Soo Bin Bae; Ha Kyung Jung; Sung Il Nam

doi:10.21790/rvs.2026.010

Articles

Page Path: HOME > Res Vestib Sci > Volume 25(2); 2026 > Article

Case Report
Rotational vertebral artery syndrome (Bow Hunter syndrome) initially misdiagnosed as benign paroxysmal positional vertigo: a case report: Soo Bin Bae¹, Ha Kyung Jung², Sung Il Nam¹; Research in Vestibular Science 2026;25(2):77-82.
DOI: https://doi.org/10.21790/rvs.2026.010
Published online: June 15, 2026

¹Department of Otorhinolaryngology, Keimyung University Dongsan Hospital, Keimyung University School of Medicine, Daegu, Korea

²Department of Radiology, Keimyung University Dongsan Hospital, Keimyung University School of Medicine, Daegu, Korea

Corresponding author: Sung Il Nam Department of Otorhinolaryngology, Keimyung University Dongsan Hospital, Keimyung University School of Medicine, 1035 Dalgubeol-daero, Dalseo-gu, Daegu 42601, Korea. E-mail: entnamsi@dsmc.or.kr

• Received: May 7, 2026 • Revised: June 5, 2026 • Accepted: June 9, 2026

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

783 Views
12 Download

Full Article

Download PDF

Abstract
INTRODUCTION
CASE REPORT
DISCUSSION
ARTICLE INFORMATION
REFERENCES

Abstract

Rotational vertebral artery syndrome (RVAS), or Bow Hunter syndrome, is an uncommon cause of vertebrobasilar insufficiency mimicking benign paroxysmal positional vertigo (BPPV). We describe a 66-year-old woman with recurrent vertigo that consistently occurred during leftward head rotation. Despite previous BPPV treatment, symptoms persisted. Videonystagmography during the supine head-roll test revealed an atypical multiphasic positional nystagmus, characterized by an initial down-beating followed by prolonged right-beating nystagmus. Positional computed tomography angiography demonstrated severe focal narrowing of the right vertebral artery at the C1-C2 level during leftward rotation, combined with a hypoplastic left V4 segment. Diagnosed with RVAS, she was first treated conservatively by avoiding provocative head rotation, with surgical stabilization considered due to persistent symptoms. This case underscores that RVAS must be included in the differential diagnosis of positional vertigo, particularly when symptoms are specifically rotation-induced or nystagmus patterns are atypical. Vascular imaging in the provocative head position is essential for an accurate diagnosis.
Keywords: Positional vertigo; Vertebrobasilar insufficiency; Case reports

INTRODUCTION

Rotational vertebral artery syndrome (RVAS), historically referred to as “Bow Hunter syndrome,” is a rare but potentially life-threatening condition involving episodes of posterior circulation ischemia specifically triggered by head rotation [1]. This occurs when the vertebral artery (VA) is dynamically compressed by external structural factors—most commonly degenerative osteophytes, ligamentous laxity, or congenital anomalies [2]. Although normal neck rotation causes minimal changes in cerebral blood flow, patients with RVAS can suffer severe hemodynamic compromise or thromboembolic events when rotation exceeds the compensatory capacity of the contralateral VA or the circle of Willis [3]. Consequently, RVAS is often recognized late because its symptoms manifest heterogeneously and overlap considerably with more common vestibular disorders [4].

One major diagnostic challenge is that RVAS can be mistaken for benign paroxysmal positional vertigo (BPPV) or other peripheral vestibular conditions [5]. Both disorders cause vertigo triggered by head or body position. However, RVAS can lead to syncope, visual field defects, and even permanent brainstem infarction. It is frequently misclassified because routine neuroimaging in a neutral position—such as static magnetic resonance imaging (MRI) or computed tomography (CT)—often fails to capture the transient vascular compromise occurring only during provoking movements. Recent evidence suggests that clinicians must look beyond typical peripheral vestibular findings, paying special attention to central oculomotor signs—like down-beating nystagmus (DBN)—as a “red flag” for an underlying vascular occlusion [6,7].

The pathophysiology of RVAS is increasingly understood as a dual mechanism of hypoperfusion and thromboembolism. Repeated mechanical injury from osteophytes or fibrous bands can damage the vessel lining over time, promoting in situ thrombus formation even without complete arterial occlusion [2]. This understanding has shifted research toward the value of dynamic vascular evaluation. While digital subtraction angiography (DSA) combined with provocative head rotation remains the reference standard [8], three-dimensional CT angiography (CTA) is emerging as a safer, less invasive option for visualizing the continuous kinking of the artery during motion [9].

Treatment for RVAS ranges from conservative behavioral modifications to complex surgical decompression or instrumented fusion [10]. Surgical interventions achieve high success rates, but the optimal approach—whether simple motion-preserving decompression or definitive spinal fixation—remains debated [10]. Endovascular stenting is discouraged due to the risk of device fracture from persistent mechanical forces.

Consequently, establishing standardized diagnostic protocols is crucial to prevent posterior circulation strokes. Here, we present a rare case of a patient with RVAS who was initially misdiagnosed with BPPV.

Ethics Statement

This study was approved by the Institutional Review Board of Keimyung University Dongsan Hospital (No. DSMC IRB 2026-04-127). Due to the retrospective nature of this case report and the use of de-identified patient data, the requirement for informed consent was officially waived.

CASE REPORT

A 66-year-old woman with a history of hypertension presented with recurrent vertigo for several months, brought on specifically and consistently by turning her head to the left. Leftward head rotation in both the seated and supine positions reproduced the identical vertigo and a subjective feeling of falling backward. This symptom onset occurred at an approximate head rotation of 60° to 70° (near-maximal rotation) with a brief latency of about 2 seconds after completing the turn. During short-duration leftward rotation, the induced vertigo completely resolved within 5 to 10 seconds after returning her head to the neutral position. When the provocative leftward position was maintained, the intense vertigo persisted for over 10 seconds.

Each episode was also described as a “thumping” pulsatile sensation in her head. When carefully questioned regarding associated symptoms, she reported subjective backward falling during peak neck rotation, but denied any posterior circulation symptoms such as diplopia, dysarthria, limb ataxia, occipital headache, or neck pain. She had previously been misdiagnosed and treated for BPPV at a local clinic, but her symptoms persisted despite therapy. She also denied any ear-related complaints, including hearing loss or tinnitus.

To distinguish peripheral vestibular problems from central causes or vascular positional vertigo, a full set of vestibular function tests was performed. There was no spontaneous or gaze-evoked nystagmus. However, the supine head-roll test to the left triggered a multiphasic nystagmus pattern. After a short delay of about 2 seconds, a prominent DBN appeared and lasted for roughly 10 seconds. Following a pause of approximately 10 seconds, a sustained right-beating horizontal nystagmus developed, with a maximum slow-phase velocity of 14°/sec, and continued for over 30 seconds. The right-beating nystagmus then gradually resolved even though she kept her head turned to the left (Fig. 1).

Video head impulse testing revealed normal vestibulo-ocular reflex gains without overt corrective saccades. Caloric testing showed right canal paresis of 12%, which was within the non-pathologic range. Smooth pursuit, optokinetic nystagmus, and saccade tests were unremarkable. Although these findings do not by themselves definitively exclude canalolithiasis or cupulolithiasis, the absence of a canal-specific nystagmus pattern, the initial downbeat component, the multiphasic transition from vertical to horizontal nystagmus, and the strict reproducibility with leftward neck rotation made a peripheral BPPV mechanism less likely and raised suspicion for a central or vascular cause of positional vertigo.

To evaluate potential dynamic vascular compromise, positional neck CTA was performed. Imaging in the neutral position demonstrated normal patency of both VAs (Fig. 2A, C, E, G). However, when the head was rotated to the left, there was focal, severe narrowing of the right VA at the C1-C2 level, specifically at the V2-V3 junction (Fig. 2B, D, F, H). This narrowing was hemodynamically significant because the patient had a hypoplastic left VA at the V4 segment (Fig. 2G, H), which limits collateral compensation during head rotation.

To further evaluate surrounding structures and rule out other potential causes, cervical spine MRI and X-ray were performed. While they identified multilevel degenerative changes and moderate canal stenosis at C4-C6, no fixed compression was noted at the C1-C2 level. Based on the definitive dynamic occlusion on CTA, the patient was diagnosed with RVAS.

Management initially focused on strict behavioral modifications. The patient was educated to avoid provocative leftward head rotation and restrict rapid neck movements. Despite the absence of focal neurologic deficits, antiplatelet therapy with aspirin was initiated to prevent potential thromboembolism and hypoperfusion.

During a 6-month outpatient follow-up, the frequency of vertigo episodes significantly decreased through symptom avoidance. No recurrent transient ischemic attacks, falls, or new neurologic deficits occurred. While surgical C1-C2 fusion was initially considered, it has been deferred because her symptoms remain well-controlled with behavioral modifications. She continues regular follow-up to monitor for any clinical progression.

DISCUSSION

The case highlights the diagnostic difficulty that RVAS creates in clinical practice due to its ability to mimic peripheral vestibular disorders [4]. Vertigo and dizziness are typical complaints in RVAS, leading to frequent misdiagnosis as BPPV [5]. While DBN is not specific to RVAS and may occasionally occur in atypical positional vertigo or other central vestibular disorders, in the context of strictly rotation-induced symptoms it should be regarded as a red flag for possible vertebrobasilar insufficiency (VBI) [6,7]. Although each nystagmus could individually be misinterpreted as atypical BPPV, the multiphasic transition from vertical to horizontal nystagmus is an important diagnostic clue suggesting a central or vascular mechanism rather than routine peripheral conditions.

In this case, the underlying mechanical compression at the C1-C2 level during contralateral rotation fits a typical RVAS profile. When the head is turned, the artery contralateral to the direction of rotation becomes stretched and may be compressed at the atlantoaxial junction [2]. This hemodynamic strain was significantly exacerbated by the patient’s coexisting hypoplastic contralateral V4 segment, which limited sufficient collateral compensation to the circle of Willis [3].

A limitation of this study is that the exact structural etiology of the dynamic compression—such as a specific fibrous band or hidden osteophyte—was not clearly demonstrated on structural imaging, which may suggest an underlying dynamic rotational instability rather than fixed bony compression [2]. Additionally, diffusion-weighted imaging was not performed to rule out acute micro-ischemic lesions, representing another clinical limitation.

Diagnosis in the modern era relies on capturing these transient dynamic events. Although DSA remains the reference standard to evaluate real-time, continuous hemodynamic flow changes [8], positional CTA alone was diagnostically sufficient in this case. The value of positional CTA lies in its ability to non-invasively provide crucial anatomical information about the relationship between the arterial lumen and surrounding structures [9], successfully demonstrating that a vessel patent in the neutral position transforms into a hemodynamically significant stenosis during provocative head rotation. This underscores how silent the condition can be during routine radiologic assessments, often resulting in a delay between symptom onset and correct diagnosis.

Treatment for RVAS must be tailored individually, weighing stroke risks against the permanent loss of cervical mobility. Conservative behavioral modifications are often the initial approach; however, long-term conservative management alone carries a substantial risk of symptom recurrence or subsequent ischemic events. Therefore, surgical intervention like C1-C2 fusion is typically preferred for high-risk presentations or when conservative measures fail, although it permanently restricts neck rotation [10]. Accordingly, clinicians and patients must engage in shared decision-making based on neurological status and lifestyle needs.

In conclusion, this case highlights that RVAS remains an under-recognized but potentially devastating cause of positional vertigo. The diagnostic delay driven by the syndrome’s ability to mimic BPPV can be improved through greater clinical awareness and specific diagnostic indicators. Clinicians should actively look for central oculomotor signs, including the reproducible DBN and multiphasic pattern seen in this patient, as these findings suggest VBI rather than peripheral vertigo. Closing this diagnostic gap depends on routinely adding dynamic, provocative imaging—like positional CTA or DSA—when neutral position scans come back normal despite symptoms triggered by rotation. Identifying RVAS early is crucial to stopping transient ischemic attacks from progressing to an irreversible stroke in the posterior circulation.

ARTICLE INFORMATION

Funding/Support

None.

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Availability of Data and Materials

The datasets are not publicly available but are available from the corresponding author upon reasonable request.

Authors’ Contributions

Conceptualization: Nam SI, Bae SB; Data curation: Bae SB; Formal analysis: Bae SB, Jung HK; Project administration: Nam SI; Visualization: Bae SB, Jung HK; Investigation: Bae SB, Jung HK; Resources: Nam SI, Jung HK; Supervision: Nam SI; Validation: Nam SI, Jung HK; Writing–original draft: Bae SB; Writing–review and editing: All authors. All authors read and approved the final manuscript.

Fig. 1.

Videonystagmography during the supine head-roll test to the left, showing an atypical multiphasic positional nystagmus. (A) Vertical eye position: After a brief latency of 2 seconds, an initial down-beating nystagmus (a) occurs and lasts for approximately 10 seconds. The inset provides a magnified view of the waveform, clearly demonstrating the downward direction of the fast phases. (B) Horizontal eye position: following a 10-second intermission, a secondary right-beating horizontal nystagmus (b) persists for over 30 seconds, eventually resolving while the provocative head position is maintained.

Fig. 2.

Neck computed tomography angiography: (A, B) axial view, (C, D) coronal view, (E, F) sagittal view, and (G, H) maximum intensity projection. (A, C, E, G) In the neutral position, the right vertebral artery shows normal patency without definite vascular compression (arrows). (B, D, F, H) In contrast, during leftward head rotation, focal severe narrowing of the right vertebral artery is observed at the C1-C2 level (arrows), consistent with a diagnosis of rotational vertebral artery syndrome. Concurrently, posterior inferior cerebellar artery termination of a hypoplastic V4 segment of the left vertebral artery is noted (arrowheads in G, H).

REFERENCES

1. Choi KD, Choi JH, Kim JS, et al. Rotational vertebral artery occlusion: mechanisms and long-term outcome. Stroke 2013;44:1817–1824. Article PubMed
2. Jost GF, Dailey AT. Bow Hunter’s syndrome revisited: 2 new cases and literature review of 124 cases. Neurosurg Focus 2015;38:E7. Article
3. Marti S, Hegemann S, von Büdingen HC, Baumgartner RW, Straumann D. Rotational vertebral artery syndrome: 3D kinematics of nystagmus suggest bilateral labyrinthine dysfunction. J Neurol 2008;255:663–667.Article PubMed PDF
4. Gans RE. When positional vertigo is not “benign” [Internet]. The Hearing Review; c2025 [cited 2026 May 1]. Available from: https://hearingreview.com/hearing-loss/vestibular-care/when-positional-vertigo-is-not-benign
5. Heidenreich KD, Carender WJ, Heidenreich MJ, Telian SA. Strategies to distinguish benign paroxysmal positional vertigo from rotational vertebrobasilar ischemia. Ann Vasc Surg 2010;24:553. Article
6. Choi KD, Shin HY, Kim JS, et al. Rotational vertebral artery syndrome: oculographic analysis of nystagmus. Neurology 2005;65:1287–1290. Article PubMed
7. Kim HA, Yi HA, Lee CY, Lee H. Origin of isolated vertigo in rotational vertebral artery syndrome. Neurol Sci 2011;32:1203–1207. Article PubMed PDF
8. Rastogi V, Rawls A, Moore O, et al. Rare etiology of Bow Hunter's syndrome and systematic review of literature. J Vasc Interv Neurol 2015;8:7–16. PubMed PMC
9. Torre GS, Failla BB, Portela FS, et al. Dynamic computed tomography angiography for noninvasive diagnosis of Bow Hunter’s syndrome: a case report. Einstein (Sao Paulo) 2024;22:eRC0582. Article PubMed PMC
10. Zaidi HA, Albuquerque FC, Chowdhry SA, Zabramski JM, Ducruet AF, Spetzler RF. Diagnosis and management of Bow Hunter’s syndrome: 15-year experience at Barrow Neurological Institute. World Neurosurg 2014;82:733–738. Article PubMed

Figure & Data

References

Citations

Citations to this article as recorded by

PubReader
ePub Link

Cite

Cite: export Copy Download Format; Close

Download Citation

Download a citation file in RIS format that can be imported by all major citation management software, including EndNote, ProCite, RefWorks, and Reference Manager.

Format:

RIS — For EndNote, ProCite, RefWorks, and most other reference management software
BibTeX — For JabRef, BibDesk, and other BibTeX-specific software

Include:

Citation for the content below
Citation and abstract for the content below

Rotational vertebral artery syndrome (Bow Hunter syndrome) initially misdiagnosed as benign paroxysmal positional vertigo: a case report

Res Vestib Sci. 2026;25(2):77-82. Published online June 15, 2026

DOI: https://doi.org/10.21790/rvs.2026.010

XML Download

Figure

Related articles

Rotational vertebral artery syndrome (Bow Hunter syndrome) initially misdiagnosed as benign paroxysmal positional vertigo: a case report

Fig. 1. Videonystagmography during the supine head-roll test to the left, showing an atypical multiphasic positional nystagmus. (A) Vertical eye position: After a brief latency of 2 seconds, an initial down-beating nystagmus (a) occurs and lasts for approximately 10 seconds. The inset provides a magnified view of the waveform, clearly demonstrating the downward direction of the fast phases. (B) Horizontal eye position: following a 10-second intermission, a secondary right-beating horizontal nystagmus (b) persists for over 30 seconds, eventually resolving while the provocative head position is maintained.

Fig. 2. Neck computed tomography angiography: (A, B) axial view, (C, D) coronal view, (E, F) sagittal view, and (G, H) maximum intensity projection. (A, C, E, G) In the neutral position, the right vertebral artery shows normal patency without definite vascular compression (arrows). (B, D, F, H) In contrast, during leftward head rotation, focal severe narrowing of the right vertebral artery is observed at the C1-C2 level (arrows), consistent with a diagnosis of rotational vertebral artery syndrome. Concurrently, posterior inferior cerebellar artery termination of a hypoplastic V4 segment of the left vertebral artery is noted (arrowheads in G, H).

Fig. 1.

Fig. 2.

Rotational vertebral artery syndrome (Bow Hunter syndrome) initially misdiagnosed as benign paroxysmal positional vertigo: a case report