Video demonstration showing examples of vocal fold paralysis, specifically indicating the left vocal fold paralyzed on the right side of the screen.
Central nerve paralysis usually leads to paralysis close to the midline, often due to conditions such as stroke.
Types of Paralysis
a. Superior Laryngeal Nerve Paralysis
- Difficult to detect nerve injury. While difficult to detect, injury often leads to subtle voice changes like difficulty with pitch control, reduced vocal range, and occasional voice fatigue, rather than complete glottic closure issues observed in recurrent laryngeal nerve paralysis.
- Good body closure and fairly symmetric vibratory patterns observed.
b. Peripheral Nerve Damage
- Illustrated through right vocal fold not moving; indicates severe impaired glottic closure.
- Further demonstration of left vocal fold paralysis showing poor closure.
- Typically affects the recurrent laryngeal nerve branch of the vagus nerve, leading to significant glottic insufficiency.
Compensatory Behaviors
Individuals may engage in compensatory behaviors to achieve glottic closure using supraglottic structures such as ventricular folds. These behaviors often occur to compensate for glottic insufficiency, but can lead to increased vocal effort and secondary muscle tension issues over time.
Observed lateral medial compression and anterior-posterior (AP) compression.
Neurogenic Voice Disorders
Spasmodic Dysphonia
Definition: A type of focal dystonia characterized by unwanted muscle contractions impacting voice during phonation.
a. Subtypes:
ADSD (Adductor Spasmodic Dysphonia)
Involves hyperadduction of vocal folds during voiced speech, producing a spasm-like quality.
ABSD (Abductor Spasmodic Dysphonia)
Involves involuntary abduction when producing voiceless sounds.
b. Treatment Options
Botox injections to prevent unwanted muscle contractions. Botox injections work by temporarily weakening specific laryngeal muscles, reducing the involuntary spasms that characterize spasmodic dysphonia. The effects typically last 3-6 months.
Voice therapy for additional support; discussed in module four.
c. Risk Factors
History of other focal dystonia, Caucasian ethnicity, and notably higher prevalence in females (1.4:1 ratio female to male).
d. Vocal Impairments Associated with Dysphonias
Adductor Spasmodic Dysphonia: Voice has strained, rough quality with effortful phonation; intermittent breaks during voiced production.
Abductor Spasmodic Dysphonia: Intermittent breathiness and pitch breaks mainly during voiceless sounds.
Sample words/sentences eliciting these conditions discussed, e.g., "How hard did he hit him?" for ABSD.
Vocal Tremor
Definition
Tremor: Rhythmic contraction of muscles; can occur elsewhere in the body.
Frequency ranges from 4 Hz to 8 Hz impacting voice quality.
Characteristics
Voice exhibits tremulous quality, especially evident in sustained vowels.
Vocal tremor differs from other dysphonias as it can be exacerbated by stress and fatigue.
Treatment Options
Botox injections: Used to reduce the severity of the rhythmic muscle contractions.
Beta-blockers (e.g., Propranolol): Can help reduce tremor by blocking nerve impulses that cause involuntary muscle movements.
Voice therapy focusing on lifestyle changes and trigger management, and strategies to minimize the perceptual impact of the tremor and improve breath support.
Neurogenic Disease and Dysphonia
General Note
Neurogenic diseases like stroke or multiple sclerosis can lead to dysphonias due to degradation or injury to the central nervous system affecting motor neurons.
Examples of Conditions Affecting Voice
Central Vocal Fold Paralysis from stroke or traumatic brain injury causes unilateral paralysis influenced by vagus nerve damage.
Spastic Dysarthria resulting from bilateral injury leading to hyperadduction and roughness in voice.
a. Multiple Sclerosis (MS)
Relapsing condition impacting motor function, including the voice. Voice involvement includes dysarthria, with characteristics like impaired breath control, reduced loudness, harshness, and sometimes a monotonous pitch, due to demyelination impacting neurological pathways.
b. Amyotrophic Lateral Sclerosis (ALS)
Progressive loss affecting both upper and lower motor neurons impacting vocal function. The progressive loss of upper and lower motor neurons leads to a mixed dysarthria, causing a strained-strangled voice quality (spasticity) and breathiness or weakness (flaccidity), often progressing to aphonia. Patients may also experience dysphagia.
c. Myasthenia Gravis
Impacts nerve transmission to muscles; voice can be significantly affected during symptom exacerbation. Characterized by fluctuating muscle weakness that worsens with sustained effort. Voice symptoms include rapid voice fatigue, breathiness, and hypernasality, often improving after rest.
Other Disorders Related to Dysphonia
a. Parkinson's Disease
- Characterized by losing dopaminergic neurons leading to voice weakness and monotonic quality. Loss of dopaminergic neurons in the substantia nigra leads to hypokinetic dysarthria, resulting in a weak, breathy, monotone voice, reduced pitch and loudness variability (hypophonia), and sometimes a rapid, imprecise articulation (festinating speech).
b. Treatment Approaches Include:
- Medications such as Sinemet lead to voice improvements.
- Specific voice therapies, e.g., Lee Silverman Voice Treatment, Speak Out, focusing on increasing vocal effort and spontaneous speech.
Paradoxical Vocal Fold Movement (PVFM)
Definition and Clarification
The condition is often confused with Vocal Cord Dysfunction (VCD); however, PVFM is more specific, leading to episodes of breathing difficulty due to inappropriate adduction of vocal folds.
Triggering Events
Can result from exercise, stress, or even mild environmental stimuli, leading to stridor sounds and misdiagnosis as asthma.
Diagnostic Techniques
Flow-Volume Loop: Important imaging used in pulmonary function tests to reveal inspiratory impairment during PVFM episodes. A pulmonary function test that graphically displays airflow during inspiration and expiration. In PVFM, it typically shows "plateauing" or flattening of the inspiratory limb, indicating upper airway obstruction, while the expiratory limb remains normal.
Risk Factors
Include laryngopharyngeal reflux, upper airway hypersensitivity, and environmental triggers such as chemical exposure, especially in military or first responders.
Management and Therapy
Effective therapeutic interventions that include breathing strategies can lead to improvement within a short duration. These interventions include laryngeal control techniques (e.g., sniff-hold-exhale, pursed-lip breathing), speech-language pathology breath retraining, and relaxation strategies (e.g., diaphragmatic breathing) to facilitate vocal fold abduction during inspiratory phases.
Muscle Tension Dysphonia (MTD)
Overview
Maladaptive behaviors leading to dysphonia characterized by excessive muscle tension in the pharynx and larynx.
Can be caused by postural issues, emotional stress, or injuries leading to altered phonation techniques.
Treatment Focus
Primarily voice therapy aimed at reducing tension; myofascial release techniques frequently used. Voice therapy utilizes a variety of techniques to reduce excessive muscle tension, such as laryngeal massage or manual circumlaryngeal therapy, resonant voice therapy, confidential voice, yawn-sigh, and chewing exercises, to achieve more efficient and less effortful phonation.
Patients often demonstrate significant recovery and voice quality improvements.
Functional Voice Disorder
Definition
Occur when individuals experience dysphonia or aphonia without an identifiable medical condition, often termed conversion disorder.
Psychological Connections
These disorders are closely linked to psychological stressors, including trauma or high emotional states.
Assessment and Diagnosis
Involves thorough history and endoscopic evaluation; stimulability testing is crucial.
Therapeutic Approaches
Explaining voice anatomy, gradual non-stressful techniques to encourage vocal production, and possibly collaboration with mental health professionals for emotional support. Gradual non-stressful techniques for encouraging vocal production might include vegetative acts (e.g., coughing, throat clearing), humming, or using a "confidential voice" (a soft, breathy voice) before gradually progressing to normal voice.
Conclusion
Importance of comprehensive understanding of dysphonias, their characteristics, risk factors, and treatment options.