Favorable Long-Term Outcomes for Positional Vertebral Artery Occlusion with Treatment Strategy Prioritizing Spinal Fusion Surgery

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.

A Surgical Case of Bow Hunter’s Syndrome Diagnosed by Cervical Rotational MRA

Bow hunter's syndrome is an ischemic manifestation of vertebrobasilar artery (VA) insufficiency due to stenosis or occlusion of the contralateral VA at the bony elements of the atlas and axis during neck rotation. In early reports, VA stenosis at the craniovertebral junction was the main cause, but later, symptoms due to VA occlusion at the middle and lower cervical vertebrae were also included in this pathology. Although the confirmed diagnosis is usually determined by dynamic digital subtraction angiography (DSA), we have experienced a method of minimally invasive MR angiogram (MRA) that provides the same diagnostic value as DSA and would like to present it here. The patient was a 61-year-old man who had been visiting the outpatient clinic for cervical spondylosis due to neck pain for 9 months. When he rotated his neck to the left side, dizziness and syncope appeared. Initial MRA in the neutral position did not show any steno-occlusive changes in the vertebrobasilar artery. In our hospital, repeated MRA with the neck rotated 45 degrees to the left demonstrated ipsilateral left VA severe stenosis. Subsequent DSA showed the same findings, with occlusion of the left VA. CT of the cervical spine revealed a ventral C3/4 osteophyte within the foramen. Based on these findings, instability at the C3-4 during head rotation was considered the cause of the vertebrobasilar insufficiency. The patient underwent anterior discectomy and fusion (ACDF) at the C3/4 level using a cylindrical titanium cage. Immediately after the surgery, the patient's symptoms improved dramatically and did not appear even when the neck were fully rotated to the left. More than 5 years have passed since the surgery, and the patient is still in good health.

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.