam stays central (Uzun, 2026). In a dynamic CT angiography study, subclavian artery narrowing showed up in 100 of 208 outlets (48%) in people with TOS, and significant narrowing in 59 (28%). Having symptoms was independently tied to significant narrowing (Noureddine, 2026).

Finding a squeeze answers only half the question, and the other half is whether it changes what reaches your brain when you're upright. The 3D tour shows how the clinic measures brain blood flow and heart rate on standing.

What Happens When Compression Is Found?

When TOS is confirmed, the surgical options the reviews describe include decompressing the brachial plexus, cutting or removing the scalene muscles (scalenotomy or scalenectomy), and removing the first rib, along with cervical rib removal or pectoralis minor release in some cases (Panther, 2022; Li, 2026).

Whether surgery helps dizziness or orthostatic symptoms has only case-level answers. Thoracic outlet decompression was part of the treatment that relieved vertigo in the venous compression series (Cha, 2025). One ME/CFS patient diagnosed with TOS had major drops in many symptoms after surgery on both sides (Christoforou, 2025). That's a single patient, and it can't predict how anyone else will respond.

In one of the clinic's case studies, compression in the subclavian system was one part of the picture for a patient who went from housebound to coaching again.

Thoracic Outlet Syndrome, Dizziness and POTS: FAQ

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