- Department of Neurosurgery, Ehime University School of Medicine, Ehime, Japan.
Akihiro Inoue, Department of Neurosurgery, Ehime University School of Medicine, Ehime, Japan.
DOI:10.25259/SNI_786_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Seiji Shigekawa, Akihiro Inoue, Masahiko Tagawa, Daisuke Kohno, Takeharu Kunieda. Utility of O-arm navigation for atlantoaxial fusion with Bow Hunter’s syndrome. 06-Sep-2021;12:451
How to cite this URL: Seiji Shigekawa, Akihiro Inoue, Masahiko Tagawa, Daisuke Kohno, Takeharu Kunieda. Utility of O-arm navigation for atlantoaxial fusion with Bow Hunter’s syndrome. 06-Sep-2021;12:451. Available from: https://surgicalneurologyint.com/surgicalint-articles/11090/
Background: In spinal instrumentation surgery, safe and accurate placement of implants such as lateral mass screws and pedicle screws should be a top priority. In particular, C2 stabilization can be challenging due to the complex anatomy of the upper cervical spine. Here, we present a case of Bow Hunter’s syndrome (BHS) successfully treated by an O-arm-navigated atlantoaxial fusion.
Case Description: A 53-year-old male presented with a 10-year history of repeated episodes of transient loss of consciousness following neck rotation to the right. Although the unenhanced magnetic resonance imaging showed no pathological findings, the MR angiogram with dynamic digital subtraction angiography revealed a dominant left vertebral artery (VA) and hypoplasia of the right VA. The latter study further demonstrated significant flow reduction in the left VA at the C1-C2 level when the head was rotated toward the right. With these findings of BHS, a C1-C2 decompression/posterior fusion using the Goel-Harms technique with O-arm navigation was performed. The postoperative cervical X-rays showed adequate decompression/fixation, and symptoms resolved without sequelae.
Conclusion: C1-C2 posterior decompression/fusion effectively treats BHS, and is more safely/effectively performed utilizing O-arm navigation for C1-C2 screw placement.
Keywords: Atlantoaxial fusion, Bow hunter’s syndrome, Laminar screw, O-arm navigation system, Surgical treatment
Bow hunter’s syndrome (BHS) involves the occurrence of vertebrobasilar symptoms following mechanical compression of the dominant vertebral artery (VA) (i.e. contralateral VA hypoplasia) and can result in symptomatic infarctions of the cerebellum and/or brain stem.[
Clinical presentation and radiological evaluation of BHS
A 53-year-old male presented with a 10-year history of repeated episodes of transient loss of consciousness following rotation of the head to the right. He did not describe any other symptoms and had no history of trauma. The MR fluid-attenuated inversion recovery study was normal [
Preoperative dynamic digital subtraction angiography (a-1: neutral head position, a-2: head rotation to the right side) and three-dimensional computed tomography angiography (b-1: neutral head position, b-2: head rotation to the right side). When the head is rotated to the right side, near-complete occlusion of the left vertebral artery is observed at the C1-C2 level (white and black arrow). Cervical X-ray (lateral view) and dynamic X-ray images. Lateral view in the neutral position shows an atlantodental interval of 3.2 mm (c-1) and in the flexed position shows an atlantodental interval of 2.4 mm (c-2).
Surgery for BHS
The patient underwent an IRB-approved C1-C2 posterior fusion using O-arm navigation. C1 lateral mass screws were placed using the Goel-Harms technique [
Operative imaging for C1-C2 posterior fusion using O-arm navigation systems. (a) C1 lateral mass screws are placed using the Goel-Harms technique. (b and c) For C2 screw placement, a pedicle screw is inserted on the right side (b). However, intraoperative real-time planning using the O-arm navigation system shows a risk of left vertebral artery injury during tapping the tract for left pedicle screw insertion (white arrow: transverse foramen; yellow arrowhead: trajectory on the navigation system) (c). (d) We switch to performing a translaminar technique for left-side fixation of C2 and the laminar screws are inserted.
BHS is caused by posterior circulation insufficiency resulting from occlusion or compression of one of the VA during rotation of the head, most typically occurring at the C1-C2 level.[
Screw placement facilitated with O-arm intraoperative navigation
The C1-C2 posterior fusion technique offers higher fusion rates and obviates the need for rigid immobilization. However, Acosta et al. reported that 24% of C1-C2 could not have been safely placed without intraoperative imaging.[
We have described a case of BHS in successfully treated with decompression/fusion using an O-arm navigation for C1-C2 screw placement.
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