Endoscopic Endonasal Resection of the Odontoid Process as a Standalone Decompressive Procedure for Basilar Invagination in Chiari Type I Malformation

Background: The expanded endonasal approach of the cranio-cervical junction provides comfortable working space while avoiding some of the disadvantages of the transoral route. We report a purely endonasal endoscopic resection of the odontoid process for basilar invagination in a patient with a Chiari type I malformation, without posterior decompression or fusion. Case Report: A 54-year-old female patient presented with cranial nerve and brainstem deficits. CT and MRI showed a Chiari type I malformation and compression of the medulla by basilar invagination of the odontoid process. The tip of the latter was displaced up to the bulbo-pontine sulcus. The odontoid process was resected via the expanded endoscopic endonasal approach, without additional posterior decompression or fusion. The post-operative course was uneventful, including the absence of velopharyngeal insufficiency. Neurological deficits regressed rapidly. The preoperative cervical pain virtually disappeared. At 9 months follow-up, the patient had normal activity with minimal residual neurological deficits. Post-op dynamic radiography and CT showed stability of the cranio-cervical junction. Conclusion: Decompression of the bulbomedullary junction by purely endoscopic transnasal resection of the odontoid process is well tolerated and efficient. Immediate stabilization is not mandatory in all cases of congenital causes of basilar invagination.