Nerve supply to the soft palate muscles with special reference to the distribution of the lesser palatine nerve

Demystifying Velopharyngeal Dysfunction for Plastic Surgery Trainees-Part 1: Anatomy and Physiology

The velopharyngeal (VP) port separates the nasopharynx from the oropharynx and is bordered by the velum, lateral pharyngeal walls, and posterior pharyngeal wall. Velopharyngeal dysfunction (VPD) is the inability to achieve proper closure of the VP port, affecting speech and swallowing. This 3-part series provides a comprehensive discussion on (1) the anatomy and physiology of the velopharyngeal mechanism; (2) fundamental speech terminology and principles of perceptual speech assessment for VPD; and (3) techniques for objective evaluation of the VP port and surgical decision-making process. In part 1, the authors focus on the anatomy and physiology of the velopharyngeal port, the anatomy of cleft palate, and the causes of VPD. There are 3 types of VPD: velopharyngeal insufficiency, involving structural deficits; velopharyngeal incompetence, resulting from neuromuscular issues; and velopharyngeal mislearning, due to maladaptive speech habits. VPD is commonly associated with cleft palate due to anatomic disruptions that impair velopharyngeal function. However, there are numerous causes of noncleft VPD, including congenital or acquired structural defects, neuromuscular conditions, and developmental/behavioral factors. Diagnosis and management of VPD require a multidisciplinary approach involving, at a minimum, surgeons and speech-language pathologists. Plastic surgery trainees often receive education on the surgical treatment of VPD, but without a foundational knowledge of the disease spectrum and speech pathology, the complex terminology can impede a thorough understanding of its diagnosis and management. This series serves as an accessible resource, providing the foundational knowledge required for surgical trainees new to this topic.

Review of Current Techniques of Cleft Palate Repair Concerning Palatal Innervation: A Preliminary Assumption

OBJECTIVE

To highlight the possible surgical steps that could affect the neural supply of soft palate and velopharyngeal sphincter during Furlow palatoplasty and posteriorly-based myo-mucosal buccal flaps in patients with persistent velopharyngeal insufficiency after primary cleft palate repair.

DESIGN

Institution-based retrospective study.

SETTING

Academic Medical Center.

PATIENTS

Non-syndromic patients with persistent hypernasality (after primary cleft palate repair) who had Furlow palatoplasty or posteriorly-based buccal myo-mucosal flaps and were followed up for at least 60 months after the secondary surgery.

INTERVENTIONS

All patients were examined using a fiberoptic endoscopy, the movement of components of the velopharyngeal sphincter: soft palate, and lateral pharyngeal walls were traced on the monitor and given a score from 0-4. The pattern of VPS closure was reported whether coronal, circular, or sagittal for each case.

MAIN OUTCOME MEASURES

Patients' characteristics, auditory perceptual assessment, the severity of hypernasality, intraoperative lengthening of the palate, and operative complications were recorded.

RESULTS

At postoperative (at least 60 months) evaluation of the patients statistically non-significant differences were reported when comparing the pre-versus post-operative auditory perceptual assessment following both procedures (P value ≥0.05). A greater tendency towards improvement was noticed with BF but was non-significant.

CONCLUSION

The nerve supply of the palate could be jeopardized by many techniques of primary or secondary repair of the cleft palate leaving behind a deceiving intact but weak poor-functioning palate. All efforts should be made to provide more neural-preservation techniques in primary/secondary repair of the cleft palate. Further wide-scale research is essential to have final clear conclusions.

The palatopharyngeal muscle in otolaryngology practice: an anatomical-based surgical report

OBJECTIVES

The author discusses current otolaryngological procedures employing the palatopharyngeus muscle, based on the surgical anatomy of the muscle and its neural supply. These techniques should be deeply revised for more conservative, anatomically-based maneuvers.

METHODS

Revision of anatomical and surgical research and comments with the provision of a primary concept.

RESULTS

The palatopharyngeus muscle is innervated by the pharyngeal plexus (the vagus and the accessory nerves) with additional fibers from the lesser palatine nerves. The innervation enters the muscle mainly through its lateral border.

CONCLUSIONS

The palatopharyngeus muscle has a fundamental role in swallowing and speech. The muscle helps other dilators to maintain upper airway patency. Sphincter pharyngoplasty should be revised as regards its role as a sphincter. Palatopharyngeal procedures for OSA employing the palatopharyngeus muscle should follow the conservative, anatomically-based, and non-neural ablation concept.

LEVEL OF EVIDENCE: 4

Functional cleft palate surgery

Cleft lip and palate (CLP) as a dislocation malformation confronts parents with a malformation of their child that could not be more central and visible: the face. In addition to the stigmatizing appearance, however, in cases of a CLP, food intake, physiological breathing, speech and hearing are also affected. In this paper, the principles of morphofunctional surgical reconstruction of the cleft palate are presented. With the closure of the palate, and restoration of the anatomy, a situation is achieved enabling nasal respiration, normal or near normal speech without nasality, improved ventilation of the middle ear, normal oral functions with coordinated interaction of the tongue with the hard and soft palate important for the oral and pharyngeal phases of feeding. With the establishment of physiological function, in the early phases of the infant and toddler, these activities initiate essential growth stimulation, leading to normalisation of facial and cranial growth. If these functional considerations are disregarded during primary closure, lifelong impairment of one or more of the abovementioned processes often follows. In many cases, despite secondary surgery and revision, it might not be possible to correct and achieve the best possible outcomes, especially if critical stages of development and growth have been missed or there has been significant tissue loss due to resection of existing tissue while primary surgery. This paper describes functional surgical methods and reviews long term, over many decades, results of children with cleft palate.

A Fuzzy Neural Network Model for Rapid Prediction of Optimal Positive Airway Pressures in OSAS Patients

Manual titration of positive airway pressure (PAP) is a gold standard to provide an optimal pressure for the treatment of obstructive sleep apnea-hypopnea syndrome (OSAS). Since manual titration studies were costly and time-consuming, many statistical models for predicting effective PAPs were reported. However, the prediction accuracies of the models associated with nocturnal parameters still remain low. This study proposes a fuzzy neural prediction network (FNPN) with input candidate variables, selected among easily available measurements (e.g., body mass index (BMI), waist circumstance (WC), and body composition) and OSAS related questionnaires, to rapidly predict an optimal PAP. The FNPN comprises fuzzy rules and is characterized with the ability of automatic rule growing and pruning from training data. A total of 147 participants from April 2018 to April 2019 were enrolled in Taichung Veterans General Hospital, Taiwan. After two selection processes for feature extraction, WC and BMI were the significant variables for entering the FNPN to predict optimal PAP. Experimental results showed that the average successful prediction rate of the proposed method was 71.8%. This study also found that Epworth sleepiness scales (ESS) and body composition, such as visceral fat area and percent body fat, were excluded in the final prediction model. Compared with existing models, the proposed prediction approach provided a rapid prediction of optimal PAP with higher accuracy.

Three-Dimensional Anatomy of the Palatopharyngeus and Its Relation to the Levator Veli Palatini Based on Micro-Computed Tomography

BACKGROUND

Although multiple studies have been reported on the palatopharyngeus and levator veli palatini, their subtle anatomy and functions remain unclear. The authors elucidated the relationship between these muscles and their functional implications based on three-dimensional digital techniques.

METHODS

Cadaveric specimens were stained with iodine-potassium iodide and scanned using micro-computed tomography. The muscle fibers were drawn on the exported Imaging and Communications in Medicine images to reconstruct a three-dimensional model and further simplified.

RESULTS

In the soft palate, the palatopharyngeus was divided into three bundles. The largest inferior head was found to attach to the palatine aponeurosis, soft palate, and the hard palate on the oral side, which occupied approximately the anterior 28.4 to 36.2 percent of the soft palate in the midline. The superior head was thin and attached to the palatine aponeurosis and the surrounding mucosa on the nasal side. The posterior head was located posterior to the levator veli palatini with fibers attaching to the levator veli palatini and the median portion of the uvula. The levator veli palatini was clasped by the three heads of the palatopharyngeus. The fasciculi of the palatopharyngeus converged into a bundle of muscles at the pharynx and inserted into the lateral and posterior pharyngeal wall.

CONCLUSIONS

The palatopharyngeus is the largest muscle that connects the soft palate and pharyngeal wall; it closely coordinates with the levator veli palatini to control levator veli palatini overlifting, narrow the velopharyngeal port with the help of the superior constrictor, and elevate the pharynx. The palatopharyngeus and levator veli palatini help each other in velopharyngeal closure through coordination from other muscles.

Acute idiopathic velopharyngeal insufficiency

Idiopathic velopharyngeal insufficiency is a rare clinical entity. Typical clinical features are rhinolalia and nasopharyngeal regurgitation. It is usually observed in children. We report a case of a 28-year-old female with this rare disorder. The symptoms were rhinolalia and regurgitation of liquids into the nose. The magnetic resonance imaging of the brain and upper cervical region was normal. The infectious serologies were negative.

Innervation of human soft palate muscles

Our objective was to determine the branching and distribution of the motor nerves supplying the human soft palate muscles. Six adult specimens of the soft palate in continuity with the pharynx, larynx, and tongue were processed with Sihler's stain, a technique that can render large specimens transparent while counterstaining their nerves. The cranial nerves were identified and dissection followed their branches as they divided into smaller divisions toward their terminations in individual muscles. The results showed that both the glossopharyngeal (IX) and vagus (X) nerves have three distinct branches, superior, middle, and inferior. Only the middle branches of each nerve contributed to the pharyngeal plexus to which the facial nerve also contributed. The pharyngeal plexus was divided into two parts, a superior innervating the palatal and neighboring muscles and an inferior innervating pharyngeal constrictors. The superior branches of the IX and X nerves contributed innervation to the palatoglossus, whereas their middle branches innervated the palatopharyngeus. The palatoglossus and palatopharyngeus muscles appeared to be composed of at least two neuromuscular compartments. The lesser palatine nerve not only supplied the palatal mucosa and palatine glandular tissue but also innervated the musculus uvulae, palatopharyngeus, and levator veli palatine. The latter muscle also received its innervation from the superior branch of X nerve. The findings would be useful for better understanding the neural control of the soft palate and for developing novel neuromodulation therapies to treat certain upper airway disorders such as obstructive sleep apnea.

A Review of and Algorithmic Approach to Soft Palate Reconstruction

Importance

The soft palate contributes to deglutition, articulation, and respiration. Current reconstructive techniques focus on restoration of both form and function. The unique challenges of soft palate reconstruction include maintenance of complex upper aerodigestive tract function, with minimal local or donor site morbidity.

Objective

To review the literature on soft palate reconstruction and present an algorithm on how to approach soft palate defects based on this review.

Evidence Review

A review of the literature for articles reporting studies on and that described concepts related to soft palate reconstruction was conducted in March 2017. In all, 1804 candidate titles and abstracts were independently reviewed. English-language articles that discussed acquired soft palate defect reconstruction were included. Non-English language studies without available translations, studies on primary soft palate defect reconstruction (ie, cleft palate repair) and primary cleft palate repair, studies in which the soft palate was not the focus of the article, and studies involving animals were excluded.

Findings

The following observations were made from the review of 92 included articles. Soft palate anatomy is a complex interplay of multiple structures working in a 3-dimensional area. Three of the authors created an initial algorithmic framework based on the selected studies. After this, a round table discussion among 3 authors considered experts was used to refine the algorithm based on their expert opinion. The 4 most important factors were determined to be defect size, defect extension to other subsites, defect thickness, and history of radiotherapy or planned radiotherapy. This algorithm includes both surgical and nonsurgical options. Defects in the soft palate not only affect the size and shape of the organ but, more critically, the function. The reconstructive ladder is used to help maximize the remaining soft palate functional tissue and minimize the effect of nonfunctional implanted tissue. Partial-thickness defects or defects less than one-fourth of the soft palate may not require locoregional tissue transfer. Patients with a history of radiotherapy or defects of up to 75% of the soft palate may require locoregional tissue transfer. Defects greater than 75% of the soft palate, defects that include exposure of the neck vasculature, or defects that include significant portions of the hard palate or adjacent oropharyngeal subsites may require free tissue transfer. Obturation should be considered a second-line option in most cases.

Conclusions and Relevance

Ideal reconstruction of the soft palate relies on a comprehensive understanding of soft palate anatomy, a full consideration of the armamentarium of surgical techniques, consideration for adjacent subsite deficits, and a detailed knowledge of various intrinsic and extrinsic patient factors to optimize speech, swallowing, and airway outcomes. The included algorithm may serve as a useful starting point for the surgeon when considering reconstruction.

Using a Sniff Controller to Self-Trigger Abdominal Functional Electrical Stimulation for Assisted Coughing Following Cervical Spinal Cord Lesions

Individuals with cervical spinal cord lesions (SCLs) typically depend on caregivers to manually assist in coughing by pressing against their abdominal wall. Coughing can also be assisted by functional electric stimulation (FES) applied to abdominal muscles via surface electrodes. Efficacy of FES, however, depends on precise temporal synchronization. The sniff controller is a trigger that enables paralyzed individuals to precisely control external devices through alterations in nasal airflow. We hypothesized that FES self-triggering by sniff controller may allow for effective cough timing. After optimizing parameters in 16 able-bodied subjects, we measured peak expiratory flow (PEF) in 14 subjects with SCL who coughed with or without assistance. Assistance was either manual assistance of a caregiver, caregiver activated FES, button self-activated FES (for SCL participants who could press a button), or sniff-controlled self-activated FES. We found that all assisted methods provided equally effective improvements, increasing PEF on average by 25 ± 27% (F[4,52] = 7.99, p = 0.00004 ). There was no difference in efficacy between methods of assistance ( F[3,39] = 0.41, p = 0.75 ). Notably, sniff-controlled FES was the only method of those tested that can be activated by all paralyzed patients alone. This provides for added independence that is a critical factor in quality of life following SCL.

Effect of Dissection and Reconstruction of Palatal Muscles on Morphological Features and Ultrastructure of the Oral Musculature in Cats

The study was designed to determine the effect of dissection and reconstruction of palatal muscles on muscle morphology in cats. 27 cats were randomly divided into three groups according to the extent of muscle dissection from the palatal midline. All dissections were performed from the posterior border of the hard palate, and the muscles were allowed to reconstruct over time. The morphological features were determined by hematoxylin and eosin staining of tissue sections, and ultrastructure was observed under a transmission electron microscope. As a result, no obvious differences were evident in the morphological features or ultrastructure of animals in the <1/3rd and 1/3rd-2/3rd area groups. In the >2/3rd area group, the muscles fibers were disordered and inflammatory cell infiltration and naïve muscle cells were found at one month after surgery. At the second and third month after surgery, the muscle fibers showed regular alignment, the naïve muscle fibers gradually matured, and the number of infiltrating inflammatory cells decreased. Muscle ultrastructure analysis revealed that myocommata were correctly aligned, and the Z line was more distinct. In conclusion, extensive dissection of palatal muscles does not result in fibrosis. Injury to oral musculature can be repaired and the musculature regenerated over time.

The Lesser Palatine Nerve Innervates the Levator Veli Palatini Muscle

When the lesser palatine nerve (LPN) is supposed to be a branch of the trigeminal nerve and innervate sensation of the soft palate, whether the LPN contains motor fibers is unclear. In this study, we monitored the electromyogram of the levator veli palatini (LVP) muscle on stimulating the LPN during palatoplasty in 3 patients. The electromyogram of the muscles showed the myogenic potential induced by electrostimulation of the LPN. Taken together with the finding from our previous anatomical study that the motor fibers come from the facial nerve, this result supports the double innervation theory of the LVP, which posits that both the pharyngeal plexus and the facial nerve innervate it. Identifying and preserving the LPN during palatoplasty might improve postoperative speech results.

The innervation of the soft palate muscles involved in cleft palate: a review of the literature

OBJECTIVE

Surgical techniques to obtain adequate soft palate repair in cleft palate patients elaborate on the muscle repair; however, there is little available information regarding the innervation of muscles. Improved insights into the innervation of the musculature will likely allow improvements in the repair of the cleft palate and subsequently decrease the incidence of velopharyngeal insufficiency. We performed a literature review focusing on recent advances in the understanding of soft palate muscle innervation.

MATERIAL AND METHODS

The Medline and Embase databases were searched for anatomical studies concerning the innervation of the soft palate.

RESULTS

Our literature review highlights the lack of accurate information about the innervation of the levator veli palatini and palatopharyngeus muscles. It is probable that the lesser palatine nerve and the pharyngeal plexus dually innervate the levator veli palatini and palatopharyngeus muscles. Nerves of the superior-extravelar part of the levator veli palatini and palatopharyngeus muscles enter the muscle form the lateral side. Subsequently, the lesser palatine nerve enters from the lateral side of the inferior-velar part of the levator veli palatini muscle. This knowledge could aid surgeons during reconstruction of the cleft musculature. The innervation of the tensor veli palatini muscle by a small branch of the mandibular nerve was confirmed in all studies.

CONCLUSION

Both the levator veli palatini and palatopharyngeus muscles receive motor fibres from the accessory nerve (through the vagus nerve and the glossopharyngeal nerve) and also the lesser palatine nerve. A small branch of the mandibular nerve innervates the tensor veli palatini muscle.

CLINICAL RELEVANCE

Knowledge about these nerves could aid the cleft surgeon to perform a more careful dissection of the lateral side of the musculature.

Histopathologic and immunohistochemical features of soft palate muscles and nerves in dogs with an elongated soft palate

OBJECTIVE

To histologically evaluate and compare features of myofibers within the elongated soft palate (ESP) of brachycephalic and mesocephalic dogs with those in the soft palate of healthy dogs and to assess whether denervation or muscular dystrophy is associated with soft palate elongation.

SAMPLE

Soft palate specimens from 24 dogs with ESPs (obtained during surgical intervention) and from 14 healthy Beagles (control group).

PROCEDURES

All the soft palate specimens underwent histologic examination to assess myofiber atrophy, hypertrophy, hyalinization, and regeneration. The degrees of atrophy and hypertrophy were quantified on the basis of the coefficient of variation and the number of myofibers with hyalinization and regeneration. The specimens also underwent immunohistochemical analysis with anti-neurofilament or anti-dystrophin antibody to confirm the distribution of peripheral nerve branches innervating the palatine myofibers and myofiber dystrophin expression, respectively.

RESULTS

Myofiber atrophy, hypertrophy, hyalinization, and regeneration were identified in almost all the ESP specimens. Degrees of atrophy and hypertrophy were significantly greater in the ESP specimens, compared with the control specimens. There were fewer palatine peripheral nerve branches in the ESP specimens than in the control specimens. Almost all the myofibers in the ESP and control specimens were dystrophin positive.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggested that palatine myopathy in dogs may be caused, at least in part, by denervation of the palatine muscles and not by Duchenne- or Becker-type muscular dystrophy. These soft palate changes may contribute to upper airway collapse and the progression of brachycephalic airway obstructive syndrome.

Endotracheal Tube Electrodes to Assess Vocal Cord Motor Function During Surgery in the Cerebellopontine Angle

BACKGROUND

The 10th cranial nerve (CN X) is at risk during surgery in the lower cerebellopontine angle (CPA).

OBJECTIVE

To evaluate endotracheal surface electrodes for assessment of CN X motor function during CPA surgery.

METHODS

Twenty patients were enrolled. Electrophysiological recordings were analyzed and retrospectively correlated with clinical, imaging, and intraoperative data.

RESULTS

Recordings from endotracheal surface electrodes were reliable and eligible for analyses in 17 patients; in 3 patients, no surface electrode compound motor action potentials (CMAPs) could be obtained. Those patients with sufficient recordings underwent surgery in the CPA for tumors in 14 patients and for nontumor pathologies in 3 patients. In 12 patients, bipolar stimulation of motor rootlets in the CPA resulted in simultaneous CMAPs recorded from both surface electrodes and needle electrodes placed in the soft palate. Coactivation was particularly seen in patients with an intricate relationship between lower cranial nerves and tumor formations (n = 9/10). Amplitudes and latencies of vocal cord CMAPs showed high interindividual but low intraindividual variability. Parameters were not well correlated with the type of surgery (tumor vs nontumor surgery) and lower CN anatomy (displaced vs undisplaced). In 2 patients, vocal cord CMAPs were lost during tumor surgery, which was associated with postoperative dysphagia and hoarseness in 1 patient.

CONCLUSION

Endotracheal surface electrodes allow identification of vocal cord motor rootlets in the CPA. Worsening of CMAP parameters might indicate functional impairment. These aspects support the use of endotracheal surface electrodes in selected patients in whom the vagus nerve might be at risk during CPA surgery.

Detection of response to command using voluntary control of breathing in disorders of consciousness

BACKGROUND

Detecting signs of consciousness in patients in a vegetative state/unresponsive wakefulness syndrome (UWS/VS) or minimally conscious state (MCS) is known to be very challenging. Plotkin et al. (2010) recently showed the possibility of using a breathing-controlled communication device in patients with locked in syndrome. We here aim to test a breathing-based "sniff controller" that could be used as an alternative diagnostic tool to evaluate response to command in severely brain damaged patients with chronic disorders of consciousness (DOC).

METHODS

Twenty-five DOC patients were included. Patients' resting breathing-amplitude was measured during a 5 min resting condition. Next, they were instructed to end the presentation of a music sequence by sniffing vigorously. An automated detection of changes in breathing amplitude (i.e., >1.5 SD of resting) ended the music and hence provided positive feedback to the patient.

RESULTS

None of the 11 UWS/VS patients showed a sniff-based response to command. One out of 14 patients with MCS was able to willfully modulate his breathing pattern to answer the command on 16/19 trials (accuracy 84%). Interestingly, this patient failed to show any other motor response to command.

DISCUSSION

We here illustrate the possible interest of using breathing-dependent response to command in the detection of residual cognition in patients with DOC after severe brain injury.

A Very Rare Cause of Asymmetric Velopharyngeal Incompetence: Unilateral Palate Hypoplasia

Asymmetric velopharyngeal incompetence (VPI) may be caused by neuromuscular disorders, trauma, tumor resection, cleft palate, or unilateral hypoplasia of the velum and pharynx. However, VPI due to isolated unilateral hypoplasia is extremely rare. In this case report, a 4-year-old girl with unilateral palate hypoplasia and her two-staged management is presented. The speech quality of the patient improved noticeably after these procedures. The first stage allowed us to make the second stage pharyngeal flap more conservatively than possible in a one-stage procedure. We think that this two-step procedure could be an alternative to other methods in the treatment of asymmetric VPI.

Sniffing enables communication and environmental control for the severely disabled

Paradoxically, improvements in emergency medicine have increased survival albeit with severe disability ranging from quadriplegia to "locked-in syndrome." Locked-in syndrome is characterized by intact cognition yet complete paralysis, and hence these individuals are "locked-in" their own body, at best able to communicate using eye blinks alone. Sniffing is a precise sensory-motor acquisition entailing changes in nasal pressure. The fine control of sniffing depends on positioning the soft palate, which is innervated by multiple cranial nerves. This innervation pattern led us to hypothesize that sniffing may remain conserved following severe injury. To test this, we developed a device that measures nasal pressure and converts it into electrical signals. The device enabled sniffs to control an actuator with speed similar to that of a hand using a mouse or joystick. Functional magnetic resonance imaging of device usage revealed a widely distributed neural network, allowing for increased conservation following injury. Also, device usage shared neural substrates with language production, rendering sniffs a promising bypass mode of communication. Indeed, sniffing allowed completely paralyzed locked-in participants to write text and quadriplegic participants to write text and drive an electric wheelchair. We conclude that redirection of sniff motor programs toward alternative functions allows sniffing to provide a control interface that is fast, accurate, robust, and highly conserved following severe injury.

Morphologic characteristics of palatopharyngeal muscle

In an effort to clarify the morphologic characteristics of the palatopharyngeal muscle, we examined its origin, insertion, and positional relationship with other muscles. We found that the origin of the palatopharyngeal muscle was both the oral and the nasal side of the soft palate; it was also attached to both the palatal aponeurosis and the soft palate median. However, in some cases the muscle originated on the nasal side was lacked. When the palatopharyngeal muscle originated from both the oral and the nasal side, it traveled through its insertion via the levator muscle of the palatine velum. This insertion was seen in a wide area and could be divided into three parts: the pharynx anterior, central, and posterior walls. In the central pharyngeal wall, insertion into the pharyngeal aponeurosis, inferior constrictor pharyngeal muscle, and esophagus were observed. The present results suggest that the palatopharyngeal muscle has a close positional relationship with the levator and tensor muscles of the palatine velum, the pharyngeal constrictor muscles, and the esophagus.