Yolanda D. Heman-Ackah

Cepstral Peak Prominence: A More Reliable Measure of Dysphonia

Quantification of perceptual voice characteristics allows the assessment of voice changes. Acoustic measures of jitter, shimmer, and noise-to-harmonic ratio (NHR) are often unreliable. Measures of cepstral peak prominence (CPP) may be more reliable predictors of dysphonia. Trained listeners analyzed voice samples from 281 patients. The NHR, amplitude perturbation quotient, smoothed pitch perturbation quotient, percent jitter, and CPP were obtained from sustained vowel phonation, and the CPP was obtained from running speech. For the first time, normal and abnormal values of CPP were defined, and they were compared with other acoustic measures used to predict dysphonia. The CPP for running speech is a good predictor and a more reliable measure of dysphonia than are acoustic measures of jitter, shimmer, and NHR.

Laryngeal Electromyography: Clinical Application

Laryngeal electromyography (LEMG) is a valuable adjunct in clinical management of patients with voice disorders. LEMG is valuable in differentiating vocal fold paresis/paralysis from cricoarytenoid joint fixation. Our data indicate that visual assessment alone is inadequate to diagnose neuromuscular dysfunction in the larynx and that diagnoses based on vocal dynamics assessment and strobovideolaryngoscopy are wrong in nearly one-third of cases, based on LEMG results. LEMG has also proven valuable in diagnosing neuromuscular dysfunction in some dysphonic patients with no obvious vocal fold movement abnormalities observed during strobovideolaryngoscopy. Review of 751 patients suggests that there is a correlation between the severity of paresis and treatment required to achieve satisfactory outcomes; that is, LEMG allows us to predict whether patients will probably require therapy alone or therapy combined with surgery. Additional evidence-based research should be encouraged to evaluate efficacy further.

Flexible Laryngoscopy: A Comparison of Fiber Optic and Distal Chip Technologies. Part 1: Vocal Fold Masses

This study was designed to evaluate the usefulness of fiber optic (FO) and distal chip (DC) flexible imaging platforms in the diagnosis of true vocal fold pathology when compared to the gold standard rigid transoral laryngeal telescopic examination. The recorded strobovideolaryngoscopic examinations of 34 consecutive patients were evaluated retrospectively by five raters. All stroboscopy segments were evaluated by two laryngologists, an otolaryngologist, a laryngology fellow, and an otolaryngology resident. Seventeen patients were examined with a high-quality, large-diameter, FO flexible laryngoscope (FO group) and 17 random patients were examined with a DC flexible laryngoscope (DC group). Each patient was also examined using rigid laryngeal videostroboscopy at the same sitting. Examinations of three patients from each group were presented twice to monitor internal consistency. Diagnoses of intrinsic vocal fold pathology made with the flexible laryngoscopes were compared for accuracy to the diagnoses provided using the rigid laryngeal telescope. The ability to make clinical diagnoses via stroboscopy was statistically equivalent with FO technology and DC technology. Rigid examination provided more information than the flexible examination in 27% of the FO examinations and in 32% of the DC examinations. DC technology did not add diagnostic information to the examination when compared to a high-quality, large-diameter, FO endoscope. Rigid endoscopy provides superior images of the true vocal folds and is necessary for precise diagnosis in patients with true vocal fold pathology. Thus, the most cost-effective means of evaluation of voice disorders remains FO flexible endoscopy for dynamic voice assessment and the neurolaryngologic examination followed by rigid stroboscopy for evaluation of the vocal fold edge and mucosal wave. Strobovideolaryngoscopy using high-quality FO or DC flexible equipment should be reserved for patients who cannot tolerate transoral rigid examination, such as children and those with a very strong gag reflex.

Glottic Closure Patterns: Type I Thyroplasty Versus Type I Thyroplasty With Arytenoid Adduction

OBJECTIVES/HYPOTHESIS The goal of laryngeal framework surgery in patients with unilateral vocal fold paralysis is to improve glottic closure by medializing the paralyzed vocal fold. Type I thyroplasty (Th) and arytenoid adduction (AA) are two of the most commonly performed procedures. Two of the main rationales for performing an AA are to improve closure of the posterior glottis and correct vertical height discrepancy. The purpose of this study was to evaluate if AA with Th yields better posterior glottic closure and vertical height equality than Th alone. STUDY DESIGN Retrospective. METHODS Using visual analog scales, three blinded reviewers evaluated glottic closure patterns in patients who underwent Th or Th with AA. Pre- and postoperative videostroboscopic examinations of 45 patients with unilateral vocal fold paralysis, who underwent laryngeal framework surgery, were evaluated. RESULTS No significant difference was identified in postoperative scores for midmembranous glottis closure (P=0.282), closure just anterior to the vocal processes (P=0.426), respiratory glottis closure (P=0.158), or vertical height discrepancy (P=0.113). CONCLUSIONS Although larger glottic gaps and vertical height discrepancies may lead some surgeons to predict that an AA is warranted, the usefulness of AA may not always be related to these parameters. Ultimately, voice improvement and not geometry should guide the surgeons decision making.

The laryngeal chemoreflex: An evaluation of the normoxic response

The laryngeal chemoreflex is a reflexive central apnea, bradycardia, and cardiovascular collapse that occurs in young, maturing mammals in response to exposure of the laryngeal mucosa to acidic and/or organic stimuli. The severity of the laryngeal chemoreflex varies within a species from one animal to another, and in some animals, the response can be fatal. This study seeks to identify those factors that contribute to fatal laryngeal chemoreflex responses when the larynx is stimulated under normoxic conditions, and to define how the normoxic response differs from the hypoxic laryngeal chemoreflex response.

Effects of intralaryngeal carbon dioxide and acetazolamide on the laryngeal chemoreflex

Sudden infant death syndrome is the leading cause of death in infants in the United States. The laryngeal chemoreflex (LCR) is thought to contribute to its pathogenesis. In adult animals, increasing levels of intralaryngeal CO2 result in a decrease in ventilatory activity. Intravenous acetazolamide (AZ) abolishes this response. The purpose of this study was to determine the effects of intralaryngeal CO2 and AZ on the LCR and respiratory physiology of piglets under normoxic and hypoxic conditions. We applied 0% or 10% CO2 in a randomized order to the larynx of 26 piglets. Intubation via tracheotomy prevented inhalation of the gas mixtures. Laryngeal stimulation was performed under normoxic conditions (Pao2 of >70 mm Hg) in 15 animals and under hypoxic conditions (Pao2 of 50 to 65 mm Hg) in 11 animals both with and without intravenous AZ (5 mg/kg). Respiratory and cardiovascular response data were recorded. Ten percent intralaryngeal CO2 has no significant effect on mean baseline respiratory rate, systemic Paco2 or Pao2 levels, or apnea duration (p > .05). The use of AZ (versus no AZ) resulted in significantly higher baseline respiratory rates (64 versus 51 breaths per minute; p = .016), a decreased baseline systemic Paco2 level (38.8 versus 45.9 mm Hg; p < .001), a higher baseline Pao2 level (97.9 versus 82.8 mm Hg; p < .001), shorter mean apnea durations (15.5 versus 24.8 seconds; p = .001), a higher lowest O2 saturation level after the stimulus (78.0% versus 68.4%;p = .003), and fewer profound apneas (10 of 90 versus 41 of 90 trials; p < .001). We conclude that 10% intralaryngeal CO2 does not decrease ventilatory activity in piglets and has no significant effect on the LCR. Acetazolamide, however, appears to have a protective effect against the LCR, resulting in shorter and less severe apneas. The protective effect of AZ against the LCR appears to be related to its ability to stimulate the respiratory drive and increase oxygenation at baseline.

Consensus statement: Using laryngeal electromyography for the diagnosis and treatment of vocal cord paralysis.

Introduction: The purpose of this study was to develop an evidence‐based consensus statement regarding use of laryngeal electromyography (LEMG) for diagnosis and treatment of vocal fold paralysis after recurrent laryngeal neuropathy (RLN). Methods: Two questions regarding LEMG were analyzed: (1) Does LEMG predict recovery in patients with acute unilateral or bilateral vocal fold paralysis? (2) Do LEMG findings change clinical management in these individuals? A systematic review was performed using American Academy of Neurology criteria for rating of diagnostic accuracy. Results: Active voluntary motor unit potential recruitment and presence of polyphasic motor unit potentials within the first 6 months after lesion onset predicted recovery. Positive sharp waves and/or fibrillation potentials did not predict outcome. The presence of electrical synkinesis may decrease the likelihood of recovery, based on 1 published study. LEMG altered clinical management by changing the initial diagnosis from RLN in 48% of cases. Cricoarytenoid fixation and superior laryngeal neuropathy were the most common other diagnoses observed. Conclusions: If prognostic information is required in a patient with vocal fold paralysis that is more than 4 weeks and less than 6 months in duration, then LEMG should be performed. LEMG may be performed to clarify treatment decisions for vocal fold immobility that is presumed to be caused by RLN. Muscle Nerve 53: 850–855, 2016

The Prevalence of Undiagnosed Thyroid Disease in Patients With Symptomatic Vocal Fold Paresis

OBJECTIVE Vocal fold paresis has a multifactorial etiology and is idiopathic in many individuals. The incidence of thyroid-related neuropathy in the larynx has not been previously described. The purpose of this study was to evaluate the prevalence of previously undiagnosed thyroid disease in patients with laryngeal neuropathy and to compare this prevalence with that in a cohort of patients with a neurotologic neuropathy. STUDY DESIGN AND SETTING Case series with chart review; tertiary care, otolaryngology practice. SUBJECTS AND METHODS Charts of 308 consecutive patients with dysphonia and vocal fold paresis and 333 consecutive patients with sensorineural hearing loss, who presented for evaluation during a 3-year period, were reviewed. RESULTS One hundred forty-six of 308 (47.4%) patients with vocal fold paresis were diagnosed with concurrent thyroid disease, whereas 55 of 333 (16.5%) patients with sensorineural hearing loss were diagnosed with concurrent thyroid disease (P<0.001, Pearson chi-square = 92.896; degrees of freedom = 5). Thyroid diagnoses among those with vocal fold paresis included benign growths (29.9%), thyroiditis (7.8%), hyperthyroidism (4.5%), hypothyroidism (3.6%), and thyroid malignancy (1.6%). CONCLUSIONS Thyroid abnormalities are more prevalent in patients with dysphonia and vocal fold paresis than in patients with symptomatic sensorineural hearing loss, suggesting a greater association between previously undiagnosed thyroid abnormalities and laryngeal neuropathy than that between neurotologic neuropathy and thyroid disease.

Determinants of fatal apnea responses to acid stimulation of the larynx in piglets.

Objectives: This study explores the physiological determinants of laryngeal chemoreflex (LCR) response severity under hypoxic conditions. Methods: Thirty-four piglets underwent hypoxic laryngeal stimulation. Physiologic data were collected, and responses were graded as mild, moderate, or profound. Results: Prestimulation hypoxia caused respiratory depression and carbon dioxide retention in profound responders and respiratory stimulation in mild and moderate responders (p < .05). Resumption of respiration occurred in all animals when the Paco2 rose by a mean ± SD of 15.1 ± 6.5 mm Hg (p > .05). There was a significant difference between mild, moderate, and severe responders in change in arterial Pao2 and hydrogenated hemoglobin saturation during the LCR-induced response (p < .001 for both). Conclusions: Resumption of respiration is associated with accumulation of arterial Paco2. The respiratory response to hypoxia predicts the severity of the LCR response. The severity of the LCR-induced response is associated with changes in arterial Pao2 and hydrogenated hemoglobin saturation during the LCR-inducedapnea.

Second Place—Resident Clinical Science Award 1999 Laryngeal Chemoreflex Severity and End-Apnea Pao2 and Paco2

OBJECTIVE: The laryngeal chemoreflex (LCR) is a model for investigating the sudden infant death syndrome. The severity of the LCR-induced response may vary. This study examines the conditions under which recovery from the LCR-induced apnea occurs. METHODS: Twenty-five piglets underwent normoxic laryngeal stimulation (Pao2 > 70 mm Hg); 11 then underwent hypoxic stimulation (Pao2 50–65 mm Hg). Cardiovascular and respiratory responses were recorded. RESULTS: Recovery Pao2 was lower during profound responses (Pao2 = 45.9 ± 12.8 mm Hg) than during moderate (Pao2 = 54.9 ± 7.5 mm Hg) and mild (Pao2 = 60.6 ± 10.3 mm Hg) responses (analysis of variance [ANOVA], P = 0.05). Recovery Paco2 did not vary (ANOVA, P > 0.05). Blood pressure and O2 saturation declined at faster rates with increasing severity of response (ANOVA, P < 0.05 for both). CONCLUSIONS: Resumption of respiration after LCR-induced apnea is associated with a consistent level of Paco2. The severity of the response is associated with recovery Pao2 levels.