Endoscopic Endonasal Odontoidectomy Preserving Atlantoaxial Stability: a Pediatric Case.

We illustrate endoscopic endonasal odontoidectomy for the Chiari-I malformation respecting craniovertebral junction (CVJ) stability.  Case report of a 12-year-old girl affected by the Chiari-I malformation. Magnetic resonance imaging (MRI) showed tonsillar herniation, basilar invagination, and dental retroversion, causing angulation and compression of the bulbomedullary junction. Patient underwent endoscopic third ventriculostomy (ETV) with reduction of ventricular size and resolution of gait disturbances, but she complained the Valsalva-induced headaches, hiccup, and dysesthesias in the lower limbs. Endoscopic endonasal odontoidectomy was chosen to decompress the cervicomedullary junction.  The research was conducted at University Hospital "Ospedale di Circolo," Department of Neurosurgery at Varese in Italy.  Patients were from neurosurgical and ENT (ear, nose, and throat) skull base team.  A bilateral paraseptal approach was performed, using a four-hand technique. After resection of posterior edge of the nasal septum, the choana is entered and a rhinopharynx muscle-mucosal flap is dissected subperiosteal and transposed in oral cavity. The CVJ is exposed and, using neuronavigation and neuromonitoring, odontoidectomy is fulfilled until dura is reached, preserving the anterior arch of C1. Reconstruction is obtained suturing the flap previously harvested.  Postoperative course was unremarkable and the patient experienced improvement of symptoms. Postoperative MRI documented the appearance of tight cerebrospinal fluid (CSF) film anterior to bulbomedullary junction and in retrotonsillar spaces, opening of the bulbomedullary angle, and slight tonsils reduction. No CVJ instability was occurred with any need of posterior fixation.  Endoscopic endonasal odontoidectomy is a feasible approach for CVJ malformation. In this case, bulbar decompression was achieved preserving CVJ stability and avoiding posterior fixation. The link to the video can be found at: https://youtu.be/VIobocHfCuc .