Introduction
Bow Hunter’s Syndrome (BHS)—also called rotational vertebral artery syndrome—is a rare, treatable cause of dizziness, fainting, and other “posterior circulation” symptoms that appear only when the head is turned or tilted in certain directions. In BHS, rotating (or sometimes extending) the neck mechanically narrows or briefly blocks one of the vertebral arteries—the paired blood vessels that travel through the neck to supply the brainstem and cerebellum. When blood flow drops during that head position, the brain regions those arteries feed are transiently under-supplied, and symptoms appear; when the head returns to neutral, blood flow and symptoms usually normalize.
Below is a plain-language guide to what BHS is, how it’s diagnosed, and what treatments look like—distilling findings from reputable, peer-reviewed medical sources and NIH-hosted references.
What does it feel like?
People with BHS often notice dizziness, vertigo (a spinning sensation), blurred or double vision, unsteadiness, or nausea when they turn their head to one side (or occasionally when they look up). Some develop nystagmus (involuntary eye movements) that clinicians can see during an exam. More severe episodes can cause near-fainting or fainting, slurred speech, clumsiness, or even stroke-like symptoms if blood flow is critically reduced. The hallmark is positional triggering: symptoms reliably show up in the same neck position and resolve when the head returns to neutral.
Because other conditions can mimic BHS—such as inner ear disorders, migraine, or generalized vertebrobasilar insufficiency—specialized evaluation is important. (As background, vertebrobasilar insufficiency is a reduction of blood flow in the brain’s posterior circulation and is a broader category than BHS.)
Why does head turning cause a blood-flow problem?
The vertebral arteries course through small canals in the neck bones and then curve around the C1–C2 level (the top of the spine). In some people, age-related bone spurs (osteophytes), tight bands of tissue, unstable joints, or unusual vessel anatomy create a pinch point. When the head rotates or extends, that structure can compress the artery (or less commonly, stretch it), reducing blood flow. In many case series, the C1–C2 level is most often involved, though lower levels can also be the culprit. Rarely, the issue is an atypical origin or course of the vertebral artery itself.
How rare is it?
BHS is uncommon. Most clinicians will see few cases in their careers, and most dizziness with head turning has other, more common explanations. That said, for people whose symptoms only occur with specific neck positions—and especially when exam or imaging shows changes in vertebral artery flow—BHS becomes an important consideration because it is potentially treatable.
How is BHS diagnosed?
A careful history (exact head positions that trigger symptoms), a targeted neurologic and eye movement exam, and vascular imaging are the keys. No single test fits every case, but specialists often use a stepwise approach:
- CTA or MRA of the neck (CT or MR angiography): Looks for bony spurs, vessel narrowing, or unusual anatomy. Standard studies are usually done with the head in neutral and may look normal.
- Dynamic studies that watch the artery during the provoking head position are much more revealing. These can include:
- Dynamic digital subtraction angiography (DSA), considered the gold standard in many reports. The interventional radiology team images vertebral artery flow while gently rotating the head to the symptomatic position, stopping at the first sign of significant narrowing or symptom provocation.
- Duplex ultrasound with head rotation, which can show flow dropping off in the affected artery in the provoking position. Some centers pair this with head-mounted video to correlate symptoms and eye findings.
Because posterior-circulation symptoms can be serious and because dynamic imaging carries small risks, these evaluations are typically done by stroke neurologists, neuro-otologists, neurosurgeons, or interventional neuroradiologists in experienced centers.
How is BHS treated?
Treatment is individualized, based on the cause and the person’s overall health and goals. Broadly, there are conservative and surgical strategies:
Conservative options
- Activity modification: Avoiding the exact head positions that trigger symptoms (for example, turning the whole body instead of just the head).
- Soft cervical collar in select cases to limit extreme rotation while the condition is being worked up.
- Medical therapy: Depending on the patient, clinicians may use antiplatelet medication (such as aspirin) to reduce clot risk, especially if there is evidence of transient ischemia.
These measures may be reasonable for people with mild, infrequent symptoms or those who prefer to avoid surgery; however, they may not fully eliminate risk if flow compromise is significant.
Surgical options
If a clear mechanical pinch point is identified and symptoms are substantial, surgery can address the anatomic problem. Two main strategies are reported:
- Decompression: Removing the offending structure (often a bone spur or fibrous band) that compresses the artery, sometimes with microvascular decompression techniques.
- Stabilization (fusion): In people with unstable joints or when decompression alone may not prevent recurrent compression, the surgeon may add cervical fusion (often at C1–C2 or lower levels) to limit the motion that leads to occlusion.
Modern case series and reviews suggest many patients improve after surgery, but outcomes vary. Choice of anterior vs posterior approach depends on the level and anatomy; there is no single “best” procedure that fits everyone, and decisions are made by a multidisciplinary team.
Endovascular treatments (like stenting) play a limited role because the problem is usually external mechanical compression rather than a fixed plaque inside the artery, though complex, individualized cases exist. A stroke specialist can discuss whether this is relevant in rare scenarios.
What’s the risk of stroke?
Because BHS affects the arteries supplying the brainstem and cerebellum, severe or repeated flow interruptions could, in theory, lead to transient ischemic attacks (TIAs) or posterior-circulation strokes. Fortunately, with diagnosis and appropriate management—especially avoiding provocative head positions and addressing the anatomic cause when needed—the risk can often be reduced considerably. If new or severe symptoms occur (particularly sudden weakness, trouble speaking, severe imbalance, or vision loss), treat it as an emergency and seek immediate care; stroke guidelines emphasize rapid evaluation for any suspected stroke symptoms.
Who tends to develop BHS?
BHS has been described across a wide adult age range. Degenerative changes (like osteophytes) are common contributors in older adults. In others, the cause may be congenital or developmental anatomy—for example, an unusual course or origin of a vertebral artery—which only becomes symptomatic later in life when other changes accumulate. Prior neck trauma or instability can be contributing factors in some cases.
How do clinicians tell BHS apart from inner ear dizziness?
This is a frequent and important question. Inner ear disorders can cause vertigo with head movements, but the mechanism and exam findings differ. In BHS, the trigger is typically sustained head rotation or extension (not just brief changes in position), symptoms may include faintness or neurologic signs, and vascular imaging shows a flow dropduring the provoking position. Because overlap exists and people may have more than one condition, a team approach—often including neuro-otology and vascular neurology—is best.
Living with (and beyond) BHS
If you’ve been told you might have BHS, practical steps include:
- Keep a symptom log with the exact head positions that cause trouble.
- Avoid those positions, especially in situations where a brief loss of balance could be dangerous (ladders, driving, swimming alone).
- Bring all prior neck and brain imaging to your specialty visit; prior CT/MRI often help.
- Ask where dynamic imaging is done; not all centers have protocols for head-turned DSA or dynamic ultrasound.
- Discuss the full menu of options—conservative, surgical, and the risks of each—so the plan matches your goals and daily life.
The most encouraging message from the literature is that, once accurately diagnosed, many patients do well, and for those with a clear mechanical compression, surgery can be durably effective. Still, the published reviews emphasize that individual variation is high, and expert evaluation is essential.
Key takeaways
- BHS is a rare, mechanical blood-flow problem that happens only in certain neck positions.
- The gold standard diagnostic test is usually dynamic angiography that images the vertebral artery during the provoking head turn.
- Conservative measures may help, but surgery to decompress and/or stabilize the artery is often considered when symptoms are significant and a clear pinch point is identified.
- With the right diagnosis and plan, many people improve and reduce their stroke risk.
