Velopharyngeal surgery: a prospective randomized study of pharyngeal flaps and sphincter pharyngoplasties

Residual velopharyngeal insufficiency after palatal repair varies from 10 to 20 percent in most centers. Secondary velopharyngeal surgery to correct residual velopharyngeal insufficiency in patients with cleft palate is a topic frequently discussed in the medical literature. Several authors have reported that varying the operative approach according to the findings of videonasopharyngoscopy and multiview videofluoroscopy significantly improved the success of velopharyngeal surgery. This article compares two surgical techniques for correcting residual velopharyngeal insufficiency, namely pharyngeal flap and sphincter pharyngoplasty. Both techniques were carefully planned according to the findings of videonasopharyngoscopy and multiview videofluoroscopy. Fifty patients with cleft palate and residual velopharyngeal insufficiency were randomly divided into two groups: 25 in group 1 and 25 in group 2. Patients in group 1 were operated on by using a customized pharyngeal flap according to the findings of videonasopharyngoscopy and multiview videofluoroscopy in each case. Those in group 2 received a sphincter pharyngoplasty also customized according to the findings of videonasopharyngoscopy and multiview videofluoroscopy. The median age of the patients in both groups was not significantly different (p > 0.5). The frequency of residual velopharyngeal insufficiency after the individualized velopharyngeal surgery was not significantly different between the patient groups (12 percent versus 16 percent; p > 0.05). It seems that customized pharyngeal flaps and sphincter pharyngoplasties performed according to the findings of videonasopharyngoscopy and multiview videofluoroscopy are safe and reliable procedures for treating residual velopharyngeal insufficiency in cleft palate patients.     

Does velopharyngeal closure pattern affect the success of pharyngeal flap pharyngoplasty?

Historically at The Hospital for Sick Children in Toronto, pharyngeal flap pharyngoplasty has been the treatment of choice for treatment of velopharyngeal insufficiency, regardless of velopharyngeal closure pattern. The authors hypothesize that pharyngeal flap pharyngoplasty is more effective in treating velopharyngeal insufficiency in patients with circular or sagittal velopharyngeal closure and less effective in treating the coronal closure pattern. Ninety-three patients who underwent superiorly based pharyngeal flap surgery for velopharyngeal insufficiency were evaluated in a retrospective chart review. Closure pattern was determined preoperatively by nasopharyngoscopy or multiview videofluoroscopy. Nasalance was assessed preoperatively and at 6 weeks and 1 year postoperatively. Nasalance during nonnasal speech was decreased on average, for all closure patterns, postoperatively. However, a significantly higher percentage of patients were corrected to normal nasalance scores in thenoncoronal group than in the coronal group (57 percent versus 35 percent, respectively) at 1 year postoperatively (p < 0.05). Surgical overcorrection, as determined by postoperative hyponasality, occurred at a rate of 13 percent in the coronal group versus 7 percent in the noncoronal group (not statistically significant). The results demonstrate that hypernasality in patients with a coronal velopharyngeal closure pattern can be improved by pharyngeal flap pharyngoplasty. This procedure, however, is more frequently effective in correcting noncoronal closure pattern velopharyngeal insufficiency than coronal pattern velopharyngeal insufficiency. The authors are now more selective in their approach to the management of velopharyngeal insufficiency and are more inclined to treat coronal pattern velopharyngeal insufficiency with sphincter pharyngoplasty.     

Surgical treatment of submucous cleft palate: a comparative trial of two modalities for palatal closure

Submucous cleft palate is a congenital malformation with specific clinical and anatomical features. It can be present with or without velopharyngeal insufficiency. Surgical treatment of this malformation is indicated only when velopharyngeal insufficiency has been demonstrated. This article compares two modalities of surgical treatment for submucous cleft palate. The first includes a minimal incision palatopharyngoplasty, as described in a previous report. The second combines the first technique with additional individualized velopharyngeal surgery (individualized pharyngeal flap or sphincter pharyngoplasty) performed simultaneously. The individualized part of the procedure was selected and performed according to the findings of videonasopharyngoscopy and multiview videofluoroscopy, as reported previously. Two hundred and three patients with submucous cleft palate were studied from 1990 to 1999. Videonasopharyngoscopy and multiview videofluoroscopy demonstrated velopharyngeal insufficiency in 72 patients, who were randomly divided into two groups. Those in group 1 (n = 37) underwent a minimal incision palatopharyngoplasty. Patients in group 2 (n = 35) also underwent that procedure but simultaneously received individualized pharyngeal flap or sphincter pharyngoplasty, according to the findings of videonasopharyngoscopy and multiview videofluoroscopy. The median age of the patients from both groups was not significantly different (p > 0.5). The frequency of residual velopharyngeal insufficiency after palatal closure was not significantly different in both groups of patients (14 percent versus 11 percent; p > 0.5). The mean size of the gap at the velopharyngeal sphincter during speech was not significantly different in both groups of patients before surgery (23 percent versus 22 percent; p > 0.5). After the surgical procedures, there was a nonsignificant difference between both groups of patients in mean residual size of the gap in cases of velopharyngeal insufficiency (7 percent versus 8 percent; p > 0.5). It seems that minimal incision palatopharyngoplasty is a safe and reliable procedure for palatal closure in patients with submucous cleft palate. The use of additional individualized velopharyngeal surgery performed simultaneously did not seem to decrease the frequency of residual velopharyngeal insufficiency. Moreover, the residual size of the gap at the velopharyngeal sphincter was not significantly reduced when an additional surgical procedure was performed simultaneously with palatal closure.     

Anatomy of musculus levator veli palatini in the 15-week human fetus

The morphology of musculus levator veli palatini in the 15-week fetus was analyzed using 30-micrometer subserial sections. The sample included 26 specimens, of which 9 each were sectioned coronally and sagittally while 8 were sectioned in the transverse plane. At this stage of development m. levator veli palatini takes a general attachment to the precursor of the petrous part of the temporal bone, and, in some cases, auxiliary attachments to the auditory tube complex were also observed. At its origin, the muscle is located anterior to the tube. It then runs medially, passing beneath the auditory tube prior to entering the velum. As it nears the region of the lateral pharyngeal wall, a small fascicle trails posteriorly and inferiorly to the main muscle mass and occasionally runs into the upper margin of m. constrictor pharyngis superior. The levator muscle is more localized within the velum at this stage of development than it has been reported to be in the adult, being confined here to the central third of the soft palate. Most of the fibers of the muscle appear to form a sling within the central 20% of the velum, although some were seen to take attachment to loose connective tissue and the palatine raphe. Upon its entry into the velum, m. levator veli palatini is intersected vertically by bundles of both mm. palatoglossus and palatopharyngeus.     

A new operation for velopharyngeal insufficiency: the palatoglossus myomucosal pharyngoplasty.

Myomucosal flaps employing the palatoglossi were used to correct posttonsillectomy velopharyngeal insufficiency because the palatopharyngeus were resected with the posterior tonsillar pillar. This new sphincter pharyngoplasty may have a role as a secondary option for treatment of velopharyngeal insufficiency. It should be remembered that this operation has only been performed in a single patient without cleft palate, and, therefore, its application in the cleft population and its potential complication rate are unknown.     

弥猴单侧软腭肌肉对针式电极刺激的反应

目的建立针电极口内刺激猴软腭肌肉诱发腭咽闭合运动的模式,取得软腭肌肉运动的有效刺激数值,为软腭肌肉功能重建奠定基础。方法通过解剖成年猕猴软腭的五组肌肉,确定其体表位置;利用实验动物用腭部肌肉电极定位刺激器及针式电极对软腭肌肉进行有效刺激;结合鼻咽纤维镜、头颅侧位X片及软腭造影技术观察、记录肌肉收缩及腭咽闭合动作。结果在猕猴口内定位目标肌肉进行针电极刺激可诱发肌肉收缩。刺激电压为3 V、刺激频率为20 Hz时均能诱发单侧软腭肌肉的有效收缩;单侧腭帆提肌在刺激电压为5 V、20 Hz时可发生腭咽闭合动作。咽腭肌、舌腭肌在刺激电压5 V、刺激频率100 Hz时发生软腭下降动作。腭帆张肌仅发生收缩,而未发生腭咽闭合。应用鼻咽纤维镜和X线成像技术配合能记录腭咽闭合动作。结论弥猴可作为研究软腭肌肉运动模式的实验动物。应用电极刺激软腭肌肉,可初步建立腭咽闭合的动作模式。     

Results with Furlow palatoplasty in management of velopharyngeal insufficiency.

A retrospective study was undertaken to assess speech outcomes in patients undergoing Furlow palatoplasty. Since 1994, the authors have used the position of the levator veli palatini musculature to determine type of surgical intervention recommended for the management of velopharyngeal insufficiency. Furlow palatoplasty has been used in patients with clinical evidence of sagittally oriented levator veli palatini musculature. Forty-eight patients who underwent a Furlow palatoplasty between June of 1994 and August of 1998 were included. All patients underwent preoperative and postoperative perceptual speech analyses to describe velopharyngeal insufficiency severity, nasal air emissions, and resonance, and preoperative nasendoscopy to assess velopharyngeal gap size and palatal and lateral pharyngeal wall movement. Other patient characteristics considered included gender, age at time of surgery, previously repaired cleft palate, submucous cleft palate, and syndrome diagnosis. Speech outcomes were determined on the basis of postoperative perceptual speech analyses and were categorized in one of three ways: (1) complete resolution of velopharyngeal insufficiency, (2) substantial improvement of velopharyngeal insufficiency, and (3) audible residual velopharyngeal insufficiency. Complete resolution of velopharyngeal insufficiency was defined as normal resonance and an absence of nasal air emissions. Substantial improvement of velopharyngeal insufficiency was defined as an improvement of at least two categories in velopharyngeal insufficiency severity in those patients without complete resolution. Audible residual velopharyngeal insufficiency refers to patients with postoperative velopharyngeal insufficiency severity ratings of mild, moderate, or severe. The male:female ratio in the study was 27:21. Twelve patients were syndromic; three had velocardiofacial syndrome. The median age at surgery was 6.5 years (range, 2 to 22 years). The average duration of follow-up was 14.7 months (range, 1.3 to 58.6 months). Postoperatively, the severity of velopharyngeal insufficiency was rated as none in 19 of the 48 patients (39.6 percent), minimal in eight (16.7 percent), mild in six (12.5 percent), moderate in nine (18.75 percent), and severe in six (12.5 percent). Substantial improvement was seen in seven of the 29 patients without complete resolution. There was a significant association between male gender and complete resolution of velopharyngeal insufficiency (p < 0.05). Presence of syndrome and female gender was associated with audible residual velopharyngeal insufficiency (p < 0.05). The main complication was palatal fistula (two cases). In conclusion, most patients who underwent a Furlow palatoplasty had a complete resolution or substantial improvement of velopharyngeal insufficiency postoperatively, and there were few surgical complications.     

Levator veli palatini muscle and eustachian tube function

Thirty previously unoperated patients with submucous cleft palate, occult submucous cleft palate, and unilateral congenital paralysis of the levator veli palatini muscle were examined. All patients were subjected to a comprehensive otoscopic, endoscopic, audiologic, and tympanometric evaluation. A correlation was made between levator veli palatini muscle anomalies, eustachian tube orifice anomalies, and middle ear ventilation and disorders. Normal middle ear ventilation was found in 23 patients. Negative middle ear pressure that consequently normalized following treatment of coexisting sinusitis was found in 3 patients. Only in 4 patients was chronic middle ear disease found. In one of them, middle ear effusion disappeared following successful treatment of sinusitis. Our conclusion is that the levator veli palatini muscle has no significant function in the opening mechanism of the eustachian tube and must be considered as a velopharyngeal valve muscle only.     

Eustachian tube cartilage and medial movement of lateral pharyngeal wall on phonation

Several authors have demonstrated the importance of medial movement of the lateral pharyngeal wall in velopharyngeal closure upon phonation. However, it remains controversial what muscle is responsible for lateral pharyngeal wall movement and where is the main site of this movement. The purpose of this study was to address the above two unanswered questions. In 22 subjects (12 normal volunteers, 10 patients with cleft palate), lateral pharyngeal wall movement upon phonation was evaluated by using rapid magnetic resonance imaging (MRI). Before rapid MRI, their lateral pharyngeal wall movements were classified into three groups: the poor, moderate, and good, according to the findings of nasopharyngoscopy. Inward displacement of the eustachian tube cartilages upon phonation, which was quantified as distance ratio in the transverse plane of MR images, was compared with nasopharyngoscopic findings. In addition, the level of lateral pharyngeal wall movement was observed in the plane 5 mm lateral to the mid-sagittal plane of MR images. Inward displacement of the eustachian tube cartilage in the transverse plane of MR images was coincident with medial movement of lateral pharyngeal wall observed by nasopharyngoscopy in all 22 subjects. By using one-way analysis of variance, a statistically significant correlation was found between nasopharyngoscopic classification and distance ratio. The sagittal plane of MR images revealed that the main site of movement occurred at the level of the hard palate and above. It is concluded that medial movement of the lateral pharyngeal wall consists of inward displacement of the eustachian tube cartilage, which is caused by contraction of the levator veli palatini muscle, and that the primary site of this movement is at the level of the hard palate and above, where the eustachian tube, but not the superior constrictor muscle, exists.     

An outcome evaluation of sphincter pharyngoplasty for the management of velopharyngeal insufficiency

Sphincter pharyngoplasty is frequently used for the management of children with velopharyngeal insufficiency. The purpose of this study was to evaluate outcome and revision rates of sphincter pharyngoplasty at the authors' institution. Two hundred fifty patients underwent sphincter pharyngoplasty for velopharyngeal insufficiency between January of 1987 and March of 2001. There were 117 female patients and 133 male patients, with a mean age at primary sphincter pharyngoplasty of 7.6 years (range, 1 to 45 years). Diagnoses included velopharyngeal insufficiency alone (n = 63), velopharyngeal insufficiency associated with cleft palate (n = 127), velocardiofacial syndrome (n = 32), submucous cleft (n = 15), and other (n = 13). Pharyngoplasty revision was defined as any secondary surgical revision of the sphincter as determined by clinical evaluation and objective speech assessment. The pharyngoplasty revision rate was found to be 12.8 percent (n = 32). A favorable outcome was demonstrated in 30 of these patients (93.8 percent) after pharyngoplasty revision. Two patients, one with a diagnosis of a submucous cleft and velocardiofacial syndrome and the other with a cleft palate, required a second revision because of persistent velopharyngeal insufficiency. The revision rate was highest in those patients with velocardiofacial syndrome (21.8 percent) and lowest in patients with velopharyngeal insufficiency alone (6.3 percent). Patients who required revision had significantly higher preoperative oral sentence nasometry (55.2 percent versus 46.1 percent; p < 0.01) and larger velopharyngeal areas (23.7 mm2 versus 18.9 mm2). There was no significant difference in age or sex for those patients who required a revision compared with those who did not require revision. Mean follow-up was 2.4 years (range, 4 months to 13.6 years). Sphincter pharyngoplasty is an effective procedure for the treatment of velopharyngeal insufficiency using revision rate as the standard of success. It had an 87 percent primary success rate that increased to 99 percent after a single revision. Patients with velocardiofacial syndrome, more severe preoperative hypernasal resonance, and larger velopharyngeal areas were more likely to require pharyngoplasty revision.     

Morphology of the soft palate of the vervet monkey (Cercopithecus pygerythrus)

The heads of 31 vervet monkeys were dissected to investigate the morphology of the soft palate. This extended posteriorly from the hard palate and was delineated laterally by a fold raised by the pterygomandibular raphé. The palatoglossal arch was more prominent than the palatopharyngeal arch and four types of uvulae were seen. These were conical, bifid, trifid, and triangular. Twenty five to forty raised papillae were present on the anterior half of the oral surface. Within the soft palate, the bulk of tissue consisted of glands with a lesser amount of striated muscle. The muscles consisted of the tensor veli palatini, levator veli palatini, palatoglossus, palatopharyngeus, and uvular muscles which differed slightly in their attachments to similar muscles in man. The innervation of the tensor veli palatini muscle was a branch of the mandibular nerve but no nerves could be traced to the other muscles. The soft palate of the vervet monkey is sufficiently similar to that in man to be of practical use in experimental surgery aimed at correcting human soft palate abnormalities.     

Surgical anatomy of the levator veli palatini: a previously undescribed tendinous insertion of the anterolateral fibers

The purpose of this study was to describe the previously unreported tendinous insertion of the anterolateral fibers of the levator veli palatini (levator) and discuss possible implications for levator function and cleft palate repair. The velopharyngeal anatomy in normal adult cadavers was studied, with histologic confirmation of anatomical findings. These findings were compared with a more limited study of levator anatomy in cleft palates at the time of intraoperative muscle dissection. Just before entering the velum, the levator divides into two parts. The smaller bundle of muscle fibers (anterolateral part) runs anteriorly, close to the lateral pharyngeal wall, and inserts into the palatine aponeurosis through a number of fine tendons. The main part of the muscle runs medially into the velum, where it fans out and forms the levator sling with the contralateral levator. The possible function of the anterolateral part of the levator is discussed. Inadequate release of the tendinous insertions at the time of palate repair may tether the levator anteriorly and compromise muscle retropositioning or may result in splitting of the levator, so that only part of the levator is retropositioned.     

Levator repositioning and palatal lengthening for submucous clefts

Submucous clefts of the palate may present with velopharyngeal incompetence (VPI) or a history of recurrent otitis media. Many surgeons have favored a pharyngeal flap as primary treatment of the velopharyngeal incompetence associated with this disorder. The increasing number of case reports of sleep apnea and airway compromise associated with pharyngeal flaps prompted the use of levator muscle repositioning with palatal lengthening as initial therapy in 15 patients in an attempt to correct the pathologic anatomy while avoiding the postoperative sequelae. Patients were divided into two groups: group A (N = 8) had surgery before age 2 (11.8 +/- 5.7 months), and group B (N = 7) had surgery after 2 years of age (64.3 +/- 24.2 months). No patient in group A required a secondary operative procedure for velopharyngeal incompetence. Normal speech was obtained in 75 percent (N = 6), and slight velopharyngeal incompetence not requiring secondary correction was obtained in 25 percent (N = 2). Group B obtained less dramatic speech results: normal in 14 percent (N = 1), slight velopharyngeal incompetence in 58 percent (N = 4), and no improvement or severe velopharyngeal incompetence requiring a secondary procedure in 28 percent (N = 2). Patients with preoperative otologic disorders (N = 10) obtained significant improvement in 90 percent of cases (p = 0.002). Early surgical intervention in patients with abnormal speech prior to age 2 appears to result in normal speech in the majority of instances. Late repair with levator repositioning and palatal lengthening provided improved speech in 72 percent of patients.     

A rationale for modifying the site of insertion of the orticochea pharyngoplasty

A modification of the insertion level of Orticochea flaps is proposed. The purpose of the modification is to place the pharyngoplasty at a higher site, in the area of attempted velopharyngeal contact. The site of velopharyngeal contact can be identified using lateral radiographic techniques. A success rate of 93 percent was achieved in improved oral-nasal resonance balance when the pharyngoplasty was placed at a site in the nasopharynx.     

In search of the optimal surgical treatment for velopharyngeal dysfunction in 22q11.2 deletion syndrome: a systematic review

Background

Patients with the 22q11.2 deletion syndrome (22qDS) and velopharyngeal dysfunction (VPD) tend to have residual VPD following surgery. This systematic review seeks to determine whether a particular surgical procedure results in superior speech outcome or less morbidity.

Methodology/ Principal Findings

A combined computerized and hand-search yielded 70 studies, of which 27 were deemed relevant for this review, reporting on a total of 525 patients with 22qDS and VPD undergoing surgery for VPD. All studies were levels 2c or 4 evidence. The methodological quality of these studies was assessed using criteria based on the Cochrane Collaboration''s tool for assessing risk of bias. Heterogeneous groups of patients were reported on in the studies. The surgical procedure was often tailored to findings on preoperative imaging. Overall, 50% of patients attained normal resonance, 48% attained normal nasal emissions scores, and 83% had understandable speech postoperatively. However, 5% became hyponasal, 1% had obstructive sleep apnea (OSA), and 17% required further surgery. There were no significant differences in speech outcome between patients who underwent a fat injection, Furlow or intravelar veloplasty, pharyngeal flap pharyngoplasty, Honig pharyngoplasty, or sphincter pharyngoplasty or Hynes procedures. There was a trend that a lower percentage of patients attained normal resonance after a fat injection or palatoplasty than after the more obstructive pharyngoplasties (11–18% versus 44–62%, p = 0.08). Only patients who underwent pharyngeal flaps or sphincter pharyngoplasties incurred OSA, yet this was not statistically significantly more often than after other procedures (p = 0.25). More patients who underwent a palatoplasty needed further surgery than those who underwent a pharyngoplasty (50% versus 7–13%, p = 0.03).

Conclusions/ Significance

In the heterogeneous group of patients with 22qDS and VPD, a grade C recommendation can be made to minimize the morbidity of further surgery by choosing to perform a pharyngoplasty directly instead of only a palatoplasty.     

Soft palate muscle responses to negative upper airway pressure

The afferentpathways and upper airway receptor locations involved in negative upperairway pressure (NUAP) augmentation of soft palate muscle activity havenot been defined. We studied the electromyographic (EMG) response toNUAP for the palatinus, tensor veli palatini, and levator veli palatinimuscles in 11 adult, supine, tracheostomized, anesthetized dogs. NUAPwas applied to the nasal or laryngeal end of the isolated upper airwayin six dogs and to four to six serial upper airway sites from the nasalcavity to the subglottis in five dogs. When NUAP was applied at thelarynx, peak inspiratory EMG activity for the palatinus and tensorincreased significantly (P < 0.05) and plateaued at a NUAP of 10cmH₂O. Laryngeal NUAP failed toincrease levator activity consistently. Nasal NUAP did not increase EMGactivity for any muscle. Consistent NUAP reflex recruitment of softpalate muscle activity only occurred when the larynx was exposed to the stimulus and, furthermore, was abolished by bilateral section of theinternal branches of the superior laryngeal nerves. We conclude thatsoft palate muscle activity may be selectively modulated by afferentactivity originating in the laryngeal and hypopharyngeal airway.     

A single surgeon's experience with the Delaire palatoplasty

The purpose of this review was to evaluate the clinical outcomes regarding velopharyngeal insufficiency and fistulization in patients with cleft palate who underwent primary repair with the one-stage Delaire palatoplasty. All patients who had a primary Delaire-type palatoplasty performed by the senior surgeon over a 10-year period (1988 to 1998) were studied. During this period, each consecutive patient with an open palatal cleft underwent the same type of repair by the same surgeon. Speech quality and velopharyngeal competence as determined by a single speech pathologist were recorded. A total of 95 patients were included in this series. The average length of follow-up was 31 months (range, 1 to 118 months). Average age at time of surgery was 13.3 months (range, 6 to 180 months). Thirty-one patients (32.6 percent) had significant associated anomalies. The average length of hospital stay was 1.9 days (range, 1 to 8 days) with a trend in recent years toward discharge on postoperative day 1. There were no intraoperative complications, either surgical or anesthetic. Three patients (3.2 percent) developed palatal fistula; none of them required repair. Six patients (6.3 percent) had velopharyngeal incompetence. In patients with more than 1 year of follow-up, the incidence of velopharyngeal incompetence was 9.2 percent (6 of 65). The incidence of fistula after the Delaire palatoplasty was lower than usually reported. The incidence of velopharyngeal incompetence requiring pharyngoplasty was equal to or lower than that seen after other types of palatoplasty, suggesting superior soft-palate muscle function attributable to approximation of the musculus uvulae. The Delaire palatoplasty results in a functional palate with low risk for fistula formation and velopharyngeal incompetence.     

Positive narrowing pharyngoplasty with forearm flap for functional restoration after extensive soft palate resection

The restoration of velopharyngeal function after extensive soft palate resection to treat malignant oropharyngeal tumors is a major challenge to reconstructive surgeons. The authors had previously reconstructed soft palatal defects routinely with the folded forearm flap. A patient who had more than half of the soft palate excised experienced postoperative velopharyngeal dysfunction. To restore efficient velopharyngeal function, pharyngoplasty was additively applied where the folded ridge of the forearm flap was sutured to the posterior pharyngeal wall in an inverse manner of the pharyngeal flap technique. The essence of the procedure was positive narrowing of the nasopharyngeal space. Five patients who underwent this pharyngoplasty and another five who did not were evaluated for postoperative functions of speech intelligibility and of nasal regurgitation during oral feeding. The velopharyngeal movements of all patients were examined under a nasopharyngeal endoscope. The evaluations demonstrated that this surgical procedure afforded satisfactory results. This positive narrowing pharyngoplasty technique is simple, easy, and minimally invasive to the remaining healthy tissue, and it is the method of choice for the reconstruction of the soft palate after malignant tumor resection.     

Respiratory function of velopharyngeal constrictor muscles during wakefulness in normal adults

Launois, Sandrine H., Judy Tsui, and J. Woodrow Weiss.Respiratory function of velopharyngeal constrictor muscles during wakefulness in normal adults. J. Appl.Physiol. 82(2): 584-591, 1997.The levator velipalatini (LVP) and the superior pharyngeal constrictor (SPC) influencevelopharyngeal patency and soft palate position, but their behaviorduring respiration is incompletely characterized. To further clarifytheir respiratory function, we recorded electromyographic activity(EMG) in the LVP and the SPC in awake normal subjects breathing orally.EMG data were obtained in six subjects for the LVP and in nine subjectsfor the SPC. EMG activity and timing and ventilation were measuredduring isocapnic hypoxia and hyperoxic hypercapnia. Phasic EMG activitywas inconsistently present during unstimulated oral breathing. Timingof EMG phasic activity was variable for both muscles. Peak LVP activitywas mainly or exclusively expiratory in three of six subjects. Peak SPCactivity was mainly or exclusively expiratory in five of nine subjects.With chemostimulation, recruitment of phasic activity was observed inthe LVP in four of six subjects and in the SPC in five of ninesubjects. Tonic activity increased in four of six subjects for the LVPand in three of nine subjects for the SPC. However, the response wasalinear, and intersubject as well as breath-to-breath variability wassubstantial. In conclusion, LVP and SPC are characterized by the highinter- and intrasubject variability of EMG activity, timing ofactivation, and response to chemostimulation.