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Bow hunter’s syndrome treated by anterior decompression with fusion: A case report
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How to cite this article: Morita K, Tamase A, Abe H, Mori K, Fukui I, Yamashita R, et al. Bow hunter’s syndrome treated by anterior decompression with fusion: A case report. Surg Neurol Int 2022;13:115.
Abstract
Background:
Bow hunter’s syndrome (BHS) is a rare condition induced by occlusion or compression of the vertebral artery (VA) during head movement or rotation. Here, we report a patient with BHS effectively treated with an anterior cervical discectomy and fusion (ACDF).
Case Description:
A 75-year-old male experienced recurrent embolic strokes to the posterior circulation. This was attributed angiographically to transient stenosis of the right VA due to a right-sided C5-C6 osteophyte when the head was rotated to the right; the stenosis was improved when the patient rotated his head to the left. The patient successfully underwent a C5-C6 ACDF for removal of the right-sided lateral osteophyte which resulted in no further transient right-sided VA occlusion.
Conclusion:
Following a C5-C6 ACDF for removal of a right lateral osteophyte, a 75-year-old male’s intermittent right-sided VA occlusion responsible for multiple posterior circulation emboli was relieved.
Keywords
ACDF
Bow hunter’s syndrome
Osteophyte
Repeated infarction
INTRODUCTION
Bow hunter’s syndrome (BHS) is a rare condition characterized by vertebrobasilar insufficiency associated with transient occlusion typically of the dominant vertebral artery (VA) due to bony impingement (i.e., osteophyte formation) during head movement/rotation.[2,4] Common symptoms of BHS include positional vertigo, dysarthria, dysphagia, nausea, and syncope.[4] Surgery for BHS usually includes decompression with/without fusion. Here, we successfully treated a 75-year-old male with BHS responsible for multiple/recurrent posterior cerebral circulation emboli/infarctions by performing a C5-C6 anterior cervical discectomy/fusion (ACDF) with resection of the offending right-sided C5-C6 osteophyte.
CASE PRESENTATION
A 75-year-old male presented with the left upper limb weakness. The brain magnetic resonance images (MRI) and MR angiography (MRA) showed evidence of multiple embolic infarctions from the right VA to the right cerebellum, right parieto-occipital junction, and right occipital lobe. The cervical MRI documented significant spinal stenosis and contrast-enhanced computed tomography (CE-CT) revealed a large lateral right-sided C5-C6 osteophyte. Angiography showed it transiently compressed the right VA when the head was rotated to the right, but with relief of VA compression, when the head was rotated to the left [Figures 1-3].
Surgery
To prevent recurrent thromboembolic events, the right VA was decompressed by performing a routine C5-C6 ACDF with excision of the right-sided C5-C6 osteophyte; this successfully decompressed the right VA [Figures 4a and b]. Patency and sufficient blood flow through the right VA were confirmed intraoperatively utilizing indocyanine green video angiography [Figure 4c]. As the preoperative MRI had also demonstrated spinal canal stenosis at C4-C5, an additional C4-C5 ACDF was performed. Following these decompressions, threaded titanium cages filled with bone graft substitutes were inserted into the C4/5 and C5/6 intervertebral spaces [Figure 5a].
Postoperative confirmation of VA decompression
The patient’s postoperative course was uneventful. Sufficient right-sided C5-C6 osteophyte resection and right VA decompression were confirmed on the postoperative CECT and 3D-CTA [Figure 5b]. The postoperative MRA documented right VA patency along with no further evidence of cerebellar infarctions awhile [Figure 5c]. Angiography 3 months later again demonstrated no residual right-sided C5-C6 VA stenosis in any position and the MRI showed no additional/recurrent posterior circulation strokes [Figure 6].
DISCUSSION
BHS
BHS is characterized by transient symptoms induced by rotation or extension of the neck resulting in occlusion/stenosis of a VA, and resultant compromises to the posterior circulation. Symptoms typically include syncope, vertigo, dizziness, impaired vision, paresis, and pain in the extremities.[1,2] Most cases of VA stenosis involve the V2 (58%) or V3 (36%) VA segments. In our patient, the right VA was compressed by a right-sided osteophyte at the C5/6 level. On multiple MRA/ CTA studies, the right-sided VA blood flow was transiently impaired by head rotation to the right (ipsilateral) side at the C5-C6 level, partially compromised in the neutral position, but relieved by rotation of the head to the left. Thrombus formation in the transiently compressed VA, as seen in our patient, can result in distal embolization/strokes; with emboli extending into the posterior cranial circulation. Thus, for patients presenting with repeated ischemic posterior circulation events, BHS with transient VA stenosis must be considered and remediated.
The treatment of BHS
The treatments for BHS include anterior cervical discectomy/ corpectomy fusion with decompression/removal of osteophytes (90.6%), posterior decompression with/without fusion addressing occlusions of the V2 or V3 segments of the VA, or endovascular management (i.e., stenting for significant tortuosity of the VA without bony compression).[3,5]
CONCLUSION
A 75-year-old male with BHS due to a right-sided C5-C6 osteophyte that would transiently compress the right VA when the patient’s head was rotated to the right, presented with repeated cerebral/cerebellar posterior circulation infarctions. Following a routine C5-C6 ACDF with the right-sided osteophyte resection, the transient right VA occlusion was alleviated, and the patient’s symptoms were permanently resolved.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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