Posterior Inferior Cerebellar Artery to Posterior Inferior Cerebellar Artery In Situ Bypass for the Treatment of Bow Hunter's-Type Dynamic Ischemia in Holovertebral Dissection

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.

Safety and efficacy of dynamic catheter-directed cerebral digital subtraction angiography for diagnosis of bowhunter syndrome spectrum disorders: A systematic review of the literature

INTRODUCTION

Dynamic catheter-directed cerebral digital subtraction angiography (dcDSA) is the gold standard for diagnosing dynamic vascular occlusion syndromes such as bowhunter syndrome (BHS). Nonetheless, concerns about its safety exist and no standardized protocols have been published to date.

METHODS

We describe our methodology and insights regarding the use of dcDSA in patients with BHS. We also perform a systematic literature review to identify cases of typical and atypical presentations of BHS wherein dcDSA was utilized and report on any procedural complications related to dcDSA.

RESULTS

Our study included 104 cases wherein dcDSA was used for the diagnosis of BHS. There were 0 reported complications of dcDSA. DcDSA successfully established diagnosis in 102 of these cases. Thirty-eight cases were deemed atypical presentations of BHS. Fourteen patients endorsed symptoms during neck flexion/extension. In eight cases, there was dynamic occlusion of bilateral vertebral arteries during a single maneuver. Three patients had multiple areas of occlusion along a single vertebral artery (VA). An anomalous entry of the VA above the C6 transverse foramen was observed in four patients. One patient had VA occlusion with neutral head position and recanalization upon contralateral lateral head tilt.

CONCLUSION

Our study highlights the safety and diagnostic benefits of dcDSA in characterizing the broad spectrum of BHS pathology encountered in clinical practice. This technique offers a powerful means to evaluate changes in cerebral blood flow and cervical arterial morphology in real time, overcoming the constraints of static imaging methods. Our findings pave the way for further studies on dcDSA to enhance cross-sectional imaging methods for the characterization of BHS and other dynamic vascular occlusion syndromes.

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.

Evolution of Intracranial-Intracranial Bypass Surgery: A Bibliometric Analysis

OBJECTIVE

Modern cerebrovascular bypass surgery uses either extracranial-intracranial (EC-IC) or intracranial-intracranial (IC-IC) approaches. Compared with EC-IC bypasses, IC-IC bypasses allow neurosurgeons to safely address tumors, aneurysms, and other lesions using shorter grafts that are well matched to the size of recipient vessels. Fewer than 100 articles have been published on IC-IC bypasses compared with more than 1000 on EC-IC bypasses. This study examined the increase of interest and innovation in IC-IC bypass.

METHODS

PubMed and Web of Science were searched using keywords specific to IC-IC bypass, yielding 717 articles supplemented with 36 reports from other databases and gray literature. The articles were reviewed, and 98 articles were selected for further evaluation. Final articles were categorized as innovations or retrospective studies. Publication metrics were passed through an analytic program to assess statistical measures of growth.

RESULTS

The number of publications describing innovations (n = 52) and retrospective studies (n = 46) in IC-IC surgical techniques increased exponentially (R2 = 0.983 and R2 = 0.993, respectively), with both interest and research in the field increasing. The rate of publications in each group also increased. In recent years, increasing numbers of global institutions have researched and published on IC-IC bypasses.

CONCLUSIONS

As more work is undertaken on IC-IC bypasses, it is critical for knowledge to be shared through research, collaboration, publication, and early teaching within residency training programs. This field has increased exponentially in the past 2 decades and has yet to reach an inflection point, indicating possible additional interest and growth over time.

Repeated cerebellar infarction in the affected nondominant vertebral artery distribution with reversible vertebral artery occlusion elicited by head tilt: illustrative case

BACKGROUND

Bow hunter’s syndrome or stroke (BHS) is characterized by rotational vertebrobasilar insufficiency elicited by rotation of the neck. It is caused by dynamic and reversible occlusion of the vertebral artery (VA). Reversible symptoms of rotational vertebrobasilar insufficiency are described as bow hunter’s syndrome, although brain infarction is rarely reported as bow hunter’s stroke.

OBSERVATIONS

A 70-year-old man experienced repeated cerebellar infarctions three times in the posterior inferior cerebellar artery (PICA) distribution of the nondominant right VA connecting the basilar artery. The onset of symptoms indicating cerebellar infarcts and the patient’s head position changes were unrelated. Dynamic digital angiography (DA) revealed that the nondominant right VA was occluded by an osteophyte from the C4 vertebral body, and the right PICA branches were shown to be passing through the distal right VA from the left VA. These findings were observed when the patient’s head was tilted to the right. An arterio-arterial embolic mechanism was suggested as the cause of repeated cerebellar infarctions.

LESSONS

Transient nondominant VA occlusion has been rarely reported as a cause of BHS when the head is tilted. To confirm the diagnosis of BHS, additional head tilt is recommended when performing dynamic DA in patients with a cervical osteophyte.

Clinical Importance of the Posterior Inferior Cerebellar Artery: A Review of the Literature

The posterior inferior cerebellar artery (PICA), with its unique anatomical complexity, is of great clinical importance and involved in many diseases including aneurysm, ischemic stroke, neurovascular compression syndrome (NVCS), arteriovenous malformation (AVM), and brain tumor. However, a comprehensive systematic review of the importance of the PICA is currently lacking. In this study, we perform a literature review of PICA by searching all the associated papers in the PUBMED database hoping to provide a better understanding of the artery. The PICA has tortuous and variable course and territory, divided into 5 segments. Various aneurysms involving PICA were not uncommon, of which the treatment is challenging. The PICA infarct typically manifests lateral medullary syndrome (LMS) and is more likely to cause mass effects. The PICA frequently compresses the medulla and the cranial nerves resulting in various neurovascular compression syndromes (NVCS). Arteriovenous malformation (AVM) fed by PICA are associated with aneurysm and dissection which have high risk of rupture and worse outcome. PICA injured by head trauma can cause fatal SAH. VA terminating in PICA probably cause Bow hunter's syndrome (BHS). The PICA supplies many brain tumors and can be used in intracerebellar chemotherapy. The PICA can be exposed and injured during surgeries especially in telovelar approach, and it also plays an important role in bypass surgeries, hinting the surgical importance of PICA. In conclusion, PICA is very important in clinical practice.

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.