25

Food is cut and chewed by movements of the dentate mandible and afterward intermixed with saliva to form a cohesive bolus. The tongue is constantly moving the bolus toward the occlusal surface of the teeth. The lips and buccal muscles of the oral cavity help keep the bolus within the oral cavity. At the same time, the tongue and the soft palate create a seal serving to prevent the newly formulated bolus from spilling into the pharynx prematurely (Fig. 25.1A).

The trigger of the pharyngeal swallow is initiated through sensory information traveling to the medulla via the ninth and tenth cranial nerves. This trigger is activated when the bolus reaches the oropharynx. The duration of the normal pharyngeal transport lasts for about 1 second. During a short phase of apnea during the early stage of expiration, the nasopharynx is closed by the soft palate and the pharyngeal constrictors contract while the cricopharyngeal muscle relaxes (Fig. 25.1B). To prevent aspiration of food or liquids, the larynx is elevated by contraction of the suprahyoid musculature and closed by adduction of the true and false cords, epiglottic deflection, and approximation of the arytenoids to the base of the epiglottis (Fig. 25.1C). The actions of laryngeal elevation, along with relaxation of the cricopharyngeus muscle, lead to a negative pressure in the esophagus that enables the movement of the bolus from the hypopharynx to the esophagus (Fig. 25.1D).

Esophageal Phase

Through peristaltic contractions of the esophageal musculature, traveling approximately 3 to 4 cm/s, the bolus is transported into the stomach. These wave-like contractions serve to clear the residue of food from the esophagus and limit gastric reflux for approximately 1 hour after intake. In contrast to both the oral transport and pharyngeal phase, the esophageal phase is longer in duration, lasting between 8 and 20 seconds. With advancing age, the decreased amplitude of these peristaltic waves in the esophagus may contribute to reflux disease.

Dysphagia and Aspiration

Dysphagia derives from the Greek word dysphagein and describes a delay or even obstruction of fluid and solid food during swallowing. As a consequence of dysphagia, food and liquid may spill into the respiratory tract and cause aspiration. Aspiration can be divided as occurring before, during, or after the trigger of the pharyngeal swallow. Reduced oral motor control and delayed or even absent trigger of the pharyngeal swallow can lead to aspiration before swallowing. Reduced laryngeal closure, decreased epiglottic deflection, or reduced laryngeal elevation may result in aspiration during swallowing. Structural abnormalities, dysfunction of pharyngeal peristalsis and/or the cricopharyngeus muscle, or reduced laryngeal elevation can cause aspiration after the swallow.

Iatrogenic Causes of Dysphagia Following Treatment of Head and Neck Cancer

Treatment of malignant tumors of the head and neck may include surgery, radiotherapy, and chemotherapy either as single modalities or in combination. These treatments, while treating the cancer, may, in turn, cause or exacerbate dysphagia in the HNC patient.

Resection of Malignant Tumors of the Skin, Lips, and Salivary Glands

Facial Nerve Paralysis

Facial nerve paralysis is a significant factor for patients with HNC, leading to a variety of aesthetic and functional problems including dysphagia. A common functional disability related to dysphagia is the loss of oral sphincter function often leading to drooling of food and liquids and even saliva.

Treatment of facial nerve paralysis in HNC patients depends on the cause of the paralysis. Peripheral facial nerve paralysis can be caused by the presence of malignant tumors of the temporal bone, major salivary glands, skin, and lip. Where resection or transection of the facial nerve occurs after surgical procedures the preferred treatment is primary repair of the facial nerve or an interposition graft from either the greater auricular nerve or sural nerve. These interventions can result in functional and dynamic reconstruction by maintaining good facial movement and muscular tone. Static options include suspension of facial soft tissue and muscles using the palmaris longus tendon or fascia lata slings, or Gore-Tex or AlloDerm.1 Dynamic surgical procedures that target facial reamination use temporalis muscle transfer or the gracilis muscle free flap with cross-face nerve grafting.²

Lip Cancer

Before resection of malignant tumors of the facial skin or lips, it is critical to meticulously plan the reconstruction of oral sphincter function. Resection of small lesions around the mouth–lip–nose unit can be reconstructed simply with advancement or rotation flaps to achieve the best functional and cosmetic results.³ Although lower lip defects (up to 80% of total lower lip) can be reconstructed with local flaps, microstomia and nonfunctional lip are still major challenges and usually require secondary procedures to maximize function and cosmetic outcome. Studies show that lip reconstruction with local flaps can result in minimal functional compromise in terms of oral competence, facial expression, diet, denture and cutlery usage, and sensation despite reduced circumference of the oral stoma.⁴ Reconstruction of defects larger than 80% of the lower lip, especially with the resection of chin or cheek tissue, requires reconstruction with regional flaps or free flaps.

Oral and Oropharyngeal Surgery

Reconstructing the oral cavity and the oropharynx to achieve a satisfactory functional outcome after ablative surgery is one of the most challenging problems in head and neck surgery. Depending on the size small defects may heal by secondary intention, with other small defects being amenable to reconstruction by primary closure or skin grafting, whereas advanced tumor resections require reconstruction with pedicled or free flaps. Nevertheless, the surgeon should be ready to use a variety of techniques for reconstruction because the extent of the resection is not always predictable. In general, the likelihood of dysphagia depends on the site of resection and the extent of the resection, with the quality of the reconstruction being a determinant of the final functional outcome. McConnel et al⁵ have shown that small resections of the oral tongue (smaller than 30%) and tongue base (smaller than 60%) reconstructed with free flaps show no significant improvement in swallowing efficiency compared with primary closure. Moreover, patients with primary closure had better swallowing results on liquids than the patient group with free flaps. The authors speculated that the free flap acts as an adynamic segment that impairs the driving force of the remaining tongue, thereby reducing the swallowing efficiency.⁵ In an earlier publication it was demonstrated that skin grafts gave better functional results than pedicled distal flaps.⁶ Many of these studies are hampered by the fact that heterogeneous groups are compared with differing extents of resection and different modalities of reconstruction.

Sessions et al7 determined that it was not the size but the location of the ablation that is best predictive for dysphagia. In particular, dysphagia is worse in patients suffering from tumors in the tongue base compared with patients with anterior floor of mouth tumors. Seikaly et al⁸ prospectively examined swallowing outcome in 27 patients with soft palate, lateral pharyngeal wall, or base of tongue involvement. All defects were reconstructed with a radial artery forearm free flap. Swallowing data were collected preoperatively and before and after radiation therapy. Patients with resections of half or more of the soft palate had significantly higher nasalance values and larger velopharyngeal orifice areas than individuals who had less than a half of the soft palate resected (Fig. 25.2). A majority (94%) of the patients were able to resume a normal or soft diet. There was a 6% incidence of aspiration in 128 swallows that were analyzed. In 44 patients the effect of sensory reinnervation with reanastomosis of the lingual and/or hypoglossal nerves was prospectively investigated.⁹ Videofluoroscopic swallowing studies were performed preoperatively and 12 months postoperatively to record the oral residue, bolus oral transit time, and aspiration for all patients. The authors showed that the oral transit time and oral residue score were the poorest in patients where both the lingual and hypoglossal nerves were resected. The most interesting finding of this study was that oral swallowing efficiency was preserved if one or both of the lingual and hypoglossal nerves were preserved or reconstructed following cancer resection. Most (91%) of these patients swallowed safely at 12 months postoperatively.⁹ Another step forward in oral cancer reconstruction was the introduction of the anterolateral thigh flap by Song in 1984. de Vicente et al¹⁰ compared the functional outcome in 20 patients undergoing hemiglossectomy. In this study, 10 patients had primary reconstruction with a forearm free flap and 10 with an anterolateral thigh flap. The patients’ functional outcome was assessed after 6 months, and it was seen that there was no significant difference in the mean scores for deglutition between the two groups. However, in this study a significant difference in the donor site morbidity was observed where the harvest site was closed primarily in the anterolateral thigh flap group but skin grafts were used for closure in the forearm group. In 4 out of 10 patients, a partial skin graft failure was observed with donor sites healing by secondary intention.10 In more advanced disease, a total glossectomy has been associated with the risk of aspiration; therefore, simultaneous total laryngectomy is often performed prophylactically. Several studies show that the rectus abdominis musculocutaneous free flap is a valuable option for tongue reconstruction after total glossectomy. Yun et al¹¹ described 14 patients who were able to eat a soft diet and resume verbal communication after reconstruction with the rectus abdominis musculocutaneous or anterolateral thigh free flap. In this study, the rectus abdominis musculocutaneous flap had better speech and swallowing outcomes. This success might be because the rectus abdominis musculocutaneous free flap produced a reconstructed tongue with a significantly greater volume than the anterolateral thigh free flap.¹¹ It was also shown that deglutition was significantly poorer in patients with flat or depressed tongues in comparison with patients with protuberant or semiprotuberant tongues. The authors suggested that wider and thicker flaps, such as the rectus abdominis musculocutaneous flap, should be used for reconstruction of the tongue.

Advanced oral cavity tumors may infiltrate the mandible requiring bone resection. In those patients requiring mandibular resection the functional outcome is poor unless reconstitution of a stable mandibular skeleton is performed. The fibula free flap is a widely used reconstruction technique following mandibular resection. Studies comparing different free flaps, such as the osseocutaneous radial forearm free flap with free-fibular and scapular flaps,¹² show that there is no difference in the functional outcome.

Maxillectomy

Tumors involving the palate and maxillary sinus that are treated by surgical extirpation often result in oronasal and oromaxillary fistulae with loss of dentition. Adequate restoration of the three-dimensional maxillary structure is required to replace form and function of the native tissue.

Obturators

In patients who undergo a partial maxillectomy the use of a maxillectomy obturator that can be fabricated preoperatively or immediately postoperatively is an effective reconstruction option. Preoperatively fitted obturators are intended to provide temporary closure; therefore, the fit is not usually ideal and adjustment is required to optimize the function. Another option is to fabricate obturators immediately after surgery. Such hollow-type obturators are very light and provide reasonable levels of swallowing and mastication.¹³ In a 2009 published study of 42 patients who underwent partial maxillectomies and had reconstruction of the defect with postoral obturators showed a generally good overall quality of life and oral function.¹⁴ Postoperative quality of life questionnaires showed that chewing difficulties in general and oral leakage during swallowing foods (29%, n = 12) were the most frequently reported problems.

Free Flap Reconstruction

To optimize reconstruction of larger volume maxillectomies or in patients who do not have stable dentition to support an obturator after ablative surgery, several different options are proposed. The choice of reconstruction depends on size and localization of the defect. Small defects can be covered by local flaps, whereas large defects involving soft tissue and bone need composite flap reconstruction.¹⁵ Triana et al¹⁶ evaluated the functional outcome in 55 patients with palatal defects after composite flap reconstruction with fibula, rectus abdominis, scapular, radial forearm, and latissimus dorsi flaps. Thirty-eight patients (69%) were on a regular diet and the remaining patients maintained a soft diet.¹⁶ In a retrospective series of 14 patients who underwent maxillectomy and reconstruction with scapular angle flap showed acceptable functional outcomes.¹⁷ In particular, with a range of 4 to 29 days postoperatively five patients were able to maintain a normal diet and nine were able to tolerate a soft-to-firm diet. None of the patients required nutritional supplementation.¹⁷

Larynx Surgery

The goal of treatment for larynx cancer is to achieve cure and to preserve laryngeal function as much as possible.

Endoscopic Laser Surgery on the Larynx

Laser surgery for HNC patients has been introduced in 1972 by Jako in Boston and popularized in Europe by Burian in Vienna, Austria, and Steiner in Goettingen, Germany.

Glottic Cancer

To date the largest study comparing functional outcomes in patients with glottic T1a and T1b glottic cancer has shown that the transoral endoscopic laser approach is superior compared with open functional procedures when comparing the rate of aspiration and tracheotomy requirement. Swallowing after endoscopic resections tends to be restored more quickly because the laser denervates only tumor tissue keeping the innervation of healthy tissue intact. Transsection of the superior laryngeal nerves during the transcervical approach leads to a sensory field defect that interferes with bolus detection and recognition, and to a weakening of the glottic closure response. Analyzing this factor, Sasaki et al¹⁸ demonstrated that the glottic closure reflex remained intact 48 to 72 hours after endoscopic laser surgery compared with 3 weeks to 12 years after open supraglottic laryngectomy. The authors concluded that the sensory field defect caused by superior laryngeal nerve section is largely irreversible. Indeed, preservation of the glottic closure response appears to enhance recovery of swallowing following laser surgery, while compensatory mechanisms are learned.

Supraglottic Cancer

Agrawal et al19 reported that 24 (70.5%) of 34 patients with supraglottic cancer subjects achieved fully adequate oral nutrition before discharge from the hospital, 7 subjects (21%) required prolonged use of feeding tubes (2 weeks postoperatively) and 3 patients (9%) did not achieve recovery of oral alimentation after laser resection of stage I–III supraglottic larynx. Hinni et al²⁰ performed laser surgery for advanced larynx cancer in 117 patients. They observed that out of the 68 patients alive on follow-up, only 7% were feeding tube-dependent. Thirty patients were evaluated and showed normal swallowing function with no episodic or daily symptoms of dysphagia.^20,21 Steiner²² has shown that airway closure at the laryngeal entrance and the movement of the tongue base to make complete contact with the posterior pharyngeal wall can be preserved with laser surgery^22,23

Tumor stage is a significant clinical predictor for dysphagia. Patients with T3/4 tumors are more at risk of poor functional outcome than are those requiring simple epiglottectomy or resection of only one vestibular fold.²⁴ Controversy still exists about management of recurrent laryngeal carcinomas after primary radiotherapy. Piazza et al²⁵ published recently their experience with laser treatment of 22 patients with rT2-rT4 larynx carcinomas. All patients had a good functional result in terms of swallowing with lower complication rates and shorter hospitalization times.²⁵

Base of Tongue Cancer

Transoral laser resections have excellent functional and comparable oncological outcome in patients with malignant tumors of the base of the tongue. Steiner²⁶ has shown that in 20 patients with T2–4 base of tongue carcinomas treated with transoral laser surgery that 92% had normal diet intake. Camp et al²⁷ reported transoral laser resections in 67 patients with oropharyngeal tumors. Quality of life data were collected from 46 patients and out of them 45 patients had only minimally impaired to normal swallowing.²⁷

Open Functional Surgery on the Larynx

The development and improvement of transoral endoscopic laser surgery technique has replaced the previously standard techniques of open partial laryngectomy for early cancer stages. Implementation of new technology using robotic manipulation coupled with a flexible CO₂ laser arm has the unique advantage of cutting tissue very precisely in a variety of angles with minimal peripheral thermal injury. Recently published studies show that transoral robotic surgery provides a significant emerging alternative for selected primary and salvage head and neck tumors with low morbidity and acceptable functional outcomes.²⁸

Partial Laryngectomy

Partial laryngectomy is divided into vertical and horizontal partial laryngectomies. Vertical partial laryngectomy was first described by Som in 1951 and includes laryngofissure with cordectomy, extended hemilaryngectomies with cricoid excision, and epiglottic reconstruction. The procedures require a vertical transection of the thyroid cartilage and a glottic resection extending into the paraglottic space. A study found that 12 of 25 total laryngectomy patients and 1 of 11 frontolateral laryngectomy patients had significant dysphagia, with an overall incidence of 36% (n = 13) in all treated patients.²⁹ In another study, functional outcome was significantly worse in patients who underwent open surgery compared with patients with a simple cordectomy.³⁰

Horizontal Partial Laryngectomies

Supraglottic laryngectomy was originally described by Alonso in 1947. Supraglottic laryngectomy spares the true vocal cords, arytenoids, tongue base, and the hyoid. Peretti et al³¹ compared supraglottic laryngectomy versus laser resection in selected T1 to T3 larynx cancer patients. Fourteen patients treated with endoscopic laser surgery were compared with 14 patients matched for T category treated with open functional supraglottic laryngectomy. Aspiration rates showed no statistically significant differences; however, significant better outcome was found for swallowing, feeding tube duration, and tracheotomy duration in the transoral laser group. From the oncological point of view Cabanillas et al³² have shown that the oncologic result of endoscopic laser approach is equivalent to those of the classic open surgery. In summary, both the endoscopic transoral laser resection and the functional open supraglottic laryngectomy should be considered as established therapeutic modalities. However, tumor extent, the technical skill of the surgeon, surgical experience, and the feasibility to perform an endoscopic procedure will determine the surgical approach in each patient.

Supracricoid Laryngectomy

Supracricoid partial laryngectomy (SCPL) was first reported in Vienna, in 1959, by Meyer and Rieder. This surgery consists of removing of the entire supraglottis, the false and true vocal folds, and the thyroid cartilage including the paraglottic and pre-epiglottic spaces. The cricoid cartilage, hyoid bone, and at least one arytenoid are preserved. Phonatory and swallowing functions are maintained by the movement of the spared arytenoid to the tongue base. There are two types of reconstruction techniques: SCPL cricohyoidopexy and SCPL cricohyoidoepiglottopexy.

In summary, the functional results of transoral laser resection are superior to those of the conventional open approach in terms of the time required to restore swallowing, tracheotomy rate, incidence of pharyngocutaneous fistulae, and shorter hospital stay. These functional advantages can be attributed to the more conservative nature of the endoscopic procedure, because normal tissues are not disrupted during the operation. However, it must be recognized that most studies that compare the outcomes of patients with an endoscopic versus conservative or radical open approaches are selected; therefore, it is difficult to definitively compare patient outcomes. Clearly, however, therapeutic decision making must balance maximizing local and regional disease control versus minimizing collateral damage to normal tissue that presumably translates to improved postoperative function.

Because of the overall poor prognosis of patients with hypopharyngeal carcinomas, the aim of hypopharyngeal resections is to minimize morbidity and mortality, shorten hospital stay, and restore swallowing function as soon as possible. Depending on the localization and tumor size a partial pharyngectomy can be performed. Defects of the lateral pharyngeal wall have been reconstructed with radial forearm free flaps and the functional outcome regarding swallowing is satisfactory.33

Laser treatment of patients with hypopharyngeal carcinomas showed that 27% of patients achieved oral intake on the first postoperative day without nasogastric feeding tube. The median duration of nasogastric feeding in the remaining 94 (72.9%) patients was 7 days.²² Kutter et al³⁴ found that feeding tubes were necessary in 67% (n = 37) of the 55 patients following transoral laser resections of pharyngeal cancer compared with 100% (n = 100) of the patients in the open surgery group. The feeding tubes remained in place for a shorter period in the transoral group than in patients who underwent open surgery and radiotherapy.³⁴

Near-Total Laryngectomy

Oysu and Aslan³⁵ compared patients’ functional outcome with T1b glottic cancer. Seventeen patients were treated by cricohyoidoepiglottopexy and 21 patients underwent near-total laryngectomy with epiglottic reconstruction (NTLER). The time of removal of the nasogastric tubes was shorter in the NTLER group; however, on long-term follow-up swallow function was good in both groups.³⁵ In another prospectively conducted study 28 patients with laryngeal cancer were treated with NTLER.³⁶ Five patients (18%) developed fistulas and that was subsequently associated with increased likelihood of aspiration.

Laryngectomy

Patients who require a total laryngectomy for local disease control can also experience postoperative dysphagia. Studies could show that dysphagia may result from tumor recurrence or even a second primary stricture or because of the loss of the pharyngeal constrictor function. Early radiographic studies defined the mucosal fold at the junction between the base of the tongue and the reconstructed circumferential pharynx as a “pseudo-epiglottis.”³⁷ This area is particularly prone to collapsing against the tongue base to form a pocket. This pocket can accumulate food and cause dysphagia.

In 2009, one published study analyzed swallowing function after total laryngectomy and laryngopharyngectomy and found that dysphagia was observed in 18 (64%) of 28 patients,³⁸ with two-thirds of this group having mild dysphagia. Comparing the swallowing function of patients who had a laryngectomy and either a T- or vertical closure it was observed that patients who had a T-closure had better swallowing functions than the vertical closure group.³⁹

Laryngopharyngectomy

In general, the prognosis of advanced hypopharyngeal carcinomas is still dismal. Therefore, it is of extreme importance that after treatment patients remain with satisfying swallowing functions and thus with good quality of life. Resections of the whole circumference of the pharynx and esophagus require reconstruction with visceral transpositions or tubed free flaps (anterolateral thigh, radial forearm, omental or jejunal free flaps) or myocutaneous flaps.⁴⁰ The pectoralis major flap for circumferential reconstruction represents a viable second option with satisfying functional results after total pharyngolaryngectomy.⁴¹ Recently published studies could show that the use of the pectoralis major flap can also be performed in combination with a jejunal free flap.⁴² In a study of 55 patients who underwent total laryngectomy and 37 who underwent laryngopharyngectomy with jejunal reconstruction, it was observed that 15 (27%) patients of the laryngectomy group and 24 (65%) patients of the laryngopharyngectomy group developed swallowing-related complications⁴³ (Fig. 25.3). Circumferential reconstruction is particularly prone to stenosis. Varvares et al⁴⁴ employed the use of salivary tubes to stent the tubed radial forearm free flap. In a study of 20 patients postoperative stricture was observed in 2 (10%) patients. However, 17 (85%) patients were able to take a normal diet whereas 3 (15%) patients remained G-tube dependent. The anterolateral thigh flap has also been used for circumferential reconstruction with excellent functional outcome. In a study of 114 patients, Yu et al⁴⁵ reported that pharyngocutaneous strictures occurred in 6% (n = 7) of patients and 91% (n = 104) of patients tolerated an oral diet without the need for tube feeding.

Radiotherapy

One of the cornerstones of treatment of HNC patients is radiation therapy. The radiation fields often include critical structures necessary for normal deglutition, including the oral mucosa, tongue, larynx, pharynx, and pharyngeal muscles. One of the major acute and long-term side effects of radiation therapy is dysphagia.⁴⁶ In addition to dysphagia, other chronic side effects include trismus, stenosis of the pharynx, larynx, and esophagus, and damage to the laryngeal skeleton. In particular, radiation therapy can lead to significant impairment of the oropharyngeal phase, including insufficient velopharyngeal closure, reduced pharyngeal contraction, reduced hyoid and laryngeal motion, and reduced opening of the upper esophageal sphincter.⁴⁷

On average, 3 months after patients finish their treatment, acute dysphagia symptoms, that is, mucositis, edema, erythema, and desquamation of the skin, resolve and the normal swallowing function improves in most patients. Unfortunately, continuous activation of cytokines, ongoing hypoxia, and hyperactivation through hydroxyl radicals of transforming growth factor-b1 may perpetuate tissue damage. Contractility of soft tissues and muscles decreases over time because of fibrosis and lymphedema. Abnormal motility of deglutition muscles can lead to impaired pharyngeal contraction48 and impaired laryngeal elevation causing dysphagia and aspiration.⁴⁹