Bow-hunter's syndrome caused by dynamic vertebral artery stenosis at the cranio-cervical junction--a management algorithm based on a systematic review and a clinical series

Vertebral artery stenosis from osteophyte: A systematic review and case series

BACKGROUND

Rotational vertebral artery syndrome, also referred to as Bow Hunter's syndrome (BHS), manifests when the vertebral artery (VA) is compressed following head rotation. This compression is often caused by an osteophyte and may lead to symptoms of a posterior stroke. This systematic review aims to shed light on the current management strategies for BHS resulting from osteophytes. Additionally, we present two illustrative cases where the VA compression by an osteophyte was effectively resolved by complete resection of the problematic bone spur.

METHODS

A literature search was conducted across Embase, PubMed and Medline in September 2023. Keywords related to vertebral artery [MESH], vertebrobasilar insufficiency [MESH] and osteophyte [MESH] were the focus of this review. Risk of bias in retained studies was assessed using the Joanna Briggs Institute Critical Appraisal tools for Qualitative Research. A narrative synthesis of our findings is presented.

RESULTS

A total of 30 studies were included in this review. Vertigo was the most reported symptom by patients (n = 16). On imaging, the VA was often compressed at C4-5 (n = 10) and C5-6 (n = 10) with no evident side predominance observed. Anterior cervical discectomy and fusion (ACDF, n = 13) followed by anterior decompression without fusion (n = 8) were the most performed surgical procedures to manage BHS.

CONCLUSION

Surgical decompression of the VA is a safe and effective intervention for patients experiencing symptomatic osteophytic compression during head rotation. This procedure restores normal vascular function and reduces the risk of ischemic events. This review highlights the importance of timely diagnosis and intervention in such cases.

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.

Mechanical disorders of the cervicocerebral circulation in children and young adults

Mechanical disorders of the cervicocerebral circulation (MDCC) are conditions in which neurological symptoms result from a disturbance of cerebral blood flow attributable to external mechanical forces exerted on extracranial blood vessels by adjacent musculoskeletal structures during head movement that is presumably within a physiological range. The disease spectrum includes bow hunter's syndrome, carotid-type Eagle syndrome, and various dynamic venous compression syndromes. These conditions have distinct phenotypes in children which differ from those expressed in older adults. In contemporary practice, recognition and diagnostic evaluation is the domain of the neuroendovascular specialist. The diagnostic evaluation of MDCC involves significant technical nuance that can be critical to directing appropriate management, particularly in children. This report aims to provide a comprehensive overview of the pathophysiology, anatomical patterns, diagnosis, and treatment for the full spectrum of MDCC that is commonly encountered in clinical practice.

Photorealistic 3-Dimensional Models of the Anatomy and Neurosurgical Approaches to the V2, V3, and V4 Segments of the Vertebral Artery

BACKGROUND

The vertebral artery (VA) has a tortuous course subdivided into 4 segments (V1-V4). For neurosurgeons, a thorough knowledge of the 3-dimensional (3D) anatomy at different segments is a prerequisite for safe surgery. New technologies allowing creation of photorealistic 3D models may enhance the anatomic understanding of this complex region.

OBJECTIVE

To create photorealistic 3D models illustrating the anatomy and surgical steps needed for safe neurosurgical exposure of the VA.

METHODS

We dissected 2 latex injected cadaver heads. Anatomic layered dissections were performed on the first specimen. On the second specimen, the two classical approaches to the VA (far lateral and anterolateral) were realized. Every step of dissection was scanned using photogrammetry technology that allowed processing of 3D data from 2-dimensional photographs by a simplified algorithm mainly based on a dedicated mobile phone application and open-source 3D modeling software. For selected microscopic 3D anatomy, we used an operating microscope to generate 3D models.

RESULTS

Classic anatomic (n=17) and microsurgical (n=12) 3D photorealistic models based on cadaver dissections were created. The models allow observation of the spatial relations of each anatomic structure of interest and have an immersive view of the approaches to the V2-V4 segments of the VA. Once generated, these models may easily be shared on any digital device or web-based platforms for 3D visualization.

CONCLUSIONS

Photorealistic 3D scanning technology is a promising tool to present complex anatomy in a more comprehensive way. These 3D models can be used for education, training, and potentially preoperative planning.

Bow Hunter's syndrome with clicking sounds: A rare etiology of transient loss of consciousness with tonic-clonic seizure

We present the case of a young male patient experiencing a transient loss of consciousness and manifesting a seizure when he tilted his head backward. Transcranial Doppler ultrasound (TCD) and carotid artery ultrasound (CAU) examination were normal when the patient's neck was in the neutral position. However, the CAU revealed vertebral artery (VA) transient occlusion during neck rotation or backward movement. Electroencephalogram (EEG) monitoring was performed with multiple neck rotation-induced tests. The patient developed dizziness, which was the same as the prodromal symptoms of the first seizure, and the EEG showed a large number of spinal slow waves and sharp slow waves in the frontal-to-frontal midline area, with an occasional generalization trend. CT angiography revealed occipitalization of the atlas and the lack of contrast agent filling in the local area of the VA when the patient's head was turned contralaterally. Thus, the patient was diagnosed with Bow Hunter's syndrome (BHS) and treated conservatively with neck immobilization. No recurrence occurred at 3 and 6 months of follow-up. Therefore, this case alerts neurologists to suspect BHS on observing seizure manifestations during neck rotation, and CAU may be a recommended dynamic screening method for BHS. This report is accompanied by a discussion of the phenomenon and diagnosis in the context of the existing literature.

Lateral Approach to the Cervical Spine to Manage Degenerative Cervical Myelopathy and Radiculopathy

BACKGROUND

The cervical lateral approach can enlarge the spinal canal and foramen to achieve an effective neural decompression without needing spine stabilization. For this review, the authors' main objective was to illustrate the rationale, advantages, disadvantages, complications, and pitfalls of this technique, highlighting also areas for future development.

MATERIALS AND METHODS

A Medline via PubMed database search was carried out by using both keywords, namely "cervical oblique corpectomy," "multilevel oblique corpectomy and foraminotomy," and "lateral vertebrectomy," and Medical Subject Headings (MeSH) terms from 1 January 1991, up to 31 December 2021.

RESULTS

The analyzed articles suggested that the use of such a technique has declined over time; only 29 clinical studies met all the inclusion criteria and were retained for data analysis, including 1200 patients undergoing such an approach for the management of degenerative cervical myelopathies (DCMs) or of radiculopathies. The main etiopathogeneses were cervical stenosis, degenerative disk disease, or a mix of them-78% of which had a favorable outcome; the most frequent complications were transient and permanent Horner syndrome in 13.6% and 9.2% of cases, respectively. Long-term stability was reported in 97% of patients.

CONCLUSION

Multilevel cervical oblique vertebrectomy and/or lateral foraminotomy allow wide neural structure decompression and optimal stability given that the physiological spinal motion is preserved.

Suboccipital Muscles, Forward Head Posture, and Cervicogenic Dizziness

Dizziness or vertigo can be caused by dysfunction of the vestibular or non-vestibular systems. The diagnosis, treatment, and mechanism of dizziness or vertigo caused by vestibular dysfunction have been described in detail. However, dizziness by the non-vestibular system, especially cervicogenic dizziness, is not well known. This paper explained the cervicogenic dizziness caused by abnormal sensory input with references to several studies. Among head and neck muscles, suboccipital muscles act as stabilizers and controllers of the head. Structural and functional changes of the suboccipital muscles can induce dizziness. Especially, myodural bridges and activation of trigger point stimulated by abnormal head posture may be associated with cervicogenic dizziness.

Vertebral Artery Stenosis: A Narrative Review

Vertebral artery stenosis (VAS) is the cause of approximately 20% of ischemic strokes in the posterior circulation. There are several causes of vertebral artery stenosis, including atherosclerosis, calcification, dissections, fibromuscular dysplasia, giant cell arteritis, neurofibromatosis type 1, and bony compressions. The most common cause of VAS is atherosclerosis which is derived from the macrophage-induced oxidation of low-density lipoproteins (LDLs), alongside the accumulation of cholesterol. Calcification of the vertebral artery occurs when there is excess calcium and phosphate deposition in the vessel. Dissection of the vertebral artery can lead to the formation of a hematoma causing stenosis of the vertebral artery. Fibromuscular dysplasia can result in stenosis due to the deposition of collagen fibers in the tunica media, intima, or adventitia. Giant cell arteritis, an autoimmune disorder, causes inflammation of the internal elastic membrane resulting in eventual stenosis of the artery. Neurofibromatosis type 1, an autosomal dominant disorder, results in the stenosis of the vertebral artery due to the altered function of neurofibromin. Mechanical compression of the vertebral artery by bone can also cause stenosis of the vertebral artery. Digital subtraction angiography (DSA) is considered the current gold standard in diagnosing vertebral artery stenosis; however, its associated morbidity and mortality have led to increased use of non-invasive techniques such as duplex ultrasonography (DUS), computed tomography angiography (CTA), and magnetic resonance angiography (MRA). Currently, asymptomatic and symptomatic vertebral artery stenoses are treated by risk factor modification and medical treatment. However, it is recommended that surgical (endarterectomy, reconstruction, and decompression) and endovascular (balloon coronary, bare-metal, and drug-eluting stents) treatments are also used for symptomatic vertebral artery stenosis.

Neurological vertigo in the emergency room in pediatric and adult age: systematic literature review and proposal for a diagnostic algorithm

Neurological vertigo is a common symptom in children and adults presenting to the emergency department (ED) and its evaluation may be challenging, requiring often the intervention of different medical specialties. When vertigo is associated with other specific symptoms or signs, a differential diagnosis may be easier. Conversely, if the patient exhibits isolated vertigo, the diagnostic approach becomes complex and only through a detailed history, a complete physical examination and specific tests the clinician can reach the correct diagnosis. Approach to vertigo in ED is considerably different in children and adults due to the differences in incidence and prevalence of the various causes. The aim of this systematic review is to describe the etiopathologies of neurological vertigo in childhood and adulthood, highlighting the characteristics and the investigations that may lead clinicians to a proper diagnosis. Finally, this review aims to develop an algorithm that could represent a valid diagnostic support for emergency physicians in approaching patients with isolated vertigo, both in pediatric and adult age.

Bow hunter’s syndrome successfully treated with a posterior surgical decompression approach: A case report and review of literature

BACKGROUND

Bow hunter’s syndrome (BHS) is a rare but surgically treatable cause of vertebrobasilar insufficiency due to dynamic rotational occlusion of the vertebral artery. Typically, patients present with posterior circulation transient ischaemic symptoms such as presyncope, syncope, vertigo, diplopia, and horizontal nystagmus, but irreversible deficits, including medullary and cerebellar infarctions, have also been described.

CASE SUMMARY

A 70-year-old patient presented an acute onset of vertigo and gait instability triggered by right head rotation. His medical history included previous episodes of unilateral left neck and occipital pain followed by light-headedness, sweating, and blurred vision when turning his head, and these episodes were associated with severe degenerative changes in the atlanto-dens and left atlanto-axial facet joints and right rotation of the C2 cervical vertebrae. Brain magnetic resonance imaging revealed the presence of acute bilateral cerebellar ischaemic lesions, while static vascular imaging did not reveal any vertebral artery abnormalities. Dynamic ultrasonography and angiography were performed and confirmed the presence of a dynamic occlusion of the vertebral artery V3-V4 segment when the head was rotated to the right secondary to left C1-C2 bone spur compression. Surgical decompression led to complete resolution of paroxysmal symptoms without neurological sequelae.

CONCLUSION

BHS should be considered in cases of repeated posterior circulation transient ischaemic attack or ischaemic stroke, particularly when associated with high cervical spine abnormalities.

Thyroid Cartilage Compression Causing Bow Hunter's Syndrome

OBJECTIVES AND METHODS

We report a unique case of Bow Hunter's syndrome with a dominant aberrantly coursing right vertebral artery (VA), presenting with persistent dizziness and syncope despite previous decompressive surgery at vertebral levels C5-C6.

RESULTS

Re-evaluation with computed tomography-scan during provocation of dizziness by neck rotation revealed compression of the right VA at level C6 from against the ipsilateral posterior border and superior cornu of the thyroid cartilage. Laryngoplasty resulted in complete resolution of symptoms.

CONCLUSION

This extremely rare cause of Bow's Hunter's syndrome should be considered, especially in refractory cases after neurosurgical decompression, and surgical management is straightforward and successful.

Ischemic Stroke Secondary to Dynamic Vertebral Artery Stenosis: Case Report and Review of the Literature

Ischemic stroke secondary to dynamic vertebral artery stenosis or occlusion, also known as “bow hunter's syndrome,” is a rare stroke mechanism. We report a case of a 24-year-old man with multiple hereditary exostosis (MHE) diagnosed at childhood. His first presentation to a neurologist was due to neck pain and clinical syndrome suggestive of ischemia in the vertebrobasilar territory. A therapeutic occlusion was done successfully without complication. The patient was discharged two days later on aspirin alone. In follow up one year later he continued to be symptom free. Moreover, this stroke mechanism has been reported extensively in the literature in isolation or secondary to many underlying diseases. In total, there are 168 cases reported in the published English literature, in either case reports or small series. In this review, we found that by far, vertebral artery occlusion at the atlanto-axial (C1-2) level dominated most reported cases. The most frequent presentation that led to further investigation was syncope or pre-syncope provoked by head rotation to one side. To our knowledge, there is no previous report of any stroke syndrome related to MHE before our case. In this paper, we report the first case secondary to MHE and review the literature up to date since the first reported case in 1952.

The Enduring Controversy of Cervicogenic Vertigo, and Its Place among Positional Vertigo Syndromes

The idea of cervicogenic vertigo (CV) was proposed nearly a century ago, yet despite considerable scrutiny and research, little progress has been made in clarifying the underlying mechanism of the disease, developing a confirmatory diagnostic test, or devising an appropriately targeted treatment. Given the history of this idea, we offer a review geared towards understanding why so many attempts at clarifying it have failed, with specific comments regarding how CV fits into the broader landscape of positional vertigo syndromes, what a successful diagnostic test might require, and some practical advice on how to approach this in the absence of a diagnostic test.

Atlanto-Occipital Decompression of Vertebral Artery for a Variant of Bow Hunter's Syndrome: 2-Dimensional Operative Video

Rotational vertebral artery (VA) occlusion syndrome, also known as bow hunter's syndrome, is an uncommon variant of vertebrobasilar insufficiency typically occurring with head rotation.1-3 The most common presenting symptom is dizziness (76.8%), followed by visual abnormalities and syncope (50.4% and 40.4%, respectively).2 Osteophytic compression due to spinal spondylosis has been shown to be the most common etiology (46.2%), with other factors, such as a fibrous band, muscular compression, or spinal instability, being documented.1,2 Treatment is dependent on the level and site of VA compression with anterior, anterolateral, or posterior approaches being described.1,4 We present the case of a 72-yr-old male with osteophytic compression of the V3 segment of the vertebral artery at the occipital-cervical junction. The patient underwent a C1 hemilaminectomy and removal of osteophytic compression from the occipital-cervical joint. The patient had complete resolution of compression of his vertebral artery on postoperative imaging and remained neurologically intact following the procedure. We review the literature on this topic, the technical nuances of the procedure performed, and review the different treatment modalities available for this rare condition.1-11  The patient consented to the procedure and to publication of their image.

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.

Vertebral Artery Compression by the Greater Cornu of the Thyroid Cartilage

A case of symptomatic unilateral vertebral artery compression by the greater cornu of the thyroid cartilage is described. Imaging shows ossification of the greater cornu of the thyroid cartilage with compression of an aberrant vertebral artery that enters the transverse foramen at the level of C4. Diagnostic workup and surgical treatment are described. Laryngoplasty with a transverse cervical approach and resection of the greater cornu of the thyroid cartilage resulted in resolution of symptoms.

Bow hunter's syndrome due to an embolic mechanism: illustrative case

BACKGROUND

Bow hunter's syndrome (BHS) is an uncommon cause of vertebrobasilar ischemic stroke, which results from occlusion or injury to the vertebral artery (VA) during neck rotation. Although hemodynamic insufficiency is the predominant underlying mechanism of this entity, BHS due to embolic mechanisms is rare. The authors report a case of BHS characterized by repeated posterior circulation embolism and present some considerations of BHS with an embolic mechanism.

OBSERVATIONS

A 57-year-old man suffered from repeated embolic stroke in the posterior circulation. Digital subtraction angiography revealed caliber irregularity of the V3 segment of the left nondominant-side VA, which occluded when the neck rotated to the right side. The patient was diagnosed with BHS with an embolic mechanism due to endothelial damage caused by osteophytes at the C1 foramen transversarium. After C1-C2 fusion surgery, the patient never experienced the recurrence of stroke. According to a literature review, BHS due to embolic mechanisms tends to occur in young male adults, manifesting as recurrent stroke in the posterior circulation. Involvement of the nondominant-side VA can cause BHS with an underlying embolic mechanism.

LESSONS

BHS due to an embolic mechanism should be considered as a differential diagnosis if patients have repeated embolic strokes in the posterior circulation.

Intervention for symptomatic vertebrobasilar disease

Disease of the vertebral (VA) and basilar arteries (BA) can lead to stroke of the posterior circulation and may warrant management strategies which differ from the anterior circulation. The mechanism and location of the disease determine its natural history and therefore affect the relative risks and benefits of the possible treatment options. Vertebrobasilar (VB) atherosclerotic disease is a source of both hemodynamic and embolic posterior circulation stroke. Advances in medical therapy have decreased the rate of stroke after initial symptomatic presentation. Antiplatelet therapy, blood pressure control, and optimization of secondary risk factors can reduce recurrent stroke risk in both intracranial and extracranial VB disease. However, symptomatic intracranial disease is still associated with a high risk of subsequent stroke, particularly those with hemodynamic compromise who represent a higher risk population. Patients with hemodynamic impairment may benefit from judicious application of endovascular and microsurgical interventions to augment blood flow. Stenting, angioplasty alone, bypass surgery, and endarterectomy, represent endovascular and surgical tools available to address medically refractory VB disease. Apart from atherosclerotic disease, dissection is another etiology of VB stroke, most frequently affecting the extracranial VA. Treatment is predominantly antithrombotic therapy although surgical or endovascular intervention can be required in rare cases of persistent embolism or hemodynamic compromise. In contrast, extrinsic compromise of the VA represents a separate extracranial pathology and is best treated with mechanistically targeted surgeries or extracranial bypass.

Rotational vertebral artery occlusion ("bow hunter syndrome")

PURPOSE

To review the literature, analyze and discuss diagnostic and treatment options for the Bowhunter Syndrome. A clinical case of idiopathic rotatory C1-C2 subluxation causing dynamic vertebral artery occlusion is presented.

METHODS

Literature review between 1960 and 2019, discussion of diagnostic methods and treatment options. Description of diagnostic and treatment methods in the aforementioned case.

RESULTS

We present a patient with dynamic left vertebral artery occlusion associated with idiopathic rotatory C1-C2 subluxation. A dynamic Angio-CT showed rotatory C1-C2 subluxation with significant flow reduction at the left vertebral artery at the exit of the C2 transverse foramen until the V3 segment when the head rotated towards the right. Due to clinical and radiological worsening in the following months, posterior C1-C2 arthrodesis was performed, with the disappearance of the symptoms. There are 193 cases reported with dynamic vertebral artery occlusion, but in only two, the etiology was primary rotational atlantoaxial instability. The most prevalent etiology was degenerative.

CONCLUSION

Rotatory vertebral artery occlusion is a rare condition presented mostly in adults, aged 50-70 years. Vertebrobasilar insufficiency is triggered by the rotation of the head to the contralateral side of the dominant vertebral artery. Dynamic subtraction angiography is considered the diagnostic gold-standard method, but dynamic Angio-CT scan, Angio-MRI, or Doppler ultrasonography are less invasive options. The treatment options are conservative or surgical. Endovascular surgery is another option in specific cases.

Bow Hunter's Syndrome in Children: A Review of the Literature and Presentation of a New Case in a 12-Year-Old Girl

BACKGROUND

Bow hunter's syndrome, or occlusion of the vertebral artery with head rotation leading to ischemia and sometimes stroke, is rarely described in children. The authors review the literature and present a new case.

METHODS

Both OVID dating back to 1946 and PubMed records were reviewed using the terms ("Bow hunter syndrome" OR "bow hunter's") OR "rotational vertebral artery occlusion" combined with "child," and limited to English language. SCOPUS and the bibliographies of cases found in the search were used to identify additional articles.

RESULTS

Twelve articles were found describing 25 patients; there were 26 patients when combined with our case. Ages ranged from 1 to 18 years. Most (88.5%, 23/26) were male. Medical treatments included aspirin, clopidogrel, abciximab, enoxaparin, warfarin, and cervical collar. Stenting was tried in 2 cases but did not work long-term. Surgical treatments included decompression, cervical fusion, or a combination. We present a new case of a 12-year-old girl with recurrent stroke who had bilateral vascular compression only visible on provocative angiographic imaging with head turn. She was referred for cervical fusion, and abnormal ligamentous laxity was noted intraoperatively.

CONCLUSIONS

Bow hunter's syndrome is a rare but important cause of stroke since many of the patients experience recurrent strokes before the diagnosis is made. Reasons for the male predominance are unclear. Provocative angiography plays a key role in diagnosis, and both medical treatment and neurosurgical intervention may prevent recurrence.

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.

Profiles of Vertebral Artery Dissection with Congenital Craniovertebral Junction Malformation: Four New Cases and a Literature Review

OBJECTIVE

Vertebral artery dissection (VAD) combined with congenital craniovertebral junction malformation (CVJM) is rare. This study aimed to analyze the etiology, clinical and imaging features, treatment, and prognosis of VAD with CVJM.

METHODS

Four new cases of VAD with congenital CVJM and 28 similar cases found in the literature were included. Detailed clinical data from all cases were retrospectively analyzed.

RESULTS

A total of 32 patients (28 men, four women; mean age 19.01±12.53 years) were included. Seventeen of 32 cases (53.1%) had had multiple ischemic episodes. The most common neurological symptoms were limb numbness/weakness (20/32), ataxia (15/32), and dizziness/vertigo (12/32). In sum, 31 of 32 cases had multiple infarcts scattered throughout the posterior circulation area on cranial computed tomography or resonance imaging. Dissection had occurred in the V3 segment of the VA in 29/31 cases (93.5%). The most common congenital CVJMs were atlantoaxial dislocation and atlantoaxial subluxation (found in 20/32 cases [62.5%]), while 27/32 cases (84.3%) had multiple combined abnormalities. Seven of eleven cases (63.6%) with initial antiplatelet treatment and one of eleven (9.1%) with initial anticoagulation treatment experienced stoke recurrence. Fusion or vertebral fixation was performed in 16 patients and aneurysm resection in one patient. There was no reported recurrence after surgery in 13 patients with follow-up data.

CONCLUSION

Underlying CVJM is a rare but overlooked etiology in VAD, and is prone to induce recurrent ischemic stroke. Patients with VAD, especially that localized in the V3 segment, should be examined for CVJM. Timely assessment is critical for determining the specific cause and to provide targeted intervention.

Rare cause of Bow Hunter's syndrome due to an aberrant course of a vertebral artery

Bow Hunter's syndrome (BHS) is a rare cause of vertebrobasilar insufficiency and is reported to most commonly be caused by vertebral artery impingement on cervical vertebrae osteophytes. We report a case in a 56-year-old male patient who on investigation of recurrent posterior circulation ischaemic strokes was found to have BHS. The aetiology of the syndrome in this patient is due to a particularly unusual aberrancy in the path of the atlantoaxial portion of the culprit left vertebral artery. Aberrancy of the distal portion of the vertebral artery is in itself a rare entity, and there are few reports of it in relation to BHS. The patient in this case was successfully treated with endovascular sacrifice of the vertebral artery with no further dynamic occlusive symptoms.

Vascular Ultrasound Measurements After Atlas Orthogonal Chiropractic Care in a Patient With Bow Hunter Syndrome

Objective

This case report describes chiropractic treatment for a patient diagnosed with bow hunter syndrome with transient vision loss (TVL).

Clinical Features

A 39-year-old woman presented to a chiropractic clinic with hand and arm numbness that began after she was injured in a motor vehicle collision 18 months earlier. The primary symptom was TVL that began 3 days after the motor vehicle collision. At that time, she had been diagnosed with bow hunter syndrome using dynamic angiography findings. She had previously declined surgery recommended by her attending neurosurgeon at a local hospital.

Intervention and Outcome

The patient was treated using atlas orthogonal chiropractic technique for 8 visits over a 6-week period. Examination before and the after the initial treatment included cervical radiographic analysis and vascular ultrasound measurement of the right and the left vertebral artery (VA). After the initial spinal manipulation, there was an improvement in blood flow volume of 8.2% in the left VA and 22.2% in the right VA. There was improvement of the symptom of TVL and a measured reduction of rotational misalignment of the first and second cervical vertebra on the radiographic views. After 6 weeks, the patient's perception of TVL was absent.

Conclusion

A patient with TVL improved under chiropractic care using atlas orthogonal technique.

Republished: Rotational carotid insufficiency: an unusual cause of bow hunter's syndrome

We report an unusual case in which physiologic neck rotation impeded perfusion through the internal carotid artery. The patient had a history of prior radical neck surgery and radiation for malignancy. He presented withbow hunter's-like symptoms with transient loss of consciousness and right-sided weakness with left lateral neck rotation. A self-expanding peripheral stent was successfully used to treat the patient by preventing rotatory carotid compression. In select patients with prior neck surgery and radiation, carotid injections should be part of a dynamic cerebral angiogram if the vertebral arteries are unremarkable.

Rotational vertebral artery occlusion in a patient with basilar invagination

Basilar invagination (BI) is a congenital or acquired craniovertebral junction (CVJ) anomaly with odontoid process superiorly migrating into the foramen magnum. Compression of neural structures is the most relevant complication of BI. However BI is also a rare cause of ischemic stroke. In this case we reported a 30-year-old female with BI who developed recurrent ischemic stroke in posterior circulation. Before the onset of ischemic stroke, she didn't present neck pain or clinical signs of lower cranial nerve dysfunction, brainstem compression or transient ischemic attack. At first she suffered from sudden onset of left-sided hemidysesthesia. Magnetic resonance imaging from a local hospital revealed an acute infarction in the right thalamus. Cerebral MR angiography was unremarkable at that time. The tip of the odontoid process had protruded into the foramen magnum and could be observed at the level of the lower medulla, but unfortunately it was ignored by the clinicians and the radiologists. She was given antiplatelet therapy and the sensory disturbance disappeared gradually. However she experienced a recurrence in the pontine and midbrain region 2 months later. At this time she was transferred to our hospital, and reconstructed computed tomography of cervical spine demonstrated basilar invagination, atlanto-axial dislocation, and atlanto-occipital assimilation. Computed tomographic angiography (CTA) revealed a dominant right vertebral artery (VA) and a redundant loop in its third segment. Dynamic cerebral angiogram demonstrated that the patient had a Bow Hunter's type phenomenon, with dynamic occlusion of the right dominant VA during contralateral head turn. This case highlighted the necessary of hemodynamic evaluation in asymptomatic basilar invagination.

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.

Rotational carotid insufficiency: an unusual cause of bow hunter's syndrome

We report an unusual case in which physiologic neck rotation impeded perfusion through the internal carotid artery. The patient had a history of prior radical neck surgery and radiation for malignancy. He presented withbow hunter's-like symptoms with transient loss of consciousness and right-sided weakness with left lateral neck rotation. A self-expanding peripheral stent was successfully used to treat the patient by preventing rotatory carotid compression. In select patients with prior neck surgery and radiation, carotid injections should be part of a dynamic cerebral angiogram if the vertebral arteries are unremarkable.

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.

Beauty parlor stroke syndrome due to a bone fragment from an osteophyte of the atlas: case report

Beauty parlor stroke syndrome (BPSS) is a rare condition characterized by mechanical impingement of a vertebral artery (VA) during neck rotation and/or hyperextension followed by vertebrobasilar insufficiency. However, there have been no reports of BPSS in which the cause of mechanical impingement was identified and no cases for which surgical treatment was reported. The authors report the case of a 56-year-old Japanese man who presented with presyncope that occurred during cervical extension. Given the possibility of vertebrobasilar insufficiency, digital subtraction angiography and CT angiography were performed. These studies revealed that the right VA was hypoplastic and the left VA was dominant. Moreover, in the position of cervical extension, the dominant left VA showed constriction caused by a bone fragment of an osteophyte of the atlas. Removal of the bone fragment was performed. Postoperative left vertebral angiography showed improvement of blood flow in the extended position, and the presyncope completely disappeared. The pathomechanism of this case was a bone fragment compressing the left VA in the C-1 groove during neck extension. In BPSS patients with recurrent transient symptoms, the possibility of this mechanism of VA constriction by a free bone fragment should be considered.

Combined Use of Intraoperative Indocyanine Green and Dynamic Angiography in Rotational Vertebral Artery Occlusion

Rotational vertebral artery occlusion (RVAO) is a well-documented surgically amenable cause of vertebrobasilar insufficiency. Traditionally, patients have been imaged using dynamic rotational angiography. We report a case of RVAO in which intraoperative indocyanine green angiography (ICGA) was used to confirm adequate surgical decompression of the VA. A 57-year-old female who presented with multiple episodes of syncope provoked by turning her head to the right. Rotational dynamic angiography revealed a dominant right VA that became occluded at the level of C5/6 with head rotation to the right. The patient underwent successful surgical decompression of the VA via an anterior cervical approach. ICGA demonstrated VA patency with head rotation. This was further confirmed by intraoperative dynamic catheter angiography. To the best of our knowledge, we present the first use of ICG combined with intra-operative dynamic rotational angiography to document the adequacy surgical decompression of the VA in a patient with RVAO.

Occipital Bony Abnormality and Multiple Strokes in a Pediatric Patient: Case Report and Review of the Current Literature

This study presents a case of a 15-year-old boy who had a right vertebral artery dissection with distal embolization from repeated trauma from an occipital bony spicule. The authors hypothesize that this bony spicule was contacting the left vertebral artery during head rotation, resulting in trauma to the vessel and formation of emboli which then showered distally, causing strokes in the posterior circulation of the brain. This specific phenomenon has previously been reported three times, only one of which was in pediatric literature. It is important for individuals to be aware of this rare anatomic cause of vertebral artery dissection in patients presenting with an odd constellation of symptoms related to strokes from vertebro-basilar system. Treatment options including early intervention with intravascular coil embolization are also discussed.

Dynamic Arterial Compression in Pediatric Vertebral Arterial Dissection

Background and Purpose—

The pathogenesis of spontaneous pediatric vertebral artery dissections (VAD) is poorly understood but most often involves the V3 segment where C1 rotates on C2. We studied children with VAD with provocative digital catheter angiography and found an association between VAD and rotational compression.

Methods—

Seven boys (12 months to 9 years; median 4 years) presented over 38 consecutive months with V3 VAD and underwent digital catheter angiography with provocative passive bilateral neck rotation.

Results—

VAD were bilateral in 2 patients and unilateral in 5. Provocative digital catheter angiography showed dynamic V3 compression in 6 of 9 dissections, most pronounced or seen only with head rotation to the contralateral side. Two patients had VAD without dynamic compression; both returned 4 months later with a new dissection in a previously normal VA and worsening VAD in 1 patient each. Dynamic compression was also seen in 2 nondissected VA. Surgical management was C1/2 posterior fusion in 5 of 7 patients; 1 underwent unilateral C2 decompression with recurrent VAD and was subsequently fused.

Conclusions—

The association of dynamic VA compression and VAD at the same level suggests that the compression may contribute to the VAD. However, as dynamic compression was observed in nondissected VA and some VAD were not associated with dynamic compression, VAD may be multifactorial.

DynaCT angiography for the diagnosis of bilateral bow hunter's syndrome

We herein present a rare case of bilateral positional vertebrobasilar insufficiency secondary to mechanical obstruction of the V2 segment of the vertebral artery in a 71-year-old patient presenting with vertigo, occipital headache, tremors and respiratory irregularities. Two-dimensional digital subtraction angiography is the traditional diagnostic imaging standard but does not capture any peri-vascular bony or soft tissue abnormalities that are important to understand the three-dimensional pathophysiology. Intra-procedural cone-beam computed tomography (CT) is an increasingly used diagnostic adjunct, available in most modern angiographic suites that allows for the three-dimensional visualization of the vasculature as well as CT-like soft tissue visualization of its surrounding anatomy. In this case, we report the additional value of three-dimensional reconstructed cone-beam CT angiographic imaging that led to the successful diagnosis of bilateral positional vertebrobasilar disease. The patient subsequently received C4-C6 cervical decompression and fusion and remains symptom free at 1 year follow-up.

Advances in the Pathogenesis, Diagnosis and Treatment of Bow Hunter's Syndrome: A Comprehensive Review of the Literature

Bow hunter's syndrome (BHS), also known as rotational vertebral artery (VA) occlusion syndrome, is a rare yet treatable type of symptomatic vertebrobasilar insufficiency resulting from mechanical occlusion or stenosis of the VA during head and neck rotation or extension. The symptoms of BHS range from transient vertigo to posterior circulation stroke. The underlying pathology is dynamic stenosis or compression of the VA by abnormal bony structures with neck rotation or extension in many cases, such as osteophyte, disc herniation, cervical spondylosis, tendinous bands or tumors. Imaging approaches, such as Doppler sonography, computed tomography and angiography, as well as magnetic resonance imaging and angiography, are widely used in the diagnosis and evaluation of this syndrome. Digital subtraction angiography with head rotation remains the gold standard diagnostic method. Conservative management, surgery and endovascular procedures are the three major treatment methods for BHS, whereas some symptomatic patients may need operative treatment including surgery and endovascular procedures when conservative management is not adequate.

Bow hunter's syndrome revisited: 2 new cases and literature review of 124 cases

Rotational occlusion of the vertebral artery (VA), or bow hunter's syndrome, is a rare yet surgically treatable cause of vertebrobasilar insufficiency. The underlying pathology is dynamic stenosis of the VA by osteophytes, fibrous bands, or lateral disc herniation with neck rotation or extension. The authors present 2 previously unreported cases of bow hunter's syndrome and summarize 124 cases identified in a literature review. Both patients in the new cases were treated by VA decompression and fusion of the subaxial spine. Each had > 50% occlusion of the left VA at the point of entry into the transverse foramen with a contralateral VA that ended in the posterior inferior cerebellar artery. Analyzing data from 126 cases (the 2 new cases in addition to the previously published 124), the authors report that stenosis was noted within V1 in 4% of cases, in V2 in 58%, in V3 in 36%, and distal to C-1 in 2%. Patients presented in the 5th to 7th decade of life and were more often male than female. The stenotic area was decompressed in 85 (73%) of the 116 patients for whom the type of treatment was reported (V1, 4 [80%] of 5; V2, 52 [83%] of 63; V3/V4, 29 [60%] of 48). Less commonly, fusion or combined decompression and fusion was used (V2, 7 [11%] of 63; V3/V4, 14 [29%] of 48). Most patients reported complete resolution of symptoms. The authors conclude that patients with bow hunter's syndrome classically have an impaired collateral blood flow to the brainstem. This condition carries an excellent prognosis with decompression, fusion, or combined surgery, and individual patient characteristics should guide the choice of therapy.

Recurrent juvenile ischemic stroke caused by bow hunter's stroke revealed by carotid duplex ultrasonography

Bow hunter's stroke (BHS) is a rare cause of vertebrobasilar insufficiency due to rotational vertebral artery (VA) occlusion associated with head turning. We report a juvenile patient presenting with recurrent ischemic stroke caused by BHS, which was revealed by carotid duplex ultrasonography. Carotid duplex ultrasonography performed in the neutral position showed normal findings. However, disappearance of end-diastolic blood flow of contralateral VAs was observed with head rotation. Digital subtraction angiography confirmed occlusion at C1/2 levels in the VA contralateral to the head rotation, bilaterally. Importantly, our patient did not recognize the association of head rotation and previous episodes of stroke. We suggest that BHS should be considered in patients with cryptogenic stroke occurring in the vertebrobasilar artery territory.