Differential diagnosis of muscle tension dysphonia and spasmodic dysphonia
ABSTRACT Muscle tension dysphonia (MTD) can mimic the voice features of adductor spasmodic dysphonia (ADSD) leading to diagnostic confusion. Researchers have begun to compare characteristics of MTD and ADSD to determine whether there are markers which reliably distinguish the two disorders and lead to improved differential diagnosis.
Differences between MTD and ADSD have been identified during fiberoptic laryngoscopy, phonatory airflow measurement, acoustic analysis, and variable sign expression based upon phonatory task. In general, evidence of task-dependent sign expression and intraword phonatory breaks should raise suspicion of ADSD over MTD. However, on the basis of conventional standards of diagnostic precision, no single diagnostic test currently exists that reliably distinguishes the two disorders.
Although perceptual voice evaluation remains the standard for differential diagnosis of ADSD and MTD, knowledge of factors that influence the severity of sign expression in ADSD is important to differential diagnosis. During clinical assessment, voice clinicians who use generic stimulus materials that do not control for specific phonetic environments or voice tasks may miss critical phenomenological features of ADSD.
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ABSTRACT: Voice tremor is a feature of many neurological conditions. Historically, clinical evaluation of voice tremor has relied on auditory-perceptual evaluation. We review developments in understanding of voice tremor that advocate additional approaches (acoustic, fibreoptic nasolaryngoscopic examination) to evaluation and stress the contribution from multiple sites in the speech mechanism to perceived tremor. An isolated focus on the speech signal does not identify the source/s of tremor. Structures in the pharynx and larynx can be important sources of perceived voice tremor. In addition to a sustained vowel phonatory task for evaluation, fibreoptic nasolaryngoscopic examination is recommended to observe tremor behaviour in different anatomic sites using different speech tasks; acoustic analysis is recommended to quantify tremor and enhance understanding of underlying mechanisms. Tremor measures (rate, periodicity, magnitude of frequency and amplitude tremor) have proved useful in differentiating speakers with tremor from normal speakers. Differentiating between tremor aetiologies is proving more challenging. The investigation of a conceptual model of voice tremor to understand the effect that oscillations in different parts of the speech mechanism have on the speech signal is an important development in the field. A sustained phonatory vowel task with fibreoptic nasolaryngoscopic examination of pharyngeal and laryngeal musculature, supplemented by acoustic measures, is currently recommended for clinical identification, quantification and characterization of voice tremor.Current opinion in otolaryngology & head and neck surgery 04/2011; 19(3):155-9. DOI:10.1097/MOO.0b013e328345970c · 1.39 Impact Factor
- Movement Disorders 03/2012; 27(3):346-8. DOI:10.1002/mds.24055 · 5.63 Impact Factor
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ABSTRACT: To determine the short-term disability (STD) and lost work productivity related to laryngeal disorders. A retrospective analysis of a national database of work absence and STD claims was performed. Patients with 12 months of follow-up who had an STD claim specifically linked to a dysphonia diagnosis based on ICD-9 codes were identified during the period of January 1, 2004, to December 31, 2008. Patient age, sex, and diagnosis and the total number of work days absent were determined. Using the mean national hourly wage, productivity losses in terms of lost wages were calculated. Of the 18,466 unique patients with an STD claim, 386 (2.1%) had an STD claim due to a laryngeal disorder. The mean age was 45.9 years (standard deviation, 9.6) with 53.2% male. The mean number of work days absent was 39.2 days (95% confidence interval: 31.9-46.5). Total STD payments in 2008 dollars were $647,269.30 with a mean per person in 12 months of $3,406.68. Total and mean lost wages in 12 months were $843,198.72 and $4,437.89, respectively. Patients with laryngeal cancer had the most days absent and highest total STD payment. Laryngeal disorders lead to work-related disability with STD and productivity losses and represent a significant societal burden. Managing work limitations from laryngeal disorders is an important public health goal.The Laryngoscope 07/2012; 122(7):1589-94. DOI:10.1002/lary.23197 · 2.03 Impact Factor