Nasopharyngeal Stenosis 

Updated: Nov 04, 2018
Author: Gauri Mankekar, MD, PhD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Background

The nasopharynx is defined as the superior portion of the pharynx that lies between the choanae of the nasal cavity and the oropharynx (ie, the level of the posterior limit of the soft palate). Stenoses of this area are rare. They are classified according to their etiology, which may be primary (ie, due to a disease process) or secondary (ie, iatrogenic). However, most current cases are understood to be secondary to tonsillectomy, adenoidectomy, uvulopalatoplasty, or radiotherapy for nasopharyngeal carcinoma.

Because of a high incidence of recurrence, the treatment of this condition is challenging. Even with optimal planning and surgical technique, many patients require repeat operations to obtain a satisfactory result. Therefore, many treatment modalities are being tried to cure this problem.

Nasopharyngeal stenosis (NPS) should not be confused with choanal atresia. Choanal atresia is a congenital deformity that causes a narrow or completely obstructed airway at the choanae that often extends into the nasal cavity.[1] Generally, choanal atresia includes a bony component. Conversely, nasopharyngeal stenosis (NPS), by definition, is outside of the nasal cavity, is not congenital, and is caused by scar tissue secondary to a disease process or traumatic insult.

An image depicting complete nasopharyngeal stenosis can be seen below.

Complete nasopharyngeal stenosis. Complete nasopharyngeal stenosis.

History of the Procedure

Historically, many procedures have been used in an attempt to correct nasopharyngeal stenosis (NPS).

  • Simple dilatation is generally not successful except in mild partial occlusion.

  • A seton technique has been used with limited success. A heavy silk suture or other seton material is put in place, and, as it passes through the scar tissue, epithelialization of the tract develops. This tract can then be divided with the hope that the epithelialization prevents the stenosis from recurring.

  • One reportedly successful technique involves division of the obstruction and resection of the scar tissue, using a stent to maintain the opening. The principle is similar to that used in correction of choanal atresia. Many variations of this procedure have been performed, including one in which a split-thickness graft is used to help resurface the raw areas.

  • One of the most successful methods of repair is division of the obstruction and resection of the scar tissue along with resurfacing using rotational mucosal flaps.

  • Since 2008, endoscopic transnasal repair using either powered shavers or lasers has become a popular method of repairing nasopharyngeal stenosis.

  • Endoscopic transnasal CO2 laser ablation of the stenosis followed by balloon dilation and mitomycin application has been reported.[2]

Problem

Patients with nasopharyngeal stenosis could frequently suffer from other significant morbidities like phonatory changes, sleep disordered breathing and otologic disturbances e.g. secretory otitis media and hearing loss.[3, 4, 5]

Epidemiology

Frequency

Nasopharyngeal stenosis (NPS) is relatively rare. The true incidence of this rare condition is difficult to assess. In 1944, in a 10-year review of 100,000 tonsillectomies and adenoidectomies at the Manhattan Eye, Ear, and Throat Hospital, Imperatori found only 3 cases.[6] This condition has no sex predilection.

Etiology

Most cases of nasopharyngeal stenosis (NPS) are caused by inexpert surgery and postsurgical scarring. Overly enthusiastic adenoidectomies or uvulopalatoplasties are the usual operations that lead to nasopharyngeal stenosis (NPS). However, tonsillectomies, surgery of the soft palate, and pharyngeal surgeries to treat velopharyngeal incompetence can also cause nasopharyngeal stenosis (NPS). The literature prior to 1929 reports that most cases were due to the gumma of tertiary syphilis of the mouth, pharynx, and palate and the treatment of these lesions with caustic chemicals.

Giannoni et al (1998) have reported 9 cases of nasopharyngeal stenosis in children following adenoidectomy with KTP Laser. Many reports have been published of nasopharyngeal stenosis following radiotherapy for nasopharyngeal carcinoma.[7, 8, 9, 3, 10] Other rare causes in the literature include rhinoscleroma, lupus, diphtheria, scarlet fever, bullous pemphigoid, tuberculosis, and acid burns.

A retrospective study by Kouga et al indicated that in patients with craniosynostosis-related respiratory problems, nasopharyngeal stenosis is more often the culprit in those with Pfeiffer syndrome than in patients with Crouzon or Apert syndrome.[11]

Pathophysiology

Nasopharyngeal stenosis (NPS) may appear months to years after adenoidectomy or uvuloplasty or radiotherapy. It results from excess mucosal removal or scarring during surgery or radiotherapy followed by scar contracture and maturation. The degree and extent of the stenosis may vary from patient to patient. The scar tissue may cause a circumferential narrowing, a web, or bands. A discrete circumferential web or a long stenosed segment that forms a narrow tunnel several centimeters long may be present.

Presentation

The severity of symptoms is related to the degree of nasopharyngeal stenosis (NPS). The history includes a traumatic insult (iatrogenic, traumatic, or infective) to the nasopharynx. Symptoms include mouth breathing, snoring, rhinorrhea, hyponasality, dysphagia, otalgia, loss of hearing (otitis media), and anosmia. If these symptoms develop following a surgical procedure in the nasopharynx or radiotherapy, nasopharyngeal stenosis (NPS) should be considered.

Upon examination, the mucosa of the nasal airway may be blue and boggy, as is seen with nasal obstruction. Airflow through the nostrils may be reduced or eliminated. Scar tissue that involves the soft palate and tonsil pillars may be visible. A postnasal mirror or a rigid or flexible nasendoscope aids in making the stenosis visible.

Indications

The severity of the symptoms must be balanced against the difficulty of surgical repair and the possibility of recurrence and multiple operations. Many patients are young and have to live with potentially progressive symptoms for many years. Symptoms are usually severe at presentation, and surgical intervention is usually required.

Relevant Anatomy

The nasopharynx can be thought of as an essentially cuboidal space. The roof is formed by the base of the skull and the sphenoid sinus, anteriorly bounded by the choanae and posterior portion of the vomer. The floor consists of the superior surface of the soft palate and uvula. Incorporated into the lateral walls are the eustachian tube orifices and the Rosenmüller fossae. The posterior wall is the superior extension of the posterior pharyngeal wall.

The mucosa of the nasopharynx is the respiratory type. The midline usually contains a large deposit of lymphoid tissue that often extends into the Rosenmüller fossae.

The shape of the nasopharynx changes with respiration and deglutition. During respiration, the soft palate is drawn away from the posterior pharyngeal wall to open an airway. During deglutition, the palate elevates and contacts the nasopharynx so that food and fluid do not pass into the nose.

Contraindications

Surgical correction of nasopharyngeal stenosis (NPS) may be contraindicated in the presence of the patient's comorbidities and inability to tolerate anesthesia or surgery, but the symptoms, which are usually severe at presentation, usually require surgical intervention.

 

Workup

Imaging Studies

CT scanning and virtual endoscopy of the nasopharyngeal region can enable diagnosis and proper evaluation of the degree and extent of stenosis. This can, in turn, help to plan the surgical treatment. Axial CT scans can accurately define the nature and thickness of the atresia, the narrowing of the posterior nasal cavity, and the thickening of the vomer. A thorough preoperative assessment is needed to ensure the best surgical option for the individual lesion.

Diagnostic Procedures

Preoperative rigid nasal endoscopic examination and/or flexible nasopharyngolaryngoscopy is essential to assess the thickness, nature and extent of the stenosis, the deformity of the posterolateral aspect of the nasal cavity, and to identify anatomical deformities at the level of the vomer and the posterior nasal cavity. Identifying concurrent upper aerodigestive tract stenosis, which may be present, is important.

Histologic Findings

Histology of the resected scar tissue from the stenotic segment usually reveals respiratory epithelial lined stromal tissue with chronic inflammation, edema, and fibrosis.

Staging

Krespi and Kacker proposed the following scale to grade the severity of nasopharyngeal stenosis:[12]

  • Nasopharyngeal stenosis (NPS) type I (mild)

  • Nasopharyngeal stenosis (NPS) type II (moderate)

  • Nasopharyngeal stenosis (NPS) type III (severe, wherein the entire palate fuses with the posterior and lateral palatal wall, leaving a residual nasopharynx opening with a diameter of less than 1 cm.)

Wang et al (2009) have divided acquired nasopharyngeal stenosis based on the duration between causative trauma/radiotherapy and diagnosis into the following 3 types:[13]

  • Type 1 - Diagnosed within 3 months of causative trauma/radiotherapy

  • Type 2 - Diagnosed between 3-6 months of causative trauma/radiotherapy

  • Type 3 - Diagnosed more than 6 months after trauma or radiotherapy

 

Treatment

Medical Therapy

Nasopharyngeal stenoses (NPS) are typically challenging to correct and often recur. Prevention is the best form of treatment. Careful operative technique, judicious use of electrocautery, and adequate preoperative evaluation for adenoidectomy or uvulopalatoplasty during the primary surgery are essential to prevent nasopharyngeal stenosis (NPS). In cases of mild scarring, McLaughlin et al found some success with triamcinolone acetonide injections, but the only curative treatments for acquired nasopharyngeal stenosis (NPS) are surgical.[14]

Surgical Therapy

A thorough preoperative assessment of the lesion is needed to ensure that the best surgical option for the individual lesion is used.Nasopharyngeal stenosis rarely exists in isolation. Often concurrent stenosis of the upper aerodigestive tract may require general anesthesia for management.[2]

Many surgical approaches have been suggested for nasopharyngeal stenosis, including transnasal, transpalatal, transantral, sublabial transnasal endoscopic, and transseptal approaches.[3, 8, 9] The transpalatal approach offers excellent exposure and a high success rate but is time consuming and may be associated with bleeding and sequelae like palatal muscle dysfunction, palatal fistula, and maxillofacial disturbances.[15] The transnasal approach provides narrow exposure, making raising of the mucosal flaps difficult. Also, injury to the eustachian tube and the skull base is possible.[16]

Other surgical options include steroid injections, scar lysis with CO2 laser, plasma hook, yttrium-aluminum-garnet (YAG) laser,[3] or with power instruments like shavers, Surgitron high-frequency radio waves,[17] skin grafts, Z-plasty repair, various local mucosal flaps, insertion of prosthetic stents, silastic grommets, nasopharyngeal obturators, and topical application of mitomycin C and balloon dilation of the stenotic segment.[2, 18, 19] .

A study by Karakoc et al in which endoscopy-assisted coblation was used in two patients with acquired nasopharyngeal stenosis reported that the procedure is less painful than other surgical options and can be successfully used without the need for postoperative stents.[20]

Bivalved palatal transposition flap

Described by Toh et al in 2000, this procedure is performed with the patient under general anesthesia with orotracheal intubation.[21] The patient is supine with the neck extended. A mouth gag is used to expose the oropharynx. Local anesthetic (1% lidocaine) with adrenaline (1:100,000) is infiltrated into the operative site. A transverse and slightly curvilinear incision is marked out on either side of the stenosis. This incision is extended inferolaterally to the expected position of the base of the posterior tonsillar pillars.

The stenosis is then bivalved by elevating mucosal flaps on a submucosal plane off the oral and nasopharyngeal surfaces of the soft palate. The superiorly based flap represents the nasopharyngeal surface of the soft palate, and the inferiorly based flap from the oropharyngeal side is attached to the posterior pharyngeal wall. The posterior half of the bivalved palate is then transposed anteriorly and sutured to the incision on the oral side of the soft palate. The inferiorly based mucosal flap is transposed superiorly and sutured to the denuded portion of the posterior pharyngeal wall.

Laterally based pharyngeal flap

For this procedure, as described by Cotton in 1985, the patient is anesthetized and local anesthetic and adrenaline are infiltrated, as in the bivalved palatal transposition flap.[22] A lateral incision is made through the scar tissue into the lateral pharyngeal wall. The incision is deepened as far as possible without damaging important structures in the parapharyngeal space. The mucosa is now elevated to allow a considerable amount of scar tissue removal. The entire posterior pharyngeal wall is elevated as a laterally based pharyngeal flap (thus, only one side of the nasopharyngeal stenosis is dissected).

The laterally based pharyngeal flap is elevated as a mucomuscular flap at the plane of the prevertebral fascia. The inferior limit of the flap is dissected as far back as possible. The inferior limit of the flap is dissected as far back as possible, and the pharyngeal mucomuscular flap is mobilized and sewn into position, covering the denuded area of the lateral walls of the nasopharynx and oropharynx. Smith has used sternocleidomastoid myocutaneous flap reconstruction for nasopharyngeal stenosis (NPS).[23]

Facial artery musculomucosal flap

In a prospective study, Nangole and Khainga described the efficacy of the facial artery musculomucosal (FAMM) flap as an alternative treatment for severe postsurgical nasopharyngeal stenosis. To perform the procedure, they identified the position of the facial artery using a hand-held Doppler ultrasonography scanner and mapped its position in the musculomucosal pedicle flap. In the first stage of the surgery, the flap was raised and advanced to the defect. In the second stage, the flap was detached from its donor site, and redundant tissue was excised. The surgeons did not use stents or obturators, as the epithelial surface was already established. Nangole and Khainga reported that the flap was easy to raise and was associated with very minimal donor site morbidity.[24]

Carbon dioxide laser

Krespi and Kacker have reported on the largest number of patients who have undergone successful nasopharyngeal stenosis (NPS) correction with a CO2 laser.[12] After scar tissue was excised with the laser, patients with moderate-to-severe stenosis received a nasopharyngeal obturator to be worn at night for 2-6 months to prevent restenosis. The CO2 laser was reported to cause less thermal damage to adjacent tissue and minimal mucosal de-epithelialization, and it offered better hemostasis.

Jones et al used a CO2 laser under general anesthesia to create an opening in the nasopharynx.[4] The patients were then fitted with removable and adjustable palatal obturators to keep the nasopharynx open. A daytime insert piece with a small obturator hole for diminished velopharyngeal insufficiency and a night-time piece without an insert to maximize recumbent airflow were also used. The obturators were removed after 6 months, and a topical application of mitomycin C was used as a fibroblast inhibitor. These authors monitored their patients with polysomnography and have reported satisfactory results.

Igwe et al and Sidell et al report the use of a flexible CO2 laser fiber through the working channel of a nasal endoscope to make radial incisions on the stenosis under direct visualization.[2, 18] The laser is then removed and a controlled radial expansion balloon dilation device is inserted, advanced to span the stenotic segment and inflated to achieve adequate dilation. Mitomycin-C is then topically applied to the area of dilation. They report successful long lasting dilation without complications with a follow-up period of 12-18 months.

Plasma hook

Madgy et al treated 3 cases of severe nasopharyngeal stenosis (NPS) with plasma radiofrequency–based coblation.[5] A crescent of scar tissue was excised with the plasma hook. The crescent extended approximately 5 mm laterally to each side and approximately 5 mm posteriorly to the pharyngeal wall. In one case, they applied mitomycin C to the raw edges to reduce scarring and recurrence. They reported that the plasma hook excision incurs less epithelial damage and produces a smaller area of collagen denaturation than conventional electrocautery. In addition, the procedure itself is easy to perform and offers satisfactory results.

Eppley et al compared the use of (1) preoperatively fabricated stents made from a clasped palatal appliance onto which hollow acrylic conduits were extended through surgically re-created pharyngeal ports with (2) intraoperatively fashioned silastic grommets.[25] They found that the palatal stents were less tolerated than the silastic grommets. In addition, the grommet stent obviates the need for extensive preoperative preparation and is easy to insert and remove; also, during the stenting, an exchange of air occurs. Patient tolerance was found to be better with the grommet stents, which could, therefore, be retained longer with better results.

Transnasal endoscopic repair

The advantages of this method are that it offers a good vision of the operative field and enables accurate removal of the stenotic plate without damaging neighboring structures, thereby reducing the incidence of re-stenosis. This is a safe procedure with minimal blood loss, rapid recovery, and short hospitalization. During follow-up, remove postoperative granulations or polyps at the site of the neochoana.[10]

Ku et al in 2007 described transnasal endoscopic YAG laser resection of posterior choanal stenosis following radiotherapy for nasopharyngeal carcinoma in 5 patients.[9] All 5 were symptom free postoperatively, although 2 developed mild re-stenosis not requiring surgery. In 2008, Wang et al described successful transnasal endoscopic repair without postoperative stenting in 18 out of 19 patients with nasopharyngeal stenosis (NPS) following radiotherapy for nasopharyngeal carcinoma. One patient required revision surgery.[10]

Wang et al (2009) used temperature controlled radiofrequency repair (TCRF) with the aid of an endoscope in 32 patients. All patients with type 1 and 2 received silicon stents. Three patients required revision of the procedure, and one patient required a third revision, which was performed via transpalatal approach. They found that the technique worked best in those patients who were diagnosed more than 3 months after trauma/radiotherapy (ie, type 2 and type 3 cases).

Hussein et al (2013)[17] have described the use of Surgitron high-frequency radio waves to remove scar tissue, followed by application of mitomycin C to the wound and then placement of stents for 2 weeks.

Intraoperative Details

Bivalved palatal transposition flap

Described by Toh et al in 2000, this procedure is performed with the patient under general anesthesia with orotracheal intubation. The patient is supine with the neck extended.[21] A mouth gag is used to expose the oropharynx. Local anesthetic (1% lidocaine) with adrenaline (1:100,000) is infiltrated into the operative site. A transverse and slightly curvilinear incision is marked out on either side of the stenosis. This incision is extended inferolaterally to the expected position of the base of the posterior tonsillar pillars.

The stenosis is then bivalved by elevating mucosal flaps on a submucosal plane off the oral and nasopharyngeal surfaces of the soft palate. The superiorly based flap represents the nasopharyngeal surface of the soft palate, and the inferiorly based flap from the oropharyngeal side is attached to the posterior pharyngeal wall. The posterior half of the bivalved palate is then transposed anteriorly and sutured to the incision on the oral side of the soft palate. The inferiorly based mucosal flap is transposed superiorly and sutured to the denuded portion of the posterior pharyngeal wall.

Laterally based pharyngeal flap

For this procedure, as described by Cotton in 1985, the patient is anesthetized and local anesthetic and adrenaline are infiltrated as for the bivalved palatal transposition flap.[22] A lateral incision is made through the scar tissue into the lateral pharyngeal wall. The incision is deepened as far as possible without damaging important structures in the parapharyngeal space.

The mucosa is now elevated to allow a considerable amount of scar tissue removal. The entire posterior pharyngeal wall is elevated as a laterally based pharyngeal flap (thus, only one side of the nasopharyngeal stenosis is dissected). The laterally based pharyngeal flap is elevated as a mucomuscular flap at the plane of the prevertebral fascia. The inferior limit of the flap is dissected as far back as possible. A back-cut is now performed inferiorly to mobilize the pharyngeal flap. This mucomuscular flap is mobilized and sewn into position, covering the denuded area of the lateral walls of the nasopharynx and oropharynx.

Palatal eversion

Abdel–Fattah described this procedure for patients who develop nasopharyngeal stenosis following adenotonsillectomy. The soft palate is divided in the midline. The fibrous tissue causing stenosis is removed, followed by eversion and fixation of the two palatal divisions on either side for 6 weeks to allow complete epithelialization of the stenotic area, followed by another operation to reunite the soft palate in the midline.[26, 27]

Transnasal endoscopic repair

This procedure is performed under general anesthesia, as described by Wang et al.[10] The nose is decongested using pledgets soaked in a solution of 1% lidocaine hydrochloride and 0.25% phenylepinephrine. A solution of 1% lidocaine hydrochloride with 1:100,000 epinephrine is administered with a spinal needle to the stenotic portion and posterior septum under direct visualization using the 4mm 0° rigid telescope.

Under endoscopic visualization, a flaps knife is used to trim the scarred mucosa in the posterior choanae. Additional scar tissue at the posterior end of the inferior or middle turbinate can be excised with a powered shaver or Blakesley forceps. Ku et al have used the YAG laser to remove the scar tissue under endoscopic vision.[9] Hussein et al[17] have described the use of Surgitron high-frequency radio waves to remove the scar tissue, followed by application of mitomycin C and stenting for 2 weeks. Care is taken to avoid damage to the normal nasal mucosa. Tissue is also taken for histopathology to rule out recurrence of carcinoma in cases of stenosis following radiotherapy for nasopharyngeal carcinoma. After the surgical procedure, some authors used Merocel as a stent,[9] while others did not use any stents.[10] At the follow-up visit, an endoscopic examination is performed and any granulation tissue or polyps at the site of the neochoana are removed.

Postoperative Details

A nasopharyngeal tube is left in for 24-48 hours to allow the flap to settle, to maintain an airway, and to help with suctioning. The patient is maintained on clear fluids for up to a week. Postoperative antibiotics are used. The stents are removed 2-6 weeks after surgery, depending on the surgeon. The patients are advised to perform nasal douching with normal saline and steroid nasal sprays.

Follow-up

Monitor the patient with a rigid nasal endoscope to check that the surgery is successful and the patient has no complications. In the long-term, polysomnography and nasal endoscopy help to monitor for restenosis.

Complications

Postoperative airway problems and hemorrhage have not been reported. Velopharyngeal reflux has been reported but is transient and gradually resolves. The main complication is re-stenosis. This condition is common, and the literature suggests that a repeat operation is performed in 10-20% of patients.

Outcome and Prognosis

Even with optimal planning and surgical technique, many patients require repeat operations to obtain a satisfactory result. Giannoni et al showed that acquired nasopharyngeal stenosis (NPS) symptoms had an average onset time of 3.1 weeks postsurgery.[28] Stepnick reported recurrent scarring and stenosis within 6 weeks of treating nasopharyngeal stenosis (NPS) with the placement of a free flap.[29] Ku et al have reported nasopharyngeal stenosis (NPS) symptoms developing an average of 10.5 months (range 2-40 months) postradiation in patients who have nasopharyngeal carcinoma.[8]

Future and Controversies

Since the discovery and widespread use of antibiotics, the incidence of nasopharyngeal stenosis (NPS) has declined. The main etiologies in current practice include tonsillectomy, adenoidectomy, velopharyngeal surgery, uvulopalatopharyngoplasty, and postradiotherapy cases of nasopharyngeal carcinoma.

The nature of the stenosis renders it difficult to treat successfully. This, coupled with its rarity, leaves most surgeons with limited experience in the condition. Mucosal flaps of the palate and pharynx were the most successful techniques for repair. However, the advent of the rigid nasal endoscope, powered shavers, and lasers has made it easier to diagnose, operate under direct vision with minimal hospital stay, and monitor the patient postoperatively.