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Contributions to be made to "Dysphonia" article

No where on the current dysphonia page is any mention about the causes of dysphonia. There are many potential causes of dysphonia including neurological, inflammatory and systemic . As well, dysphonia may have no physiological cause, in which case it is called functional or psychogenic . An overview of these causes will be further discussed in a new section of the Dysphonia article.

Although there already exists a section on Clinical Measurement, this section can use some expansion. A more through explanation of the vocal qualities being assessed with the subjective measures (i.e. GRBAS, CAPE-V) would be useful. As well, a better division of the types of assessment tools (imaging, aerodynamic, acoustic, perceptual) would be beneficial.

Causes of dysphonia

A variety of different etiologies, which result in abnormal vibrations of the vocal folds, can cause dysphonia. These causes can range from vocal abuse and misuse to systemic diseases. Causes of dysphonia can be divided into five basic categories, although overlap may occur between categories . (Note that this list is not exhaustive):

Organic causes

1. Neoplastic: Abnormal growths of the vocal fold tissue.
   • Dysplasia
   • Cysts
   • Polyps 
   • Nodules
   • Carcinoma
2. Inflammatory: Changes in the vocal fold tissue as a result of inflammation.
   • Allergy
   • Infections
   • Reflux
   • Smoking
   • Trauma
   • Voice abuse
3. Neuromuscular: Disturbances in any of the components of the nervous system that control laryngeal function.
   • Multiple Sclerosis
   • Myasthenia Gravis
   • Parkinson’s disease
   • Spasmodic Dysphonia
   • Nerve injury
4. Associated Systemic Diseases: Systemic diseases which have manifestations that affect the voice.
   • Acromegaly
   • Amyloidosis
   • Hypothyroidism
   • Sarcoidosis
5. Functional/psychogenic: Associated with poor muscle functioning or psychological stresses, with no corresponding physiological abnormalities of the larynx.
   • Psychogenic
   • Excess demands
   • Stress

Clinical assessment

The assessment of the dysphonic voice is completed by a multidisciplinary team, and involves the use of both objective and subjective measures to evaluate the quality of the voice as well as the condition of the vocal fold tissue and vibration patterns .

Auditory-Perceptual Measures

Auditory-perceptual measures are the most commonly used tool by clinicians to evaluate the voice quality due to its quick and non-invasive nature . Additionally, these measure have been proven to be reliable in a clinical setting . Ratings are used to evaluate the quality of a patient's voice for a variety of voice features, including overall severity, roughness, breathiness, strain, loudness and pitch. These evaluations are done during spontaneous speech, sentence or passage reading or sustained vowel productions. The GRBAS (Grade, Roughness, Breathiness, Asthenia, Strain) and the CAPE-V (Consensus Auditory Perceptual Evaluation—Voice) are two formal voice rating scales commonly used for this purpose.

Vocal Fold Imaging

Vocal fold imaging techniques are used by clinicians to examine the vocal folds and allows them to detect vocal pathology and assess the quality of the vocal fold vibrations. Laryngeal stroboscopy is the primary clinical tool used for this purpose. Laryngeal stroboscopy uses a synchronized flashing light passed through either a rigid or flexible laryngoscope to provide an image of the vocal fold motion; the image is created by averaging over several vibratory cycles and is thus not provided in real-time . As this technique relies on periodic vocal fold vibration, it cannot be used in patients with moderate to severe dysphonia. High speed digital imaging of the vocal folds (videokymography), another imaging technique, is not subject to the same limitations as laryngeal stroboscopy. A rigid endoscope is used to take images at a rate of 8000 frames per second, and the image is displayed in real time. As well, this technique allows imaging of aperiodic vibrations and can thus be used with patients presenting with all severities of dysphonia.

Acoustic Measures

Acoustic measures can be used to provide objective measures of vocal function. Signal processing algorithms are applied to voice recordings made during sustained phonation or during spontaneous speech. The acoustic parameters which can then be examined include fundamental frequency, signal amplitude, jitter, shimmer, and noise-to-harmonic ratios . However, due to limitations imposed by the algorithms employed, these measures cannot be used with patients who exhibit severe dysphonia .

Aerodynamic Measures

Aerodynamic measures of voice include measures of air volume, air flow and sub glottal air pressure. The normal aerodynamic parameters of voice vary considerably among individuals, which leads to a large overlapping range of values between dysphonic and non-dysphonic patients. This limits the use of these measures as a diagnostic tool . Nonetheless, they are useful when used in adjunct with other voice assessment measures, or as a tool for monitoring therapeutic effects over time .

Lead section- draft 1

Dysphonia can be categorized into two broad main types: organic and functional. The type of dysphonia is dependent on the etiology (i.e. cause) of the pathology. While the causes of dysphonia can be divided into five basic categories, all of them result in an interruption of the ability of the vocal folds to vibrate normally during exhalation, which affects the voice. The assessment and diagnosis of dysphonia is done by a multidisciplinary team, and involves the use of a variety of subjective and objective measures, which look at both the quality of the voice as well as the physical state of the larynx.