1 INTRODUCTION

Nasopharyngeal stenosis (NPS) after uvulopalatopharyngoplasty (UPPP) is a serious problem. More palatal procedures are being performed leading to an increased incidence of nasopharyngeal stenosis, but little has been written about this severe complication and its management.

Historically, adult NPS was a consequence of maxillofacial trauma or severe infection such as syphilis. Now NPS is seen as a complication of surgery such as tonsillectomy and adenoidectomy in the pediatric population, and UPPP in the adult population with obstructive sleep apnea. Rhinoscleroma, lupus, diphtheria, tuberculosis, acid burn, scarlet fever and aggressive velopharyngeal repair can also cause nasopharyngeal stenosis.^1,2

The complication of severe nasopharyngeal stenosis following UPPP is well understood. Most cases are problems of surgical technique. The management of intraoperative or postoperative bleeding with nasopharyngeal packing and electrocautery is an important cause of NPS. Adenoidectomy in conjunction with UPPP carries an increased risk of nasopharyngeal stenosis. Other technical errors include excessive excision and cauterization of the posterior tonsillar pillars or undermining the posterior and lateral pharyngeal walls. Wound dehiscence, infection, necrosis and scarring in keloid-forming patients are some other causes of acquired NPS. Also, the use of KTP (potassium titanyl phosphate) laser to perform adenoidectomy is associated with an extremely high incidence of NPS.¹

The management of NPS is difficult and reoperation using conventional methods results in only short-term improvement in symptoms with restenosis.

2 SURGICAL TECHNIQUE

Nasopharyngeal stenosis is graded as type I (mild) when the lateral aspects of the palate adhere to the posterior pharyngeal wall. Type II (moderate) is the occurrence of circumferential scarring with small central opening of the soft palate. This circumferential opening is between 1 and 2 cm in diameter. Type III (severe) is when the entire palate fuses with the posterior and lateral palatal wall, leaving a residual opening less than 1 cm (Fig. 58.1&). Treatment for type I stenosis can be carried out as an outpatient, whereas treatment for type II and III stenosis may require general anesthesia in an inpatient setting. CO₂ laser is used in conjunction with a scanning device at 30 watts, with a pharyngeal handpiece in a continuous mode in type I patients. During surgery, two nasopharyngeal tubes (size 6 or 7) are passed and left in place for 3–4 days as temporary stents (Fig. 58.2). A customized nasopharyngeal obturator is used in type II and III patients and inserted after removal of the stents on the third or fourth postoperative day (Figs 58.3 and 58.4). The nasopharyngeal obturator consists of an upper dental appliance with a customized nasopharyngeal extension as an obturator to stent open the nasopharynx. The patients use the stent during the day and remove it at night. The stent is left in place for 3–6 months (Fig. 58.5).

Fig. 58.1 A, Mild nasopharyngeal stenosis. B, Severe nasopharyngeal stenosis.

Fig. 58.2 Intraoperative view after the release of stenosis with temporary stents in place.

Fig. 58.3 Customized palate obturator with nasopharyngeal extension.

Fig. 58.4 Palate obturator with nasopharyngeal extension (oral and nasopharyngeal views).

Fig. 58.5 Postoperative photo showing a widely patent nasopharynx.

For patients with severe stenosis (type II or III), we have also used a topical 6–8 minute application of 0.04% mitomycin-C to the raw surface area of the nasopharynx.

3 DISCUSSION WITH RESULTS ANDALTERNATIVE TREATMENT OPTIONS

UPPP remains the most commonly performed surgical treatment for obstructive sleep apnea/hypopnea syndrome. NPS is a severe complication of UPPP, though its incidence is not known. The incidence of severe type II and type III is estimated to be under 1%. Factors that increase the incidence of NPS include postoperative bleeding, infection, overheated tissues by the use of KTP laser, over-resection or excessive undermining of lateral pillars and combination of adenoidectomy with UPP. No uniform risk factors or surgical errors have been identified in our study.

Many methods of repair of NPS have been reported in the literature with variable results. These methods include passage of a heavy silk suture through the stenotic lumen, cervical pedicled skin flap, local rotation and advancement flaps, Z-plasty, intralesional steroid injection, free flaps and CO₂ laser.

The type I stenosis is treated under local anesthesia in an office setting using CO₂ laser without the use of a nasopharyngeal obturator. Moderate and severe cases of NPS are treated in the operating room under general anesthesia. Most of these patients require prolonged use of the nasopharyngeal obturator. The obturator used has been custom designed by the senior author to treat severe cases of nasopharyngeal stenosis. The nasopharyngeal obturator consists of a standard dental obturator, which is constructed after a dental impression has been taken, and a nasopharyngeal extension with an airway to fill the neo-nasopharynx. This nasopharyngeal extension is contoured to the shape of the neo-nasopharynx using a drill after surgery to tightly fit the neo-nasopharynx after temporary stents have been removed. Use of the nasopharyngeal obturator in conjunction with CO₂ laser led to a patent nasopharynx (defined for the purpose of this study as a nasopharyngeal opening of greater than 3 cm with no bands between the lateral pharyngeal wall and the palate in all patients.

In most cases NPS occurred 4–5 weeks postoperatively. The timing of repair is important and repair is usually performed 6–8 months after the primary surgery to allow for the maturation of nasopharyngeal scar tissue and complete re-epithelialization of nasopharyngeal mucosa. Early intervention can lead to restenosis and failure of this procedure, as scar bands continue to contract and reshape the nasopharynx.

The advantages of using the CO₂ laser scanning device with high energy density when compared to Nd-Yag laser, KTP laser, electrocautery or radiofrequency ablation devices for repair of NPS include reduced thermal damage to nasopharyngeal tissue and minimal de-epithelialization of nasopharyngeal mucosa. The advantage of the CO₂ laser scanner over a surgical knife is improved hemostasis and reduced lateral scanner zone damage with limited tissue slough.

Disadvantages of using the CO₂ laser include the increased cost, and expertise needed in using the special handpiece with the surgical scanner.

The success rate of the techniques described in the literature is not known, due to the small number of patients in the various series.

Mitomycin-C (MMC) is an anti-neoplastic agent, which causes inhibition of DNA and protein synthesis. Data are available on the topical application of mitomycin-C (0.4 mg/ml applied for 8–10 minutes) in laryngotracheal reconstruction patients where reduced granulation formation has been reported. The use of MMC to prevent postoperative scarring has been the focus of several recent studies. A natural antibiotic derived from Streptomyces caespitosus, MMC has been demonstrated to have both anti-neoplastic and anti-proliferative properties. The former is attributed to its ability to cross-link DNA and inhibit DNA, RNAand protein synthesis while the latter is a result of its suppression of fibroblast activity. Within ophthalmology, MMC has been used with success in glaucoma filtration and strabismus surgery, optic nerve decompression, pterygium excision and dacryocystorhinostomy. Use of MMC in our series has led to less scar formation and reduced the length of time an obturator needs to be worn. This is due to the inhibition of fibroblasts and similar effects have been seen in the nose (choanal atresia repair) and the airway.