Endoscopic Transnasal Transodontoid Treatment of a Ruptured Anterior Spinal Artery Aneurysm

Introduction: Isolated spinal artery aneurysms are a rare cause of subarachnoid hemorrhage (SAH). Patients have been treated conservatively or with surgical clipping when amenable. Endovascular treatment is limited due to technical difficulty and risk of cord infarction. We present the first case of a ruptured anterior spinal artery aneurysm in the cervical spine treated through an endoscopic transnasal transodontoid approach.

Case Report: A 49-year-old female presented with sudden-onset severe headache and nausea. She was Hunt–Hess grade 3 and Fisher's grade 4 with IVH and SAH in the premedullary cistern. Initial DSA revealed no intracranial aneurysms. Seven days later, she had a severe headache and a CT showed new IVH in the fourth ventricle. Her second DSA showed a small (1 × mm 1 × mm 1.3 mm) aneurysm arising from the proximal anterior spinal artery, as well as angiographic vasospasm. The decision was made to undergo C1 to C2 posterior instrumented fusion and then an anterior transnasal transodontoid approach for anterior spinal artery aneurysm wrapping.

The patient was positioned supine, under general anesthesia, the head placed in a fixation device and slightly tilted to the left. Image guidance was used. A 0-degree endoscope was used and a nasoseptal flap (NSF) was raised. The posterior nasal septum was removed from the sphenoid rostrum. The basopharyngial fascia was peeled down from the sphenoid floor to the inferior clivus, then toward the anterior arch of C1. A flap was made in the nasopharynx to expose the paraspinal muscles which were reflected laterally, the C1 anterior arch was visualized and drilled down until the odontoid process was seen. The odontoid process was then drilled down with a high-speed diamond burr to the C2 vertebral body. The inferior aspect of the C1 anterior arch was left, so that the pharyngobasilar fascia could be buttressed and secured inferiorly. The tectorial membrane was removed using a Tru-Cut and 2-mm Kerrison's rongeours. The dura was then visualized, opened, and reflected inferiorly. The anterior spinal artery aneurysm was exposed deemed too small to be clipped. It was wrapped with wisps of cotton then secured using a fibrin sealant (Tiseel).

The dura was repaired with intradural DuraGen followed by an extradural DuraGen onlay. An abdominal fat graft was packed into the skull base defect. The pharyngobasilar fascia was reflected up over the fat graft and sutured superiorly. The fascia and surrounding mucosa were cauterized to create a raw surface. The NSF was laid over the raw surface of the clivus and pharyngobasilar fascia. Surgicel was laid down followed by Tisseel. The entire construct was buttressed with nasopore followed by the nasal Foley balloon. The patient tolerated the procedure well and was extubated.

Conclusion: Spinal artery aneurysms should be considered in cases of intracranial SAH when no other source is found. The endoscopic transnasal transodontoid route provides an effective corridor to the ventral spinal cord and was used effectively to treat a twice ruptured anterior spinal artery aneurysm. Cotton wrapping with fibrin sealant was enough to protect against aneurysm growth or rerupture with 2 years of follow-up.

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021