- Email: [email protected]
Effect of Fasting on Voice in Women
Effect of Fasting on Voice in Women *Abdul-Latif Hamdan, †Abla Sibai, and *Charbel Rameh *†Beirut, Lebanon
Summary: Objective/Hypothesis: to study the effect of fasting on voice in women: abstinence from food and water intake between 14 and 18 hours. Study Design: a prospective study on female subjects. Material and Method: A total of 28 female subjects were included in this study. Their age ranged between 21 and 45 years. Subjects with vocal symptoms or vocal fold lesions were excluded. The subjects were tested when they were not fasting and while fasting after the first week of intermittent fasting during Ramadan. Each subject was first asked about her vocal symptoms and the ease of phonation or phonatory effort. Then each underwent acoustic analysis and laryngeal video-endostroboscopy. Results: Vocal fatigue was the most common reported complaint (53.6%) followed by deepening of the voice (21.4%) and harshness (10.2%). Self-reported phonatory effort was significantly affected by fasting (P value ! 0.001). Out of the 28 subjects, 23 had an increase in their phonatory effort. Vocal acoustic parameters did not change markedly except for the maximum phonation time, which decreased significantly. Laryngeal video-endostroboscopy did not reveal any significant changes during fasting. All stroboscopic parameters were the same except for a decrease in the amplitude of the mucosal waves in one subject and the presence of a posterior chink in three subjects. Conclusion: Fasting affects voice. There is an increase in the phonatory effort, and vocal fatigue is the most common symptom. Key Words: Fasting—Voice—Dehydration.
Consequently, dehydration, electrolyte imbalance, malnutrition, and general malaise may occur. This condition warrants serious attention and the need for fluid administration to alleviate the patient’s discomfort. As a result, a new consensus in the preoperative requirement for general anesthesia is being reformed.2 During the month of Ramadan, Moslems refrain from drinking and eating between sunrise and sunset. The effect of this intermittent lack of water and food intake on the well-being of the participant has been studied in various groups. Most studies agree that there are significant metabolic changes with slowing down of the body metabolism during the day to conserve energy stores.3 The changes in the lifestyle witnessed during this month of fasting
INTRODUCTION Fasting overnight can lead to fluid deficit measured up to 1 L after 8 hours of abstinence.1 Accepted for publication January 24, 2006. From the *Department of Otolaryngology Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon; and the †Department of Epidemiology and Population Health, Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon. Address correspondence and reprint requests to Abdul-Latif Hamdan, MD, FACS, American University of Beirut, Department of Otolaryngology, PO Box 11-0236, Beirut, Lebanon. E-mail: [email protected] Journal of Voice, Vol. 21, No. 4, pp. 495–501 0892-1997/$32.00 Ó 2007 The Voice Foundation doi:10.1016/j.jvoice.2006.01.009
495
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ABDUL-LATIF HAMDAN ET AL
result in alterations in the circadian rhythm and sleep deprivation. Weight loss between 0.1 and 1.4 kg of body weight and signs of dehydration are invariably encountered.4–6 Hypoglycemia and raised serum concentrations of uric acid, sodium, chloride, and proteins during the first week of fasting emphasize the state of dehydration.7–9 Fasting with fluid restriction also results in a hyper-lipid level compared with fasting with salt and water supplementation, which accentuate further the role of hydration in the fluctuation of the lipid profile during fasting.10 All of these metabolic changes may give rise or accelerate health problems such as cardiovascular, respiratory, and even ocular.11,12 Many studies have focused on the effect of hydration on vocal fatigue and the phonatory threshold pressure, highlighting the biological mechanisms underlying voice changes due to dehydration.13–18 It has also been shown how important is the hydration level as a physiologic variable in vocal fold vibration and sound production. Most of these studies were either in vitro studies or performed on a relatively small number of subjects where the dehydration was artificially or drug induced. Based on a PubMed search, the effect of fasting in normal subjects on voice has not been reported. The purpose of this study is to investigate the effect of fasting on voice in a large number of subjects who abstained from water and food between 14 and 18 hours. The phonatory effort, acoustic analysis of the vocal signal, and stroboscopic examination of the larynx were performed. MATERIAL AND METHOD A total of 28 female subjects were included in this study after receiving approval by the Institution Review Board of the American University of Beirut, Lebanon. Subjects with a history of dysphonia or laryngeal lesion or surgery were not included in the study. The subjects were tested when they were not fasting and while fasting after the first week of intermittent fasting during Ramadan. By fasting, the authors mean abstinence or lack of water and food intake between sunrise and sunset. The testing was performed 1 to 2 hours before sunset to ensure at least 14 hours of fasting. Each subject was first asked about her vocal symptoms and the ease of phonation Journal of Voice, Vol. 21, No. 4, 2007
or phonatory effort, where 0 stands for no effort, 1 stands for mild effort, 2 for moderate, and 3 for a lot of effort. Then each subject underwent evaluation of her voice using the Kay Elemetric VISI Pitch (Model 3300; Kay Elemetrics Corporation, Lincoln Park, NJ). Although the patient is seated in a quiet office, the patient’s vocal signal was recorded directly into the system using a condenser microphone at a distance of 15 cm from the mouth. The following acoustic variables were measured: average fundamental frequency, relative average perturbation, shimmer, noise-to-harmonic ratio, voice turbulence index, habitual pitch, and maximum phonation time. The habitual pitch was measured by asking the subject to count to 10 in a normal voice. The maximum phonation time was calculated by asking the subject to take a deep breath and sustain phonation for as long as possible. The remaining variables were measured by asking the subject to sustain the vowel ‘‘ah’’ for 2 seconds, using the voice quality assessment module of the VISI Pitch system. The subjects also underwent in the same setup laryngeal video-endostroboscopy using the 70-degree rigid telescope coupled to the Karl Storz Laryngostrobe model 8020 and to a 30-mm single chip color Storz endoscopic telecam Dx pal 202320 20 (Karl Storz, Tuttlingen, Germany). The following parameters were looked at: symmetry, amplitude, mucosal wave, periodicity, and closure. Frequencies and means (6SD) were used to describe the sample, for categorical and continuous variables, respectively. For each subject, the parameters were collected before and after fasting, and the appropriate statistical analysis for small-size samples (Wilcoxon nonparametric paired test) was conducted. The analysis took into consideration the design (before and after) and modality of data collection (paired data). Differences were considered significant for P ! 0.05. All analysis was conducted using SPSS software (SPSS Corporation, Chicago, IL). RESULTS A total of 28 women were examined and assessed for voice changes while fasting and while not fasting. The age of the participants ranged from 21 years to 45 years with a mean of 29.7 years and a standard
EFFECT OF FASTING ON VOICE deviation of 7.7 years. Vocal fatigue was the most common reported complaint (53.6%) followed by deepening of the voice (21.4%) and harshness (10.2%) (Table 1). Phonatory effort was significantly affected by fasting (P value ! 0.001). Although most participants reported no effort (28.6%) or mild effort (71.4%) during nonfasting, 64.3% and 7.1% expressed moderate or severe effort, respectively, during fasting (Table 2). Out of the 28 subjects, 23 had an increase in their phonatory effort, 7 of whom had a two-point increase in scale. Vocal acoustic parameters, in most participants, did not change markedly. The relative average perturbation slightly increased, but the increase was not statistically significant. The shimmer, habitual pitch, and maximum phonation time decreased; however, the difference was significant only for the maximum phonation time (MPT) (15.972 vs 13.269, respectively, P value ! 0.001). The remaining vocal parameters were not affected by fasting (Table 3). Laryngeal video-endostroboscopy did not reveal any changes during fasting. All stroboscopic parameters were the same except for a decrease in the amplitude of the mucosal waves in one subject and the presence of a posterior chink in three subjects. DISCUSSION The effect of hydration on voice has been investigated in several studies. Vocal fold stiffness and viscosity increase with the osmotically induced dehydration and decrease with rehydration.13,14 Experiments on excised canine larynges first dehydrated with warm dry air and then rehydrated TABLE 1. Characteristics of Study Sample
Sex (% females) Age (mean 6 SD) Vocal complaints during fasting Vocal fatigue Deepening Harshness Sore throat Throat itching Increased pitch Abbreviation: SD, standard deviation.
No.
%
28
100 29.7 6 7.7
15 6 3 2 1 1
53.6 21.4 10.2 7.1 3.6 3.6
497
TABLE 2. Self-Perceived Phonation Effort Nonfasting
No effort Mild effort Moderate effort Severe effort
Fasting
No.
%
No.
%
P Value
8 20 0 0
28.6 71.4 0.0 0.0
0 8 18 2
0.0 28.6 64.3 7.1
!0.001
with a bath of normal saline solution have proven that hydration results in increased efficiency and a decrease in phonation threshold pressure.15,16 Phonation threshold pressure, the clinical correlate of phonatory effort, is defined as the minimum subglottic pressure required to initiate phonation and sustain vocal fold oscillation. The dependence of the phonatory effort on the hydration level has been reported by Verdolini et al.17,18 After subjecting 12 adults to a 4-hour hydration treatment, a 4-hour dehydration treatment, and a 4-hour placebo treatment, the results of measurements of the phonatory effort have demonstrated the inverse relation between phonatory effort and hydration. In pursuit of that, a study conducted on two men and two women treated with a single dose of diuretic and a single dose of oral antihistamine, the study has indicated that systemic dehydration, rather than secretory dehydration, can mediate an increase in the phonatory threshold pressure, especially on the high pitch.19 This increase in PTP, also witnessed after vocal loading, has been attenuated in three out of the four women in this study after ample drinking of water, but it seemed to be beneficial in only two of four men.20,21 These findings are based on the assumptions that the PTP effects induced by systemic hydration and dehydration are due to fluid shifts in laryngeal tissue and that these fluid shifts are significant enough to affect vocal performance and are not counteracted by other feedback mechanisms.19 More so, knowing that substantial extracellular volume depletion even without body dehydration can induce voice symptoms22 and with the suspected role of dehydration in the etiology of various vocal fold lesions, there is now a general consensus that hydration is very advisable and recommended in the treatment of many vocal disorders.23,24 Journal of Voice, Vol. 21, No. 4, 2007
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Dehydration observed during fasting, ie, lack of water and food intake for at least 14 hours, is perceived perceptually as an increase in the phonatory effort. It has been translated in our study by the increase in the score for phonatory effort from 0.7 to 1.7; ie, when the subjects were not fasting and resumed their regular daily intake of water, the phonatory effort dropped back by one point. Parallel to this increase in the phonatory effort, there was a predominance of vocal fatigue as a symptom in 15 out of the 28 subjects. Despite its various description in the literature, the exact definition, nature, and salient features of voice fatigue remains unclear. There is a lack of understanding of whether it is the result or the cause of another voice disorder. As such it is a multifaceted entity that manifests differently in relation to the individual vocal needs and capacities. The symptoms of vocal fatigue have been described by several authors as hoarseness, huskiness, breathiness, loss of voice, pitch breaks, reduced pitch range and power, unsteady voice, throat discomfort, pain or tightness, and many others.25,26 If the authors were to include these complaints as symptoms of vocal fatigue in this study, they could conclude that almost all of these subjects had vocal fatigue secondary to fasting. Nathan et al has suggested several hypotheses that may contribute to vocal fatigue in addition to the increase in vocal fold viscosity.27 These hypotheses include neuromuscular fatigue, reduced blood circulation, nonmuscular tissue strain, and respiratory muscle fatigue.27–30 Fasting submits the body to transient metabolic modifications that are more pronounced under stressful situations such as heavy exercise or illnesses.4–7,9 The daily mean of hormonal levels, lipids, proteins, and carbohydrates seems to be affected.31 These metabolic changes may account at least in part for the vocal fatigue and the increase in the phonatory effort witnessed during fasting. Also, the authors have to keep in mind that the alterations in body composition and cellular and biochemical blood constituents may not always be significant enough to adversely affect muscle performance32 and that the thyroarytenoid muscle is highly resistant to neuromuscular fatigue in view of the high proportion of type I to type II muscle fibers and the considerable oxidative capacity of type II fibers.33,34 Journal of Voice, Vol. 21, No. 4, 2007
There are also mild changes in the cardiorespiratory responses to exercises during fasting. The ventilation and ventilatory responses are reduced, and this has been attributed to hormonal changes associated with dehydration, fasting, and the changes in the circadian rhythm. This effect seems to be dependent on the vocal tasks that require significant breath support.35 The sense of effort has also been shown to increase with expiratory and inspiratory muscle loading, which indicates that a prolonged strenuous breathing task can result in an increased sense of effort for breathing.36–38 Hence, the effect of fasting, lack of water and food intake, on respiration may be transmitted to phonation. Titze et al25,29 has further suggested that respiratory muscle fatigue may contribute to vocal fatigue, at least in highly demanding vocal tasks. The same heterogeneity in the clinical presentation and symptomatology of vocal fatigue is present in the acoustic results of the voice analysis performed on patient with vocal fatigue. With the negative changes in voice quality witnessed in patients with vocal fatigue after the performance of prolonged vocal tasks, there has been mixed outcomes in the recording of the habitual pitch, fundamental frequency, and perturbation parameters. Some have reported no changes and others an increase in F0.39–42 In this study, if it was assumed that most subjects had a form of vocal fatigue while fasting, based on the aforementioned heterogeneity of this symptom and the increase in the phonatory effort observed in more that two thirds while fasting, the authors can fairly say that vocal fatigue secondary to fasting did not result in an increase in the average fundamental frequency. There were mild variations in the perturbation parameters; however, the increase in the relative average perturbation and the decrease in the shimmer were not statistically significant. There was also a nonsignificant decrease in the habitual pitch even though the authors would have anticipated a decrease in the fundamental frequency in view of dehydration and the known inverse relationship between mass and vocal pitch. Eustace et al43 in their study on 88 patients with vocal fatigue, the F0, jitter, and airflow volume were all within normal limits. There was, however, a reduction in the MPT compared with normative data. In this study, the MPT was also
EFFECT OF FASTING ON VOICE
499
TABLE 3. Means of Acoustic Parameters by Fasting Status Vocal Acoustic Parameters Fundamental Frequency (F0)
RAP
Shimmer (%)
NHR
VTI
Habitual Pitch (Hz)
MPT (s)
0.0312 0.0303 0.525
207.210 206.300 0.539
15.972 13.269 !0.001
Total (n 5 28) Nonfasting Fasting P value
213.138 213.507 0.909
0.807 0.996 0.219
3.168 2.891 0.524
0.1132 0.1217 0.174
Abbreviations: MPT, maximum phonation time; NHR, noise-to-harmonic ratio; RAP, relative average perturbation; VTI, voice turbulence index.
reduced by almost 2 seconds, which was statistically significant. The decrease in the MPT can be explained on the basis of a decrease in the breath support and control often witnessed in cases of vocal fatigue. Nevertheless, the normal and intersubject variations of this parameter should be considered.44 The laryngo-stroboscopic findings in subjects during fasting have not been reported. Secondary to dehydration, an increase in vocal fold viscosity and a secondary reduction in vocal fold oscillation would be anticipated that usually parallel the increase in the phonatory effort. In this study, there was a decrease in the mucosal wave amplitude only in one subject. The laryngoscopic and stroboscopic findings in patients with vocal fatigue have also differed with various studies. The glottal closure pattern varied across the literature. Vocal fatiguing tasks can result in either a posterior or an anterior gap. Stemple et al has reported an anterior glottal chink in 6 out of 10 women.47 Solomon and DiMattia reported a spindle-shaped closure,45 whereas others have described incomplete closure and anterior and posterior chinks. The anterior gap can be explained on the basis of either edema of the midthird of the vocal fold often observed after prolonged loud talking or secondary to bowing of the thyroarytenoid muscle, which has been fatigued.46–48 The discrepancy in the findings may be attributed to the differences in the methodology and reading of the laryngeal stroboscopic findings. In this study, a posterior chink was present in only three subjects during fasting and absent while nonfasting. These chinks can be interpreted in relation to the vocal pitch, intensity, and probably the laryngeal position. It is also not uncommon to observe
stroboscopically a reduction in mucosal wave with an increase in the vocal register. The presence of a posterior chink is also a frequent finding in women.49,50
CONCLUSION Fasting has an effect on voice. The effect is more perceived by the fasting subject as an increase in the phonatory effort. Acoustic analysis is not revealing except for the decrease in the MPT, which is significant, and laryngeal videostroboscopy fails to reveal any obvious changes. The increase in the phonatory effort is most likely secondary to dehydration and an element of muscular fatigue at the respiratory and phonatory levels.
REFERENCES 1. Holte K, Kehlet H. Compensatory fluid administration for preoperative dehydration: does it improve outcome? Acta Anaesthesiol Scand. 2002;46:1089–1093. 2. Watson K, Rinomhota S. Preoperative fasting: we need a new consensus. Nurs Times. 2002;98:36–37. 3. Sweileh N, Schnitzler A, Hunter GR, Davis B. Body composition and energy metabolism in resting and exercising Muslims during Ramadan fast. J Sorts Med Phys Fitness. 1992;32:156–163. 4. Mosek A, Korczyn AD. Fasting headache, weight loss and dehydration. Headache. 1999;39:225–227. 5. Dadeya S, Kamlesh, Shibal F, Khurana C, Khanna A. Effect of religious fasting on intra-ocular pressure. Eye. 2002;16:463–465. 6. Kayikcioglu O, Guler C. Religious fasting and intraocular pressure. J Glaucoma. 2000;9:413–414. 7. Awada A, al Jumah M. The first of Ramadan headache. Headache. 1999;39:490–493. Journal of Voice, Vol. 21, No. 4, 2007
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8. Roky R, Houti I, Moussamih S, Ootbi S, Aadil N. Physiological and chronobiological changes during Ramadan intermittent fasting. Ann Nutr Metab. 2004;48:296–303. 9. Schmahl FW, Metzler B. The health risks of occupational stress in Islamic industrial workers during the Ramadan fasting period. Pol J Occup Med Environ Health. 1991;4: 219–228. 10. Campbell NR, Wickert W, Magner P, Shumak SL. Dehydration during fasting increases serum lipids and lipoproteins. Clin Invest Med. 1994;17:570–576. 11. Leiper JB, Molla AM, Molla AM. Effects on health of fluid restriction during fasting in Ramadan. Eur J Clin Nutr. 2003;57:S30–S38. 12. Inan UU, Yucel A, Ermis SS, Ozturk F. The effects of dehydration and fasting on ocular blood flow. J Glaucoma. 2002;11:411–415. 13. Chan RW, Tayama N. Biomechanical effects of hydration in vocal fold tissues. Otolaryngol Head Neck Surg. 2002; 126:528–537. 14. Finkelhor BK, Titze IR, Durham PL. The effect of viscosity changes in the vocal folds on the range of oscillation. J Voice. 1988;1:320–325. 15. Jiang J, Ng J, Hanson D. The effects of rehydration on phonation in excised canine larynges. J Voice. 1999;13:51–59. 16. Jiang JJ, Verdolini KN, Hanson DG. Effects of dehydration on phonation. Ann Otol Rhinol Laryngol. 2000;109: 568–575. 17. Verdolini K, Titze IR, Fennell A. Dependence of phonatory effort on hydration level. J Speech Hear Res. 1994; 37:1001–1007. 18. Verdolini-Martson K, Titze IR, Druker DG. Changes in phonation threshold pressure with induced conditions of hydration. J Voice. 1990;4:142–151. 19. Verdolini K, Min Y, Titze IR, Lemke J, Brown K, Van Mersbergen M, et al. Biological mechanisms underlying voice changes due to dehydration. J Speech Lang Hear Res. 2002;45:268–281. 20. Solomon NP, DiMattia MS. Effects of a vocally fatiguing task and systemic hydration on phonation threshold pressure. J Voice. 2000;14:341–362. 21. Solomon NP, Glaze LE, Arnold RR, van Mersbergen M. Effects of a vocally fatiguing task and systemic hydration on men’s voices. J Voice. 2003;17:31–46. 22. Fisher KV, Ligon J, Sobecks JL, Roxe DM. Phonatory effects of body fluid removal. J Speech Lang Hear Res. 2001;44:354–367. 23. Verdolini-Marston K, Sandage M, Titze IR. Effect of hydration treatments on laryngeal nodules and polyps and related measures. J Voice. 1994;8:30–47. 24. Yiu EM, Chan RM. Effect of hydration and vocal rest on the vocal fatigue in amateur karaoke singers. J Voice. 2003;17:216–227. 25. Titze IR. Principles of Voice Production. Englewood Cliffs, NJ: Prentice-Hall; 1994. 26. Scherer RC, Titze IR, Raphael BN, Wood RP, Ramig LA, Blager RF. Vocal fatigue in a professional voice user. In:
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Lawrence VL, ed. Transcripts of the Fourteenth Symposium: Care of the Professional Voice. New York: The Voice Foundation; 1986:124–130. Welham NV, Maclagan MA. Vocal fatigue: current knowledge and future directions. J Voice. 2003;17:21–30. Titze IR. Vocal fatigue: some biomechanical considerations. In: Lawrence VL, ed. Transcripts of the Twelfth Symposium: Care of the Professional Voice, Part One: Scientific Papers. New York: The Voice Foundation; 1984:97–104. McArdle WD, Katch FI, Katch VL. Exercise Physiology: Energy, Nutrition and Human Performance. 4th ed. Baltimore, MD: Williams & Wilkins; 1996. Lamb DR. Physiology of Exercise. 2nd ed. New York: Macmillan; 1984. Keller U, Szinnai G, Bilz S, Berneis K. Effects of changes in hydration on protein, glucose and lipid metabolism in man: impact on health. Eur J Clin Nutr. 2003;57: S69–S74. Ramadan J. Does fasting during Ramadan alter body composition, blood constituents and physical performance? Med Princ Pract. 2002;11:41–46. Cooper DS, Rice DH. Fatigue resistance of canine vocal fold muscle. Ann Otol Rhinol Laryngol. 1990;99:228– 233. Zealer DL. The contractile properties and functions of single motor units of thyroartenoid muscle in the cat. In: Bless DM, Abbs J, eds. Vocal Fold Physiology: Contemporary Research and Clinical Issues. San Diego, CA: College-Hill Press; 1983:96–106. Ramadan JM, Barac-Nieto M. Cardio-respiratory responses to moderately heavy aerobic exercise during the Ramadan fasts. Saudi Med J. 2000;21:238–244. Suzuki S, Suzuki J, Ishii T, Akahori T, Okubo T. Relationship of respiratory effort sensation to expiratory threshold loading. Am Rev Respir Dis. 1992;145:461–466. Gandevia SC, Killian KJ, Campbell EJM. The effect of respiratory muscle fatigue on respiratory sensations. Clin Sci. 1981;60:463–466. Supinski GS, Clary SJ, Bark H, Kelsen SG. Effect of inspiratory muscle fatigue on perception of effort during loaded breathing. J Appl Physiol. 1987;62:300–307. Stone RE, Scharf DJ. Vocal change associated with the use of atypical pitch and intensity levels. Folia Phoniatr. 1973; 25:91–103. Neils LR, Yairi E. Effects of speaking in noise on vocal fatigue and vocal recovery. Folia Phoniatr. 1987;39: 104–112. Vilkman E, Lauri E, Alku P, Sala E, Shivo M. Effects of prolonged oral reading on F0, SPL, subglottal pressure, and amplitude characteristics of glottal flow waveforms. J Voice. 1999;13:303–315. Verstraete J, Forrez G, Mertens P, Debruyne F. The effect of sustained phonation at high and low pitch on vocal jitter and shimmer. Folia Phoniatr. 1993;45:223– 228.
EFFECT OF FASTING ON VOICE 43. Eustace CS, Stemple JC, Lee L. Objective measures of voice production in patients complaining of laryngeal fatigue. J Voice. 1996;10:146–154. 44. Behrman A. Evidence-based treatment of paralytic dysphonia. Otolaryngol Clin N Am. 2004;37:75–104. 45. Solomon NP, DiMattia MS. Effects of a vocally fatiguing task and systemic hydration on phonation threshold pressure. J Voice. 2000;14:341–362. 46. Scherer RC, Titze IR, Raphael BN, Wood RP, Ramig LA, Blager RF. Vocal fatigue in a trained and untrained voice user. In: Baer T, Sasaki C, Harris K, eds. Laryngeal Function in Phonation and Respiration. San Diego, CA: Singular Publishing Group; 1991:533–555.
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47. Stemple JC, Stanley J, Lee L. Objective measures of voice production in normal subjects following prolonged voice use. J Voice. 1995;9:127–133. 48. Linville SE. Changes in glottal configuration in women after loud talking. J Voice. 1995;9:57–65. 49. Bless DM, Glaze L, Biever Lowery D, Campos G, Peppard R. Stroboscopic, acoustic and perceptual analysis of voice production in normal speaking adults. In: Bless DM, ed. Vocal Fold Physiology. Vol. 3. New York: Raven Press; 1990. 50. Ford C, Bless D. Phonosurgery: Assessment and Surgical Management of Voice Disorders. New York: Raven Press; 1991.
Journal of Voice, Vol. 21, No. 4, 2007
Summary: Objective/Hypothesis: to study the effect of fasting on voice in women: abstinence from food and water intake between 14 and 18 hours. Study Design: a prospective study on female subjects. Material and Method: A total of 28 female subjects were included in this study. Their age ranged between 21 and 45 years. Subjects with vocal symptoms or vocal fold lesions were excluded. The subjects were tested when they were not fasting and while fasting after the first week of intermittent fasting during Ramadan. Each subject was first asked about her vocal symptoms and the ease of phonation or phonatory effort. Then each underwent acoustic analysis and laryngeal video-endostroboscopy. Results: Vocal fatigue was the most common reported complaint (53.6%) followed by deepening of the voice (21.4%) and harshness (10.2%). Self-reported phonatory effort was significantly affected by fasting (P value ! 0.001). Out of the 28 subjects, 23 had an increase in their phonatory effort. Vocal acoustic parameters did not change markedly except for the maximum phonation time, which decreased significantly. Laryngeal video-endostroboscopy did not reveal any significant changes during fasting. All stroboscopic parameters were the same except for a decrease in the amplitude of the mucosal waves in one subject and the presence of a posterior chink in three subjects. Conclusion: Fasting affects voice. There is an increase in the phonatory effort, and vocal fatigue is the most common symptom. Key Words: Fasting—Voice—Dehydration.
Consequently, dehydration, electrolyte imbalance, malnutrition, and general malaise may occur. This condition warrants serious attention and the need for fluid administration to alleviate the patient’s discomfort. As a result, a new consensus in the preoperative requirement for general anesthesia is being reformed.2 During the month of Ramadan, Moslems refrain from drinking and eating between sunrise and sunset. The effect of this intermittent lack of water and food intake on the well-being of the participant has been studied in various groups. Most studies agree that there are significant metabolic changes with slowing down of the body metabolism during the day to conserve energy stores.3 The changes in the lifestyle witnessed during this month of fasting
INTRODUCTION Fasting overnight can lead to fluid deficit measured up to 1 L after 8 hours of abstinence.1 Accepted for publication January 24, 2006. From the *Department of Otolaryngology Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon; and the †Department of Epidemiology and Population Health, Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon. Address correspondence and reprint requests to Abdul-Latif Hamdan, MD, FACS, American University of Beirut, Department of Otolaryngology, PO Box 11-0236, Beirut, Lebanon. E-mail: [email protected] Journal of Voice, Vol. 21, No. 4, pp. 495–501 0892-1997/$32.00 Ó 2007 The Voice Foundation doi:10.1016/j.jvoice.2006.01.009
495
496
ABDUL-LATIF HAMDAN ET AL
result in alterations in the circadian rhythm and sleep deprivation. Weight loss between 0.1 and 1.4 kg of body weight and signs of dehydration are invariably encountered.4–6 Hypoglycemia and raised serum concentrations of uric acid, sodium, chloride, and proteins during the first week of fasting emphasize the state of dehydration.7–9 Fasting with fluid restriction also results in a hyper-lipid level compared with fasting with salt and water supplementation, which accentuate further the role of hydration in the fluctuation of the lipid profile during fasting.10 All of these metabolic changes may give rise or accelerate health problems such as cardiovascular, respiratory, and even ocular.11,12 Many studies have focused on the effect of hydration on vocal fatigue and the phonatory threshold pressure, highlighting the biological mechanisms underlying voice changes due to dehydration.13–18 It has also been shown how important is the hydration level as a physiologic variable in vocal fold vibration and sound production. Most of these studies were either in vitro studies or performed on a relatively small number of subjects where the dehydration was artificially or drug induced. Based on a PubMed search, the effect of fasting in normal subjects on voice has not been reported. The purpose of this study is to investigate the effect of fasting on voice in a large number of subjects who abstained from water and food between 14 and 18 hours. The phonatory effort, acoustic analysis of the vocal signal, and stroboscopic examination of the larynx were performed. MATERIAL AND METHOD A total of 28 female subjects were included in this study after receiving approval by the Institution Review Board of the American University of Beirut, Lebanon. Subjects with a history of dysphonia or laryngeal lesion or surgery were not included in the study. The subjects were tested when they were not fasting and while fasting after the first week of intermittent fasting during Ramadan. By fasting, the authors mean abstinence or lack of water and food intake between sunrise and sunset. The testing was performed 1 to 2 hours before sunset to ensure at least 14 hours of fasting. Each subject was first asked about her vocal symptoms and the ease of phonation Journal of Voice, Vol. 21, No. 4, 2007
or phonatory effort, where 0 stands for no effort, 1 stands for mild effort, 2 for moderate, and 3 for a lot of effort. Then each subject underwent evaluation of her voice using the Kay Elemetric VISI Pitch (Model 3300; Kay Elemetrics Corporation, Lincoln Park, NJ). Although the patient is seated in a quiet office, the patient’s vocal signal was recorded directly into the system using a condenser microphone at a distance of 15 cm from the mouth. The following acoustic variables were measured: average fundamental frequency, relative average perturbation, shimmer, noise-to-harmonic ratio, voice turbulence index, habitual pitch, and maximum phonation time. The habitual pitch was measured by asking the subject to count to 10 in a normal voice. The maximum phonation time was calculated by asking the subject to take a deep breath and sustain phonation for as long as possible. The remaining variables were measured by asking the subject to sustain the vowel ‘‘ah’’ for 2 seconds, using the voice quality assessment module of the VISI Pitch system. The subjects also underwent in the same setup laryngeal video-endostroboscopy using the 70-degree rigid telescope coupled to the Karl Storz Laryngostrobe model 8020 and to a 30-mm single chip color Storz endoscopic telecam Dx pal 202320 20 (Karl Storz, Tuttlingen, Germany). The following parameters were looked at: symmetry, amplitude, mucosal wave, periodicity, and closure. Frequencies and means (6SD) were used to describe the sample, for categorical and continuous variables, respectively. For each subject, the parameters were collected before and after fasting, and the appropriate statistical analysis for small-size samples (Wilcoxon nonparametric paired test) was conducted. The analysis took into consideration the design (before and after) and modality of data collection (paired data). Differences were considered significant for P ! 0.05. All analysis was conducted using SPSS software (SPSS Corporation, Chicago, IL). RESULTS A total of 28 women were examined and assessed for voice changes while fasting and while not fasting. The age of the participants ranged from 21 years to 45 years with a mean of 29.7 years and a standard
EFFECT OF FASTING ON VOICE deviation of 7.7 years. Vocal fatigue was the most common reported complaint (53.6%) followed by deepening of the voice (21.4%) and harshness (10.2%) (Table 1). Phonatory effort was significantly affected by fasting (P value ! 0.001). Although most participants reported no effort (28.6%) or mild effort (71.4%) during nonfasting, 64.3% and 7.1% expressed moderate or severe effort, respectively, during fasting (Table 2). Out of the 28 subjects, 23 had an increase in their phonatory effort, 7 of whom had a two-point increase in scale. Vocal acoustic parameters, in most participants, did not change markedly. The relative average perturbation slightly increased, but the increase was not statistically significant. The shimmer, habitual pitch, and maximum phonation time decreased; however, the difference was significant only for the maximum phonation time (MPT) (15.972 vs 13.269, respectively, P value ! 0.001). The remaining vocal parameters were not affected by fasting (Table 3). Laryngeal video-endostroboscopy did not reveal any changes during fasting. All stroboscopic parameters were the same except for a decrease in the amplitude of the mucosal waves in one subject and the presence of a posterior chink in three subjects. DISCUSSION The effect of hydration on voice has been investigated in several studies. Vocal fold stiffness and viscosity increase with the osmotically induced dehydration and decrease with rehydration.13,14 Experiments on excised canine larynges first dehydrated with warm dry air and then rehydrated TABLE 1. Characteristics of Study Sample
Sex (% females) Age (mean 6 SD) Vocal complaints during fasting Vocal fatigue Deepening Harshness Sore throat Throat itching Increased pitch Abbreviation: SD, standard deviation.
No.
%
28
100 29.7 6 7.7
15 6 3 2 1 1
53.6 21.4 10.2 7.1 3.6 3.6
497
TABLE 2. Self-Perceived Phonation Effort Nonfasting
No effort Mild effort Moderate effort Severe effort
Fasting
No.
%
No.
%
P Value
8 20 0 0
28.6 71.4 0.0 0.0
0 8 18 2
0.0 28.6 64.3 7.1
!0.001
with a bath of normal saline solution have proven that hydration results in increased efficiency and a decrease in phonation threshold pressure.15,16 Phonation threshold pressure, the clinical correlate of phonatory effort, is defined as the minimum subglottic pressure required to initiate phonation and sustain vocal fold oscillation. The dependence of the phonatory effort on the hydration level has been reported by Verdolini et al.17,18 After subjecting 12 adults to a 4-hour hydration treatment, a 4-hour dehydration treatment, and a 4-hour placebo treatment, the results of measurements of the phonatory effort have demonstrated the inverse relation between phonatory effort and hydration. In pursuit of that, a study conducted on two men and two women treated with a single dose of diuretic and a single dose of oral antihistamine, the study has indicated that systemic dehydration, rather than secretory dehydration, can mediate an increase in the phonatory threshold pressure, especially on the high pitch.19 This increase in PTP, also witnessed after vocal loading, has been attenuated in three out of the four women in this study after ample drinking of water, but it seemed to be beneficial in only two of four men.20,21 These findings are based on the assumptions that the PTP effects induced by systemic hydration and dehydration are due to fluid shifts in laryngeal tissue and that these fluid shifts are significant enough to affect vocal performance and are not counteracted by other feedback mechanisms.19 More so, knowing that substantial extracellular volume depletion even without body dehydration can induce voice symptoms22 and with the suspected role of dehydration in the etiology of various vocal fold lesions, there is now a general consensus that hydration is very advisable and recommended in the treatment of many vocal disorders.23,24 Journal of Voice, Vol. 21, No. 4, 2007
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Dehydration observed during fasting, ie, lack of water and food intake for at least 14 hours, is perceived perceptually as an increase in the phonatory effort. It has been translated in our study by the increase in the score for phonatory effort from 0.7 to 1.7; ie, when the subjects were not fasting and resumed their regular daily intake of water, the phonatory effort dropped back by one point. Parallel to this increase in the phonatory effort, there was a predominance of vocal fatigue as a symptom in 15 out of the 28 subjects. Despite its various description in the literature, the exact definition, nature, and salient features of voice fatigue remains unclear. There is a lack of understanding of whether it is the result or the cause of another voice disorder. As such it is a multifaceted entity that manifests differently in relation to the individual vocal needs and capacities. The symptoms of vocal fatigue have been described by several authors as hoarseness, huskiness, breathiness, loss of voice, pitch breaks, reduced pitch range and power, unsteady voice, throat discomfort, pain or tightness, and many others.25,26 If the authors were to include these complaints as symptoms of vocal fatigue in this study, they could conclude that almost all of these subjects had vocal fatigue secondary to fasting. Nathan et al has suggested several hypotheses that may contribute to vocal fatigue in addition to the increase in vocal fold viscosity.27 These hypotheses include neuromuscular fatigue, reduced blood circulation, nonmuscular tissue strain, and respiratory muscle fatigue.27–30 Fasting submits the body to transient metabolic modifications that are more pronounced under stressful situations such as heavy exercise or illnesses.4–7,9 The daily mean of hormonal levels, lipids, proteins, and carbohydrates seems to be affected.31 These metabolic changes may account at least in part for the vocal fatigue and the increase in the phonatory effort witnessed during fasting. Also, the authors have to keep in mind that the alterations in body composition and cellular and biochemical blood constituents may not always be significant enough to adversely affect muscle performance32 and that the thyroarytenoid muscle is highly resistant to neuromuscular fatigue in view of the high proportion of type I to type II muscle fibers and the considerable oxidative capacity of type II fibers.33,34 Journal of Voice, Vol. 21, No. 4, 2007
There are also mild changes in the cardiorespiratory responses to exercises during fasting. The ventilation and ventilatory responses are reduced, and this has been attributed to hormonal changes associated with dehydration, fasting, and the changes in the circadian rhythm. This effect seems to be dependent on the vocal tasks that require significant breath support.35 The sense of effort has also been shown to increase with expiratory and inspiratory muscle loading, which indicates that a prolonged strenuous breathing task can result in an increased sense of effort for breathing.36–38 Hence, the effect of fasting, lack of water and food intake, on respiration may be transmitted to phonation. Titze et al25,29 has further suggested that respiratory muscle fatigue may contribute to vocal fatigue, at least in highly demanding vocal tasks. The same heterogeneity in the clinical presentation and symptomatology of vocal fatigue is present in the acoustic results of the voice analysis performed on patient with vocal fatigue. With the negative changes in voice quality witnessed in patients with vocal fatigue after the performance of prolonged vocal tasks, there has been mixed outcomes in the recording of the habitual pitch, fundamental frequency, and perturbation parameters. Some have reported no changes and others an increase in F0.39–42 In this study, if it was assumed that most subjects had a form of vocal fatigue while fasting, based on the aforementioned heterogeneity of this symptom and the increase in the phonatory effort observed in more that two thirds while fasting, the authors can fairly say that vocal fatigue secondary to fasting did not result in an increase in the average fundamental frequency. There were mild variations in the perturbation parameters; however, the increase in the relative average perturbation and the decrease in the shimmer were not statistically significant. There was also a nonsignificant decrease in the habitual pitch even though the authors would have anticipated a decrease in the fundamental frequency in view of dehydration and the known inverse relationship between mass and vocal pitch. Eustace et al43 in their study on 88 patients with vocal fatigue, the F0, jitter, and airflow volume were all within normal limits. There was, however, a reduction in the MPT compared with normative data. In this study, the MPT was also
EFFECT OF FASTING ON VOICE
499
TABLE 3. Means of Acoustic Parameters by Fasting Status Vocal Acoustic Parameters Fundamental Frequency (F0)
RAP
Shimmer (%)
NHR
VTI
Habitual Pitch (Hz)
MPT (s)
0.0312 0.0303 0.525
207.210 206.300 0.539
15.972 13.269 !0.001
Total (n 5 28) Nonfasting Fasting P value
213.138 213.507 0.909
0.807 0.996 0.219
3.168 2.891 0.524
0.1132 0.1217 0.174
Abbreviations: MPT, maximum phonation time; NHR, noise-to-harmonic ratio; RAP, relative average perturbation; VTI, voice turbulence index.
reduced by almost 2 seconds, which was statistically significant. The decrease in the MPT can be explained on the basis of a decrease in the breath support and control often witnessed in cases of vocal fatigue. Nevertheless, the normal and intersubject variations of this parameter should be considered.44 The laryngo-stroboscopic findings in subjects during fasting have not been reported. Secondary to dehydration, an increase in vocal fold viscosity and a secondary reduction in vocal fold oscillation would be anticipated that usually parallel the increase in the phonatory effort. In this study, there was a decrease in the mucosal wave amplitude only in one subject. The laryngoscopic and stroboscopic findings in patients with vocal fatigue have also differed with various studies. The glottal closure pattern varied across the literature. Vocal fatiguing tasks can result in either a posterior or an anterior gap. Stemple et al has reported an anterior glottal chink in 6 out of 10 women.47 Solomon and DiMattia reported a spindle-shaped closure,45 whereas others have described incomplete closure and anterior and posterior chinks. The anterior gap can be explained on the basis of either edema of the midthird of the vocal fold often observed after prolonged loud talking or secondary to bowing of the thyroarytenoid muscle, which has been fatigued.46–48 The discrepancy in the findings may be attributed to the differences in the methodology and reading of the laryngeal stroboscopic findings. In this study, a posterior chink was present in only three subjects during fasting and absent while nonfasting. These chinks can be interpreted in relation to the vocal pitch, intensity, and probably the laryngeal position. It is also not uncommon to observe
stroboscopically a reduction in mucosal wave with an increase in the vocal register. The presence of a posterior chink is also a frequent finding in women.49,50
CONCLUSION Fasting has an effect on voice. The effect is more perceived by the fasting subject as an increase in the phonatory effort. Acoustic analysis is not revealing except for the decrease in the MPT, which is significant, and laryngeal videostroboscopy fails to reveal any obvious changes. The increase in the phonatory effort is most likely secondary to dehydration and an element of muscular fatigue at the respiratory and phonatory levels.
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