Intracranial Angioplasty via Type II Proatlantal Intersegmental Artery.

A proatlantal intersegmental artery (PIA) is an exceedingly rare primitive anastomosis between the carotid and vertebrobasilar circulations. PIAs may be accompanied by ipsilateral or bilateral vertebral artery (VA) agenesis and can originate from the cervical internal carotid artery (ICA, type I) or external carotid artery (ECA, type II) before eventually joining the vertebrobasilar system. Several authors have described this anomaly in different clinical scenarios, but to our knowledge, there are no studies documenting VA angioplasty through a type II PIA in the setting of vertebrobasilar stroke. We present the case of vertebrobasilar stroke in which the right VA did not originate from the right subclavian artery but instead from the ECA. The patient was subsequently determined to have a type II PIA. We performed right VA angioplasty via the PIA, followed by partial restoration of vertebrobasilar blood flow. This is the first documented case of intracranial vertebral angioplasty through a type II PIA and serves as a reminder for neuroendovascular surgeons about persistent fetal circulation. In such instances, an angiogram of both the ICA and ECA should be performed to exclude right VA stenosis and visualize persistent fetal circulation. This case underscores the complexity of arterial thrombotic events, the beneficial role of endovascular intervention, and the necessity of future studies to identify the optimal treatment methods for vertebrobasilar stroke.

A Case of Basilar Artery Thrombus Improved With Anticoagulation.

Basilar artery (BA) occlusions are rare causes of ischemic strokes but can lead to devastating consequences if not addressed immediately. Herein, we discuss a case of an ischemic stroke due to near occlusion of the basilar artery with a good outcome due to timely presentation and intervention.

Parálisis bilateral de las cuerdas vocales con obstrucción aguda de la vía aérea y traqueotomía urgente en una paciente con ictus vertebrobasilar agudo / Bilateral vocal cord paralysis with acute airway obstruction and urgent tracheotomy in a patient with an acute vertebrobasilar stroke

Introducción El ictus vertebrobasilar puede suponer un reto diagnóstico. La parálisis bilateral de las cuerdas vocales como manifestación de ictus agudo es muy rara, pero potencialmente mortal, por la posibilidad de obstrucción aguda de la vía aérea. No hay casos descritos de parálisis bilateral de las cuerdas vocales como presentación de ictus agudo de etiología neurológica mixta central y periférica. Caso clínico Mujer de 88 años con disfonía secuelar a parálisis de la cuerda vocal derecha postiroidectomía que presentó un cuadro brusco de vértigo, dismetría y disartria leve (National Institutes of Health Stroke Scale: 2) asociado a hipertensión arterial. La tomografía computarizada cerebral urgente demostró trombosis distal oclusiva de la arteria vertebral izquierda sin isquemia establecida. Por mejoría sintomática con control tensional, no se realizó terapia de revascularización. Cuatro horas después, la paciente desarrolló de forma brusca estridor inspiratorio e insuficiencia respiratoria grave por parálisis bilateral de las cuerdas vocales con obstrucción completa de la vía aérea. Se realizó una traqueotomía urgente con mejoría respiratoria. Una tomografía computarizada cerebral de control a las 24 horas mostró un infarto establecido en el hemicerebelo izquierdo y la región bulbar lateral, congruente con territorio de la arteria cerebelosa posterior inferior izquierda. Conclusión Nuestro caso ilustra la posibilidad de la rara aparición de una parálisis bilateral aguda de las cuerdas vocales en el contexto de un ictus agudo junto con una afectación periférica crónica del nervio recurrente laríngeo. Aunque es excepcional, ejemplifica el potencial riesgo asociado a los ictus vertebrobasilares. Un tratamiento más agresivo de reperfusión podría ser adecuado en estos casos, pese a un déficit inicialmente leve, por la posibilidad de progresar a complicaciones vitales. (AU)

INTRODUCTION Vertebrobasilar stroke can be a diagnostic challenge. Bilateral vocal cord paralysis is very rare as a manifestation of acute stroke, yet it is potentially life-threatening because of the possibility of acute airway obstruction. No cases of bilateral vocal cord paralysis have been reported as a presenting symptom of acute stroke of mixed central and peripheral neurological aetiology. CASE REPORT An 88-year-old woman with dysphonia resulting from paralysis of the right vocal cord following a thyroidectomy presented with sudden onset of vertigo, dysmetria and mild dysarthria (National Institutes of Health Stroke Scale: 2) associated with arterial hypertension. An urgent brain computed tomography (CT) scan evidenced distal occlusive thrombosis of the left vertebral artery without established ischaemia. Due to the improvement of symptoms achieved with control of her blood pressure, revascularisation therapy was not performed. Four hours later, the patient suddenly developed inspiratory stridor and severe respiratory failure due to bilateral vocal cord paralysis with complete airway obstruction. An urgent tracheotomy was performed, which resulted in an improvement in her breathing. A control brain CT scan performed at 24 hours showed established infarction in the left hemicerebellum and lateral medullary region, consistent with the territory of the left posterior inferior cerebellar artery. CONCLUSION. Our case illustrates the possibility of the rare occurrence of acute bilateral vocal cord paralysis in the context of acute stroke in conjunction with chronic peripheral involvement of the recurrent laryngeal nerve. Although exceptional, it exemplifies the potential risk associated with vertebrobasilar strokes. A more aggressive reperfusion therapy may be appropriate in these cases, despite an initially mild deficit, because of the possibility of progression to life-threatening complications. (AU)

High-Flow Saphenous Vein Graft Bypass from Common Carotid Artery to Vertebral Artery (V2) for the Treatment of Vertebrobasilar Insufficiency Due to Bilateral Vertebral Artery Origin Stenosis.

Vertebrobasilar insufficiency can lead to devastating brainstem and posterior cerebral infarction without timely treatment.1 A 56-year-old man with a history of hypertension, hyperlipidemia, and diabetes mellitus presented to the clinic with right hemiparesis due to previous left cerebral hemispheric stroke. He also harbored a giant asymptomatic parieto-occipital meningioma incidentally diagnosed 2 years ago. Neuroimaging showed old left cerebral infarcts and a tumor that had remained stable in size. Cerebral angiography identified bilateral vertebral artery stenosis near their origin from the subclavian arteries with severe vertebrobasilar insufficiency. There was some collateral flow to the posterior cortex via the internal maxillary and occipital artery branch anastomoses. Despite recommendation, the patient decided to not undergo tumor resection, but opted for a high-flow bypass to the posterior circulation to prevent stroke. We used a saphenous vein graft to perform a high-flow extracranial-to-extracranial bypass revascularization of the ischemic vertebrobasilar circulation (Video 1). The patient tolerated the procedure well and was discharged without new deficits 4-days postoperatively. Most recent follow-up examination at 3 years after surgery revealed a patent bypass graft with no new adverse cerebrovascular events. The tumor remains asymptomatic without change in imaging characteristics. Cerebral bypasses remain useful tools in carefully selected patients for the treatment of complex aneurysms, complex tumors, and ischemic cerebrovascular diseases.2-7 We demonstrate an extracranial-to-extracranial high-flow bypass to revascularize the posterior cerebral circulation using a saphenous vein graft in a patient with vertebrobasilar insufficiency.

Diagnosis of dizziness in the emergency department: A 1-year prospective single-center study.

BACKGROUND: The management of dizziness and vertigo can be challenging in the emergency department (ED). It is important to rapidly diagnose vertebrobasilar stroke (VBS), as therapeutic options such as thrombolysis and anticoagulation require prompt decisions. OBJECTIVE: This study aims to assess the rate of misdiagnosis in patients with dizziness caused by VBS in the ED. METHODS AND RESULTS: The cohort was comprised of 66 patients with a mean age 56 years; 48% were women and 52% men. Among dizzy patients, 14% had VBS. We used Cohen's kappa test to quantify the agreement between two raters -namely, emergency physicians and neurologists -regarding the causes of dizziness in the ED. The Kappa value was 0.27 regarding the final diagnosis of central vertigo disorders and VBS, thus showing the low agreement. We used the χi2 test to show the association between the presence of two or more cardiovascular risk factors and admission to the stroke unit (p = 0.015). CONCLUSION: There is a substantial rate of misdiagnosis in patients with dizziness caused by VBS in the ED. To reduce the number of missing diagnoses of VBS in the future, there is a need to train emergency physicians in neurovestibular examinations, including the HINTS examination for acute vestibular syndrome (AVS) and the Dix-Hallpike (DH) maneuver for episodic vestibular syndrome. Using video head impulse test could help reduce the rate of misdiagnosis of VBS in the ED.

Listeria rhombencephalitis mimicking stroke in a patient with giant cell arteritis.

Listeria monocytogenes sometimes causes central nervous system infections. However, rhombencephalitis is a rare form of L. monocytogenes infection. Its clinical symptoms and magnetic resonance imaging (MRI) findings are often similar to those of vertebrobasilar stroke. We present the case of a 79-year-old woman with Listeria rhombencephalitis presenting with rhinorrhea and productive cough. She had giant cell arteritis (GCA) treated with prednisolone and methotrexate. She was admitted for loss of appetite, rhinorrhea, and productive cough. These symptoms were alleviated without specific treatment; however, she suddenly developed multiple cranial nerve palsies, and MRI showed hyperintense signals on diffusion-weighted imaging and hypointense signals on apparent diffusion coefficient in the brainstem. Ischemic stroke due to exacerbation of GCA was suspected, and treatment with intravenous methylprednisolone was initiated; however, seizures occurred, and a lumbar puncture was performed. Cerebrospinal fluid and blood cultures revealed L. monocytogenes, and she was diagnosed with Listeria rhombencephalitis. Although antibiotic treatment was continued, the patient died. Thus, when patients with rhinorrhea or productive cough develop sudden cranial nerve palsy, Listeria rhombencephalitis should be considered as a differential diagnosis, and lumbar puncture should be performed.

Clinical Features Differ Between Patients With Vertigo Attack Only and Weakness Attack Accompanying Vertigo Before Vertebrobasilar Stroke: A Retrospective Study.

Objective: To determine the different clinical features of patients with vertigo attacks alone and of those with weakness accompanying vertigo attacks before the vertebrobasilar ischemic stroke. Methods: In this 4-year retrospective study, we manually screened the medical records of 209 patients, hospitalized with vertigo attack as the main complaint who were finally diagnosed with acute vertebrobasilar ischemic stroke. Patients were divided into two groups according to their symptoms: patients who only experienced vertigo attacks prior to the vertebrobasilar stroke (VO group) and patients who had both vertigo and weakness attacks (VW group) prior to the stroke. Clinical parameters, such as infarction site and volume, relative risk factors, ABCD2 score, and medical intervention, were compared between the two groups. Results: The prevalence of hypertension was higher in the Vertigo attacks only (VO) group (42.2 vs. 29.0%, p < 0.05). The total cerebral infarction volume in the VO group was larger than the Vertigo and weakness attacks (VW) group (4.44 vs. 2.12 cm3, p < 0.05). Additionally, the cerebellum was more likely to be affected in the VO group. In contrast, patients in the VW group had higher carotid stenosis (14.2 vs. 27.2%, p < 0.05) and ABCD2 score (2.1 ± 1.2 vs. 3.6 ± 1.5, p = 0.02). The percentage of patients with medullary infarctions also increased in the VW group. Vertigo attack events occurred more frequently in the VW group (median 2.4 vs. 4.3, p < 0.04). We also found that the patients in the VW group were more likely to seek medical intervention after vertigo. Conclusions: Clinical parameters, such as infarction location, relative risk factors, and ABCD2 score, differed between patients with vertigo symptoms with or without weakness attacks. These findings highlight the different clinical features of patients with vertigo attack only and those with weakness attacks accompanying vertigo prior to vertebrobasilar ischemic stroke.

Endovascular Treatment of Basilar Artery Occlusion: What Can We Learn from the Results?

Background and Objectives: Current guidelines lack specific endovascular treatment (EVT) recommendations for posterior circulation stroke (PCS). The results of earlier studies are controversial. We aimed to compare early hospital outcomes of stroke caused by large-vessel occlusion (LVO) treated with EVT or bridging therapy (BT) in anterior circulation stroke (ACS) versus PCS (middle cerebral artery occlusion (MCAO) and basilar artery occlusion (BAO), and establish the risk factors for poor outcome. Materials and Methods: we analyzed the data of 279 subjects treated with EVT due to LVO-caused stroke in a comprehensive stroke centre in 2015−2021. The primary outcome was hospital mortality, secondary outcomes were National Institutes of Health Stroke Scale (NIHSS) after 24 h, early neurological deterioration, futile recanalization (FR), the ambulatory outcome at discharge, and complications. Results: BAO presented with higher baseline NIHSS scores (19 vs. 14, p < 0.001), and longer door-to-puncture time (93 vs. 82 min, p = 0.034), compared to MCAO. Hospital mortality and the percentage of FR were the same in BAO and almost two times higher than in MCAO (20.0% vs. 10.3%, p = 0.048), other outcomes did not differ. In BAO, unsuccessful recanalization was the only significant predictor of the lethal outcome, though there were trends for PAD and RF predicting lethal outcome. A trend for higher risk of symptomatic intracranial hemorrhage (sICH) was observed in the BAO group when BT was applied. Nevertheless, neither BT nor sICH predicted lethal outcomes in the BAO group. Conclusions: Compared to the modern gold standard of EVT in the ACS, early outcomes in BAO remain poor, there is a substantial amount of FR. Nevertheless, unsuccessful recanalization remains the strongest predictor of lethal outcomes. BT in PCS might pose a higher risk for sICH, but not the lethal outcome, although this finding requires further investigation in larger trials.

Impact of revascularization therapies on outcome of posterior circulation ischemic stroke: The Indo-US stroke project.

INTRODUCTION: Posterior circulation strokes (PCS) have been less extensively studied than anterior circulation strokes (ACS), especially regarding revascularization therapies. We analyzed the differences in baseline stroke characteristics, revascularization therapy and 3-month outcomes between PCS and ACS in a large prospective multicentre Indian stroke registry. METHODS: Patients with acute ischemic stroke recruited in the Indo-US collaborative stroke project from January 2012 to August 2014 were classified into PCS and ACS based on imaging-confirmed infarct location. Demographics, stroke severity, risk factors, and mechanisms were compared. We further compared these parameters in the subgroups who received revascularization therapies (RT) and no revascularization therapies (NRT). The primary outcome was 3-month modified Rankin scale (mRS). RESULTS: Of 1889 patients (1270 males), 1478 (78.2%) had ACS and 411 (21.8%) PCS. The median NIHSS was lower in PCS (7 vs 11, p < 0.001). Diabetes mellitus and hypertension were more common in PCS and rheumatic heart disease in ACS. Small artery occlusion was higher in PCS (23.8% vs 12.9%, p < 0.001). Only 28 (6.8%) PCS received RT compared to 213 (14.4%) ACS. At 90 days, a good functional outcome (mRS 0-2) was more common in PCS (56.4% vs 45.9%, p < 0.001) in NRT group, while no significant difference was noted in RT group. Stroke territory was not an independent predictor of 3-month outcome in regression analysis. In-hospital mortality was not different between the groups. CONCLUSIONS: The 3-month functional outcome and in-hospital mortality were not different between ACS and PCS. Compared to ACS, PCS received revascularization therapies less often.

General anesthesia versus monitored anesthesia care during endovascular therapy for vertebrobasilar stroke.

OBJECTIVE: The objective is to compare the effect of general anesthesia (GA) and monitored anesthesia care (MAC) on clinical outcomes in patients with endovascular therapy for vertebrobasilar occlusion stroke. METHODS: 139 patients undergoing endovascular therapy for vertebrobasilar stroke, were recruited. The patients were randomized into GA group and MAC group (about 1:1 ratio). GA group received general anesthesia and MAC group received monitored anesthesia care during endovascular therapy. The primary outcome measure was the shift in the degree of disability among the 2 groups as measured by the modified Rankin scale score (mRS) at 90 days (80-100 days). Secondary end points included infarct volume and related complications. RESULTS: The patients were assigned randomly (about 1:1 allocation) to GA group (n=72) and MAC group (n=67). The primary outcome of functional independence measured by 90-day mRS score was not significantly different between the 2 groups (median (IQR), 2 (1-3) vs. 3 (1-4); P=0.316). Final infarct volume was smaller in the GA group than in the MAC group (median (IQR), 27.60 (13.75-83.52) vs. 33.60 (26.85-92.95); P=0.045). There were no differences with statistical significance in rates of successful reperfusion (modified Thrombolysis in Cerebral Ischemia (mTICI) 2b-3) between 2 groups (73.61% vs. 76.12%; P=0.734). Early neurological outcomes measured by the 24-hour National Institutes of Health Stroke Scale scores (NIHSS) showed that 11 (interquartile range (IQR), 3-22) in GA group and 11 (interquartile range (IQR), 7-25) in MAC group, but were not statistically significant. There was no statistical difference in postoperative complications between the two groups. CONCLUSION: For patients who underwent endovascular therapy for vertebrobasilar occlusion strok caused by occlusions in the posterior circulation, MAC appears to be as effective as GA. However, MAC is associated with bigger final infarct volume. Future studies are warranted to confirm our findings.

Acute Dizziness, Vertigo, and Unsteadiness.

Vestibular symptoms, including dizziness, vertigo, and unsteadiness, are common presentations in the emergency department. Most cases have benign causes, such as vestibular apparatus dysfunction or orthostatic hypotension. However, dizziness can signal a more sinister condition, such as an acute cerebrovascular event or high-risk cardiac arrhythmia. A contemporary approach to clinical evaluation that emphasizes symptom duration and triggers along with a focused oculomotor and neurologic examination can differentiate peripheral causes from more serious central causes of vertigo. Patients with high-risk features should get brain MRI as the diagnostic investigation of choice.

Clinical presentation of vertebrobasilar stroke.

Vertebrobasilar (VB) stroke is responsible for 20% of all strokes and transient ischemic attacks. Due to the vast cerebral territory it supplies, VB ischemia can present with a wide range of symptoms and signs, sometimes even overlapping with carotid circulation stroke. Furthermore, brain computed tomography, usually performed as initial imaging modality, has a suboptimal visualization of the posterior fossa, making VB stroke an even more challenging diagnosis to any physician. Hence, awareness of the vertebrobasilar anatomy and the clinical presentation of VB ischemia is crucial to promote early recognition of this disorder.

Red flags for a concomitant giant cell arteritis in patients with vertebrobasilar stroke: a cross-sectional study and systematic review.

Giant cell arteritis (GCA) may affect the brain-supplying arteries, resulting in ischemic stroke, whereby the vertebrobasilar territory is most often involved. Since etiology is unknown in 25% of stroke patients and GCA is hardly considered as a cause, we examined in a pilot study, whether screening for GCA after vertebrobasilar stroke might unmask an otherwise missed disease. Consecutive patients with vertebrobasilar stroke were prospectively screened for GCA using erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), hemoglobin, and halo sign of the temporal and vertebral artery on ultrasound. Furthermore, we conducted a systematic literature review for relevant studies. Sixty-five patients were included, and two patients (3.1%) were diagnosed with GCA. Patients with GCA were older in age (median 85 versus 69 years, p = 0.02). ESR and CRP were significantly increased and hemoglobin was significantly lower in GCA patients compared to non-GCA patients (median, 75 versus 11 mm in 1 h, p = 0.001; 3.84 versus 0.25 mg/dl, p = 0.01, 10.4 versus 14.6 mg/dl, p = 0.003, respectively). Multiple stenoses/occlusions in the vertebrobasilar territory affected our two GCA patients (100%), but only five (7.9%) non-GCA patients (p = 0.01). Our literature review identified 13 articles with 136 stroke patients with concomitant GCA. Those were old in age. Headache, increased inflammatory markers, and anemia were frequently reported. Multiple stenoses/occlusions in the vertebrobasilar territory affected around 70% of stroke patients with GCA. Increased inflammatory markers, older age, anemia, and multiple stenoses/occlusions in the vertebrobasilar territory may be regarded as red flags for GCA among patients with vertebrobasilar stroke.

Thyroid cartilage compression causing stroke.

We describe the diagnostic workup and surgical treatment of a patient presenting with the unique case of vertebral artery (VA) occlusion subsequent to head flexion leading to compression of an aberrant VA by the ipsilateral superior cornu of the thyroid cartilage. Imaging revealed ischemic infarcts as well as the presence of an aberrant right VA, which was compressed by the ipsilateral superior cornu of the thyroid cartilage upon neck flexion. The patient was managed with laryngoplasty involving removal of the right superior cornu of the thyroid cartilage. Laryngoscope, 129:E445-E448, 2019.

Sudden Hearing Loss with Vertigo Portends Greater Stroke Risk Than Sudden Hearing Loss or Vertigo Alone.

BACKGROUND: Because it is unknown whether sudden hearing loss (SHL) in acute vertigo is a "benign" sign (reflecting ear disease) or a "dangerous" sign (reflecting stroke), we sought to compare long-term stroke risk among patients with (1) "SHL with vertigo," (2) "SHL alone," and (3) "vertigo alone" using a large national health-care database. METHODS: Patients with first-incident SHL (International Classification of Diseases, Ninth Edition, Clinical Modification [ICD-9-CM] 388.2) or vertigo (ICD-9-CM 386.x, 780.4) were identified from the National Health Insurance Research Database of Taiwan (2002-2009). We defined SHL with vertigo as a vertigo-related diagnosis ±30 days from the index SHL event. SHL without a temporally proximate vertigo diagnosis was considered SHL alone. The vertigo-alone group had no SHL diagnosis. All the patients were followed up until stroke, death, withdrawal from the database, or current end of the database (December 31, 2012) for a minimum period of 3 years. The hazards of stroke were compared across groups. RESULTS: We studied 218,656 patients (678 SHL with vertigo, 1998 with SHL alone, and 215,980 with vertigo alone). Stroke rates at study end were 5.5% (SHL with vertigo), 3.0% (SHL alone), and 3.9% (vertigo alone). Stroke hazards were higher in SHL with vertigo than in SHL alone (hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.28-2.91) and in vertigo alone (HR, 1.63; 95% CI, 1.18-2.25). Defining a narrower window between SHL and vertigo (±3 days) increased the hazards. CONCLUSIONS: The combination of SHL plus vertigo in close temporal proximity is associated with increased subsequent stroke risk over SHL alone and vertigo alone. This suggests that SHL in patients with vertigo is not necessarily a benign peripheral vestibular sign.

Duplex ultrasonography for the detection of vertebral artery stenosis: A comparison with CT angiography.

OBJECTIVES: Vertebrobasilar stenosis is frequent in patients with posterior circulation stroke and it increases risk of recurrence. We investigated feasibility of duplex ultrasonography (DUS) for screening for extracranial vertebral artery stenosis and compared it with CT angiography (CTA). MATERIALS AND METHODS: We gathered data on 337 consecutive patients who had DUS because of posterior circulation stroke or TIA. Matching CTA studies were retrieved and used as reference. Stenosis on CTA was considered "significant" if >50%, at DUS if Peak Systolic Velocity (PSV) > 140 cm/s for the V1 segment and PSV > 125 cm/s for the V2 segment. We determined the area under the ROC curve (AUROC). In addition, we calculated which PSV cut-off value resulted in highest sensitivity with acceptable specificity. RESULTS: DUS was able to make an adequate measurement in 378 of 674 V1 segments and 673 of 674 V2 segments. DUS detected a significant stenosis in 52 of 378 V1 segments; 12 were confirmed by CTA (AUROC 0.73, 95% Confidence Interval 0.63-0.83). The optimal DUS PSV cut-off value for this segment was 90 cm/s. For the V2 segment there were too few stenoses to allow reliable assessment of diagnostic characteristics of DUS. CONCLUSIONS: Although DUS has a fair AUROC for detecting significant stenosis, adequate assessment of the V1 segment is often not possible due to anatomic difficulties. Assessment of the V2 segment is feasible but yielded few stenoses. Hence, we consider usefulness of DUS for screening of extracranial vertebral artery stenosis limited.

Acute vestibular syndrome: a critical review and diagnostic algorithm concerning the clinical differentiation of peripheral versus central aetiologies in the emergency department.

Almost 20 % of cerebral ischaemic strokes occur in the posterior circulation. Estimates are that 20 % of these patients present with isolated vertigo. In approximately one-sixth to one-third of these patients, this symptom is wrongly diagnosed to be peripheral vestibular in origin. As a result, these missed stroke patients are withheld from therapeutic and secondary prophylactic treatment, which may result in unnecessary morbidity and mortality. We therefore propose a diagnostic algorithm concerning the clinical differentiation of acute vestibular syndrome (AVS) patients based on a critical review of the available literature.

Chiropractic care and the risk of vertebrobasilar stroke: results of a case-control study in U.S. commercial and Medicare Advantage populations.

BACKGROUND: There is controversy surrounding the risk of manipulation, which is often used by chiropractors, with respect to its association with vertebrobasilar artery system (VBA) stroke. The objective of this study was to compare the associations between chiropractic care and VBA stroke with recent primary care physician (PCP) care and VBA stroke. METHODS: The study design was a case-control study of commercially insured and Medicare Advantage (MA) health plan members in the U.S. population between January 1, 2011 and December 31, 2013. Administrative data were used to identify exposures to chiropractic and PCP care. Separate analyses using conditional logistic regression were conducted for the commercially insured and the MA populations. The analysis of the commercial population was further stratified by age (<45 years; ≥45 years). Odds ratios were calculated to measure associations for different hazard periods. A secondary descriptive analysis was conducted to determine the relevance of using chiropractic visits as a proxy for exposure to manipulative treatment. RESULTS: There were a total of 1,829 VBA stroke cases (1,159 - commercial; 670 - MA). The findings showed no significant association between chiropractic visits and VBA stroke for either population or for samples stratified by age. In both commercial and MA populations, there was a significant association between PCP visits and VBA stroke incidence regardless of length of hazard period. The results were similar for age-stratified samples. The findings of the secondary analysis showed that chiropractic visits did not report the inclusion of manipulation in almost one third of stroke cases in the commercial population and in only 1 of 2 cases of the MA cohort. CONCLUSIONS: We found no significant association between exposure to chiropractic care and the risk of VBA stroke. We conclude that manipulation is an unlikely cause of VBA stroke. The positive association between PCP visits and VBA stroke is most likely due to patient decisions to seek care for the symptoms (headache and neck pain) of arterial dissection. We further conclude that using chiropractic visits as a measure of exposure to manipulation may result in unreliable estimates of the strength of association with the occurrence of VBA stroke.