A voice disorder is any change in the voice which affects the sound of the voice and ability to communicate in everyday situations. Voice disorders may occur from inappropriate use of the voice, medical conditions, following illness, damage to the nerves supplying the larynx, injury to the larynx or from neurological disorders.
Voice production relies on the interaction of the respiratory, laryngeal, resonance and articulation systems and is controlled by the nervous system. The vocal folds are set into vibration, creating sound waves, as air is directed through the larynx from the lungs. The tension, mass and shape of the vocal folds as well as the shape of the vocal tract will determine the pitch, loudness and quality of the voice.
Types of Voice Disorders
Muscle Misuse Voice Disorders
Muscle misuse voice disorders develop as a result of a number of interacting factors (environmental, physical/medical, emotional, voice use and voice technique). For example, a teacher may develop poor vocal behaviour by using the voice in a noisy classroom during an episode of acute laryngitis and hoarseness. After several weeks the altered vocal behaviour persists and the voice does not recover. Rehabilitation and voice therapy may be required in order to retrieve an effective voice for teaching.
Medical conditions (asthma, allergies, reflux) and some medications may contribute to voice disorders by altering laryngeal mucosa. Emotional problems, stress and vocal behaviour (yelling, cheering, coughing, throat clearing) cause increased muscular effort and laryngeal constriction during speech. Environmental factors such as dust, air conditioning and background noise are also important factors to consider.
Management of muscle misuse voice disorders is directed at the contributing factors and may include: the management of medical problems; counselling, stress management and speech therapy.
Disorders which result from muscle misuse include:
- Muscle tension dysphonia with no pathology.
- Muscle tension dysphonia leading to changes in laryngeal mucosa such as vocal nodules.
Psychogenic disorders such as conversion (or hysterical) aphonia. In this disorder, the vocal folds move normally and produce sound during coughing, however, during speech the voice is whispered. Another psychogenic voice disorder is puberphonia (mutational or adolescent transitional dysphonia) which is the failure of the male voice to “break” during puberty thereby maintaining a high pitched voice.
Changes in the vocal folds, muscles and cartilages in the larynx, vocal tract and the respiratory system lead to voice changes in the elderly. Voice exercises and voice care will assist elderly people to maintain a functional voice.
Neurological Voice Disorders
Neurological voice disorders are caused by damage to regions of the nervous system responsible for voice production. St Vincent’s Hospital specialises in the management of neurological voice disorders and is fortunate to have Dr Paul Darveniza, Consultant Neurologist, who is an expert in this area. Specific neurological disorders treated at St Vincent’s Hospital include Spasmodic Dysphonia, vocal tremor, vocal cord paralysis and dysphonia due to Parkinson’s disease.
Spasmodic dysphonia is a rare disorder of vocal function in which the vocal folds spasm causing the voice to break off momentarily. Vocal tremor and vocal strain may be present. Assessment by a multidisciplinary team of clinicians (Neurologist, ENT Surgeon, and Speech Pathologist) is necessary to diagnose the disorder and make recommendations for management. The current treatment of choice is injection of Botulinum toxin into the vocal folds to prevent the over closure of the vocal folds. A new surgical procedure (Laryngeal Framework Surgery) developed by Professor Isshiki is available for patients who do not respond to treatment with Botulinum toxin.
Benign essential vocal tremor is a rhythmic tremor and may be familial. Medication and Botulinum toxin injections have some effect.
Vocal Cord Paralysis
Vocal cord paralysis or immobility of a vocal cord occurs from damage to the nerves supplying the larynx. This may be due to a viral infection. At times, nerves are damaged following surgery to resect a skull base tumour or during thoracic surgery. The result is incomplete closure of the vocal folds causing a weak, breathy voice. Laryngeal framework surgery will medialise the affected cord and improve voice production in those patients who do not improve with speech therapy.
People suffering from Parkinson’s disease may develop a weak breathy voice and slurred speech. A new speech therapy programme (Lee Silverman Voice Treatment) developed especially for these people with Parkinson’s disease by L.A. Ramig has been used successfully by the Speech Pathologists at St Vincent’s Hospital since 1998.
Changes in the appearance of the vocal folds may be the result of poor vocal function, viral infection, smoking and alcohol abuse, allergy, gastro-oesophageal reflux disease, laryngeal trauma or congenital abnormality. These include:
- voice nodules
- vocal fold cysts
- vocal fold polyps
- vocal process granuloma/ulcers
- Reinke’s oedema
- polypoid degeneration
- Vocal fold haemorrhage
- Sulcus Vocalis
- Laryngeal Webs
- Bowed vocal folds
- Pre-cancerous lesions and leukoplakia
- Carcinoma of the vocal fold
- Rare diseases, e.g. Amyloid Wegeners Relapsing Polychondritis
- Laryngeal trauma (vid infra)
The treatment of the above involves full assessment in the Voice Laboratory, voice therapy and surgery depending on the diagnosis. Extreme care is taken that the vibrating mucosal wave is not damaged during surgery by using the microflap technique. Laser surgery is appropriate for papilloma, haemorrhagic conditions, some cases of laryngeal stenosis and cancers.
St Vincent’s Hospital has a special interest in LARYNGOTRACHEAL RECONSTRUCTION after injury and stenosis of the larynx and also LARYNGEAL CONSERVATION SURGERY in cancers of both the larynx and hypopharynx.