Transoral Robotic Sleep Surgery




Nocturnal upper airway collapse is often multi-level in nature but typically will involve some degree of obstruction at the level of the tongue-base. Several surgical procedures have been developed in recent years to address this area in patients resistant to continuous positive airway pressure. This article outlines a novel way to treat obstructive sleep apnea lingual obstruction using the da Vinci robotic surgical system. This technique offers significant potential advantages over other established approaches and it should be included in the surgical armamentarium of sleep surgeons.


Key points








  • Obstructive sleep apnea–hypopnea syndrome is a heterogeneous disease.



  • Gold-standard therapy is continuous positive airway pressure; however, in patients who cannot tolerate this treatment, surgery may be a feasible alternative.



  • Transoral robotic surgery (TORS) offers a minimally invasive, well-visualized approach to the base of the tongue.



  • Early data looking at surgical success for TORS base-of-tongue resection is encouraging.






Introduction


Obstructive sleep apnea–hypopnea syndrome (OSAHS) is a common disorder that affects 2% to 4% of the adult population. It is a serious social health problem with significant implications for a patient’s quality of life as well as for his or her long-term health. It has been consistently shown to cause a multitude of neurobehavioral issues as well as to be an independent risk factor for cardiopulmonary derangements that significantly increase the risk of death.


The gold standard for treatment remains continuous positive airway pressure (CPAP). However, there are patients who are not able to tolerate this device and require an alternative treatment. Surgery for OSAHS has been criticized because of lack of evidence supporting its efficacy and the heterogeneous results in the published outcomes. Its effectiveness as a viable treatment option was further questioned by a large meta-analysis that showed that uvulopalatopharyngoplasty was effective in less than 50% of cases. However, much of the criticism stems from the significant variation in the surgical options available with a lack of consistency in the reporting of outcomes. Additionally, interpretation of the available literature is problematic because of the different apnea-hypopnea index (AHI) criteria for investigation and different AHI thresholds for defining surgical success or improvement.


Surgical approaches range from procedures that increase or stabilize the airway by removing or repositioning tissue to procedures that completely bypass the site of airway collapse, such as tracheostomy. OSAHS is an incredibly complex heterogeneous disorder that requires a thorough assessment before planning intervention. This ensures that the particular level of collapse is addressed on an individual patient basis.


The concept of transoral robotic surgery (TORS) as a treatment of OSAHS was first introduced in 2009 by Vicini and colleagues in their feasibility report looking at the treatment of hypertrophy of the tongue base. Since then, it has been shown to be an effective treatment option for both solely base-of-tongue procedures and when combined with multi-level surgery.


TORS has the ability to overcome the issues with surgical access that had previously hampered surgical treatment options. It has become increasingly understood that tongue base anatomy may play a more important role than previously thought in the pathophysiology of OSAHS. The robot system allows for high-quality endoscopic optics for improved visualization with three-dimensional (3D) depth perception and robotic instrumentation. These instruments have 6° of freedom and 90° of articulation that allows for superior dexterity and precision.




Introduction


Obstructive sleep apnea–hypopnea syndrome (OSAHS) is a common disorder that affects 2% to 4% of the adult population. It is a serious social health problem with significant implications for a patient’s quality of life as well as for his or her long-term health. It has been consistently shown to cause a multitude of neurobehavioral issues as well as to be an independent risk factor for cardiopulmonary derangements that significantly increase the risk of death.


The gold standard for treatment remains continuous positive airway pressure (CPAP). However, there are patients who are not able to tolerate this device and require an alternative treatment. Surgery for OSAHS has been criticized because of lack of evidence supporting its efficacy and the heterogeneous results in the published outcomes. Its effectiveness as a viable treatment option was further questioned by a large meta-analysis that showed that uvulopalatopharyngoplasty was effective in less than 50% of cases. However, much of the criticism stems from the significant variation in the surgical options available with a lack of consistency in the reporting of outcomes. Additionally, interpretation of the available literature is problematic because of the different apnea-hypopnea index (AHI) criteria for investigation and different AHI thresholds for defining surgical success or improvement.


Surgical approaches range from procedures that increase or stabilize the airway by removing or repositioning tissue to procedures that completely bypass the site of airway collapse, such as tracheostomy. OSAHS is an incredibly complex heterogeneous disorder that requires a thorough assessment before planning intervention. This ensures that the particular level of collapse is addressed on an individual patient basis.


The concept of transoral robotic surgery (TORS) as a treatment of OSAHS was first introduced in 2009 by Vicini and colleagues in their feasibility report looking at the treatment of hypertrophy of the tongue base. Since then, it has been shown to be an effective treatment option for both solely base-of-tongue procedures and when combined with multi-level surgery.


TORS has the ability to overcome the issues with surgical access that had previously hampered surgical treatment options. It has become increasingly understood that tongue base anatomy may play a more important role than previously thought in the pathophysiology of OSAHS. The robot system allows for high-quality endoscopic optics for improved visualization with three-dimensional (3D) depth perception and robotic instrumentation. These instruments have 6° of freedom and 90° of articulation that allows for superior dexterity and precision.




Treatment goals


In sleep apnea surgery, the criterion for success is not necessarily polysomnographic cure. Although this seems counterintuitive, curing a patient of sleep apnea is not the goal. The goal is achieving either a reduction in AHI scores and/or an improvement in clinical symptomatology. The argument surrounding surgery for OSAHS should be taken in the context of whether the gold-standard treatment can be applied at all times. That is, if a patient wears CPAP for only 4 hours a night, is this really better than a partial cure that is applied throughout the night?


The increase in mortality from cardiovascular risk factors for sleep apnea is in patients in the moderate to severe range. If surgery reduces a moderate or severe sleep apnea patient to a mild sleep apnea patient, although this is not a polysomnographic cure, it is likely to significantly reduce their neurocognitive and cardiopulmonary risk factors. If this is achieved in the context of improving their symptoms of daytime sleepiness and snoring, the patient has benefited from the intervention.


In most of the published series, the treatment goals are broken down into surgical cure and surgical response. A surgical cure is defined as a decrease in preoperative AHI of at least 50% and a postoperative AHI of less than 20 events per hour. A surgical response is defined as a reduction from the preoperative AHI of at least 50%.


In terms of the contribution that TORS makes to the sleep surgeon’s armamentarium, TORS allows the surgeon to perform procedures that otherwise are done only through an open approach, which usually results in significant morbidity and decreased quality of life.


Essentially, the treatment goal remains not only a significant reduction in AHI but also an improvement in the quality-of-life scores as documented by their Epworth Sleepiness Scale and Snoring Severity Scale which is, perhaps, of even more worth.




Patient selection


Indications


The chief indication for surgery in OSAHS is that the patient has failed a trial of the gold-standard treatment, CPAP, because he or she is noncompliant or cannot tolerate the device. Typically, the patient should have polysomnographic evidence of moderate to severe OSAHS in addition to daytime somnolence as documented through the Epworth Sleepiness Scale. For TORS-specific surgery, there should be significant contribution to obstruction at the base of the tongue. This is determined either by awake nasopharyngoscopy with the appropriate maneuvers or by drug-induced sleep endoscopy.


Contraindications


Contraindications for TORS are classified as patient compliance, patient anatomy, and medical comorbidities. The gold-standard treatment of sleep apnea is CPAP therapy. If the patient is compliant with this therapy, surgical intervention is discouraged.


The anatomy of the patient must also be amendable to access with the robot. A degree of trismus or limited mobility of the neck may make the base of the tongue inaccessible. Significant micrognathia and macroglossia may also limit the exposure for TORS procedures, although they may not necessarily make it impossible. Dynamic compression of the lateral airway from soft tissue is a relative contraindication because TORS essentially addresses anterior-posterior collapse of the airway.


Because surgery for OSAHS is a second-line therapy, careful thought must be directed toward the potential risks the patient may face from an anesthetic. An American Society of Anesthesiologists score greater than 2 with particular reference to significant or unstable cardiovascular disease or the need for anticoagulation must be treated with caution.




Preoperative planning


The preoperative workup is essential for adequately determining the optimum treatment plan for the patient. In those who have failed treatment with CPAP or other devices, a thorough assessment must be undertaken to ensure that their anatomy is amenable to surgery. This should help to ensure that only patients who have a chance of improvement from surgery are offered treatment and that the correct level of obstruction is targeted.


This workup should begin with a targeted sleep history in which the patient and the patient’s significant other are involved. Pertinent points to include in this assessment are a snoring history, rhinologic or allergy history, and any history of single-vehicle accidents because patients with OSAHS may have twofold to threefold increased rate of traffic accidents.


Specific to the OSAHS examination, the body mass index and neck circumference should be noted. Retrognathia or mandibular hypoplasia resulting in malocclusion or a high-arched palate should be noted. The oral tongue size, assessed with a modified Mallampati score, should be noted in addition to the length of the uvula and soft palate. The size of the tonsils, based on a Friedman grading system should also be recorded.


Nasopharyngoscopy identifies septal deviation, enlarged turbinates, inflamed nasal mucosa, and/or adenoid hypertrophy. Additionally, inspection of the hypopharynx allows for characterization of the epiglottis and the volume of hypertrophy of the base of the tongue. Müller and Woodson hypotonic maneuvers are performed in erect and supine positions to ascertain the level of collapse and help determine a targeted approach for treatment.


The preoperative assessment should also include general medical health with particular focus on the relevant comorbidities, including cardiac issues.




Relevant anatomy


The base of the tongue has a rich vascular supply from the lingual artery. Significant vessels are located laterally and inferiorly. The dorsal lingual artery is the major branch that arises from the lingual artery, usually below the hyoglossus muscle. At the level of the hyoid bone, it is located above it and medial to the hypoglossal nerve. Inferiorly located, with regard to the artery, lies the lingual vein that, in turn, accompanies the hypoglossal nerve.




Special equipment


Mouth Gags


In choosing an appropriate mouth gag or retractor for TORS surgery, the main consideration is whether the device provides adequate exposure to the anatomic structures without compromising the workspace necessary for the workings of the robotic arms and instruments. Two commonly used mouth gag systems are Davis Meyer (Karl Storz, USA) and Feyh-Kastenbauer-Weinstein-O’Malley (Gyrus ACMI, Germany). Each system includes multiple tongue blades of different lengths with integrated suction tubes for smoke evacuation. The ideal system is based on surgeon’s preference.


Robot Instrumentation


The surgery is performed with the da Vinci Surgical system (Intuitive Surgical, Sunnyvale, CA, USA). The required robotic instrumentation includes the high-definition camera and the EndoWrist instruments (Intuitive Surgical, Sunnyvale, CA, USA).


High-definition camera


The binocular camera provides magnification of up to 10 times, which results in a 3D high-definition image that allows easy identification of vessels and nerves. It is available in 12-mm and 8-mm diameter scopes, both of which provide excellent optics while providing adequate working space in the mouth.


EndoWrist instruments


For TORS, two 5-mm articulated EndoWrist instrument arms are typically used. These instrument arms provide 180° of articulation and 540° of rotation, tremor filtration, amplitude scaling, and allow bimanual tissue manipulation in multiple planes. Typically, a grasper is placed in one arm and the spatula-tip monopolar cautery in the other for dissection and coagulation. Depending on surgeon preference, the monopolar cautery may be replaced with a compatible laser fiber. The grasping device is usually a 5-mm Maryland forceps.


Additional Equipment


Other TORS surgery equipment includes



  • 1.

    Headlight


  • 2.

    Suction cautery device


  • 3.

    Yankauer suction device


  • 4.

    Appropriate length forceps, hemostats, Metzenbaum scissors, and other basic soft tissue instruments.


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Apr 1, 2017 | Posted by in OTOLARYNGOLOGY | Comments Off on Transoral Robotic Sleep Surgery
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