However, in three of these patients, reocclusion of the operated VA was recognized after surgery and two of them had more severe neurologic symptoms than preoperatively. 9) reported results for nine patients of bow hunter's stroke treated with posterior decompression of VA. Decompression of the VA at the C1-2 level by either anterior or posterior approach has been used for affected patients 4, 9, 12, 14). Treatment alternatives for rotational compression of the atlantoaxial portion of the VA have included verbal warnings or braces to restrict head and neck rotation, surgical fusions to prevent atlantoaxial rotation, and decompression of the VA at the C1-2 level. Rotational stenosis of the VA at its second cervical segment (from C3 to C6) is very rare and osteophyte formation seems to play major role in these cases 10). This is attributed to the VA being anchored by fibrous band just before its entrance into the transverse foramen and head rotation leads to stenosis of the VA at the tethered C6 level 10). The second most site of VA compromise is its entrance into the C6 transverse foramen 8).
![rf online skin bow rf online skin bow](http://2.bp.blogspot.com/-Bhzidn9to-Y/TzZI0qHUMHI/AAAAAAAAAB4/61ozhILyMTI/s1600/Resources0001.jpg)
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 segment of vertebral artery between C-1 and C-2 can be narrowed or occluded in the process 2). 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. 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). 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). In most reported cases, patients with ischemic attacks induced by rotational occlusion of one VA had an opposite VA that was hypoplastic, stenotic, or occluded. However, temporary positional occlusion of one VA during daily activities rarely produces major effects on posterior circulation blood flow. It is a common finding on angiography that head rotation produces stenosis or occlusion of a contralateral VA. Head rotation was reduced by approximately 30% compared to her preoperative status.īow hunter's stroke is a symptomatic vertebrobasilar insufficiency caused by stenosis or occlusion of the VA with head rotation 12). The patient was neurologically completely asymptomatic in follow-up. Lateral arthrodesis was performed by decorticating the exposed surfaces of the C1-2 joints with a high-speed drill and then packing cancellous iliac crest autograft over these joints ( Fig. The rod was placed into the polyaxial screw heads and secured in position. A contoured horse-shoe shaped rod was secured to the C-1 arch using sublaminar cables. The C-2 pars screw entry point and trajectory was oriented using anatomical landmarks, as described by Harms and Melcher 7). Dissection was continued laterally over the posterior arch of C-1, exposing the VA in the vertebral groove on the C-1 arch. A bilateral subperiosteal dissection of the paraspinal musculature was performed to expose the lateral margins of the facet joints at the C2-3.
![rf online skin bow rf online skin bow](http://3.bp.blogspot.com/-WY88k5vqa6E/TmGIzG4vIGI/AAAAAAAAAB0/FQ84efRbtC8/s1600/SpearDHLegacy2.jpg)
A linear skin incision was made from the occipital protuberance to the spinous process of C3. The patient was placed in prone position while the head was secured in a Mayfield holder and maintained in a neutral position.
![rf online skin bow rf online skin bow](https://1.bp.blogspot.com/-5QTIQDmZyjM/WpAREfTF4-I/AAAAAAAACN4/qhgHxMfpQA0jkiQ4LPh6yH9tIEAdphOVACK4BGAYYCw/s400/acc_ranger.jpg)
Posterior fixation and fusion of C1-2 was recommended to reduce the potential serious neurologic deficit from the vertebrobasilar stroke. B : With her head rotated 45 degrees to the right, the left vertebral artery showing severe stenosis at C2 level (black arrow). Left vertebral angiography A : With head rotation to the left, left vertebral artery shows no stenosis.