1 INTRODUCTION

Upper airway obstruction results from excess and/or collapse of soft tissue in the soft palate, tonsillar pillars, tongue, tongue base, and hypopharyngeal walls. Specific anatomic risk factors predisposing to obstructive sleep apnea/hypopnea syndrome (OSAHS) include long soft palate, shallow palatal arches, large tongue base, narrowmandibular arches, and mandibular hypoplasia.¹ Othergeneral anatomic factors often associated with OSAHS include obesity, large Body Mass Index (BMI), shortened thick neck, anterior larynx location, enlarged tonsils and/or adenoids, lingual tonsils, thickened pharyngeal walls, elongated uvula, redundant soft palate, large tonguevolume, deviated nasal septum, turbinate hypertrophy, and redundant or folded epiglottis.² Cephalometric studies employing computed tomography (CT) have correlated increased OSAHS severity with increased BMI, larger tongue and soft palate volumes, and decreasedairway space.³ Diagnostically, Fujita employed endoscopy with the Mueller maneuver (reverse Valsalva) to identify sites of obstruction in the nasopharynx, oropharynx and hypopharynx.⁴ Three general profile types were identified based on the predominant areas of obstruction:Type I – retropalatal/velopharyngeal; Type II – retropalatal/velopharyngeal and hypopharyngeal; and Type III –hypopharyngeal. Catheter pressure transducers employed in OSA sleep studies have shown that upper airway collapse occurred at the velopharyngeal/retropalatal level and the hypopharyngeal/postlingual level in comparable frequencies.⁵

The grading system most commonly used to identify retrolingual obstruction is the Friedman tongue position (FTP) (see Chapter 16). Patients with FTP III and IV have a likelihood of retrolingual obstruction contributing to OSAHS.

2 OPERATIVE PROCEDURES

2.1 HYO-MANDIBULAR SUSPENSION

In the event of severe OSAHS, a hyoid expansion and hyo-mandibular suspension procedure is performed. These surgical methods enhance the anterior superior repositioning of the tongue base, enlarge the pharyngeal airway in a lateral dimension and partially separate the tongue base from the lower airway by an infrahyoid myotomy. Hyoid expansion and hyo-mandibular suspension/myotomy may be performed in conjunction with or following transoral or transcervical tongue suspension.

The anterior neck is prepped and draped. The anterior mandible, hyoid and the thyroid cartilages are then outlined with a skin marker with the neck slightly extended. Lidocaine with epinephrine 1:100,000 is injected into the planned incision sites. Two 0.5 cm incisions are made under the chin off the midline and using blunt dissection, the soft tissues overlying the mandible are cleaned. After insertion of the first screw using the Repose device (Influent, Concord, NH), the screw inserter is loaded with a new spare screw and the inserter is positioned perpendicular to the mandible, firm pressure applied and the screw is inserted into the inferior edge of the mandible. A loop of #1 polypropylene suture is already preloaded to the screw by the manufacturer (Fig. 51.1).

Fig. 51.1 Insertion of two Repose screws to the mental area of the mandible via stab incision. Insert shows details of the screw with preloaded suture.

A second horizontal incision is made over the body of the hyoid measuring 5–6 cm. Subcutaneous fatty adipose tissue can be dissected and removed. Electrocautery is used to separate the infrahyoid muscles from the body of the hyoid bone. A single bone hook is placed to retract and stabilize the hyoid during the dissection. The sternohyoid and thyrohyoid muscles are detached from the body of the hyoid between the lesser cornuae (Fig. 51.2). Careful dissection around the body of the hyoid eliminates risk of injury to the neurovascular structures. Careful dissection and good hemostasis are mandatory to avoid injury to the pre-epiglottic fat pad. The suture passer is then loaded with the polypropylene suture and tunneled at the subplatysma layer from the mandibular incisions into the lower (hyoid) incision (Fig. 51.3). The suture passer is then removed. One free end of the polypropylene suture is then loaded into a Mayo needle and is passed through the suprahyoid muscles, catching a full thickness bite of the tissue.

Fig. 51.2 Horizontal incision exposing the body of the hyoid, separation of infrahyoid muscle with electrocautery.

Fig. 51.3 Delivery of sutures to the lower incision with a suture passer.

2.2 HYOID DISTRACTION AND EXPANSION

When the hypopharyngeal airway needs to be enlarged in a lateral direction, as determined by preoperative fiberoptic endoscopy, the hyoid bone is then divided in the midline (hyoid distraction) (Fig. 51.4). Following the division of the hyoid bone the polypropylene suture is passed around both sides of the divided edges in a figure of eight configuration (Fig. 51.5). The distracted hyoid segments are then prepared for suspension toward the mandible. In order to maintain stability of the two hyoid segments an absorbable or non-absorbable rigid or semirigid implant can be placed to keep the two ends of the divided hyoid in expansion (hyoid expansion) (“>Fig. 51.6).

Fig. 51.5 Division of the hyoid bone in the midline and suspension of the hyoid segments toward the mandible by figure of eight sutures.

Fig. 51.4 Hyoid distraction, division of the hyoid body in the midline after myotomy using a bone cutter or chisel.

Fig. 51.6 Hyoid spacer between the two cut ends of the bone, using non-absorbable graft. Hyoid expansion.

The two ends of the polypropylene suture are then tied together to achieve a superior anterior pull of the hyoid and tongue base. The inferior wound is drained and both wounds are closed in layers.

All patients were admitted for close observation overnight. Perioperative and postoperative care includes steroids, intravenous antibiotics, anti-reflux medications, humidified oxygen, intravenous fluids, nasal trumpet, and pulse oximetry monitoring.

3 RESULTS

The most common postoperative patient complaints included dysphagia, odynophagia and surgical wound pain. All patients were able to tolerate liquids and a soft diet at the time of discharge. No patients requested or required removal of the suspension sutures.

After 3–12 months of follow-up postoperatively, over 90% of the patients were subjectively improved by patient and/or spouse history. Symptomatic improvement included decrease in snoring, improved quality of sleep, and decreased daytime somnolence. Follow-up polysomnographic studies were performed 3 months to 1 year postoperatively in 52 patients. The patients that underwent hyo-mandibular suspension with or without hyoid expansion showed significant improvement in the mean Respiratory Disturbance Index (RDI) from 71.2 (+/−18.0) preoperatively to 28.4 (+/−16.8) postoperatively.

4 DISCUSSION

The most important part of surgical treatment of OSAHS is making a correct diagnosis of the site(s) of obstruction. The difficulty with OSAHS and tongue base obstruction has been the poor ability to grade severity and predict surgical success.

The advantages of the hyoid expansion and suspension are multi-fold. The splitting of the hyoid allows for potential lateral widening of the hypopharyngeal airway. Division of the infrahyoid musculature allows partial separation of the larynx from the hyoid and tongue base. This incomplete laryngeal drop can keep the inferior pulling force of intrathoracic structures from the hypopharyngeal structures separate. The negative pressures that occur during the inspiration phase of respiration in an OSA patient can significantly contribute to further collapsing the flaccid structures of the upper airway.

Potential complications of hyoid suspension and expansion include airway obstruction, prolonged odynophagia, speech problems, neck hematoma, wound infection and intense cervical pain. Our experience, however, has shown very few problems. Pain and dysphagia/odynophagia are the most common complaints, but have all resolved in reasonable time. Patients with prolonged dysphagia/odynophagia may benefit from instructions on a modified supraglottic swallow (tongue push and elevation with throat clearing) as mentioned by Woodson and Fujita.^6,7 It is important to note that there were no airway or bleeding problems in the perioperative period. There were no suture or equipment problems either.

We have found that hyo-mandibular suspension and hyoid distraction–expansion procedures for tongue base obstruction have an important place in the surgical correction of tongue base and hypopharyngeal collapse in patients with severe OSA. We prefer this relatively minor external procedure over multiple stage transoral thermal ablation of the tongue base. Hyoid expansion with interposition of a semirigid spacer implant is the only surgical method that potentially enlarges the pharyngeal airspace in a lateral direction.