Bow hunter's syndrome due to an anomalous right vertebral artery origin and contralateral absence: a case report and literature review.

BACKGROUND: Bow Hunter's syndrome (BHS), also known as rotational vertebral artery occlusion (RVAO), is a rare condition characterized by dynamic vertebrobasilar insufficiency due to position-dependent occlusion of the vertebral artery (VA). In the existing literature, most cases of BHS are attributed to osteophytic compression originating from the occipital condyle or within the transverse foramen, often accompanied by anatomical abnormalities of the VA. However, cases presenting solely with VA anomalies in the absence of any cervical vertebral structural abnormality are rare. This case report presents a unique instance of BHS in a 56-year-old male, attributed to the anomalous origin of the right VA and the absence of the left VA, without cervical structural abnormalities. CASE PRESENTATION: The patient exhibited symptoms like episodic dizziness and vertigo, which were exacerbated by rightward head rotation and alleviated upon returning to a neutral position. Diagnostic evaluation, including digital subtraction angiography, revealed that the right VA originated from the right common carotid artery and compression-induced stenosis of the right VA during head rotation. Conservative management, including avoidance of certain head movements and anti-arteriosclerosis medication, led to symptom resolution over a two-year follow-up period. CONCLUSIONS: This report contributes to the understanding of BHS by highlighting a rare vascular anomaly presentation and incorporates a review of 14 similar case reports in the literature describing that an anatomical abnormality of the VA is mainly responsible for the pathology of BHS in the absence of cervical vertebral anomalies, thus emphasizing the need for careful diagnostic and management strategies.

Bilateral Hunter's bow syndrome: a rare case diagnosed by dynamic digital subtraction angiography.

A 27-year-old female patient suffered from recurrent episodes of dizziness, visual rotation, and intermittent right-hand numbness over one month. Symptoms persisted and were triggered by rotating the head to the right or left for more than 10 seconds. Neurological examination showed that the symptoms were most pronounced when the head was rotated over 45 degrees to the right. Dynamic digital subtraction angiography (dDSA) was performed to confirm the diagnosis. Leftward head rotation caused occlusion of the right vertebral artery(VA) . However, the symptoms were mild, owing to sufficient compensation by the right posterior communicating artery (PCA) . Rightward head rotation exceeding 45 degrees resulted in occlusion of the left VA. The resultant symptoms were pronounced due to inadequate compensation of the left PCA. CT angiographic reconstruction showed bilateral vertebral arteries with tortuous loops of vessels at the level of the C2 vertebrae . CT images showed no cleavage between the left VA and the anterior surface of the left C2 transverse foramen. Conservative treatment was recommended considering the patient's young age and limited severity of her symptoms. Bow Hunter's syndrome is a rare neurovascular disorder characterized by dynamic occlusion of the VAs during head rotation, leading to inadequate blood flow to the posterior cerebral circulation. Bow hunter syndrome, where bilateral dynamic occlusion occurs without a discernible dominant side of the VA, is uncommon. The medical community must acknowledge cervical vertigo as a distinct disorder. dDSA remains the gold standard for its diagnosis.

Bilateral bow-hunter's stroke caused by sleeping in prone position: A case of recurrent posterior circulation infarction.

Objectives Bow hunter's stroke (BHS) is a condition characterized by temporary vertebrobasilar insufficiency caused by mechanical compression or occlusion of the vertebral artery when the head is rotated, leading to transient neurological symptoms such as dizziness, vertigo, nystagmus, dysarthria, and potentially stroke. Therefore, a situation in which the head remains rotated for an extended period is a significant risk factor for BHS. Materials and Methods We present a case of a 25-year-old woman who experienced three recurrent cerebral infarctions in the posterior circulation area after sleeping in a prone position with her head rotated. Results The first infarction occurred in the right thalamus, followed by bilateral cerebellar infarctions, and finally, an infarction in the left cerebellar hemisphere. Carotid Doppler ultrasonography revealed blood flow interruption in the left vertebral artery due to head rotation, and digital subtraction angiography showed that rotation of the head to one side resulted in blood flow disruption of the contralateral vertebral artery in both right and left rotation. A C1-2 posterior fixation surgery was performed to stabilize the atlas and axis using screws and rods, with no recurrence observed thereafter. Conclusions When encountering a young patient with recurrent posterior circulation infarctions upon awakening, it is crucial to inquire about the patient's sleeping position, such as prone positioning, to assess for potential vertebral artery stenosis or occlusion due to head rotation.

Transient ischemic attack and minor stroke as "surgeons affairs": a narrative review.

OBJECTIVE: The scope of this paper is to review the subtypes of transient ischemic attack (TIA) and minor stroke (mS) in which a surgical treatment is needed, discussing the importance and the timing of a multidisciplinary approach, in order to achieve an optimized management and prevent major strokes or other critical complications. MATERIALS AND METHODS: The keywords "transient ischemic attack," "minor stroke," "surgical treatment," "vascular surgery," "heart surgery," "neurosurgery," and "multidisciplinary" were searched using MEDLINE, EMBASE, and Scopus. Relevant search results were discussed by the authors for references inclusion. RESULTS: Notwithstanding that best medical therapy is usually the first choice for the most part of cases, there are specific but recurrent etiologies that must be properly recognized because of a potential surgical approach, even in urgency. In fact, symptomatic carotid stenosis, or particular cases of hemodynamic cerebrovascular events, should be promptly referred to vascular surgeon, since increasing evidences highlighted a benefit from an early artery revascularization. In addition, beyond arrhythmic causes, cardioembolic events due to bacterial endocarditis and atrial myxoma should be quickly diagnosed, possibly in emergency department, because they are a presumptive urgency for heart surgery. In addition to the above-mentioned conditions, in patients suffering from vertebrobasilar TIA or mS, clinicians should keep in mind the Bow Hunter disease, because surgical artery decompression can represent the only suitable treatment in selected cases. CONCLUSIONS: TIA and mS require a multidisciplinary in order to discuss therapeutic options, comparing risks and benefits and determining the best timing for an optimized management.

Vertebro-basilar stroke due to Bow-Hunter syndrome: an unusual presentation of rotatory atlanto-axial subluxation in a fourteen year old.

Bow Hunter's syndrome is a rare disorder usually producing transient ischemic symptoms as a result of dynamic compression of the vertebral artery during head turning. We report a case of a 14 year old male presenting with stroke due to occlusion of vertebral artery due to rotatory atlanto-axial subluxation. The patient presented with sudden onset vertigo and ataxia. History revealed led mild torticollis since childhood which was never investigated. MRI and MRA showed infarcts in the bilateral cerebellar hemispheres and the occipital lobes with a hypoplastic left vertebral artery and kinking of the right vertebral artery at the cranio-vertebral junction due to rotatory atlanto-axial subluxation. The patient was successfully treated by C1 lateral mass and C2 sub-facetal screw with rod fixation. Bow-Hunter's syndrome producing transient ischemia is well reported but stroke in the vertebro-basilar territory in a 14 year old due to rotatory atlanto-axial subluxation is uncommon, and to the best of our knowledge, this is the eighth such reported case.

Bow Hunter's syndrome combined with ipsilateral vertebral artery dissection/pseudoaneurysm: case study and literature review.

BACKGROUND: Bow hunter's syndrome (BHS), also known as rotational vertebral artery occlusion syndrome, is rare. Occasionally, it combines with dissection/pseudoaneurysm of the ipsilateral VA. METHODS: We report a case of BHS combined with ipsilateral VA dissection/pseudoaneurysm and review eight similar cases reported in the literature. Their aetiology, clinical and imaging features, treatment, and prognosis were analysed. RESULTS: Nine patients (seven male, two female; average age 22.0 ± 4.5 years) were enrolled. Visual symptoms comprised the most common clinical finding (66.7%, 7/9). Clinical symptoms were not related to neck rotation in seven patients (77.8%). Eight patients (88.9%) had multiple, scattered, new and old infarctions of the posterior circulation revealed on computed tomography/magnetic resonance imaging (CT/MRI) scans. Dissection/pseudoaneurysm was found in the ipsilateral VA - usually subtle and localised in the atlas, axis, and occipital bone - in all nine patients. Seven patients (66.7%) had special causes for the syndrome (i.e. congenital bone dysplasia). Altogether, 87.5% (7/8) experienced recurrence with cerebral infarction after antithrombotic therapy alone. Aetiologically targeted treatment, including surgical decompression or vertebral fixation, was performed in seven patients (77.8%). CONCLUSION: Young patients presenting with cryptogenic stroke in the posterior circulation and localised, subtle dissection/pseudoaneurysm of the ipsilateral VA around the atlanto-axial joint should undergo carotid ultrasonography with a neck rotation test or dynamic CT angiography/MR angiography/digital subtraction angiography, if necessary, to rule out/diagnose BHS.

Embolic stroke induced by rotational persistent 1st intersegmental artery compression.

A 45-year-old man suffered multiple cerebral infarctions in the vertebrobasilar artery territory, followed by second stroke against conservative treatment. Radiological examinations revealed intra-arterial defect in left persistent 1st intersegmental artery (PFIA) at C1 level, suggesting mural thrombus, and mechanical compression of left PFIA at the level with head rotation to the right clearly revealed by reconstructed 3-dimensional radiological images, but no findings of atlantoaxial instability. One month after the second stroke, posterior fixation was performed. Postoperative course was uneventful without subsequent stroke for 24 months. This unique case demonstrated that PFIA might associate with cerebral stroke as a clinical condition of bow hunter's stroke even in middle age. Reconstructed 3-dimensional radiological images might be useful for clear demonstration of the pathophysiology in this complex clinical entity.

Clinical response to surgical decompression in atypical pediatric Bow Hunter's syndrome suggesting alternative pathophysiology: Case report.

Bow Hunter's syndrome is a rare cause of posterior circulation ischemia, produced by the mechanical and reversible occlusion of the vertebral artery during cephalic rotation. Diagnosis requires clinical suspicion and careful inspection of images with three-dimensional reconstruction. The study of choice is dynamic digital subtraction angiography (DSA). Treatment alternatives are: medical, surgical or endovascular. We report the case of an 8-year-old boy with recurrent infarctions of the posterior circulation secondary to the dissection of the vertebral artery, in association with an occipital bone spur. Dynamic DSA was negative. Conservative initial management was elected with cervical immobilization and anticoagulation, but due to persistence of symptoms, surgical decompression was decided. The patient did not repeat symptoms postoperatively and returned to his usual life. This is the first case reported to our knowledge of a surgical pediatric patient with asymptomatic atypical compression of VA secondary to BHS, whose dynamic angiography was negative, suggesting an alternative mechanism of the syndrome.

A Case of Posterior Circulation Embolism Due to a Subtype of Bow Hunter's Syndrome Diagnosed by Non-Invasive Examination.

Bow hunter's syndrome is the mechanical compression of the vertebral artery due to cervical rotation, resulting in ischemic symptoms in the vertebrobasilar artery territory. However, some cases present without typical symptoms and exhibit compression of the non-dominant side of the vertebral artery. We encountered a case of posterior circulation embolism due to a subtype of bow hunter's syndrome in a 74-year-old man. Although the right vertebral artery was not visualized on time-of-flight magnetic resonance angiography in the neutral position, duplex ultrasonography and time-of-flight magnetic resonance angiography in the left cervical rotation position showed blood flow in the right vertebral artery. In this case, blood flow in the contralateral vertebral artery was normal, and typical bow hunter's syndrome symptoms did not occur. In a case of posterior circulation embolism with undetermined etiology, wherein the routine duplex ultrasonography and time-of-flight magnetic resonance angiography results were inconclusive, additional testing with head positioning led to the diagnosis of a subtype of bow hunter's syndrome.

New diagnostic algorithm for detection of covert Bow Hunter's Syndrome.

Bow hunter's syndrome (BHS) should not be overlooked as a cause of cerebral infarction in the posterior circulation. However, covert BHS, which does not impair blood flow with simple rotation but only at certain angles, may make the diagnosis of BHS difficult. We propose a new algorithm to detect BHS or covert BHS. We recommend that BHS and covert BHS be detected by noninvasive duplex ultrasonography, which will allow for appropriate treatment.

Dynamic compression in vertebral artery dissection in children: apropos of a new protocol.

PURPOSE: Our goals are (1) to report a consecutive prospective series of children who had posterior circulation stroke caused by vertebral artery dissection at the V3 segment; (2) to describe a configuration of the vertebral artery that may predispose to rotational compression; and (3) to recommend a new protocol for evaluation and treatment of vertebral artery dissection at V3. METHODS: All children diagnosed with vertebral artery dissection at the V3 segment from September 2014 to July 2020 at our institution were included in the study. Demographic, clinical, surgical, and radiological data were collected. RESULTS: Sixteen children were found to have dissection at a specific segment of the vertebral artery. Fourteen patients were male. Eleven were found to have compression on rotation during a provocative angiogram. All eleven underwent C1C2 posterior fusion as part of their treatment. Their mean age was 6.44 years (range 18 months-15 years). Mean blood loss was 57.7 mL. One minor complication occurred: a superficial wound infection treated with oral antibiotics only. There were no vascular or neurologic injuries. There have been no recurrent ischemic events after diagnosis and/or treatment. Mean follow-up was 33.3 months (range 2-59 months). We designed a new protocol to manage V3 dissections in children. CONCLUSION: Posterior C1C2 fusion is a safe and effective option for treatment of dynamic compression in vertebral artery dissection in children. Institution of and compliance with a strict diagnostic and treatment protocol for V3 segment dissections seem to prevent recurrent stroke.

Vertebrobasilar Infarction Due to Bow Hunter's Syndrome in a Patient with Rheumatoid Arthritis: A Case Report.

A 60-year-old woman with a 37-year history of rheumatoid arthritis (RA) had a sudden onset of headache. Head MRI showed acute multiple infarctions in the vertebrobasilar region, and MR angiography showed stenosis of the right vertebral artery (VA). 3D-CT angiography of the craniovertebral junction showed atlantoaxial subluxation and stenosis of the right VA just distal to the transverse foramen of C2, which was due to osteophytes and degenerative changes secondary to RA. Digital subtraction angiography clearly demonstrated occlusion of the right VA during rightward head rotation. Based on those findings, rotatory instability at C1-2 was considered as the primary cause of the vertebrobasilar infarctions, and Bow Hunter's syndrome was diagnosed. The patient underwent C1-5 posterior fixation, and brain infarction has not recurred.

Transitional nystagmus in a Bow Hunter's Syndrome case report.

BACKGROUND: Bow Hunter's Syndrome (BHS) is known as one of cervical diseases which causes vertigo, but the details of its vertigo, especially nystagmus and eye movement, are still incompletely understood. This time, we reported the first case of BHS with a nystagmus chart with video record of transitional nystagmus. CASE PRESENTATION: The patient, a 47-year-old female, complained of vertigo caused by head rotation. When she turned her head leftward, leftward nystagmus appeared, and this was followed by dullness of the right arm. After her head was returned to the central position, downbeat nystagmus appeared, which changed to rightward nystagmus. She was diagnosed with BHS by her symptoms and images. We recorded a nystagmus video and nystagmus chart of this transitional nystagmus including downbeat nystagmus. Her vertigo was cured by the modification of a prescription for her past medical history: hypertension. CONCLUSION: The vertigo of BHS accompanies nystagmus. In this present case, the transitional nystagmus was observed, and it occurred toward the healthy side. Then the nystagmus direction was changed to the affected side via downbeat nystagmus. This is the first report with both a nystagmus chart with video of BHS. Nowadays, various kinds of vertigo induced by neck movement are known. BHS is a rare disease among vertigo diseases, but we should consider it as a different diagnosis of vertigo patients. A precise interview and proper examination are required to make the final diagnosis.

Dynamic imaging of the craniovertebral junction is mandatory in patients with posterior circulation strokes.

INTRODUCTION: The course of the vertebral artery after exiting from the C1 foramen transversarium and prior to entering the dura lends itself to compression in C1-2 instability. However, atlantoaxial dislocation presenting with vertebrobasilar insufficiency and posterior circulation stroke (PCS) is rare. METHODS: In this retrospective study, we identified 96 patients with PCS who had complete radiological data. Ten (10.4%) patients had craniovertebral junction (CVJ) anomalies, of which six underwent surgery and four were managed conservatively. The clinical and functional outcomes were measured in the two groups. RESULTS: Left-sided strokes were seen in 7/10 patients, the majority of whom had left dominant vertebral arteries. The mean age at presentation in those with CVJ anomalies was 27.2 ± 12.8 years that was significantly lower than those without CVJ anomalies, 52.2 ± 14.5 years (p ≤ 0.001). The etiologies of PCS in those < 50 years were CVJ anomalies (30%), atherosclerosis (30%) and vasculitis (27%); however, the overwhelming majority of strokes in the > 50 year age group was atherosclerosis (91%). Postoperatively, there were no recurrent strokes in the operated patients, who also obtained significant clinical improvement on the modified Rankin Scale, Nurick Scale and modified McCormick Scale as compared to those who did not undergo surgery. CONCLUSION: Early diagnosis and surgical treatment of CVJ instability prevent recurrent strokes and improve outcomes in patients with PCS. Physicians and spine surgeons need to be sensitized regarding CVJ anomalies as a cause of PCS enabling early diagnosis with dynamic imaging particularly in the younger age group. These slides can be retrieved under Electronic Supplementary Material.

Atlanto-occipital ligament calcification: a novel imaging finding in pediatric rotational vertebral artery occlusion.

We describe a 2-year-old girl with bow hunter syndrome complicated by vertebral artery dissection and multiple ischemic infarcts. Pediatric bow hunter syndrome is a rare and likely under-recognized disorder. Interestingly, our patient had atlanto-occipital ligament calcification on CT scan, an imaging finding that has not been reported in association with bow hunter syndrome and one that might help increase recognition of this dynamic disorder of the posterior circulation.

Brain infarction due to vertebral artery dissection caused by a bone protrusion from the condylar fossa in a juvenile case.

A 16-year-old boy presented with multiple posterior circulation ischemic strokes resulting from vertebral artery (VA) dissection. Three-dimensional computed tomography showed aberrant sub-occipital bone protuberance, proximal to the VA dissection. Since the patient was a habitual neck cracker, VA dissection was thought to result from the impact shock of the rotational head movement. This could be due to either the osseous prominence or the compression between the prominence and the C1. Although it is a rare etiology of Bow Hunter's syndrome, VA dissection due to sub-occipital bone spur because of neck cracking should be considered in the diagnosis of Bow Hunter's syndrome in juvenile patients.

Compression Syndromes of the Vertebral Artery at the Craniocervical Junction.

Compression syndromes of the vertebral artery that occur at the craniocervical junction are extremely rare causes of haemodynamic insufficiency of the posterior cerebral circulation. The aetiology of the compression syndrome may be a malformation, trauma, tumour, infection or degenerative pathology. This may lead to dynamic vertebral artery occlusion where the vessel courses around the atlas and the axis-the so-called V3 segment. This in turn may result in insufficient collateral flow to the posterior fossa. The clinical picture is a vertebrobasilar insufficiency syndrome of variable expression ranging from vertigo to posterior fossa stroke. The typical clinical presentation is syncope occurring during rotation of the head, also known as 'bow hunter's syndrome'. The workup is based on dynamic angiography and computed tomography angiography. The treatment of choice is surgical vascular decompression, resulting in a good clinical outcome. However, in some instances, atlantoaxial fusion may be indicated. Alternatively, conservative and endovascular options have to be considered in inoperable patients.

Approach to cervicogenic dizziness: a comprehensive review of its aetiopathology and management.

PURPOSE: Though there is abundant literature on cervicogenic dizziness with at least half a dozen of review articles, the condition remains to be enigmatic for clinicians dealing with the dizzy patients. However, most of these studies have studied the cervicogenic dizziness in general without separating the constitute conditions. Since the aetiopathological mechanism of dizziness varies between these cervicogenic causes, one cannot rely on the universal conclusions of these studies unless the constitute conditions of cervicogenic dizziness are separated and contrasted against each other. METHODS: This narrative review of recent literature revisits the pathophysiology and the management guidelines of various conditions causing the cervicogenic dizziness, with an objective to formulate a practical algorithm that could be of clinical utility. The structured discussion on each of the causes of the cervicogenic dizziness not only enhances the readers' understanding of the topic in depth but also enables further research by identifying the potential areas of interest and the missing links. RESULTS: Certain peculiar features of each condition have been discussed with an emphasis on the recent experimental and clinical studies. A simple aetiopathological classification and a sensible management algorithm have been proposed by the author, to enable the identification of the most appropriate underlying cause for the cervicogenic dizziness in any given case. However, further clinical studies are required to validate this algorithm. CONCLUSIONS: So far, no single clinical study, either epidemiological or interventional, has incorporated and isolated all the constitute conditions of cervicogenic dizziness. There is a need for such studies in the future to validate either the reliability of a clinical test or the efficacy of an intervention in cervicogenic dizziness.

Cryptic Recanalization of Chronic Vertebral Artery Occlusion by Head Rotation.

BACKGROUND: Chronic vertebral artery occlusion (VAO) can be associated with ischemic stroke, as thrombi formed under blood flow stagnation around the stump of the VAO may migrate into the brain. We report a new mechanism of chronic VAO-associated ischemic stroke and a patient with cryptic recanalization of chronic VAO by head rotation. CASE DESCRIPTION: A 74-year-old man presented with chronic right VAO and repeated ischemic embolic stroke in the posterior circulation despite antiplatelet therapy. He also manifested vertigo with 30° leftward head rotation, indicative of rotational vertebrobasilar insufficiency due to mechanical compression of the patent left vertebral artery (VA) at the C4-C5 level. Surgical decompression of the vessel via the anterior approach resulted in the disappearance of his rotational vertebrobasilar insufficiency. Adequate decompression of the VA on the left side was confirmed on postoperative computed tomography angiography scans obtained with his head rotated more to the left than on preoperative scans. Unexpected partial recanalization of his right chronic VAO was observed at the C5-C6 level. VAO was due to VA compression by osteophytes at neutral head position; it was released by head rotation. We suspected that his repeated brain infarcts were attributable to head rotation-related opening and closing of the VA lumen and these decompressed the left VA by removing the implicated osteophyte via the anterior approach. CONCLUSIONS: Cryptic recanalization of chronic VAO by head rotation contributed to repeated infarcts in the posterior circulation and was resolved by surgical decompression.

Motion-related vascular abnormalities at the craniocervical junction: illustrative case series and literature review.

The craniocervical junction (CCJ) functions within a complicated regional anatomy necessary to protect and support vital neurovascular structures. In select instances, vascular pathology can be attributed to this complicated interplay of motion and structure found within this narrow space. The authors report 3 cases of complex vascular pathology related to motion at the CCJ and detail the management of these cases. Two cases involved posterior circulation vascular compression syndromes, and one case involved a vascular anomaly and its relation to aneurysm formation and rupture. The patient in Case 1 was a 66-year-old man with a history of syncopal episodes resulting from the bilateral vertebral artery becoming occluded when he rotated his head. Successful microsurgical decompression at the skull base resulted in patent bilateral vertebral artery V3 segments upon head movement in all directions. The patient in Case 2 was a 53-year-old woman who underwent elective resection of a right temporal meningioma and who experienced postoperative drowsiness, dysphagia, and mild right-arm ataxia. Subsequent MRI demonstrated bilateral posterior inferior cerebel-lar artery (PICA) strokes. Cerebral angiography showed a single PICA, of extradural origin, supplying both cerebellar hemispheres. The PICA exhibited dynamic extradural compression when the patient rotated her head; the bilateral PICA strokes were due to head rotation during surgical positioning. In Case 3, a 37-year-old woman found unconscious in her home had diffuse subarachnoid hemorrhage and evidence of a right PICA aneurysm. A right far-lateral craniectomy was performed for aneurysm clipping, and she was found to have a dissecting aneurysm with an associated PICA originating extradurally. There was a shearing phenomenon of the extradural PICA along the dura of the foramen magnum, and this microtraumatic stress imposed on the vessel resulted in a dissecting aneurysm. This series of complex and unusual cases highlights the authors' understanding of vascular pathology of the CCJ and its management.