Delayed subarachnoid hemorrhage following failed odontoid screw fixation

Case report

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Iatrogenic vascular injury is a rare but potentially devastating complication of cervical spine instrumentation. The authors report on a patient who developed an anterior spinal artery pseudoaneurysm associated with delayed subarachnoid hemorrhage after undergoing odontoid screw placement 14 months earlier. This 86-year-old man presented with spontaneous subarachnoid hemorrhage (Fisher Grade 4) and full motor strength on neurological examination. Imaging demonstrated pseudarthrosis of the odontoid process, extension of the odontoid screw beyond the posterior cortex of the dens, and a pseudoaneurysm arising from an adjacent branch of the anterior spinal artery. Due to the aneurysm's location and lack of active extravasation, endovascular treatment was not attempted. Posterior C1–2 fusion was performed to treat radiographic and clinical instability of the C1–2 joint. Postoperatively, the patient's motor function remained intact. Almost all cases of vascular injury related to cervical spine instrumentation are recognized at surgery. To the authors' knowledge, this is the first report of delayed vascular injury following an uncomplicated cervical fixation. This case further suggests that the risk of this phenomenon may be elevated in cases of failed fusion.

Abbreviations used in this paper: SAH = subarachnoid hemorrhage; VA = vertebral artery.

Article Information

Address correspondence to: Nicholas Theodore, M.D., c/o Neuroscience Publications, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 West Thomas Raod, Phoenix, Arizona 85013. email:

Please include this information when citing this paper: published online March 11, 2011; DOI: 10.3171/2011.1.SPINE10561.

© AANS, except where prohibited by US copyright law.



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    A sagittal CT scan (left) obtained at the time of the patient's initial injury demonstrates a minimally displaced Type 2 odontoid fracture. A postoperative lateral radiograph (right) demonstrates placement of the odontoid screw. It is unclear from this image whether the posterior odontoid cortex has been violated.

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    Admission axial head CT scan demonstrates SAH with blood predominantly located in the prepontine cistern, near the tip of the odontoid screw.

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    Sagittal soft-tissue (left) and bone window (right) cervical spine CT scans demonstrate pseudarthrosis of the odontoid process and extension of the odontoid screw beyond the tip of the dens near a preponderance of subarachnoid blood. The subarachnoid blood is best visualized in the soft-tissue window, while the pseudarthrosis and screw are most clear in the bone window.

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    Lateral (A) and anteroposterior (C) working angles on VA angiography show an anterior pseudoaneurysm (asterisk) of the spinal artery branch and proximity of the tip of the odontoid screw (arrow). The respective unsubtracted views (B and D) of the same angles provide a reference for localization of the odontoid screw tip.

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    Postoperative sagittal CT scan of the cervical spine demonstrates posterior stabilization with C-1 lateral mass screws and C-2 pars screws.

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    Sagittal (left) and coronal (right) CT angiograms of the patient's neck at discharge, 3 weeks following C1–2 stabilization, demonstrating a stable posterior construct (left) and no evidence of pseudoaneurysm growth (right).



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