1
Introduction
1.2
Indications and Contraindications
Obstruction of the airway at the retropalatinal and retropharyngeal airway is the key factor in the pathophysiology of obstructive sleep apnea syndrome (OSAS). Patient selection is crucial in successful surgery of the upper airway in OSAS. In addition to polysomnography, topical diagnostic workup is of paramount importance in this regard. We routinely perform polysomnography first and after that in cases of an Apnea/Hypopnea Index (AHI) below 30, schedule patients for sedated endoscopy (“sleep endoscopy”) with midazolam (without an anesthetist present) in those patients in whom surgery is considered. In patients with an AHI below 30 who refuse nasal continuous positive airway pressure (NCPAP) treatment up front, or in patients who cannot accept NCPAP for whatever reason, sedated endoscopy is performed as well, but by an anesthetist, with propofol. In the study period (March 2000–June 2004), in the case of mainly or only retrolingual obstruction as assessed by sleep endoscopy and a low AHI (arbitrarily <15–20, snoring up to mild sleep apnea), we usually started with radiofrequency ablation of the tongue base. In this situation, in the case of mild or moderate OSAS, oral devices were offered as an alternative. In cases of a relatively higher AHI (moderate to severe OSAS), the effect of Mandibular Repositioning Appliance (MRA) treatment is less efficacious. In the case of an index of 15 to 30 and mainly retrolingual obstruction, we performed hyoid suspension (aka hyoidthyroidpexia ) as the only procedure. In higher AHI patients we perform multilevel surgery (hyoid suspension, radiofrequency ablation of the tongue base, uvulopalatopharyngoplasty [UPPP]), with/or without genioglossal advancement (see Chapter 50 ). These patients usually have more severe and multilevel obstruction, which explains the higher AHI.
Hyoid suspension involves stabilization of the hyoid bone inferiorly by attachment to the superior border of the thyroid cartilage. The underlying principle for altering the hyoid is that anatomically, the hyoid complex is an integral part of the hypopharynx. Anterior movement of the hyoid complex increases the posterior airway space and neutralizes obstruction at the tongue base. This concept has been supported by several reports. In the United States, hyoid suspension is often performed in combination with genioglossus advancement and followed by maxillomandibular osteotomy (MMO) as phased surgery in case of failure. The rationale for using hyoid suspension only in our series was to avoid more radical and more extensive unnecessary surgery in well-selected patients. In this chapter we report our experiences with this procedure.
2
Patient Selection
Surgery was offered to symptomatic patients with moderate to severe OSAS for whom UPPP was unsuccessful ( n = 17) or who rejected or could not accept CPAP and preferred surgical therapy ( n = 14). All patients had full polysomnography and underwent upper airway examination using physical examination and sleep endoscopy under midazolam or propofol.
2.1
Upper Airway Assessment
Hyoid suspension was performed in the case of obstruction at the base of the tongue ( Fig. 53.1 ), assessed by physical examination and flexible sleep endoscopy. A high suspicion of mainly retropalatal obstruction (large tonsils and long uvula) excluded patients for hyoid suspension. Candidates for surgery were categorized into two groups: those who did not have prior surgery at the oropharyngeal or hypopharyngeal level (primary hyoid suspension) and those for whom UPPP was inadequate or detrimental (secondary hyoid suspension). In the latter group hyoid suspension was offered as salvage treatment. Multilevel obstruction (Fujita II) occurred in 20 patients; slight obstruction at the retropalatal level occurred in 9 patients (primary hyoid suspension, n = 14), and residual retropalatal obstruction after UPPP occurred in 12 patients (secondary hyoid suspension, n = 17). Only four patients who underwent primary hyoid suspension showed simple tongue base obstruction (Fujita III). Before UPPP, 15 patients showed multilevel obstruction (Fujita II), with emphasis on the palatal level; 2 patients showed retropalatal obstruction only (Fujita I). Sleep endoscopy workup according to the Fujita classification is shown in Fig. 53.2 .
2.2
Polysomnography
For sleep registration, patients stayed 1 night in the hospital. A CNS-Sleep I/T-8 recorder was used. This records sleep architecture (derived from an electroencephalogram, electrooculogram, and submental electromyogram), respiration (thoracic and abdominal measurement), airflow (mouth and nose thermistors), oxygen saturation (finger probe), movements of limbs, and the intensity of snoring.
3
Surgical Technique
3.1
Hyoidthyroidpexia and Postoperative Management
Under general anesthesia, with the head in a slightly extended position, a horizontal incision of approximately 5 cm is made in a relaxed skin tension line at the level between the hyoid and thyroid cartilage ( Fig. 53.3 ). Excessive fat tissue is excised if helpful for better visualization. In the case of a further posterior positioned hyoid, removal of fat is recommended also, because otherwise the anterior placement of the hyoid will result in a somewhat turkey-like neck contour.
Second, the strap muscles are severed just below the attachment to the hyoid. Partial removal of the severed strap muscles at the level between the hyoid and thyroid cartilage is sometimes also considered for the same cosmetic reasons, because there is no point in leaving the nonfunctional cut strap muscles in situ.
The tendon of the stylohyoid muscle is cut only if after release of the strap muscles insufficient mobilization is gained. Otherwise, the stylohyoid tendon is preserved. By mobilizing the hyoid bone in an anterocaudal direction and fixing it to the thyroid with two permanent sutures per side through the thyroid cartilage and around the hyoid bone, more space is created retrolingually. Although with increasing age ossification of the thyroid will take place, in more than 80 cases we have never needed to make drill holes. A sharp cutting needle has so far always been sufficient to pierce the thyroid cartilage.
Antibiotics are not routinely applied. A surgical drain is placed and usually removed after 24 to 72 hours postoperatively if drainage was less than 10 mL per 24 hours. Nocturnal oximetry is monitored throughout the first postoperative night in the intensive care unit, and nonopioid analgesics are used for pain relief, if necessary.
4
Postoperative Evaluation
All patients had a second polysomnography 3 months after surgery. The AHI, Epworth Sleepiness Scale (ESS), desaturation index and visual analog scores (VAS) for hypersomnolence and snoring and pain sensation were compared preoperatively and postoperatively per patient and between the two groups. Success was defined as when AHI decreased at least 50% or dropped below the threshold of 20 or Apnea Index (AI) decreased below 10 and as responders when AHI decreased.
4.1
Statistical Analysis
Tests between groups on continuous variables were performed with a Wilcoxon rank sum test. Categorical variables were tested with a Fisher exact test. All results are shown as mean ± SD. Significance was accepted for P < 0.05.
5
Results
Between March 2000 and June 2004, 31 patients (29 males and 2 females) underwent hyoid suspension. Secondary hyoid suspension was performed in 17 patients. Fourteen patients underwent primary hyoid suspension: 12 had difficulties using NCPAP and 2 refused NCPAP. Patient baseline characteristics are shown in Table 53.1 . No differences were found preoperatively for AHI, body mass index (BMI), age, ESS, desaturation indexes, and VAS scores. The BMI did not change significantly postoperatively, and all polysomnographies were considered valid.
