Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Journal Pre-proof Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience Elysia Grose, Ioana D. Moldovan, MD MSc, Shaun Kilty, MD, Charles Agbi, MD, Andre Lamothe, MD, Fahad AlKherayf, MD MSc PII:

S1878-8750(20)30237-0

DOI:

https://doi.org/10.1016/j.wneu.2020.01.219

Reference:

WNEU 14249

To appear in:

World Neurosurgery

Received Date: 27 November 2019 Revised Date:

27 January 2020

Accepted Date: 28 January 2020

Please cite this article as: Grose E, Moldovan ID, Kilty S, Agbi C, Lamothe A, AlKherayf F, Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience, World Neurosurgery (2020), doi: https://doi.org/10.1016/j.wneu.2020.01.219. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Elsevier Inc. All rights reserved.

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience Elysia Grose1, Ioana D. Moldovan MD MSc 2, 4, Shaun Kilty MD1, 3, 4, Charles Agbi MD1, 2, Andre Lamothe MD3, Fahad AlKherayf MD MSc1, 2, 4, 5 1. University of Ottawa, Ottawa, Ontario, Canada 2. Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, Canada 3. Department of Otolaryngology- Head & Neck Surgery, The Ottawa Hospital, Ottawa, Canada 4. The Ottawa Hospital Research Institute, Ottawa, Canada 5. Fahad Alkherayf Medical Professional Corporation Keywords: endoscopic endonasal odontoidectomy, skull base surgery, craniovertebral junction, basilar invagination Short title: Outcomes of Endoscopic odontoidectomy

Elysia Grose: [email protected] Shaun Kilty: [email protected] Charles Agbi: [email protected] Andre Lamothe: [email protected] Fahad Alkherayf: [email protected]

Corresponding author:

Ioana Moldovan MD MSc Ottawa Hospital Research Institute The Ottawa Hospital – Civic Campus, Division of Neurosurgery 1053 Carling Avenue, Room C412, Ottawa, Ontario, Canada. K1Y 4E9 E-mail: [email protected] 1

Abstract Background: Odontoidectomy for basilar invagination and craniovertebral junction pathology has traditionally been performed using a transoral route. However, the endoscopic endonasal approach to the anterior craniovertebral junction may offer safer and more effective access when compared to transoral approaches. The objective of this study is to review the surgical outcomes and complications associated with endoscopic endonasal odontoidectomy. Methods: This study is a retrospective chart review of all adult patients who underwent an endoscopic endonasal odontoidectomy at a single tertiary care center between January 2011 and May 2019. Results: Seventeen patients who underwent endoscopic endonasal odontoidectomy were included. The median age at admission was 67 years (range: 33-84 years) and 65% of the patients were female. One patient (1/17, 6%) had vertebral artery injury which had to be coiled with no neurological deficits and 4 patients (4/17, 24%) had intraoperative CSF leaks with no postoperative leak. Fourteen (14/17, 82%) patients were extubated by postoperative Day 1. Three patients (3/17, 18%) developed postoperative sinus infections and required antibiotics. Eight patients (8/17, 47%) developed transient postoperative dysphagia. One patient (1/17, 6%) had postoperative epistaxis and one patient (1/17, 6%) had postoperative lower cranial nerve symptoms. The median length of hospital stay was 13 days (range: 2-44 days). Conclusion: Although the transoral approach has been the traditional route for anterior decompression of the craniovertebral junction, endoscopic endonasal odontoidectomy is a feasible and well-tolerated procedure associated with satisfactory patient outcomes and low morbidity.

2

Introduction The anterior craniovertebral junction is involved in a number of pathological processes including rheumatoid arthritis, fibroconnective tissue disease, congenital anomalies, neoplasms, degenerative and traumatic lesions [1–3]. Odontoidectomy is a procedure that can be extremely effective in patients with basilar invagination and irreducible compression of the anterior craniovertebral junction causing progressive myelopathy and spinal cord compression [4].

The traditional method used to perform odontoidectomy is through a transoral approach [5, 6]. However, this approach often provides poor visualization of the craniovertebral junction and foramen magnum [1]. In many cases, the transoral approach provides a view that is too inferior to reach the tip of the odontoid, and as a result its adequate visualization and removal often necessitates a mandibulotomy, maxillotomy, or palatomy which further increases morbidity [7]. Patients with basilar invagination, trismus, macroglossia, and significant oropharyngeal tissue often present an additional challenge when utilizing a transoral approach as visualization and exposure becomes more challenging [7]. Furthermore, complications associated with the transoral approach include velopharyngeal insufficiency, contamination with oral flora, dental injury, and significant swelling of the upper airway requiring tracheostomy [1, 8].

Endoscopic endonasal skull base techniques have enabled safe and effective access to the anterior craniocervical junction which offers several advantages over the traditional transoral approach [9]. It has been reported that the endoscopic endonasal approach enhances visualization and exposure during surgery [10–12]. Moreover, the endonasal approach uses an incision located along the posterior wall of the nasopharynx, subsequently decreasing the risk of

3

contamination by oral flora and infection [3, 13]. Recent literature comparing the endonasal and transoral approach showed that the endonasal approach reduces hospital length of stay, ventilation time, rate of postoperative tracheostomy, as well as permits earlier extubation and earlier postoperative feeding [14–16]. However, there are few risks associated with the endonasal approach including cerebrospinal fluid (CSF) leakage, cervical instability, and vascular injury [1]. However, these complications can be managed effectively through the endonasal approach [1]. This study presents the surgical and clinical outcomes of a series of patients undergoing endoscopic endonasal odontoidectomy at a single, tertiary care center.

Material and Methods This study is a retrospective chart review of all adult patients (18 years and older) who underwent an endoscopic endonasal odontoidectomy with or without posterior occipitocervical fusion, at a single tertiary care center (The Ottawa Hospital, Ottawa, Ontario), between January 2011 and May 2019. Demographic, clinical, and pathological data were collected. Patient intraand postoperative complications were analyzed. Patients with tumors such as craniocervical meningiomas and chordomas with secondary odontoid involvement were excluded. This study was granted approval from the Ottawa Health Science Network Research Ethics Board (OHSNREB# 20190432-01H). Treatment Algorithm Patients with radiologically proven compression of the cervicomedullary junction or basilar invagination were first evaluated by a neurosurgeon to assess their eligibility for endoscopic endonasal odontoidectomy. Preoperatively, patients underwent computed 4

tomography angiography (CTA) scan of the cervical spine and head as well as magnetic resonance imaging (MRI) of the cervical spine and head. When determined eligible for endoscopic endonasal odontoidectomy, a referral was made to an otolaryngologist specialized in endoscopic skull base surgery and then the surgical plan was created. The majority of patients who underwent endoscopic endonasal odontoidectomy also underwent occipitocervical fusion either before, on the same day, or after the odontoidectomy. Occipitocervical fusion consisted of posterior instrumented fusion from the occiput to C3, C4, C5, or C6. Patients underwent a CT scan of the cervical spine and a cervical spine X-ray prior to discharge. Postoperatively, patients were required to wear a cervical collar, and were closely followed up by the attending otolaryngologist and neurosurgeon. Postoperative patients were instructed to continue the nasal saline rinses and after 6 months were scheduled for a follow-up appointment with their otolaryngologist. The first follow up appointment with their neurosurgeon was scheduled one month after the surgery followed by other appointments. Patients received a cervical spine CT scan or an MRI to assess spine decompression one month after the surgery as well as a cervical spine X-ray to assess hardware integrity and position if applicable. In addition, some patients received postoperative physiotherapy. Surgical Technique After induction of general anesthesia and endotracheal intubation, the patient’s head was placed in a fixed position using a Mayfield clamp. Intraoperative motor evoked potentials (MEP) and somatosensory evoked potentials (SSEP) were recorded (baseline values) while patient’s head was in neutral position. Then, the patient's head position was changed to maximum flexion to provide access to lower clivus, C1 and C2. Neuronavigation was used in all cases. All patients received prophylactic antibiotics prior to the procedure. 5

The procedure began with the endonasal part. The Eustachian tubes were identified as the lateral margins of the exposure. Vertical incisions in the nasopharynx were made with the monopolar cautery medial to the torus tubarius bilaterally. The mucosa of the superior nasopharynx was elevated to the posterior wall. It was then resected. The soft tissue of the posterior wall was removed to expose the caudal third of the clivus and the arch and lateral masses of C1.

Drilling of the caudal clivus and arch of C1 was initiated. The drilling was carried out at the lower clivus using a high-speed diamond drill bit with continuous irrigation (Figure 1.a). The arch of C1 was drilled laterally to the junction with the lateral masses. Once the arch of C1 was removed (Figure 1.b), the odontoid process and alar ligament were identified. Using high speed drill, the odontoid process was thinned. This was done all the way to the base of the odontoid process. The odontoid process was then removed in a piecemeal fashion (Figure 1.c). After removal of the base of the odontoid process, the longitudinal ligament was identified and used as a landmark for the inferior level of the decompression. The lower part of the clivus was drilled all the way to the foramen magnum. Then this was removed using Kerrison rongeurs. After achieving adequate decompression all the way from the lower quarter of the clivus down to the base of C2, as well as also achieving adequate decompression laterally, closure was done.

Damp and crushed gel foam was then placed around the area. A septal splint was placed bilaterally if necessary. Non-absorbable nasal packing coated with antibiotic ointment was then placed into each nasal cavity along the floor of the nose.

6

Results Between January 2011 and May 2019, 17 patients underwent endoscopic endonasal odontoidectomy with or without posterior occipitocervical fusion at The Ottawa Hospital (Table 1). The median patient’s age at admission was 67 years old (range: 33-84 years old) and 65% (11/17) of patients were females (Table 2). Symptoms of myelopathy were the most common presenting symptoms (13/17, 76%) (Table 2). Nine patients (9/17, 52%) underwent operations for severe compression of the cervicomedullary junction not associated with basilar invagination whereas the remaining (8/17, 47 %) patients underwent operations for severe, symptomatic basilar invagination (Figure 2). Four (4/17, 24%) patients had syrinx on MRI.

Eight patients (8/17, 47%) underwent a two-stage surgery. The median time duration for the endoscopic endonasal odontoidectomy was 280 minutes (range: 222-493 minutes) and for the occipitocervical fusion was 236 minutes (range: 137-434 minutes). The median time between the two procedures was 9.5 days (range: 1-327 days). Two of the 8 patients had fusion prior to odontoid resection. Eight patients (8/17, 47%) underwent one-stage surgery. Both procedures were performed in one surgical intervention with a median time duration of 570 minutes (range: 534-721 minutes). Only one patient (1/17, 6%) underwent endoscopic endonasal odontoidectomy without posterior fusion, due to concern that the patient would not recover well from posterior fusion due to of other present comorbidities. The median blood loss during surgery was 400 mL (range: 200-800 mL).

After surgery, seven patients (7/17, 41%) were immediately extubated. The rest of the ten patients (10/17, 59%) required prolonged intubation due to increased airway edema, and

7

were extubated on postoperative day (POD) 1(7/10, 70%), POD 2(2/10, 20%), and POD 8 (1/10, 10%).

The overall intraoperative complication rate was 29% (5/17). The reported intraoperative complications were CSF leak (4/17, 24%) and vascular injury (1/17, 6%) ( Figure 3). The CSF leaks were repaired with a duraplasty using a synthetic dural substitute (Duraform™, Codman and Shurtleff, Inc., Berkshire UK). The leak was subsequently covered by the pedicled nasoseptal flap and fibrin glue (Tisseel; Baxter Healthcare Corp., Deerfield, IL). There were no cases of postoperative CSF leaks. The intraoperative vertebral artery injury occurred at the stage of removing the upper part of the base of the odontoid. The vertebral artery was subsequently coiled and resulted in no residual deficit.

The overall postoperative complication rate was 65% (11/17). The postoperative complications included transient dysphagia (8/17, 47%), epistaxis (1/17, 6%), sinus infection (3/17, 18%), early hardware failure (1 /17, 6%), and urinary tract infections (2/17, 12%) (Figure 3). Four patients with postoperative dysphagia (4/8, 50%) had documented swallowing difficulties before surgery. All patients who experienced dysphagia postoperatively had assessments done by speech language pathologists or otolaryngologists. Their feeds were adjusted accordingly. For six patients (6/8, 75%) the resolution of dysphagia occurred before hospital discharge. In one patient (1/7, 14%) dysphagia was resolved 6 months after surgery. In another patient (1/7, 14%), with preoperative dysphagia and hypoglossal nerve paralysis, postoperative placement of a percutaneous endoscopic gastrostomy (PEG) was required.

8

Sinus infection was reported in three patients (3/17, 18%) who required antibiotics. One patient in our series developed postoperative epistaxis.

The nose was packed to prevent the

bleeding and unpacked 2 days later with full resolution of the bleed. One patient in our series developed early hardware failure requiring revision surgery but was subsequently free of complications.

The median length of hospital stay was 13 days (range: 2-44 days). All patients had no evidence of residual compression on postoperative CT and/or MRI (Figure 4). Furthermore, 14 patients (14/17, 82%) had complete resolution of myelopathy symptomatology after surgery. The three patients, whose myelopathy did not completely resolve, reported occasional paresthesia and weakness in the upper extremities which were managed with continued physiotherapy and medical management.

Discussion In the last decade, the endoscopic endonasal approach to the anterior craniovertebral junction has gained popularity due to its ability to increase visualization during surgery and improve surgical outcomes and complications [4,7,8,12,13,17]. The ability to access the odontoid process through an entirely endonasal approach was first demonstrated in a cadaveric study by Alferi et al [9] and the first clinical report of endoscopic endonasal removal of the odontoid process was published by Kassam et al in 2005 [18].

Several reports have demonstrated the effectiveness of performing combined posterior fixation and odontoidectomy for basilar invagination and compression of the craniovertebral

9

junction [19–23]. Although posterior decompression and fusion have been reported to be successful in the treatment of reducible craniovertebral junction compression cases, anterior decompression and posterior fusion is the gold standard for cases of irreducible compression of the craniovertebral junction [4, 20, 21, 24, 25]. Additionally, posterior fusion after odontoidectomy prevents acute craniovertebral junction instability which can develop after odontoidectomy [24, 26, 27]. Thus, the majority of patients in our series underwent concurrent occipitocervical fusion in conjunction with endoscopic endonasal odontoidectomy.

In this study, we presented our experience with endoscopic endonasal odontoidectomy and posterior fusion in a case series of 17 patients. Zwagerman et al as well as in our study, the majority of reported complications were transient (e.g., postoperative dysphagia, intraoperative CSF leaks, sinus infections, and epistaxis). No patients developed velopharyngeal insufficiency, required postoperative tracheostomy, or died in our series which is consistent with other studies reporting low rates of these complications for patients undergoing endoscopic endonasal decompression [1,8, 14]. A recent systematic review and meta-analysis, comparing transoral and transnasal odontoidectomy complications, concluded that there was a significant increase in postoperative tracheostomy use after transoral procedures (10.8%) compared to transnasal endoscopic procedures (3.4%) [15]. Furthermore, the postoperative mortality rates for patients undergoing transoral odontoidectomy have been reported to be between 8% and 12% [28, 29] .

In this study, we found that 82.3 % of patients undergoing endonasal odontoid resection were extubated by POD 1. Goldschlager et al assessed the time to extubation and feeding after endoscopic endonasal surgery for odontoid pathology and reported that 67% of patients were

10

extubated immediately after the procedure with the rest extubated by POD 1 [14]. The same study mentioned that the mean time to extubation following transoral surgery is 3.5 days [14]. Our study reported transient postoperative dysphagia as the most common postoperative complication (47%). Zwagerman et al found similar results with 62% of patients experiencing transient postoperative dysphagia [8]. The prevalence rate of patients with postoperative dysphagia requiring a feeding tube was much lower in our study, only reporting one (6%) patient who required a PEG tube after surgery. Notably, this patient also presented preoperative dysphagia. Zwagerman et al reported 6 (18%) patients requiring a feeding tube, however 4 presented preoperative dysphagia [8]. Furthermore, Nayak et al reported the use of a PEG tube in 4.4% of their enrolled patients [1]. Transient postoperative dysphagia is likely due to postoperative oropharyngeal swelling in addition to oropharyngeal changes secondary to occipitocervical fusion [30, 31]. However, several studies have reported that the endonasal approach reduces the risk of postoperative dysphagia [12, 32, 33].

Intraoperative and postoperative CSF leaks have been reported to occur more frequently in patients undergoing transnasal procedures relative to the transoral approach [8, 15, 34]. The intraoperative CSF leak rate of 24% in our case series was comparable with other rates reported in the literature ranging from 4% to 30% [8, 15, 34]. Our study also noted successful repair of all intraoperative CSF leaks and no postoperative CSF leak which has been demonstrated consistently throughout the literature [8, 15, 33, 34]. With respect to postoperative outcomes, 82% of patients enrolled in our study had complete resolution of their myelopathy symptomatology and all enrolled patients clinically improved after surgery. Successful craniocervical junction decompression was demonstrated on the

11

postoperative imaging in all patients in our case series. Similarly, Chibbaro et al conducted a study on 24 patients undergoing endoscopic endonasal odontoidectomy procedures and found that all patients had satisfactory neurological improvement and postoperative decompression [27]. In addition to improvement in clinical outcomes, Ottenhausen et al evaluated patient reported quality of life outcomes after combined endonasal odontoidectomy and posterior decompression and showed that patients reported doing well postoperative with respect to nasal and emotional health [35].

Limitations This study has several limitations due to the retrospective study design. In addition, the small study sample size limits the conclusions that can be drawn. However, to our knowledge, this study is one of the largest case series of patients undergoing endoscopic endonasal odontoidectomy reported to date.

Conclusions Endoscopic endonasal odontoidectomy can be performed for various odontoid and anterior craniocervical pathologies with a high rate of symptom resolution and low rates of permanent complications. Although the transoral approach has been the traditional route for anterior decompression of the craniocervical junction, endoscopic endonasal odontoid resection may be considered a safe and effective procedure for treating various odontoid pathologies.

12

Declarations Ethics approval and consent to participate This study was granted approval from the Ottawa Health Science Network Research Ethics Board (OHSN-REB# 20190432-01H). This is a retrospective study collecting patient data from the hospital electronic medical records, therefore there were no direct risks to patients enrolled in the study. Also, no patient consent was required for this study.

Consent for publication Not applicable Availability of data and materials The research data is confidential.

Acknowledgements Not applicable Authors’ contributions All authors have contributed to the conception and design of the study. EG and IDM did the acquisition of data EG, IDM, and FA contributed to the analysis and interpretation of data EG, IDM and FA contributed to the drafting of the article. All authors contributed to revising the article critically for important intellectual content. All authors have given final approval of the version to be submitted.

13

Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

14

References 1. Nayak JV, Gardner PA, Vescan AD, Carrau RL, Kassam AB, Snyderman CH. Experience with the expanded endonasal approach for resection of the odontoid process in rheumatoid disease. Am J Rhinol. 2007 Sep;21(5):601–6. 2. Singh H, Harrop J, Schiffmacher P, Rosen M, Evans J. Ventral surgical approaches to craniovertebral junction chordomas. Neurosurgery. 2010 Mar;66(3 Suppl):96–103. 3. Chibbaro S, Cebula H, Aldea S, Baussart B, Tigan L, Todeschi J, et al. Endonasal Endoscopic Odontoidectomy in Ventral Diseases of the Craniocervical Junction: Results of a Multicenter Experience. World Neurosurg. 2017 Oct;106:382–93. 4. Abbritti RV, Esposito F, Angileri FF, Cacciola F, Marino D, La Fata G, et al. Endoscopic Endonasal Odontoidectomy and Posterior Fusion in a Single-Stage Surgery: Description of Surgical Technique and Outcome [Internet]. Acta Neurochirurgica Supplement. 2019. p. 197–207. Available from: http://dx.doi.org/10.1007/978-3-319-62515-7_29 5. Elbadrawi AM, Elkhateeb TM. Transoral Approach for Odontoidectomy Efficacy and Safety [Internet]. Vol. 13, HSS Journal ®. 2017. p. 276–81. Available from: http://dx.doi.org/10.1007/s11420-016-9535-3 6. Kingdom T, Nockels R, Kaplan M. Transoral-transpharyngeal approach to the craniocervical junction [Internet]. Vol. 113, Otolaryngology - Head and Neck Surgery. 1995. p. 393–400. Available from: http://dx.doi.org/10.1016/s0194-5998(95)70074-9 7. Seker A, Inoue K, Osawa S, Akakin A, Kilic T, Rhoton AL Jr. Comparison of endoscopic transnasal and transoral approaches to the craniovertebral junction. World Neurosurg. 2010 Dec;74(6):583–602.

15

8. Zwagerman NT, Tormenti MJ, Tempel ZJ, Wang EW, Snyderman CH, FernandezMiranda JC, et al. Endoscopic endonasal resection of the odontoid process: clinical outcomes in 34 adults. J Neurosurg. 2018 Mar;128(3):923–31. 9. Alfieri A, Jho H-D, Tschabitscher M. Endoscopic endonasal approach to the ventral cranio-cervical junction: anatomical study. Acta Neurochir . 2002 Mar;144(3):219–25; discussion 225. 10. Lee A, Sommer D, Reddy K, Murty N, Gunnarsson T. Endoscopic Transnasal Approach to the Craniocervical Junction [Internet]. Vol. 20, Skull Base. 2010. p. 199–205. Available from: http://dx.doi.org/10.1055/s-0029-1246220 11. Cavallo LM, Cappabianca P, Messina A, Esposito F, Stella L, de Divitiis E, et al. The extended endoscopic endonasal approach to the clivus and cranio-vertebral junction: anatomical study. Childs Nerv Syst. 2007 Jun;23(6):665–71. 12. Ponce-Gómez JA, Ortega-Porcayo LA, Soriano-Barón HE, Sotomayor-González A, Arriada-Mendicoa N, Gómez-Amador JL, et al. Evolution from microscopic transoral to endoscopic endonasal odontoidectomy. Neurosurg Focus. 2014;37(4):E15. 13. Fujii T, Platt A, Zada G. Endoscopic Endonasal Approaches to the Craniovertebral Junction: A Systematic Review of the Literature. J Neurol Surg B Skull Base. 2015 Dec;76(6):480–8. 14. Goldschlager T, Härtl R, Greenfield JP, Anand VK, Schwartz TH. The endoscopic endonasal approach to the odontoid and its impact on early extubation and feeding. J Neurosurg. 2015 Mar;122(3):511–8.

16

15. Shriver MF, Kshettry VR, Sindwani R, Woodard T, Benzel EC, Recinos PF. Transoral and transnasal odontoidectomy complications: A systematic review and meta-analysis. Clin Neurol Neurosurg. 2016 Sep;148:121–9. 16. Sexton MA, Abcejo AS, Pasternak JJ. Comparison of Anesthetic Management and Outcomes in Patients Having Either Transnasal or Transoral Endoscopic Odontoid Process Surgery [Internet]. Journal of Neurosurgical Anesthesiology. 2017. p. 1. Available from: http://dx.doi.org/10.1097/ana.0000000000000420 17. Liu JK, Patel J, Goldstein IM, Eloy JA. Endoscopic endonasal transclival transodontoid approach for ventral decompression of the craniovertebral junction: operative technique and nuances. Neurosurg Focus. 2015 Apr;38(4):E17. 18. Kassam AB, Snyderman C, Gardner P, Carrau R, Spiro R. The expanded endonasal approach: a fully endoscopic transnasal approach and resection of the odontoid process: technical case report. Neurosurgery. 2005 Jul;57(1 Suppl):E213; discussion E213. 19. Menezes AH, Sonntag VKH, Wang MY. The management of craniovertebral junction disorders. Foreword. Neurosurgery. 2010 Mar;66(3 Suppl):1 20. Crockard HA, Calder I, Ransford AO. One-stage transoral decompression and posterior fixation in rheumatoid atlanto-axial subluxation [Internet]. Vol. 72-B, The Journal of Bone and Joint Surgery. British volume. 1990. p. 682–5. Available from: http://dx.doi.org/10.1302/0301-620x.72b4.2380227 21. Crockard HA, Pozo JL, Ransford AO, Stevens JM, Kendall BE, Essigman WK. Transoral decompression and posterior fusion for rheumatoid atlanto-axial subluxation [Internet]. Vol. 68-B, The Journal of Bone and Joint Surgery. British volume. 1986. p. 350–6. Available from: http://dx.doi.org/10.1302/0301-620x.68b3.3733795

17

22. Hwang SW, Heilman CB, Riesenburger RI, Kryzanski J. C1–C2 arthrodesis after transoral odontoidectomy and suboccipital craniectomy for ventral brain stem compression in Chiari I patients [Internet]. Vol. 17, European Spine Journal. 2008. p. 1211–7. Available from: http://dx.doi.org/10.1007/s00586-008-0706-x 23. Chang P-Y, Yen Y-S, Wu J-C, Chang H-K, Fay L-Y, Tu T-H, et al. The importance of atlantoaxial fixation after odontoidectomy. J Neurosurg Spine. 2016 Feb;24(2):300–8. 24. Mouchaty H, Perrini P, Conti R, Di Lorenzo N. Craniovertebral junction lesions: our experience with the transoral surgical approach. Eur Spine J. 2009 Jun;18 Suppl 1:13–9. 25. Menezes AH, VanGilder JC, Graf CJ, McDonnell DE. Craniocervical abnormalities. A comprehensive surgical approach. J Neurosurg. 1980 Oct;53(4):444–55. 26. Dickman CA, Locantro J, Fessler RG. The influence of transoral odontoid resection on stability of the craniovertebral junction. J Neurosurg. 1992 Oct;77(4):525–30. 27. Chibbaro S, Ganau M, Cebula H, Nannavecchia B, Todeschi J, Romano A, et al. The Endonasal Endoscopic Approach to Pathologies of the Anterior Craniocervical Junction: Analytical Review of Cases Treated at Four European Neurosurgical Centres. Acta Neurochir Suppl. 2019;125:187–95. 28. Di Lorenzo N. Craniocervical junction malformation treated by transoral approach. A survey of 25 cases with emphasis on postoperative instability and outcome. Acta Neurochir . 1992;118(3-4):112–6. 29. Jain VK, Behari S, Banerji D, Bhargava V, Chhabra DK. Transoral decompression for craniovertebral osseous anomalies: perioperative management dilemmas. Neurol India. 1999 Sep;47(3):188–95.

18

30. Huang M, Gonda DD, Briceño V, Lam SK, Luerssen TG, Jea A. Dyspnea and dysphagia from upper airway obstruction after occipitocervical fusion in the pediatric age group. Neurosurg Focus. 2015 Apr;38(4):E13. 31. Kim JY, Hong JT, Oh JS, Jain A, Kim IS, Lim SH, et al. Influence of neck postural changes on cervical spine motion and angle during swallowing. Medicine . 2017 Nov;96(45):e8566. 32. Morales-Valero SF, Serchi E, Zoli M, Mazzatenta D, Van Gompel JJ. Endoscopic endonasal approach for craniovertebral junction pathology: a review of the literature. Neurosurg Focus. 2015 Apr;38(4):E15. 33. Mazzatenta D, Zoli M, Mascari C, Pasquini E, Frank G. Endoscopic endonasal odontoidectomy: clinical series. Spine . 2014 May 1;39(10):846–53. 34. Choudhri O, Mindea SA, Feroze A, Soudry E, Chang SD, Nayak JV. Experience with intraoperative navigation and imaging during endoscopic transnasal spinal approaches to the foramen magnum and odontoid. Neurosurg Focus. 2014 Mar;36(3):E4. 35. Ottenhausen M, Alalade AF, Rumalla K, Nair P, Baaj A, Hartl R, et al. Quality of Life After Combined Endonasal Endoscopic Odontoidectomy and Posterior Suboccipital Decompression and Fusion [Internet]. Vol. 116, World Neurosurgery. 2018. p. e571–6. Available from: http://dx.doi.org/10.1016/j.wneu.2018.05.041

19

Table 1. All cases included in the study – case description Patient ID

Age

Sex

Indication for surgery

Surgical procedure

Intraoperativ e Complications

Postoperative Complications

Duration of postoperative stay (days)

Duration of follow up (months)

1

84

F

Severe atlantodental degenerative change with degenerative pannus causing severe spinal canal stenosis with compression of the spinal cord at the C1-C2 level

Two stages: Occipital-C6 posterior decompression and instrumentation Endoscopic endonasal odontoidectomy

Intraoperative CSF leak

Postoperative epistaxis

11

7

2

61

F

Basilar invagination and stenosis at craniocervical junction with pannus formation around the odontoid process.

Two stages: Occipital-C4 posterior decompression and instrumentation Endoscopic endonasal odontoidectomy

None

Postoperative infection Postoperative dysphagia

16

20

3

79

M

Large extradural mass at the cranial vertebral junction which appears to be related to the anterior atlantoaxial joint, causing significant compression of the cervical medullary junction

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C3 posterior decompression and instrumentation

None

Hardware failure

7

6

4

58

M

Basilar invagination with compression of cervicomedullary junction and atlantoaxial instability

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C4 posterior decompression and

Intraoperative CSF leak

Postoperative infection Postoperative dysphagia

9

11

1

instrumentation 5

81

M

Ventral brainstem compression from rheumatoid arthritis pannus.

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C3 posterior decompression and instrumentation

None

Postoperative dysphagia requiring PEG tube

76

8

6

45

F

Brainstem compression due to basilar invagination

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C5 posterior decompression and instrumentation

Vertebral artery injury which was coiled

Postoperative dysphagia Postoperative UTI

22

8

7

62

F

Extensive C1-C2 and clival lesion with brain stem compression, basilar invagination, and craniocervical junction instability with significant cervical spine stenosis and signal change on spinal cord with severe myelopathy

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C3 posterior decompression and instrumentation

Intraoperative CSF leak

None

9

8

8

33

F

Brain stem compression and craniocervical junction stenosis with basilar invagination

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C3 posterior decompression and instrumentation

Intraoperative CSF leak

None

2

13

9

78

F

Extensive C1-C2 and clival

One stage:

None

Postoperative

13

9

2

lesion with brain stem compression and craniocervical junction instability with significant cervical spine stenosis and signal change on spinal cord with severe myelopathy

Endoscopic endonasal odontoidectomy AND Occipital-C3 posterior decompression and instrumentation

dysphagia

10

70

F

Extensive C1-C2 and clival lesion with brain stem compression and craniocervical junction instability with significant cervical spine stenosis and signal change on spinal cord with severe myelopathy

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C6 posterior decompression and instrumentation

None

Postoperative dysphagia

14

47

11

72

F

Large retro-odontoid pannus compressing the craniocervical junction and narrowing the cranial cervical canal

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C4 posterior decompression and instrumentation

None

None

21

9

12

67

F

Brainstem compression due to basilar invagination

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C4 posterior decompression and instrumentation

None

Postoperative UTI

13

4

13

66

M

Extensive C1-C2 and clival lesion with brain stem compression and craniocervical junction instability with

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C5 posterior decompression and

None

Postoperative infection

8

8

3

significant cervical spine stenosis and signal change on spinal cord with severe myelopathy

instrumentation

14

79

F

Extensive C1-C2 and clival lesion with brain stem compression and craniocervical junction instability with significant cervical spine stenosis and signal change on spinal cord with severe myelopathy

Endoscopic endonasal odontoidectomy

None

None

15

33

15

78

F

Extradural lesion at the craniovertebral junction causing compression of the cervicomedullary junction and progressive myelopathy with quadriparesis

One stage: Endoscopic endonasal odontoidectomy and posterior C1/C2 fusion

None

Postoperative dysphagia

17

10

16

34

M

Brainstem compression due to basilar invagination

Two stage: Endoscopic endonasal odontoidectomy AND Occipital-C4 posterior decompression and instrumentation

None

None

5

10

17

39

M

Craniocervical compression related to a craniocervical junction anomaly. Platybasia in association with the panus and basilar invagination.

One stage: Endoscopic endonasal odontoidectomy AND Occipital-C4 posterior decompression and instrumentation

None

Postoperative dysphagia

7

44

4

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience Table 2: Clinical characteristics of the study participants Clinical characteristics Median age at admission in years (range) Comorbidities Lung diseases Asthma Chronic obstructive pulmonary disease Interstitial lung disease Heart diseases Coronary artery disease Heart arrhythmia Diabetes Rheumatoid arthritis Osteoarthritis Pathological Conditions C1/C2 Pannus Chiari malformation type I Congenital osseous malformation Previous odontoid fracture Surgical Procedure Two-step endoscopic endonasal odontoid removal and posterior occipitocervical fusion One step endoscopic endonasal odontoid removal and posterior occipitocervical fusion Endoscopic endonasal odontoid removal only Median follow up time in months (range) Presentation Symptoms Myelopathy Difficulty with fine hand movements Paresthesia and loss of sensation in extremities Difficulty walking Neck pain Headaches Lower cranial nerve symptoms Dizziness Tinnitus

67 (33-84) 6/17 (35%) 2/6 (33%) 3/6 (50%) 1/6 (17%) 5/17 (29%) 2/5 (40%) 3/5 (60%) 2/17 (12%) 3/17 (18%) 2/17 (12%) 11/17 (65%) 2/17 (12%) 3/17 (18%) 1/17 (6%) 8/17 (47%) 8/17 (47%) 1/17 (6%) 9 (4-47) 13/17 (76%) 10/13 (77%) 7/13 (54%) 9/13 (69%) 9/13 (69%) 5/17 (29%) 3/17 (18%) 3/17 (18%) 2/17 (12%)

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Figure 1. Endoscopic endonasal odontoidectomy images a. Clivus drilling

b. Anterior arch of C1 removal

c. Odontoidectomy

1

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience Figure 2. Preoperative CT spine images

C1 C2 C3

A.1

A.2

B.1

B.2

C

A.1&2 (Sagittal CT cervical spine): Evidence of congenital atlantooccipital fusion, with associated fusion of the C2C3 vertebra and basilar invagination; B.1 (Sagittal CT cervical spine) & B.2 (Coronal CT cervical spine): substantial pannus at the dens and clivus due to rheumatoid arthritis; C (Sagittal CT cervical spine): severe narrowing of the joint spaces between the lateral masses of C1 and C2 due to rheumatoid arthritis. There is a calcified pannus in the retroodontoid region and in the prevertebral space at the level of C1.

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Figure 3: Rates of intraoperative and postoperative complications

Transient postoperative dysphagia (8/17, 47%) and intraoperative CSF bleak (4/17, 24%) were the most common reported complications related to endoscopic endonasal odontoidectomy with or without posterior occipitocervical fusion at our hospital during the study period.

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience Figure 4. Postoperative CT spine images

A.1

A.2

B.1

B.2

C.1

C.2

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience A.1&A.2 (Sagittal & Coronal CT cervical spine): postoperative changes showing occiput to C5 surgical decompression and fusion. The anterior aspect of the C1anterior arch and the odontoid process were partially resected. B.1&B.2 (Sagittal & Coronal CT cervical spine): postoperative changes due to resection of the anterior and posterior arch of C1 and the dens, and instrumented fusion of the occiput to C4; C.1&C.2(Sagittal & Coronal CT cervical spine): postoperative changes showing resection of the dens as well as partial resection of the anterior arch of C1. Posterior cervico-occipital fusion from the occiput to C4 was performed.

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Highlights • • • •

Endoscopic odontoidectomy was effective in anterior craniovertebral junction lesions Transient postoperative dysphagia was the most common postoperative complication Endoscopic odontoidectomy had low rates of permanent complications All our enrolled patients clinically improved after endoscopic procedure

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Abbreviations: CSF- Cerebrospinal fluid MRI-Magnetic Resonance Imaging PEG-percutaneous endoscopic gastrostomy CT- Computed Tomography

Authors’ contributions All authors have contributed to the conception and design of the study. EG and IDM did the acquisition of data EG, IDM, and FA contributed to the analysis and interpretation of data EG, IDM and FA contributed to the drafting of the article. All authors contributed to revising the article critically for important intellectual content. All authors have given final approval of the version to be submitted.

Clinical outcomes of endoscopic endonasal odontoidectomy: A single center experience

Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: