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

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.

Challenges of anaesthetising a child with Bow Hunter's syndrome and dilated cardiomyopathy for occipitocervical fusion

Paediatric Bow Hunter's syndrome (BHS), or rotational vertebral artery syndrome, is a rare cause of posterior circulation insufficiency in children. It results from mechanical obstruction of the vertebral artery by the transverse process of cervical vertebrae resulting in vertebrobasilar insufficiency during the neck rotation to the sides. Paediatric dilated cardiomyopathy (DCM) is a rare myocardial disease that presents with ventricular dilatation and cardiac dysfunction. This case report describes the successful anaesthetic management of an boy with BHS due to atlantoaxial dislocation and DCM. The child was anaesthetised by keeping the following anaesthetic goals in mind such as maintenance of the heart rate, rhythm, preload, afterload and contractility close to the baseline for both DCM and BHS. Haemodynamic management with optimal fluids, inotrope and a vasopressor and titrating its volume and doses using multimodal haemodynamic monitoring while keeping both cardio and neuroprotective strategies, and the multimodal analgesia techniques helped the child for faster recovery.

Advances in the Diagnosis and Treatment of Pediatric Arterial Ischemic Stroke

Though rare, stroke in infants and children is an important cause of mortality and chronic morbidity in the pediatric population. Neuroimaging advances and implementation of pediatric stroke care protocols have led to the ability to rapidly diagnose stroke and in many cases determine the stroke etiology. Though data on efficacy of hyperacute therapies, such as intravenous thrombolysis and mechanical thrombectomy, in pediatric stroke are limited, feasibility and safety data are mounting and support careful consideration of these treatments for childhood stroke. Recent therapeutic advances allow for targeted stroke prevention efforts in high-risk conditions, such as moyamoya, sickle cell disease, cardiac disease, and genetic disorders. Despite these exciting advances, important knowledge gaps persist, including optimal dosing and type of thrombolytic agents, inclusion criteria for mechanical thrombectomy, the role of immunomodulatory therapies for focal cerebral arteriopathy, optimal long-term antithrombotic strategies, the role of patent foramen ovale closure in pediatric stroke, and optimal rehabilitation strategies after stroke of the developing brain.

Vascular flow limitations affecting the cervico-cranial region: Understanding ischaemia

BACKGROUND

Blood flow and brain ischaemia have been of interest to physical therapists for decades. Despite much debate, and multiple publications around risk assessment of the cervical spine, more work is required to achieve consensus on this vital, complex topic. In 2020, the International Federation of Orthopaedic Manipulative Physical Therapists (IFOMPT) Cervical Framework adopted the dubious terminology 'vascular pathologies of the neck', which is misleading, on the premise that 1) not all flow limitations leading to ischaemia, are associated with observable blood vessel pathology and 2) not all blood flow limitations leading to ischaemia, are in the anatomical region of the 'neck'.

OBJECTIVE

This paper draws upon the full body of haemodynamic knowledge and science, to describe the variety of arterial flow limitations affecting the cervico-cranial region.

DISCUSSION

It is the authors' contention that to apply clinical reasoning and appropriate risk assessment of the cervical spine, there is a requirement for clinicians to have a clear understanding of anatomy/anatomical relations, the haemodynamic science of vascular flow limitation, and related pathologies. This paper describes the wide range of presentations and haemodynamic mechanisms that clinicians may encounter in practice. In cases with a high index suspicion of vascular involvement or an adverse response to assessment/intervention, appropriate referral should be made for further investigations, using consistent terminology. The term 'vascular flow limitation' is proposed when considering the range of mechanisms at play. This fits the terminology used (in vascular literature) at other anatomical sites and is understood by medical colleagues.

Cryptogenic posterior circulation stroke in children

We aimed to evaluate the percentage of posterior circulation arterial ischaemic stroke (PCAIS) caused by craniovertebral junction (CVJ) anomalies and describe their clinical course. Children admitted to a tertiary care paediatric hospital with PCAIS between July 2017 and December 2020 were assessed retrospectively for disease aetiology. We reviewed the clinical, radiological, and surgical details of children with evidence of CVJ anomalies. Fourteen (24.1%) of 58 children admitted with arterial ischaemic stroke had posterior circulation involvement. The mean age of patients presenting with posterior circulation stroke was 6 years 6 months (range 3 months-15 years), 11 were male. Six of 14 cases with PCAIS were due to CVJ anomaly, their ages ranged from 4 months to 15 years (two age ranges were noted, 4 months-4 years and 11-15 years), four were male. Two children had atlantoaxial dislocation with basilar invagination, two had Bow Hunter syndrome with Chiari malformation type 1 (one with completed stroke), one had Chiari malformation type 1 alone, and one presented with Farber disease with proatlas segmentation anomaly in CVJ. The time lag to stroke and CVJ diagnosis ranged from 2 weeks to 24 months. A dynamic angiogram was required to evaluate biomechanical changes on scans with inconclusive findings on standard stroke imaging. CVJ anomalies are an important treatable cause of paediatric posterior circulation stroke. Cervical spine x-ray in flexion and extension should be done in all patients with posterior circulation stroke beyond the acute period. In cryptogenic aetiology, provocative angiography with guarded neck rotation should be considered to evaluate possible dynamic vertebral artery compression.

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.

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.

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.