Experience with intraoperative navigation and imaging during endoscopic transnasal spinal approaches to the foramen magnum and odontoid

Abstract

Object In this study the authors share their experience using intraoperative spinal navigation and imaging for endoscopic transnasal approaches to the odontoid in 5 patients undergoing C1–2 surgery for basilar invagination at Stanford Hospital and Clinics from 2010 to 2013. Methods Of these 5 patients undergoing C1–2 surgery for basilar invagination, 4 underwent a 2-tiered anterior C1–2 resection with posterior occipitocervical fusion during a first stage surgery, followed by endoscopic endonasal odontoidectomy in a separate setting. Intraoperative stereotactic navigation was performed using a surgical navigation system in all cases. Navigation accuracy, characterized as target registration error, ranged between 0.8 mm and 2 mm, with an average of 1.2 mm. Intraoperative imaging using a CT scanner was also performed in 2 patients. Results Endoscopic decompression of the brainstem was achieved in all patients, and no intraoperative complications were encountered. All patients were extubated within 24 hours after surgery and were able to swallow within 48 hours. After appropriate initial reconstruction of the defect at the craniocervical junction, no postoperative CSF leakage, arterial injury, or need for reoperation was encountered; 1 patient developed mild postoperative velopharyngeal insufficiency that resolved by the 6-month follow-up evaluation. There were no deaths and no patients required tracheostomy placement. The average inpatient stay after surgery varied between 72 and 96 hours, without extended intensive care unit stays for any patient. Conclusions Technologies such as intraoperative CT scanning and merged MRI/CT can provide the surgeon with detailed, virtual real-time information about the extent of complex endoscopic vertebral segment resection and brainstem decompression and lessens the prospect of revision or secondary procedures in this challenging surgical corridor. Moreover, patients experience limited morbidity and can tolerate early oral intake after transnasal endoscopic odontoidectomy. Essential to the successful undertaking of these endoscopic adventures is 1) an understanding of the endoscopic nasal, skull base, and neurovascular anatomy; 2) advanced and extended-length instrumentation including navigation; and 3) a team approach between experienced rhinologists and spine surgeons comfortable with endoscopic skull base techniques

The rhinopalatine line as a reliable predictor of the inferior extent of endonasal odontoidectomies

“…25,47,55 Although these extended approaches can lead to significant enhancement of the surgical exposure, they also significantly increase surgical complexity and the depth of the operative corridor, rates of morbidities such as infections from bacterial oral flora, velopharyngeal insufficiency, hypernasal speech, nasal regurgitation, soft palate dehiscence, tongue edema, and necrosis, and the potential need for tracheotomy and nasogastric feeding tube, resulting in a longer hospital recovery time. 10,37,41,45 In the last decade, some minimally invasive endoscopic approaches, such as the EEA, 7,8,11,18,19,[21][22][23][24]26,27,29,30,[33][34][35]40,44,51 the ETA, 16,17 a combined EEA/ETA with or without the assistance of robotics, 12,13,31,32,50,54 and a transcervical approach, 53 have been adopted to address CVJ pathology. The growing number of publications in the last decade shows that the EEA can be an excellent minimal-access alternative to traditional transoral surgery and offers certain anatomical advantages.…”

“…All these publications highlight the benefits of endoscopic endonasal odontoidectomy as a safe, effective, and welltolerated technique. 7,8,11,18,19,[21][22][23][24]26,27,29,30,[33][34][35]40,44,51 The main advantages of the EEA over the traditional microscopic approaches are the location of the incision (in the nasopharynx rather than the oropharynx) and the wider, closer, and brighter view provided by the endoscope.…”

Endoscopic endonasal transclival transodontoid approach for ventral decompression of the craniovertebral junction: operative technique and nuances

“…18,43,49 Postoperative recovery after endonasal skull base surgery is generally quicker, the hospital stays are shorter, and patients are fed orally and ambulate earlier in the postoperative period than patients who undergo transoral procedures. 6,14,18,43 The endoscopic endonasal approach for odontoidectomy has been investigated in cadaveric studies and in several clinical studies. 2,4,6,14,18,23,24,28,32,33,38,[40][41][42][43][44][45][46]48 Although several variations in technique exist in the literature, the aims of this report are to describe our method of the purely endoscopic endonasal transclival transodontoid approach for anterior decompression of the craniovertebral junction and to describe various operative pearls and nuances of the technique.…”

Transnasal odontoid resection: is there an anatomic explanation for differing swallowing outcomes?

“…2,3,6,26 This complication has been estimated to impact up to 60% of patients following anterior cervical spine surgery when tested carefully. 3,20,30 The etiology for postoperative dysphagia is likely multi factorial, but contributing factors may include edema and thickening of the posterior pharyngeal wall, injury to the pharyngeal plexus, recurrent or superior laryngeal nerve injury, preoperative debility, and neuromuscular scarring and fibrosis.…”

“…6,29 The question is: Why? While there may be many overlapping factors, as described above, understanding how the neu romuscular anatomy and associated physiology relate to the surgical anatomy is crucial to better predict the risk for postoperative dysphagia for these varying techniques.…”