Voice Health Conventional Wisdom: Unknown, Plausible or Confirmed? Take a look at whether or not science backs up these six common voice care recommendations. Features
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Features  |   February 2016
Voice Health Conventional Wisdom: Unknown, Plausible or Confirmed?
Author Notes
  • Elizabeth Erickson DiRenzo, PhD, CCC-SLP, is assistant professor of otolaryngology/head and neck surgery at the Stanford University School of Medicine. She is an affiliate of ASHA Special Interest Groups 3, Voice and Voice Disorders; 13, Swallowing and Swallowing Disorders (Dysphagia); and 19, Speech Science. edirenzo@stanford.edu
    Elizabeth Erickson DiRenzo, PhD, CCC-SLP, is assistant professor of otolaryngology/head and neck surgery at the Stanford University School of Medicine. She is an affiliate of ASHA Special Interest Groups 3, Voice and Voice Disorders; 13, Swallowing and Swallowing Disorders (Dysphagia); and 19, Speech Science. edirenzo@stanford.edu×
  • Kristine Tanner, PhD, CCC-SLP, is an assistant professor in the Department of Communication Disorders at Brigham Young University. She also holds adjunct appointments in the Department of Communication Sciences and Disorders and Division of Otolaryngology-Head and Neck Surgery at the University of Utah. She is an affiliate of ASHA Special Interest Groups 3, 13 and 19. kristine_tanner@byu.edu
    Kristine Tanner, PhD, CCC-SLP, is an assistant professor in the Department of Communication Disorders at Brigham Young University. She also holds adjunct appointments in the Department of Communication Sciences and Disorders and Division of Otolaryngology-Head and Neck Surgery at the University of Utah. She is an affiliate of ASHA Special Interest Groups 3, 13 and 19. kristine_tanner@byu.edu×
  • Susan L. Thibeault, PhD, CCC-SLP, professor in the Department of Surgery at the University of Wisconsin School of Medicine and Public Health, holds the Diane M. Bless Endowed Chair in Otolaryngology in the Division of Otolaryngology-Head & Neck Surgery. She is an affiliate of ASHA Special Interest Groups 3 and 13. thibeault@surgery.wisc.edu
    Susan L. Thibeault, PhD, CCC-SLP, professor in the Department of Surgery at the University of Wisconsin School of Medicine and Public Health, holds the Diane M. Bless Endowed Chair in Otolaryngology in the Division of Otolaryngology-Head & Neck Surgery. She is an affiliate of ASHA Special Interest Groups 3 and 13. thibeault@surgery.wisc.edu×
Article Information
Speech, Voice & Prosody / Features
Features   |   February 2016
Voice Health Conventional Wisdom: Unknown, Plausible or Confirmed?
The ASHA Leader, February 2016, Vol. 21, online only. doi:10.1044/leader.FTR3.21022016.np
The ASHA Leader, February 2016, Vol. 21, online only. doi:10.1044/leader.FTR3.21022016.np
Rest your voice after surgery. Drink plenty of water. Avoid e-cigs. Inhale steam. Moderate voice use to avoid vocal fold lesions. Use stroboscopy or laryngoscopy to identify laryngopharyngeal reflux.
Speech-language pathologists often accept these (and other) statements as truisms in voice care. But is there scientific evidence to back them up?
Using elements of the scientific method, we tested common voice care practices for validity and deemed them “busted” (no evidence to support), “plausible” (lesser evidence to support) or “confirmed” (high quality evidence to support). This critical appraisal of the literature helps to determine the current evidence base for voice-care practices, direct care more effectively and efficiently, and guide future investigations.
Question: Are electronic-cigs bad for your vocal folds?
Hypothesis: E-cigs are not as harmful as traditional cigarettes to vocal folds.
E-cigs, first introduced into the U.S. in 2007, are composed of three parts: rechargeable battery, cartridge of “e-liquid” containing nicotine in a liquid vehicle (typically propylene glycol and/or glycerin) and flavorings, and atomizing device. Traditional cigarettes rely on combustion of tobacco to deliver nicotine to the lungs; the atomizer of e-cigs heats and aerosolizes e-liquid prior to inhalation. Because e-cigs do not combust, estimates suggest that toxins in e-cig vapors are nine to 450 times lower than in conventional cigarettes, making them an attractive system for nicotine delivery or to aid in smoking cessation.
These products are not without concern. E-cigs are not regulated by the Food and Drug Administration and consequently have not undergone toxicological testing. Many tested chemicals in e-cigs, such as nicotine and formaldehyde, still exceed recommended hazard quotients. At this juncture, we don’t know the short- or long-term health effects of these products and no published studies have investigated the impact of e-cigs on vocal fold physiology.
Verdict: Plausible. E-cigs may not be has harmful to vocal folds as traditional cigarettes. Although they contain far fewer toxins than traditional cigarettes, this level does guarantee the safety of these products; these products lack quality control; and health effects of vapor exposure remain unknown. In addition, e-cigs may act as a “gateway” to nicotine addiction, especially in adolescents.
Question: Does seven days of voice rest after surgery improve outcomes?
Hypothesis: Excessive mechanical stress secondary to uncontrolled voice use after surgery results in poor voice outcomes.
Voice rest is commonly prescribed after vocal fold surgery to promote wound healing and improve outcomes. The literature includes varied amounts of recommended voice rest and early voice use recommendations. Orthopedic literature tells us that long-term immobilization or complete rest is detrimental to recovery because of the negative effects on the extracellular matrix (ECM) of tissue, but uncontrolled, excessive mobilization may also hamper functional recovery. Controlled remobilization in the early stage of healing appears to lead to favorable recovery.
From animal models, we know that vocal-fold wounds follow a typical wound-healing paradigm and that vocal-fold fibroblasts—the cells that respond to mechanical stresses and produce ECM of the lamina propria—appear in the wound bed approximately three days after surgery. And although re-epithelization typically occurs within the first week, it may take four to six weeks for a complete functional epithelial barrier to form. We also know that excessive phonation of vocal fold tissue has detrimental effects in normal animal vocal folds.
Few published animal studies have investigated voice rest after surgery with contradicting outcomes. Overall, differences between human and animal vocal folds—such as structure, metabolic rate and innate ability to withstand mechanical stress from phonation—may limit the animal-model’s generalizability. Limited human investigations also show equivocal results.
Verdict: Plausible. Based upon indirect data, the value of complete voice rest for seven days following surgery is not well-supported. There may be benefit from early mobilization; however, because fibroblasts are not in the wound bed to respond, mobilization during the first two post-surgery days may not be warranted.
Question: Does all that voice use cause vocal-fold lesions?
Hypothesis: Abnormalities in habitual levels of vocal intensity, fundamental frequency and/or amount of voice use contribute to the development of vocal fold lesions.
Clinicians have long believed that the ways and amounts people use their voices contribute to the development of vocal fold lesions. From experimental models of rabbit voicing, researchers discovered that increased duration and intensity of vibration induces inflammation and injury to the outermost cell layer of the vocal folds. Such cellular changes may predispose the tissue to development of lesions. In epidemiological studies, voice disorders are more prevalent in people who report higher amounts and intensity of voice use, and people in high-voice-use occupations, such as teachers, tend to report more voice symptoms and problems as compared to non-teachers.
However, objective examinations demonstrate—interestingly—that vocal intensity and fundamental frequency do not consistently differ between people with and without lesions. Also, ambulatory phonation monitoring shows no difference between those with normal voice and those with lesions in terms of intensity, fundamental frequency and amount of voice use.
Verdict: Plausible. It is likely that abnormalities in vocal intensity, fundamental frequency, and/or amount of voice use are among—but not the only—factors that can contribute to the development of vocal fold lesions.
Question: Should we recommend 64 ounces of water per day to our patients?
Hypothesis: Drinking water improves vocal hygiene.
We have long included drinking water in our vocal hygiene recommendations because of the belief that water will keep the vocal fold mucosa healthy and vibrating well. Further, people might prevent voice problems or rehabilitate after phonotrauma by drinking more water.
We know that for most people who have no medical issues that affect hydration (kidney disease, for example), the body maintains its fluid levels, regardless of how much a person drinks. Total body and cellular water homeostatic processes regulate systemic hydration within 0.2 percent, given a typical environment and moderate physical activity. Minimal changes in fluid balance affect ionic concentration of extracellular fluid, regulating thirst and urine output.
More than 14 clinical studies demonstrate equivocal results on the relationship between systemic hydration and voice function. Four more recent studies indicate some change with systemic plus environmental humidity changes, but it remains difficult to distinguish systemic from environmental effects.
Verdict: Unknown. Poor regulation of systemic hydration—to the point of significantly influencing extracellular fluid—causes extreme illness. We lack evidence and adequate measurement techniques to determine the relationship between modest changes in systemic hydration and voice function. Improved experimental models are needed.
Question: Can laryngopharyngeal reflux (LPR) be identified from stroboscopy/laryngoscopy?
Hypothesis: Acid reflux causes changes in exposed tissue that can be seen during an exam.
SLPs often evaluate laryngeal structure and function with stroboscopy/laryngoscopy. We don’t diagnose LPR, but we often report what are thought to be signs and symptoms of this disease, including increased interarytenoid erythema/edema, posterior glottis erythema/edema, pseudosulcus, hypertrophy of the posterior commissure and granulation tissue.
The literature lacks consensus on specific signs and symptoms of LPR, with varying suggestions dependent on the methodology used. Research has not correlated specific laryngoscopic findings with the presence of LPR measured in other ways. Intra- and inter-rater Reflux Finding Score reliability has been poor to fair in those diagnosed with LPR by 24-hour pH probe with impedance. The American Academy of Otolaryngology-Head and Neck Surgery’s clinical practice guidelines for hoarseness note that research is needed to determine the sensitivity, specificity and reliability of laryngoscopic examination findings in determining treatment response and best way to identify such a response (bit.ly/ohns-dysphonia). Recent guidelines from the American College of Gastroenterology go a step further, stating that reflux disease cannot be diagnosed based solely on laryngoscopy (bit.ly/acg-guidelines)
Verdict: Unknown. Diagnosis of LPR remains a challenge, and further research is needed to develop a sensitive and specific diagnostic methodology. LPR pathophysiology may be more complex and multifactorial than initially proposed, and there may be subgroups of patients with varying pathophysiology and symptomology.
Question: Does the use of steam inhalation make a difference in vocal health?
Hypothesis: Steam inhalation hydrates the vocal folds.
Steam inhalation has been used for centuries as a remedy for upper-respiratory congestion. Clinicians might recommend it to improve surface vocal-fold hydration, thin mucus on the vocal fold surface, improve voice function, reduce vocal effort, and clear nasal passages.
Steam is created with commercially available devices. More specifically, vaporizers and facial steamers boil water to create steam; cool-mist humidifiers use fans to wick moisture into the air; ultrasonic humidifiers use high-frequency vibration to create a fine mist. A growing body of literature indicates that environmental humidity influences voice production in certain populations, but there is a paucity of evidence that direct inhalation of steam produces significant effect on voice production. Further, most steam particles are too large to reach the vocal folds and instead deposit on the oropharynx. Steam that manages to reach the vocal folds can initiate a cough reflex.
Verdict: Unknown. Environmental humidity seems to improve voice function in certain populations. There is no evidence that steam inhalation improves hydration, but improved nasal inhalation might also offset mouth breathing during upper-respiratory infection.
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February 2016
Volume 21, Issue 2