Endoscopic Endonasal Approach to the Upper Cervical Spine for Decompression of the Cervicomedullary Junction Following Occipitocervical Fusion

Abstract

Basilar invagination is defined as abnormal upward and/or posterior displacement of the odontoid leading to ventral compression of the cervicomedullary junction. This condition leads to lower cranial neuropathies, sensorimotor deficits, and myelopathy. These symptoms can persist even after posterior decompression, which is an indication for ventral decompression. Transoral approaches to the upper cervical spine carry significant morbidity, limiting their utility. The endonasal approach to the upper cervical spine presents an alternative for patients with amenable anatomy. In this report, we present a case of a patient with type 1 Chiari malformation with persistent symptoms despite adequate posterior decompression through suboccipital craniectomy and C1 laminectomy. A retroflexed odontoid and dorsal clival bone lip contributed to persistent cervicomedullary compression. To address this, we performed a 2-stage procedure: an occiput-to-C4 fusion followed by endoscopic endonasal approach for dorsal clivusectomy, C1 anterior arch resection, and odontoidectomy. In the associated video, Supplemental Digital Content 1 (http://links.lww.com/CLINSPINE/A52), we demonstrate the step-by-step approach for this anterior approach including positioning, dissection through the nasopharyngeal fascia, identification of bony landmarks using an intraoperative CT scanner with 3-dimensional navigation guidance, and drilling/bony decompression of the dorsal clivus, C1, and C2. We also discuss key pearls, pitfalls, and preoperative/postoperative considerations critical to successful outcomes.

Narrative review of intraoperative imaging guidance for decompression-only surgery

“…Choudhri et al used navigation in order to properly decompress foramen magnum/odontoid for basilar invagination through a transnasal approach (11). Similarly, Hussain et al utilized navigation in a two-stage procedure for decompression of the cervicomedullary junction for Chiari malformations via a transoral approach (12).…”

Endoscopic endonasal odontoidectomy for the treatment of basilar invagination

“…In regard to some anatomical considerations, the palatine line, which is in green, is very helpful to determine the feasibility of the endonasal approach (de Almeida et al, 2009), where a line is drawn in a sagittal view, along the plane of the hard palate in the direction of the CVJ. If this lesion is located above this line, the endonasal endoscopic approach is preferred, as the working corridor is above the hard palate (Hussain et al, 2018;Liu et al, 2015).…”

A Case Report of Complete Dislocation of Atlantoaxial Joint due to a Traumatic and Pathological Axial Lesion

“…2 It is also one of the effective methods to correct upper cervical instability, and effective bone grafting is also a prerequisite for occipitocervical fusion. 3…”