26 Reconstruction of the Palate
This chapter provides an overview of soft and hard palate defects, and a discussion of management and reconstructive techniques. It is imperative that the reconstructive surgeon understand the scope of the defect, patient factors, and nuances of various reconstructive techniques outlined here.
Palatal defects following oncologic surgery can be challenging to reconstruct and profoundly impact both function and cosmesis. The reconstructive armamentarium has evolved over the past half-century allowing for more nuanced techniques, including microvascular free-tissue transfer, improving our ability to optimize phonation, alimentation, nasal function, and appearance. A comprehensive overview of these techniques and reconstructive considerations is presented in this chapter.
Through much of the 20th century, reconstruction of the palate was avoided in favor of leaving the defect open to maximize surveillance for residual/recurrent disease. 1 Palatal obturators have traditionally offered a convenient solution for hard and soft palate defects in this regard. 2 More definitive repairs were avoided because of difficulty encountered in obtaining appropriate bulk and adequately restoring the complex three-dimensionality when reconstructing such defects.
Multidisciplinary approaches, however, have modernized reconstruction. Hoopes and Edgerton outlined objectives for midface reconstruction in their 1966 publication, including consistently obtaining a healing wound, restoring palatal competence and function, and restoring facial contour. 3 These principles have been modified in subsequent classification schema, 4 , 5 and have formed the basis for modern reconstructive algorithms for midface and palatal reconstruction.
26.3 Diagnosis and Evaluation
Perhaps the most difficult decision in palatal reconstruction is determining whether to reconstruct at all. Most palatal defects are not life threatening, and the option to do nothing, obturate, or reconstruct with local or free tissue transfer requires a thorough assessment of multiple factors. These include patient age, fitness for surgery, comorbidities, dentition, access to specialist and prosthodontic care, expectations, and quality of life goals. The surgeon must also weigh factors associated with the disease process including size and functional implications of the anticipated defect, need for adjuvant therapy, and expected survival. Reconstructive decision-making, of course, is highly individualized, and will evolve with a surgeon’s experience and comfort level. Furthermore, most prosthetic and dental restorations are only nominally covered by insurance plans and the patient’s capacity and willingness to pay for these techniques needs to be assessed during the initial planning phase.
26.4 Anatomic Considerations/Relevant Anatomy
In patients for whom palatal reconstruction is pursued, the primary goal is to separate the nasal and oral cavities in order to restore presurgical function including speech, deglutition, alimentation, and cosmesis. A multidisciplinary approach is paramount to successful reconstruction and rehabilitation, and includes preoperative evaluation by speech-language pathologist, prosthodontist, physical therapist, and the head and neck surgeon. A facial plastic reconstructive surgeon may also be involved if the anticipated defect is expected to significantly impact midface and/or nasal appearance. It is important to note that surgical and prosthetic methods may be utilized separately or together, guided by the size of the defect and goals of the patient and care team. To this end, classification schema may help guide reconstructive goals including closure of the palatal defect for speech and swallowing function, optimizing facial cosmesis, and permitting dental rehabilitation. 6 – 11
With regards to timing, palatal reconstruction may be performed in either a primary or delayed/staged fashion; however, primary reconstruction is considered the standard of care in many institutions. 12 Staged reconstruction may be performed either shortly after the oncologic procedure or months to years later. One advantage of delaying the reconstruction several weeks is the ability to obtain definitive pathology and margin status prior to obscuring the field with mobilized tissue. This is especially helpful for the complex bony margins of the maxilla, which are challenging to assess intraoperatively. Should a positive margin result, the oncologic surgeon has a second opportunity to clear it, which may meaningfully impact overall survival. Furthermore, for those surgeons who employ three-dimensional modelling for palatal and midface reconstruction, a delay affords the opportunity to obtain a post-ablative computed tomography (CT) scan and time for precise planning and guide fabrication to optimally reconstruct the patient-specific defect. However, when reconstruction is delayed for months and defects are allowed to heal completely, they may result in muscle atrophy, soft tissue contracture, and cosmetic deformities that may be impossible to fully restore in a delayed fashion. Postoperative radiation + /- chemotherapy with subsequent fibrosis, loss of elasticity, and hypovascularity may exacerbate these functional difficulties and present additional challenges with later reconstruction. 13
Certain reconstructive techniques are amenable to a transoral approach whereas others may require more invasive approaches, such as lip-split mandibulotomy, for adequate access to the defect and manipulation of surrounding or donor tissue. In general, the approach for reconstruction often depends on the approach taken to resect the cancer.
26.4.1 Soft Palate Considerations
The soft palate is a mucous musculoaponeurotic shelf with a central fibrous aponeurosis layer attaching to the hard palate anteriorly and suspended by attachments to palatine muscles bilaterally. 14 It serves a critical role in the velopharyngeal mechanism, and functionally can be divided into three zones. The anterior third is attached to the hard palate and is primarily fixed, the middle third is where the majority of the muscular bulk from the levator muscles lies and is primarily involved in speaking, and the posterior third elevates during deglutition and speech. Defects involving one or more of these regions may have distinct consequences for the patient and reconstructive surgeon.
The normal velopharyngeal mechanism can be markedly disrupted if the soft palate is removed in a subtotal or total fashion, resulting in rhinolalia, nasal regurgitation, and swallowing impediments. 14 The limited mucosal surface and soft tissue in the soft palate presents a challenge for the reconstructive surgeon as sufficient tissue to close a surgical defect is often not present while maintaining function.
The primary goal of soft palate reconstruction is to optimize the function of the remaining innervated soft palate. Sufficient tissue to close the velopharyngeal port during speech and swallow is critical but not always available. Greater success may be achieved in smaller unilateral and lateralized defects in which closure is possible with preservation of a patent and functional contralateral port. The contralateral side can continue to open and close to retain a nasal airway and swallow function, respectively. With larger defects this becomes increasingly difficult. One needs to consider that the choice of reconstruction, whether it be obturator or soft tissue, is usually static, and may limit the mobility of the residual soft palate. In some cases, an obturator is necessary to support a total or near total soft palate reconstruction which otherwise would be ptotic.
26.4.2 Hard Palate Considerations
The hard palate primarily serves as a means of separation between the oral and nasal cavities, permitting articulation and oral alimentation. Defects of the hard palate, if unrepaired, may result in oronasal or oroantral fistulae, cosmetic deformities with mid-facial retraction, asymmetry and loss of nasal tip support, loss of dentition, and difficulty with oral alimentation and articulation.
Optimal reconstruction is predicated on a comprehensive understanding of the extent of the maxillary defect and relevant anatomy. The maxilla is comprised of three buttresses (nasomaxillary, zygomaticomaxillary, and pterygomaxillary), and four processes (zygomatic, alveolar, palatine, and frontal) (▶ Fig. 25.3). Buttresses serve to resist the vertical forces of mastication, and the four processes function as a frame for the palate and midface. 11 , 12
Classification schemes have guided approaches and algorithms to hard palate reconstruction, including the Okay palatomaxillary classification system derived from a review of 47 patients who underwent palatomaxillary reconstruction at the Mount Sinai Medical Center (▶ Table 26.1). 11 Patients were retrospectively assigned to three major classes of defects to provide a framework for reconstructive planning, taking into consideration not only the size but also the biomechanical forces that may predict success of prosthetic rehabilitation alone. While this schema has become a well-accepted approach to these defects, numerous other factors including patient comorbidities, history of prior radiation or surgery, tumor stage, and invasion into adjacent structures should be taken into account when planning definitive reconstruction.
As with soft palate reconstruction, a multidisciplinary approach is critical to provide patients with a comprehensive reconstructive and rehabilitative plan, including evaluation of benefits and disadvantages of various reconstructive strategies.
26.5 Surgical Considerations and Approaches
26.5.1 Reconstructive Techniques for Soft Palate Defects
Soft palate defects are perhaps the most challenging oral defects to reconstruct. This is due to the thin, muscular structure which is mobile and actively closes off the velopharyngeal port in speech and swallowing. Recreating the soft palate defects exactly is virtually impossible as most reconstructive options are not able to recapitulate the dynamic properties of the soft palate. Nonetheless, in the modern era of head and neck reconstruction, surgeons have an armamentarium of tools at their disposal with various local, regional, and complex free tissue transfer options, all designed with the primary goal of dynamic or static closure of the velopharyngeal port.
The posterior pharyngeal wall may be augmented for smaller palatal defects to bring the posterior pharyngeal wall in closer proximity to the residual soft palate. Multiple augmentation techniques have been described including injectable Teflon, 15 hyaluronic acid, calcium hydroxyapatite or other injectable implants, 16 and autologous fat. 17 While straightforward to perform and often possible in the clinic setting under local anesthesia, this technique is limited in its application to smaller defects. Additionally, it may be difficult to accurately estimate how much material to inject, resulting in over- or under- correction of the defect. Overcorrection is not without risk as patients may be at higher risk for sleep apnea, hyponasality, or dysphagia. 18
Obturators may be employed in the reconstruction of soft palatal defects in an adynamic fashion. There are numerous advantages to obturation including ease of placement at the time of surgery or immediately after, minimal additional surgical time and morbidity, and ease of surveillance of the defect postoperatively. They permit immediate restoration of speech and swallowing in the postoperative setting, obviating the need for alternative means of enteral nutrition. The ability to use an obturator is often determined by the dentate status of the patient and extent of surgical resection. Edentulous patients are difficult to rehabilitate with an obturator alone due to limited anchor points for the prosthesis.
Challenges in stabilization of the prosthesis often limit the functional and rehabilitative outcomes obtained. Additionally, obturators are frequently hindered by air leakage around the prosthesis and between the nasal and oral cavities resulting in unintended speech and eating difficulties. They may also cause injury to surrounding mobile mucosa and may be inconvenient and uncomfortable to wear. 14 , 19 Local tissue rearrangement and reconstruction may help reduce surface area of the defect and overcome challenges posed by the obturator alone.
Patients need to understand that obturators are often not worn during radiation therapy given the increased sensitivity and mucositis of the tissues, they may need multiple adjustments as tissues contract and scar tissue forms, they require regular cleaning and maintenance, and they are removed during sleep. They must be worn at times when patients desire optimal speech and swallowing function, they may cause irritation to the surrounding mucosa, and patients may have trouble with an imperfect seal resulting in undesired regurgitation or leakage. 20 , 21 Nonetheless, for the poor surgical candidate and/or patient looking for the easiest reconstructive option, obturators remain the optimal choice.
Local flaps may be employed in the reconstruction of soft palate defects, varying in complexity and utility, including the buccal mucosal flap, palatal island rotational flap, forehead flap, palatal adhesion, uvulopalatal flap, and facial artery musculomucosal (FAMM) flap. These local options are best suited for small defects involving less than half of the soft palate.
The superior constrictor advancement rotation flap (SCARF) provides a dynamic closure of the choana and restoration of the velopharynx for hemi-soft palate defects. First described by Strong et al 22 in 1971, the technique allows for recreation of the sphincteric function of the velopharynx. The transected edge of the soft palate is sutured to a transected edge of the superior constrictor muscle in the posterior pharyngeal wall, thereby creating a muscular valve to recreate the velopharynx. In patients with unilateral soft palate paralysis after high vagal injuries, a similar technique in which the paralyzed hemi-soft palate is sutured to the posterior pharyngeal wall (palatal adhesion) has been described, and may be applied to smaller soft palate defects in a similar fashion. 23 , 24 Proponents of this technique argue that unlike other local flaps, patients achieve earlier and more dynamic restoration of velopharyngeal function with a sensate flap, they do not require wide exposure such as mandibulotomy, and they benefit from shorter hospital stay and earlier initiation of diet. 19
The FAMM flap was first described in 1992, designed as a musculomucosal flap that combines the principles of nasolabial and buccal mucosal flaps. 25 In its original description, it can be based superiorly or inferiorly along the course of the facial artery, extending from the retromolar trigone to the level of the ipsilateral gingival labial sulcus at the level of the alar margin. The flap can be harvested with an average width of 1.5-2 cm and a length of 8-9 cm and an arc of rotation based at the retromolar trigone inferiorly or at the gingival labial sulcus superiorly. This flap can be used for hard and soft palate reconstructions. 25 In some cases, staged reconstruction may be necessary to divide the pedicle secondarily if it impedes mastication. The FAMM flap may be utilized in conjunction with bone grafts or other reconstruction options to provide a dual lining to the nasal and oral cavities.
The uvulopalatal flap, a myomucosal flap, was first described in 1998 by Zohar et al. 14 This full-thickness flap utilizes the contralateral distal soft palate posterior to the levator palatine muscle in a rotational fashion to ablate the ipsilateral defect. This technique employs principles of uvulopalatopharyngoplasty 26 and is an excellent option for small defects that do not involve the contralateral palate and in which a portion of the soft palate remains. It can be used to decrease the size of a palatal defect obviating the need for an obturator in most cases. 14 , 27
While local flaps are often an excellent option, contraindications to their use include ipsilateral external carotid artery ligation, prior radiation to the palate, prior oral surgery, or any other procedure that has diminished blood supply to the intended flap.