The Laryngoscope VC 2013 The American Laryngological, Rhinological and Otological Society, Inc. Effects of Uvulopalatopharyngoplasty With or Without Radiofrequency Tongue Base Reduction on Voice in Patients With Obstructive Sleep Apnea Young Gyu Eun, MD, PhD; Seung Youp Shin, MD, PhD; Sung Wan Kim, MD, PhD Objectives/Hypothesis: To investigate voice change as a complication after uvulopalatopharyngoplasty (UPPP) with or without radiofrequency tongue base reduction (RTBR) in patients with obstructive sleep apnea. Study Design: Before and after study. Methods: Twenty-two patients with suspected velopharyngeal collapse only underwent uvulopalatopharyngoplasty (UPPP group). Twenty-five patients with velopharyngeal and retrolingual collapse underwent concurrent UPPP with RTBR (RTBR group). All patients were evaluated before surgery and at 8 weeks after surgery. Acoustic measures included mean fundamental frequency (mf0), maximal phonation time (MPT), jitter, shimmer, noise-to-harmonic ratio (NHR), hypernasality test, and the first three formant frequencies (F1, F2, F3) for sustained vowels. Voice handicap index (VHI) was used to determine subjective voice change. Results: values for mf0, MPT, jitter, shimmer, NHR, hypernasality test, and F1 did not significantly change in either group following surgery. There were the significant decreases at the F2 of /u/ and the F3 of /o/ in the UPPP group, and at the F2 of /o/ and the F3 of /a/, /i/, and /o/ in the RTBR group. VHI score was increased only in the RTBR group. Conclusions: UPPP and UPPP with RTBR have an impact on formant frequencies of vowels. Despite a relatively small number of patients, it is apparent that UPPP with RTBR influences VHI. Patients, especially professional voice users, should be advised of this before considering the surgery. Key Words: Obstructive sleep apnea, voice, formant, radiofrequency, tongue base. Level of Evidence: 4 Laryngoscope, 123:1806 1810, 2013 From the Department of Otolaryngology Head and Neck Surgery, Kyung Hee University School of Medicine, Seoul, South Korea. Editor s Note: This Manuscript was accepted for publication May 3, 2012. This work was supported by the Kyung Hee University Research Fund in 2009 (KHU-20090577). The authors have no other funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Sung Wan Kim, MD, Department of Otorhinolaryngology Head and Neck Surgery, Kyung Hee University Medical Center, #1 Hoegi-dong, Dongdaemun-gu, Seoul, South Korea 130-702. E-mail: drkimsw@hanmail.net DOI: 10.1002/lary.23456 1806 INTRODUCTION Obstructive sleep apnea (OSA) is very common and increasingly recognized as a major health problem. 1 Although a variety of surgical techniques have been described to manage OSA, multilevel pharyngeal surgery is required to overcome collapse at multiple levels of the pharyngeal airway. Because the surgical procedure to treat OSA may change the nasal cavity, oral cavity, and pharynx, there is concern over the effects of the surgery on speech quality and swallowing. Many studies have examined the potential changes in perceptual and acoustic characteristics of vocal quality after upper airway operations. 2 13 Most of these studies were concerned with surgery for the palate. In general, minimal or no change was found. Among the currently available tongue base procedures that alleviate lower pharynx obstruction, radiofrequency tongue base reduction (RTBR) is widely used due to its minimal invasiveness and simplicity. 14 20 RTBR is safe and is not associated with major side effects. 21 However, RTBR can cause scarring of the submucosal tissue, resulting in reduced tissue volume, which may affect vocal quality by altering the resonant characteristics of the vocal tract. These resonances, termed formants, 22 are defined by the size and shape of the acoustic spaces of the vocal tract (i.e., oral, nasal, and pharyngeal cavities) and the coupling between those spaces. In speech, formant frequencies are manipulated by creating varying degrees of constriction of the airflow using the lips, mandible, tongue, velopharyngeal port, and pharyngeal walls. The formant frequencies define the vowels produced and significantly contribute to overall vocal quality. 22 The purpose of the study was to investigate voice change as a complication after uvulopalatopharyngoplasty (UPPP) with or without RTBR in patients with OSA. MATERIALS AND METHODS Subjects This was a prospective controlled study of 47 OSA patients treated with surgery at Kyung Hee University Medical Center.
All patients were preoperatively evaluated through historytaking, physical examination, cephalometry, fiberoptic nasopharyngoscopy with Mueller s maneuver, and an overnight polysomnography. Patients with an apnea-hypopnea index (AHI) <5, age <18 years, speech or voice dysfunction history, previous surgical history such as microlaryngoscopy or OSA surgery, and head and neck cancer history were excluded. Surgical procedures were chosen based on the presence of velopharyngeal airway or retrolingual airway narrowing of the tongue base on cephalometry, and fiberoptic nasopharyngoscopy during Mueller s maneuver. Patients with only velopharyngeal collapse underwent UPPP and constituted the UPPP group. Patients with velopharyngeal and retrolingual collapse underwent concurrent UPPP and RTBR and constituted the RTBR group. To exclude the effect of UPPP, we chose patients who underwent UPPP combined with RTBR as the subject group and patients who underwent only UPPP as the control group. Informed consent was obtained from the patients. This study was approved by the institutional review board of Kyung Hee University Hospital. Surgery In the UPPP procedure, tonsillectomy was performed first with electrocautery and then the oral soft palate mucosa and submucosa were debrided, preserving as much of the palatopharyngeus, palatoglossus, and uvula muscles as possible. The uvular tip was trimmed prior to reflecting the palate anteriorly and superiorly. The denuded flap was made by cold knife dissection, and imbricated and sutured to the residual mucosa of the soft palate. The approximation of posterior and anterior pillars was achieved by sutures with maximal lateralization for creating more retropalatal airway space. RTBR was performed using a CelonProSleep (Celon AG Medical Instruments, Berlin, Germany) to accomplish stiffening and volume reduction of the tongue base. 14 A total of nine lesions were selected for treatment. Three of these lesions were at the midline of the circumvallate papillae, and were 1 cm anterior and posterior to the middle of the circumvallate papillae. The next six lesions were 1 cm right or left of the first three lesions. The setting on the power control unit was 10 W. Application time varied from 4 to 6 seconds per puncture and was terminated by the acoustic end-indication, which is an auto-stop mechanism facilitated by a thermistor. Tissue impedance was measured using the probe tip. The delivery energy at this power setting was approximately 60 J per punctum. All surgical procedures were performed by a single surgeon (S.W.K.). Voice Analysis Subjects had their voice measured prior to and 8 weeks after surgical treatment. To minimize subjectivity, a single certified speech-language pathologist in the voice clinic at the Kyung Hee Medical Center performed all voice evaluations. The recordings of the speech samples were performed in a sound-isolated room with a high-quality condenser microphone (C 1000 S; AKG, Vienna, Austria) positioned 20 cm away from the mouth at a 45 angle, which was attached to a TASCAM US-122L digital audio tape recorder (Teac Corp., Tokyo, Japan). For the standardization and comparability of the voice samples, the patients were instructed to sustain the vowels at a comfortable pitch and level of loudness three times before recording to obtain maximum steady phonation during recording. Voice signals were recorded as sustained vowels (/a/e/i/o/u/) for 10 seconds and trimmed to 5-second midportions before analysis. Sustained vowel recordings were analyzed with the Multi- Dimensional Voice Program, model 5105, version 3.1.4 (Kay Pentax, Lincoln Park, NJ). The mean fundamental frequency (mf0) and the first three formant frequencies (F1, F2, F3) of these sustained vowels were determined. Linear predictive coding analysis was used to obtain formant frequencies. Additionally, jitter, shimmer, noise-to-harmonics ratio (NHR), and maximum phonation time (MPT) were measured. For testing nasality, the Glatzel mirror-fogging test and Gutzmann test were performed. In the mirror-fogging test, nasalization was assessed by evaluating the degree of condensation (0 4; 0 no condensation; 4 severe condensation) on a cold mirror held 0.5 cm under the nose during phonation (subjects were asked to sustain the vowels /a/ and /i/, and the consonant / m/). 23 In the Gutzmann test, subjects were asked to produce a series of /a/ and /i/ sounds alternately with the nares held open and closed (a change in vowel quality when the subject produced the vowels with the nares closed was indicative of hypernasality, in which case a score of 1 was assigned; absence of change was assigned a score of 0). 23 Patient self-assessment of voice was obtained in the Voice Handicap Index (VHI). The VHI is a validated questionnaire measuring psychosocial handicapping effects of voice disorders. 24 The VHI is a 30-item dysphonia-specific quality-of-life questionnaire with good content validity and reliability. It provides a numerical score that reflects the patient s perception of the degree to which the voice is a physical, social, or functional handicap in daily life. Scores can range from 0 (no handicap) to 120 (maximum handicap). 25 Statistical Analyses Data are expressed as mean 6 standard deviation for normally distributed data and median 6 interquartile range for not normally distributed data. All statistical analyses were performed using SPSS for Windows version 11.5 (IBM, Armonk, NY). Differences before and after surgical treatment were assessed by paired t test if data were normally distributed, or by Wilcoxon signed rank test if data were not normally distributed. Statistical significance was defined as P <.05. RESULTS There were 22 males (mean age, 38.7 6 12.9 years) in the UPPP group and 25 males (mean age, 44.9 6 13.1 years) in the RTBR group. The two groups were similar in terms of age (P ¼.110). The mean values of AI, HI, AHI, and RDI were 9.74, 8.45, 18.19, and 26.23 in the UPPP group, respectively, and 9.81, 9.06, 19.02, and 27.14 in the RTBR group, respectively. There were no significant differences of polysomnographic data between the groups. No statistical significance was found between preoperative and postoperative jitter, shimmer, NHR, MPT, and mf0 in the groups (Table I). There were significant changes at the F2 value of sustained vowel /u/ and the F3 value of sustained vowel /o/ after the surgical treatment in the UPPP group (Table II). There were the significant changes at the F2 value of sustained vowel / o/ and the F3 values of sustained vowels /a/, /i/, and /o/ after surgical treatment in the RTBR group (Table III). The mirror fogging test and the Gutzmann test showed no differences between the preoperative and postoperative data in both groups (Table IV). VHI score was 11.5 6 47.0, and postoperative VHI score was 14.0 6 23.0 in the UPPP group. No statistical significance was found between preoperative and postoperative VHI scores in the UPPP group (P ¼.407). 1807
TABLE I. Change of Vocal Parameters After Surgical Treatment. Data Data UPPP group Jitter (%) 0.64 6 0.72 0.57 6 0.64.590 Shimmer (%) 2.06 6 2.27 2.24 6 0.89.476 NHR 0.13 6 0.04 0.13 6 0.03.931 MPT (s) 14.54 6 3.38 14.46 6 7.18.527 mf0 (Hz) 105.32 6 12.69 108.87 6 10.97.808 RTBR group Jitter (%) 0.61 6 0.46 0.55 6 0.37.376 Shimmer (%) 2.34 6 1.49 2.38 6 1.98.679 NHR 0.13 6 0.24 0.12 6 0.32.331 MPT (s) 16.63 6 4.86 14.39 6 6.17.563 mf0 (Hz) 105.41 6 7.03 104.10 6 13.72.587 UPPP ¼ uvulopalatopharyngoplasty; NHR ¼ noise-to-harmonic ratio; MPT ¼ maximal phonation time; mf0 ¼ mean fundamental frequency; RTBR ¼ radiofrequency tongue base reduction. VHI score was 4.0 6 15.75 and postoperative VHI score was 9.5 6 23.5 in the RTBR group. There was a significant change after surgical treatment in the RTBR group (P ¼.022). A change over 15 points was found in one of 22 (4.5%) patients in the UPPP group and two of 25 (8%) patients in the RTBR group. DISCUSSION The aim of the present study was to evaluate the potential effects of the RTBR on speech and voice. To exclude the effect of UPPP, we chose patients who underwent UPPP combined with RTBR as the subject group and patients who underwent only UPPP as the control group. The primary findings of this study were a TABLE II. Change of Formants After Surgical Treatment in the Uvulopalatopharyngoplasty Group. Sustained Vowel F1 /a/ 705.82 6 164.86 700.92 6 100.19.306 /e/ 518.76 6 95.17 513.06 6 91.14.338 /i/ 284.57 6 47.19 282.56 6 30.85.935 /o/ 341.55 6 33.39 327.89 6 64.70.408 /u/ 276.05 6 43.99 280.51 6 36.78.833 F2 /a/ 1184.72 6 155.60 1195.11 6 203.99.961 /e/ 1910.17 6 146.22 1906.91 6 290.04.709 /i/ 2289.47 6 308.54 2280.80 6 261.69.808 /o/ 750.50 6 73.99 718.86 6 65.49.935 /u/ 790.52 6 107.48 811.83 6 146.89.031 F3 /a/ 2704.69 6 221.18 2712.02 6 649.68.615 /e/ 2805.63 6 190.74 2617.65 6 281.34.338 /i/ 2998.43 6 376.29 3030.00 6 402.77.263 /o/ 2754.81 6 181.81 2652.37 6 216.62.019 /u/ 2948.17 6 655.05 2879.16 6 1066.84.082 TABLE III. Change of Formants After Surgical Treatment in the Radiofrequency Tongue Base Reduction Group. Sustained Vowel F1 /a/ 666.37 6 73.56 663.01 6 79.98.977 /e/ 507.00 6 62.44 525.38 6 58.14.668 /i/ 281.07 6 49.99 285.07 6 42.95.440 /o/ 395.93 6 52.95 379.37 6 59.42.056 /u/ 302.97 6 33.61 306.04 6 67.24.627 F2 /a/ 1137.24 6 108.55 1113.63 6 79.57.153 /e/ 1785.94 6 210.03 1766.72 6 333.67.647 /i/ 2268.13 6 194.58 2187.13 6 138.32.137 /o/ 761.95 6 128.52 738.76 6 108.62.018 /u/ 792.34 6 109.39 791.91 6 158.59.954 F3 /a/ 2858.89 6 325.19 2850.14 6 378.06.013 /e/ 2705.49 6 223.61 2692.29 6 161.58.753 /i/ 3014.37 6 198.48 2934.63 6 301.19.001 /o/ 2816.56 6 223.70 2652.27 6 298.27.003 /u/ 2589.36 6 424.66 2512.26 6 129.53.290 significant decrease of F2 and F3 in the UPPP group and the RTBR group, and increased postoperative VHI score in the RTBR group but not in the UPPP group. The surgical procedures used for treatment of snoring and OSA syndrome commonly alter the structures of the upper airway and so have the potential to affect vocal quality. 26 Previous studies considering this issue have mainly investigated the effects of palatal surgeries such as UPPP, palatal implants, and radiofrequency palatal volumetric reduction. 2,23,26 28 To our knowledge, this is the first study to evaluate the effects of RTBR on voice and speech. RTBR causes submucosal tissue scarring, resulting in tissue volume reduction and increased TABLE IV. Change of Nasality Parameters After Surgical Treatment in the Uvulopalatopharyngoplasty Group and the Radiofrequency Tongue Base Reduction Group. UPPP group RTBR group Mirror-fogging test Data Data /a/ 0.00 6 1.50 0.00 6 1.75.861 /i/ 0.00 6 1.00 1.00 6 2.00.126 /m/ 4.00 6 0.00 4.00 6 0.00.059 Gutzmann test 1.00 6 0.0 1.00 6 0.75.180 Mirror-fogging test /a/ 0.00 6 2.00 0.00 6 0.00.086 /i/ 0.00 6 1.00 0.00 6 0.00.931 /m/ 4.00 6 1.00 4.00 6 0.00.054 Gutzmann test 1.00 6 0.25 1.00 6 0.25.655 UPPP ¼ uvulopalatopharyngoplasty; RTBR ¼ radiofrequency tongue base reduction. 1808
tension in the tongue base. UPPP with RTBR is one of the most commonly used multilevel surgeries worldwide, particularly for mild-to-moderate cases. Success rates of 50%, 41%, and about 54% have been previously reported for this technique. 14,29,30 Previous studies investigating the effects of palatal surgeries on voice have produced equivocal results. 2,4,9 11,31 ly, mf0 has been reported to decline, 31 increase up to 10 Hz, 2 or to be unchanged after UPPP. 4,9 11 Presently, no statistically significant difference was detected for mf0, jitter, shimmer, NHR, and MPT before and after surgery in the UPPP group and RTBR group. Although these data were predictable and not primarily required because the laryngeal level and vocal folds are not involved with UPPP or RTBR, they were included in the study for the purpose of being proven objectively. The results of mirror fogging test or Gutzmann test did not reveal any significant differences between the presurgical and postsurgical conditions. Regarding nasality in terms of hypernasality, the results after UPPP only or UPPP with RTBR in this study support the findings of previous studies of no significant change of nasality after UPPP. 11,13,32 Although vocal output is the function of laryngeal level, the transfer process in the supraglottic level affects voice quality and precision. Resonance of the vocal tract leads to formants. Formants are determined by size, shape, and interaction between the nasal, oral, and pharyngeal cavities of the vocal tract. 26 The F1 is associated with closure of the oropharyngeal cavity and is used as a measure of velopharyngeal function or activity. 9,26 The F1 frequencies of five vowels after surgery were found to be unchanged in the UPPP and RTBR groups. This result might reflect the lack of effect of UPPP or UPPP with RTBR on velopharyngeal function or activity. The F2 and F3 are associated with advancement of the tongue and demonstrate tongue-palate coordination. The F2 frequency of /u/ in both groups and the F3 frequencies of /o/ in the UPPP group and /a/i/o/ in the RTBR group were decreased after surgery. The formant frequencies change with respect to the upper airways anatomy. The calculations by Titze and Story suggest that a narrowing of the epilaryngeal region tends to raise the three lowest formants of the vocal tract. 33 Inversely, a widening of the epilaryngeal area lowers these formants. These results might be interpreted as the widening of the pharynx after UPPP or UPPP with RTBR. Patient s perception of voice is an important treatment outcome measure, especially in the case of benign disease where the greatest impact is on quality of life. The VHI shows that the relationship between selfassessment of voice quality and scores is clear and statistically significant (the worse the self-assessment of the voice, the lower the VHI score). 34 There is no criterion level defining presence or absence of perceived vocal handicap. The usefulness of the VHI as an outcome measure is not in the absolute value of the score, but rather in the change in score after treatment. A change of 15 points is generally considered clinically relevant. 35,36 Even though there was a small portion of patients in the present study, VHI change was found after UPPP with RTBR. This would be important for patients with concerns about postoperative vocal quality, such as singers or professional speakers. CONCLUSION Our results indicate that UPPP only and UPPP with RTBR have an impact on formant frequencies of vowels. Despite the relatively small number of patients, it was found that UPPP with RTBR influences VHI. 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