Decompression of the vertebral artery for bow-hunter's stroke

Abstract

A case of cerebellar infarction induced by repeated neck rotation ("bow-hunter's stroke") is reported. The most likely mechanism is that repeated rotational neck movement brings about thickening of the atlanto-occipital membrane, fixing the vertebral artery in the vascular groove of the atlas. The vertebral artery is thus pinched at the time of neck rotation, leading to thrombus formation. Embolization results in cerebellar infarction. Surgical decompression of the vertebral artery at the level of the atlas in this case relieved the symptoms, and postoperative angiography demonstrated good flow within the vertebral artery even when the neck was rotated. It was not necessary to restrict the patient's neck movement postoperatively.

Bow hunter’s stroke due to instability at the uncovertebral C3/4 joint

“…Surgical modalities include decompression of the vertebral artery, C1-2 posterior fusion, and decompression of the VA with anterior cervical fusion. Of course, the choice of treatment for each patient must be individualized and depends on the underlying pathology [2,5,6,[17][18][19][20]. In the present case, stretch compression of the VA at C3-4 with neck rotation was considered to be the main cause of rotational vertebrobasilar insufficiency.…”

“…Anticoagulation may alleviate symptoms [5,7], but it is only palliative and does not directly treat the underlying pathology [4,5,11,17,18]. Surgery is an option for patients who fail to respond to conservative therapy [18].…”

Bow Hunter's Stroke Caused by a Severe Facet Hypertrophy of C1-2

“…The VAs at the atlantoaxial level are particularly prone to mechanical compression during head and neck rotation because of its unique relationship to the surrounding transverse foramina, paravertebral muscles, and fibrous ligaments 1,5,6) . Axial rotation at the C1-2 level may cause VA occlusion within normal range of motion due to the relatively fixed position of the artery within the posterior arch of the atlas 5,14) . Head rotation to the right results in fixation of the right atlantoaxial joint, while the atlas moves forward on the axis on the left side.…”

“…The segment of vertebral artery between C-1 and C-2 can be narrowed or occluded in the process 2) . Atlantoaxial instability, ossification or hypertrophy of the atlantooccipital membrane, tightness of the paravertebral musculature, or severe changes of spondylosis may also contribute to vertebral artery compression 3,5,6,8,13,14) . The second most site of VA compromise is its entrance into the C6 transverse foramen 8) .…”

“…This rare and unique symptomatic vertebrobasilar insufficiency or infaction is named "bow hunter's stroke" after the first description by Sorensen 15) . Various pathologic conditions have been reported as causes of bow hunter's stroke 3,[5][6][7]11,14) . We report a 71-year-old woman with rotatory occlusion of VA from rare massive facet hypertrophy at the C1-2 level treated by C1-2 posterior fixation and fusion.…”