INTRODUCTION
Obstructive sleep apnea (OSA) is characterized by repetitive airway collapse resulting in oxygen desaturation and sleep interruption. OSA is associated with cardiopulmonary morbidity and mortality, neurocognitive impairment, and reduced quality of life. Positive airway pressure (PAP) remains the gold standard treatment for moderate-to-severe OSA.1 In patients who are not compliant or tolerant of PAP, a variety of surgical interventions exist. Surgical options for OSA aim to increase or stabilize the size of the airway via repositioning or removing the bony and/or soft tissue architecture at various subsites most prone to collapse during respiration.2 Evidence supports the role for multilevel surgery to address these areas of collapse along the upper aerodigestive tract.1 With the innovation of various medical devices, an increasing number of interventions have become available in the field of sleep surgery. Most notably, the da Vinci surgical robot by Intuitive Surgical, which was FDA approved for use in the extirpation of head and neck neoplasms, has been investigated for its potential application in treating OSA. This chapter will review the literature describing the feasibility and outcomes of transoral robotic surgery (TORS) for OSA.
TRANSORAL ROBOTIC SURGERY—BACKGROUND AND TECHNIQUE
First established as an efficacious method of resecting oropharyngeal cancers, the application of the surgical robot in the management of OSA has been investigated more recently.2–4 With the tongue base recognized as a major site of obstruction in OSA, various procedures such as genioglossus advancement, partial midline glossectomy, hyoid myotomy, and Repose stay sutures currently exist to address the region.5 However, these surgeries are potentially limited by the need for external incisions, inadequate exposure, nonarticulated instrumentation, and overall technical difficulty. In an effort 2to add to the surgical armamentarium for managing OSA, Vicini et al. in 2010 investigated the tolerability and effectiveness of transoral robotic tongue base resection.4
Through the use of the EndoWrist articulated instruments and three-dimensional high-definition cameras (0° and 30°), TORS offers an additional level of precision to excise the soft tissue of the upper aerodigestive tract that would otherwise require a complex open approach.
As with any surgery, patients should be carefully selected for transoral robotic surgical intervention. For access purposes, any anatomical limitations such as retrognathia, micrognathia, trismus, or the inability to hyperextend the neck should be examined. Candidates for TORS ideally have primary obstruction at the tongue base, though interventions at the supraglottis and soft palate via the robot have also been described. 6–9
Though it is safest to limit the tissue resection to the superficial layer of lingual lymphoid tissue, most tongue base cases require dissection into the tongue base musculature. Deeper dissection and the absence of dependable landmarks can lead to exposure of the lingual artery and its dorsal branches and injury to the hypoglossal and lingual nerves.7 Thus, familiarity with the anatomy of the underlying neurovascular bundle is paramount. Based on cadaveric and angiographic studies, the distance between the foramen cecum and hypoglossal/lingual neurovascular bundle is approximately 1.7 cm. Therefore, tongue base resection performed within approximately 1.5 cm of the foramen cecum is reported to be safe.10 Any additional tissue removal would require vigilance under sufficiently high magnification. Alternatively, some surgeons have used Doppler ultrasound to directly trace the path of bilateral lingual arteries to provide anatomical boundaries for resection.9
Various techniques for tongue base resection have been described in the literature. Resection is generally performed in a piecemeal or en bloc fashion. Preoperative sleep endoscopy may be used to delineate the lateral extent of resection.2,5 Vicini et al. utilize a piecemeal resection starting in the midline and then carefully extending the resection laterally.4 Friedman et al. describe removing a triangular wedge of the tongue base musculature after parallel cuts are made in the circumvallate papillae/foramen cecum region of the tongue base.9 Lee et al. performed a piecemeal lingual tonsillectomy and only a small amount of the underlyin g musculature.5 Figure 1.1 illustrates before and after changes to base of tongue region after robotic resection for hypertrophic lingual tonsils.
TRANSORAL ROBOTIC SLEEP SURGERY LITERATURE REVIEW
The first article to report on the use of transoral robotic tongue base resection in OSA was published by Vicini et al. in 2010. This retrospective study followed 10 patients for a minimum of 3 months who demonstrated an Epworth sleepiness scale (ESS) score > 11, apnea–hypopnea index (AHI) > 20, nonacceptance or dropout from continuous PAP use, and clinical tongue base hypertrophy with adequate tongue base exposure.3
Fig. 1.1: Schematic of narrowed retrolingual space due to lingual tonsil hypertrophy before and after robotic resection.
All patients prior to intervention underwent a tracheostomy procedure; however, no serious airway or bleeding complications were reported. Furthermore, no cases required an open conversion or need for revision surgery to address the tongue base. The blood loss and operating time were equal to or less than an open or endoscopic laser resection, while the TORS procedure allowed for multiplanar visualization of the tissue. All patients were decannulated between the 5th or 13th day and all patients had satisfactory swallowing after 2 weeks resulting in no significant reduction in postoperative BMI scores. Measuring preoperative and postoperative indices, AHI and ESS scores reached statistically significant changes (Table 1.1).
Vicini et al. followed the preliminary paper with a follow-up the subsequent year with 10 additional (20 total) patients along with anatomic analysis of the tongue base in 3 cadaveric heads. A similar inclusion criterion was utilized; however, patients were followed out for a minimum time of 410 months. In order to better differentiate between subjective improvement in OSA symptoms and objective improvement, patients were deemed surgically cured if posttreatment AHI and ESS scores were < 10. In turn, 70% of the cohort was found to be cured based on their AHI, and 90% based on their ESS. Overall, 60% (12/20) were found to be cured of both. Additionally, it was found that setting up and operating time improved with experience. Once again, measuring preoperative and postoperative indices including AHI, ESS, and additionally lowest oxygen saturation, these levels reached statistically significant improvement (Table 1.1).
In an effort to address other subsites problematic in OSA, Vicini et al. used a cadaver model to develop a technique of geniohyoidpexy to complete the basic TOR tongue base with supraglottoplasty surgery to improve outcomes to match those described by Chabolle et al. where a hyoid epiglottoplasty is utilized with an open tongue base approach.6,11
A dissection method within the sagittal avascular plane inside an ideal triangle between the mandible, hyoid bone body, and the lingual frenulum is outlined. Ultimately, the hyoid is tied under slight tension to the mandible with the procedure taking roughly < 20 minutes in total. Additionally, to elucidate the improvement in treatment of OSA when used in conjunction with TORS, Vicini et al. also investigated the modified Pang expansion sphincter pharyngoplasty (nonrobotic) to the uvulopharyngoplasty (nonrobotic) procedure.12 Though the Pang expansion sphincter pharyngoplasty required more time to perform (average of 39 minutes), it was found to be superior in post-procedure AHI and ESS to the classic uvulopharyngoplasty when used in conjunction with TORS. It is thought that that the expansion sphincter pharyngoplasty creates a greater angle between the lateral wall and palate.86
Friedman et al. inv estigated the feasibility of performing a Z-palatoplasty with a robotically assisted partial glossectomy without tracheotomy to those who underwent a Z-palatoplasty with tongue base reduction via radio frequency (radio frequency base-of-tongue reduction [RFBOT] or coblation (submucosal minimally invasive lingual excision [SMILE].) Twenty seven TORS patients were compared with 24 RFBOT patients and 22 SMILE patients. As with Vicini et al. rate of cure was defined as AHI < 20 and reduction in AHI ≥ 50%. Like the reports by Vicini et al. no incidence of significant bleeding or airway complications were reported (Table 1.1). It was found that only the robot group had a statistically significant improvement in minimum oxygen saturation, while all groups had a statistical significant decrease in AHI and ESS (though a greater percentage in absolute decrease was seen within the robot group for both AHI and ESS) (Table 1.1). Interestingly, no direct correlation was found between the weight of lingual tissue removed and the degree of improvement in minimum oxygen saturation, or ESS. TORS required longer length of stay in the hospital (1.6 ± 0.7) and return to normal diet (19.3 ± 8.4 days). The percentage of surgical cure was higher in the robot group (66.7%) versus the coblation (45.5%) and radio frequency (20.8%), though statistically significant compared with only the radio frequency group.
In similar fashion of investigating TORS with a concomitant palate surgery, Lee et al. investigate transoral robotic lingual tonsillectomy with the classic uvulopharyngoplasty. Traditional surgery involving uvulopalatopharyngoplasty alone has not reliably led to normalization of the AHI for patients with moderate-to-severe OSA. Lee et al. offered those patients who underwent drug-induced sleep endoscopy and were found to have significant obstruction at the level of the retroglossal region the option of an uvulopharyngoplasty and transoral robot lingual tonsillectomy. These patients, selected prospectively, were matched against historical controls. In alignment with reports by Vicini and Friedman, surgical success was defined as a 50% reduction of preop AHI and postop AHI of < 20, while surgical response was defined as a reduction from the preoperative AHI of at least 50%. AHI, ESS, and lowest oxygen saturation levels were all found to be statistically significant postoperatively with 13 patients meeting the criteria for surgical response and 9 meeting the criteria for surgical cure (Table 1.1). Unlike data published by Vicini and Friedman, one patient did experience a postoperative bleed (postoperative day 7) that required a visit to the operating room for cauterization (Table 1.1). Minor complications included dysphagia, dysgeusia, and transient globus—all of which resolved by 3 months.
With OSA generally resulting from obstruction at various subsites throughout the upper airway, much of the literature compares various outcomes (i.e. AHI, ESS, and minimum oxygen saturations) after performing multilevel surgery. Therefore, reports describing base of tongue resection 7concomitantly with other upper airway procedures make interpretation of the efficacy of base of tongue reduction alone difficult to assess. Lin et al. in a retrospective analysis examined 27 patients who underwent TORS for base of tongue reduction only, though the majority has previously undergone a combination of other airway procedures including a uvulopalatopharyngoplasty/Z-palatoplasty, coblation-assisted lingual tonsillectomy, hyoid advancement, and tracheostomy. Similar to the criteria outlined by Vicini, Friedman, and Lee, surgical response was defined as a 50% reduction in AHI and final AHI < 20 postoperatively. Both AHI and ESS demonstrated statistical significance with 50% of the patients achieving surgical cure comparable with the results produced by others who underwent concomitant multilevel airway surgery to treat OSA (Table 1.1). However, unlike other reported papers, one patient (8%) demonstrated oropharyngeal scarring causing dysphagia that required scar tissue lysis (Table 1.1). With the possibility of oropharyngeal scarring from tongue base resection and concomitant palatal surgery, the authors recommended considering a two-stage approach with the TORS-assisted base of tongue re section occurring prior to a second-stage palate surgery.
CONCLUSION
The application of the robot, in order to provide improved access, enhanced visualization and precision has been demonstrated to be feasible and tolerable in patients with OSA. The studies thus far reveal improved AHI, ESS, and O2 saturations with robotic sleep surgery. With additional studies and appropriate patient selection, TORS may become a powerful tool in the armamentarium of the otolaryngologist to effectively treat airway obstruction at the base of tongue and possible adjacent sites of airway collapse.
REFERENCES
- Caples SM, Rowley, JA, Prinsell, JR, et al. Surgical modifications of the upper airway for obstructive sleep apnea in adults: a systematic review and meta-analysis. Sleep. 2010;33 (10): 1369–407.
- Lin HS, Rowley, JA, Badr, MS, et al. Transoral robotic surgery for treatment of obstructive sleep apnea-hypopnea syndrome. Laryngoscope. 2013;123:1811–6.
- O’Malley BW Jr, Weinstein, GS, Synder, W, et al. Transoral robotic surgery (TORS) for base of tongue neoplasms. Laryngoscope. 2006;116:1465–1472.
- Vicini C, Dallan, I, Canzi, P, et al. Transoral robotic tongue base resection in obstructive sleep apnoea-hypopnoea syndrome: a preliminary report. ORL J Otorhinolaryngol Relat Spec. 2010;72:22–7.
- Vicini C, Montevecchi, F, Dallan, I, et al. Transoral robotic geniohyoidpexy as an additional step of transoral robotic tongue base reduction and supraglottoplasty: feasibility in a Cadaver model. Otorhinolaryngol Relat Spec. 2011;73(3):147–50.
- Vicini C, Dallan, I, Canzi, P, et al. Transoral robotic surgery of the tongue base in obstructive sleep apnea-hypopnea syndrome: anatomic considerations and clinical experience. Head Neck. 2012;34(1):15–22.
- Vicini C, Montevecchi, F, Pang, K, et al. Combined transoral robotic tongue base surgery and palate surgery in obstructive sleep apnea-hypopnea syndrome: expansion sphincter pharyngoplasty versus uvulopalatopharyngoplasty. Head Neck. 2013;00:1–7.
- Friedman M, Hamilton, C, Samuelson, CG, et al. Transoral robotic glossectomy for the treatment of obstructive sleep apnea-hypopnea syndrome. Otolaryngol Head Neck Surg. 2012;146:854–62.
- Lauretano AM, Li, KK, Caradonna, DS, Khosta, RK, Fried, MP. Anatomic location of the tongue base neurovascular bundle. Laryngoscope. 1997;107:1057–9.
- Chabolle F, Wagner, I, Blumen, MB, et al. Tongue base reduction with hyoepigottoplasty a treatment for severe obstructive sleep apnea. Laryngoscope. 1999;109:1273–80.
- Pang KP, Woodson, BT. Expansion sphincter pharyngoplasty: a new technique for the treatment of obstructive sleep apnea. Otolaryngol Head Neck Surg. 2007;30:110–4.