Bow Hunter's Syndrome: Surgical Vertebral Artery Decompression Guided by Dynamic Intraoperative Angiography

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.

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: temporary obstruction of blood flow in the affected vertebral artery during posterior occipitocervical fusion. Illustrative case

BACKGROUND

Bow hunter's syndrome (BHS) is a rare condition characterized by mechanical impingement of a vertebral artery (VA) during neck rotation followed by vertebrobasilar insufficiency. Posterior fusion is a typical surgical method for BHS.

OBSERVATIONS

The case of a 70-year-old Japanese man who presented with presyncope that occurred during right cervical rotation is reported. Given the possibility of vertebrobasilar insufficiency, digital subtraction angiography and computed tomography angiography were performed and showed a hypoplastic right VA and severe stenosis of the left VA over the occiput (O)-C2 level. The blood flow of the left VA was interrupted by right cervical rotation, with resumption of blood flow on left cervical rotation. BHS was diagnosed, and posterior fusion at the O-C2 level was performed. Immediately after implant fixation, selective arteriography confirmed disruption of blood flow in the left VA. The rods were removed immediately; resumption of blood flow was confirmed; and the rods were refixed, anatomically bent with slight left cervical rotation. Then, sustained blood flow in the left VA was confirmed.

LESSONS

Posterior fixation for BHS can induce VA occlusion due to minor changes in cervical spine alignment. Intraoperative selective arteriography is a necessary tool to identify occlusion of the affected VA.

Rotational Vertebral Artery Syndrome (Bow Hunter's Syndrome): A Rare Differential Diagnosis in Patients With Syncope

Syncope is a common symptom in clinical practice. Rotational vertebral artery occlusion syndrome, also referred to as Bow Hunter's syndrome (BHS), is a rare condition associated with syncope and is caused by mechanical occlusion or stenosis secondary to mechanical compression of the vertebral artery during head rotation. BHS is associated with a multifactorial etiology; however, in most cases, this condition is attributed to degenerative changes. A 53-year-old man visited our hospital for the evaluation of fainting and dizziness episodes that occurred when he turned his head. Evaluation as an outpatient in the Department of Neurology showed a positive result on the Frenzel goggle test. Transfemoral cerebral angiography performed at the Department of Neurosurgery revealed stenosis of the proximal right vertebral artery. Complete occlusion of the vertebral artery was observed, and the head was turned to the right. Decompression and fusion were performed, and the contributory lesion was completely removed. Postoperative imaging confirmed complete removal of the spur and sufficient vertebral artery decompression; the patient's symptoms resolved postoperatively.

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.

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.

Bow Hunter's Syndrome: A rare cause of vertebrobasilar insufficiency

Bow Hunter's syndrome, also referred to as rotational occlusion of the vertebral artery, is caused by dynamic compression of a patient's dominant vertebral artery. We reported a case of successful clinical and imaging work up of Bow Hunter's Syndrome that occurred in a 79-year-old female patient. We discussed the clinical presentation, imaging findings, and subsequent management options of this rare syndrome. The gold standard for diagnosis is dynamic cerebral angiography, which allows the reproduction of symptoms with head turn greater than 30-45 degrees. Subsequent management is based on the underlying etiology causing rotational compression.

The experience of surgery and endovascular procedure of cerebrovascular disease in the hybrid operating room; Multi-axis robotic C-arm DSA system

Objective

To report on combined surgical and/or endovascular procedures for cerebrovascular disease in a hybrid operating room (OR).

Methods

Between October 2016 and June 2020, 1832 neurosurgical procedures were performed in a hybrid OR. Our institution’s hybrid OR consists of a multi-axis robotic C-arm monoplane digital subtraction angiography (DSA) system with an operating table, 3D-rotational DSA, cone-beam computed tomography (dyna CT), and real-time navigation software. Procedures were categorized into six categories according to purpose: (1) simple diagnosis and follow-up, (2) simple endovascular procedure, (3) combination of surgery and endovascular procedures, (4) rescue surgery after endovascular procedures, (5) frameless stereotactic procedure, and (6) other surgeries requiring C-arm.

Results

Of 1832 neurosurgical procedures in the hybrid OR, 1430 were simple diagnosis and follow-up cases, 330 simple endovascular procedures, 8 combination of surgery and endovascular procedures, 15 rescue after endovascular procedure, 40 frameless stereotactic procedures, and 9 other surgeries. Eight cases of combination of surgery and endovascular procedures, safely performed without wasting time on patient transfer, were performed in seven bypass end endovascular procedures and one case of bow-hunter syndrome in complex cerebrovascular disease. After embolization, craniotomy (or craniectomy) and intracerebral hemorrhage removal were performed in eight patients in-situ. Of the 40 frameless stereotactic procedure, 37 were extraventricular drainage before/after coil embolization in subarachnoid hemorrhage patients. They all mounted conduits in their planned locations.

Conclusions

A hybrid OR for combined endovascular and surgical procedures represents a safe and useful strategy for cerebrovascular disease. In hybrid ORs various neurosurgical procedures can be safely and conveniently performed. Hybrid OR will pioneer a new era in neurosurgical procedures.

Anterolateral approach for subaxial vertebral artery decompression in the treatment of rotational occlusion syndrome: results of a personal series and technical note

OBJECTIVES

To report the results of a retrospective series and a technical note about the anterolateral approach for the treatment of the rotational occlusion syndrome (ROS) involving the subaxial V2 segment of the vertebral artery (VA).

METHODS

We retrospectively reviewed the data of a cohort of patients that underwent an anterolateral approach to decompress the VA as they suffered from ROS secondary to a subaxial compression. A dynamic study with ultrasonography, CT, MRI, and catheter-based angiography were obtained in all cases. Severe symptomatology and cerebellar-brainstem strokes were indications for surgery. The anterolateral approach involved a pre-sternocleidomastoid precarotid exposure. The retro-longus colli and pre-scalenic corridors were used to access the C5-C6 and C3-C4 segment, respectively, and to perform the decompression.

RESULTS

Twelve patients were treated. Recurrent drop attacks were present in all cases. Osteophytes at C5 and C6 were the most common causes of subaxial VA compression. Anterior decompression stand-alone was performed in all but 1 patient. A recurrent laryngeal nerve palsy and a numbness of the C5 nerve root were the only complications observed, both transient. A satisfactory untethering of the VA with a complete recovery was achieved in all patients, apart from those with severe infratentorial strokes.

DISCUSSION READ

Anterolateral approach allows for an effective and safe treatment of the ROS involving the subaxial portion of the VA. Retro-longus colli and pre-scalenic corridors, developed through a precarotid exposure, have an anatomical rationale in decreasing the risks of complications. Decompression stand-alone is adequate in almost the totality of cases.

Yes, we should abandon pre-treatment positional testing of the cervical spine

Although there seems to be no causality between cervical spine (CS) manipulation and major adverse events (MAE), it remains important that manual therapists try to prevent every potential MAE. Although the validity of positional testing for vertebrobasilar insufficiency (VBI) has been questioned, recently, the use of these tests was recommended. However, based on the low sensitivity of the VBI tests, which may result in too many false-negative results, the VBI tests seem to be less valuable in pre-manipulative screening. Moreover, because the VBI tests are unable to consistently produce a decreased blood flow in the contralateral vertebral artery in (healthy people), the underlying mechanism of the test may not be a valid construct. There are numerous cases reporting MAE after a negative VBI test, indicating that the VBI tests do not have a role in assessing the risk of serious neurovascular pathology, such as cervical arterial dissection, the most frequently described MAE after CS manipulation. Symptoms of VBI can be identified in the patient interview and should be considered as red flags or warning signs and require further medical investigation. VBI tests are not able to predict MAE and seem not to have any added value to the patient interview with regard to detecting VBI or another vascular pathology. Furthermore, a negative VBI test can be wrongly interpreted as 'safe to manipulate'. Therefore, the use of VBI tests cannot be recommended and should be abandoned.

Subaxial Vertebral Artery Rotational Occlusion Syndrome: An Overview of Clinical Aspects, Diagnostic Work-Up, and Surgical Management

Extrinsic compression of the subaxial vertebral artery (VA) may cause rotational occlusion syndrome (ROS) and contribute to vertebrobasilar insufficiency potentially leading to symptoms and in severe cases, to posterior circulation strokes. The present literature review aimed to report the main clinical findings, diagnostic work-up, and surgical management of the subaxial VA-ROS, the diagnosis of which can be difficult and is often underestimated. An illustrative case is also presented. A thorough literature search was conducted to retrieve manuscripts that have discussed the etiology, diagnosis, and treatment of ROS. Total 41 articles were selected based on the best match and relevance and mainly involved case reports and small cases series. The male/female ratio and average age were 2.6 and 55.6±11 years, respectively. Dizziness, visual disturbances, and syncope were the most frequent symptoms in order of frequency, while C5 and C6 were the most affected levels. Osteophytes were the cause in >46.2% of cases. Dynamic VA catheter-based angiography was the gold standard for diagnosis along with computed tomography angiography. Except in older patients and those with prohibitive comorbidities, anterior decompressive surgery was always performed, mostly with complete recovery, and zero morbidity and mortality. A careful neurological evaluation and dynamic angiographic studies are crucial for the diagnosis of subaxial VA-ROS. Anterior decompression of the VA is the cure of this syndrome in almost all cases.