Endoscopic endonasal approach to the craniocervical junction: the importance of anterior C1 arch preservation or its reconstruction

Abstract

We report our experience with the endoscopic endonasal approaches (EEA) for different craniocervical junction (CCJ) disorders to analyse outcomes and demonstrate the importance and feasibility of anterior C1 arch preservation or its reconstruction. Between January 2009 and December 2013, 10 patients underwent an endoscopic endonasal approach for different CCJ pathologies at our Institution. In 8 patients we were able to preserve the anterior C1 arch, while in 2 post-traumatic cases we reconstructed it. The CCJ disorders included 4 cases of irreducible anterior bulbo-medullary compression secondary to rheumatoid arthritis or CCJ anomalies, 4 cases of inveterate fractures of C1 and/or C2 and 2 tumours. Pre- and postoperative neuroradiological evaluation was always obtained by magnetic resonance imaging (MRI), computed tomographic (CT) scanning and dynamic cranio-vertebral junction x-ray. Pre- and postoperative neurologic disability assessment was obtained by Ranawat classification for patients with rheumatoid arthritis and by Nurick classification for the others. At a mean follow-up of 31 months (range: 14-73 months), an improvement of at least one Ranawat or Nurick classification level was observed in 6 patients, while in another 4 patients neurological conditions were stable. Radiological follow-up revealed an adequate bulbo-medullary decompression in all patients and a regular bone fusion in cases of C1 and/or C2 fractures. In all patients spinal stability was preserved and none required subsequent posterior fixation. The endoscopic endonasal surgery provided adequate exposure and a low morbidity minimally invasive approach to the antero-medial located lesions of the CCJ, resulting in a safe, effective and well-tolerated procedure. This approach allowed preservation of the anterior C1 arch and the avoidance of a posterior fixation in all patients of this series, thus preserving the rotational movement at C0-C2 segment and reducing the risk of a subaxial instability development.

Keywords: Anterior C1 arch preservation; C2 odontoidectomy; Endoscopic endonasal surgery; Spine instability.

Fig. 1.

Patient 2 (see Table I). A 65-year-old woman, with a long-lasting history of rheumatoid arthritis and recent onset of drop attacks. A, B. Pre-operative sagittal and axial T2 MRI images demonstrating basilar invagination and rheumatoid pannus with resulting severe bulbomedullary compression and associated myelopathy (white arrows). C. Pre-operative axial CT scan showing the peri-odontoid rheumatoid pannus (black arrow). D, E. Post-operative sagittal T1 and axial T2 MRI images showing the adequate spinal cord decompression after odontoidectomy and rheumatoid pannus removal, as highlighted by the increased cerebrospinal fluid space ventral to the bulbomedullary junction (black arrows). F. Postoperative axial CT scan illustrating the anterior C1 arch integrity (asterisk). G, H, I. One-year follow-up normal and dynamic cervical X-ray showing the absence of cranial settling and C1- C2 instability.

Fig. 2.

Patient 2 (see Table I). Intraoperative endoscopic transnasal images. A. The posterior part of the hard palate was thinned by drilling out the outer bone layer with ultrasonic bone dissector, making the hard palate more flexible to enhance the angle of ''nasopalatine line''. B, C. Linear incision in the midline of the nasopharyngeal mucosa and subperiosteal preparation of anterior C1 arch. D, E, F. Drilling out the base of odontoid process with preservation of the anterior C1 arch. This weakens the apex of dens that can be now easily pulled down by curette freed from ligaments and inflammatory tissue, and then removed with forceps. G. The rheumatoid pannus was removed by curette working behind the intact anterior C1 arch (asterisk). H. Pulsating surgical cavity after decompression with preservation of continuity of atlas ring. I. The suture of the mucosa in order to speed up the healing process. (SP: soft palate; HP: hard palate; ET: Eustachian tube, RPhx: rhinopharynx, OD: odontoid, AL: alar ligaments).

Fig. 3.

Patient 10. A 79-year-old man with a previous cervical trauma (4 months ago) and inveterate anterior C1 arch and odontoid (Anderson-D'Alonso, type II) fractures with pseudoarthrosis. A. Preoperative sagittal CT scan revealing non-union type II odontoid fracture (black arrow). B. Preoperative axial CT scan revealing inveterate anterior C1 arch fracture (black arrow). C, D, E, F. Postoperative sagittal and axial CT scans showed anterior odontoid screw fixation (white arrow) combined with endoscopic transnasal C1 arch reconstruction by placing autologous cancellous bone chips to bridge the osseous gap and then fixed by plate and screws for future arthrodesis (black arrows).

Fig. 4.

Patient 10 (see Table I). A, B. Intraoperative endoscopic transnasal images showing sub-periosteal preparation of the anterior C1 arch and non-union fracture with pseudoarthrosis inflammatory pannus in between. C, D. Drilling of the edges of odontoid fracture below anterior C1 arch after verification with the neuronavigator. The EEA allows the inflammatory pannus (pseudoarthrosis) removal and cleaning the bone borders up to the normal cancellous bone just before the subsequent anterior C2 screw fixation and C1 arch plating. E, F, G. Reconstruction of the anterior arch of C1 by positioning bone chips compressed between the bone edges and a plate fixed the insertion of cannulated screws. H. Final intra-operative fluoroscopy image showed the correct placement of plate (black arrow) and cervical screw (asterisk).