Why practice nurses need to know about occupational voice loss
Awareness of occupational voice loss is low, but there are many opportunities for the practice nurse to identify those at risk and facilitate early assessment and treatment
The voice is an essential instrument for everyday functioning. Loss of the ability to speak, either full or partial can be devastating, even for people who are not wholly reliant on their voice for their work. For teachers, barristers, singers, actors and call centre workers reduced vocal function can significantly impair their ability to work and put them at risk of job loss.
The majority of occupational voice problems are not caused by work but affect an individual's ability to do their work. People complain of weakness, failure in voice, in projection, poor volume, hoarseness, frequent throat clearing and general discomfort and irritation. In the United States it has been reported that at any one time between 3-9% of the population will report a voice abnormality.1
Short term voice problems are commonly associated with respiratory tract infections such as coughs, colds and influenza. They may produce hoarseness, sore throats and weak voices but these symptoms usually resolve spontaneously without medical treatment. During the course of the infection they affect the ability to speak and project the voice and so can lead to temporary restrictions on activity.
Voice problems actually caused by work are much less common and can be prevented. Surprisingly there is no UK data on the percentage of people who are crucially dependent on their voice at work, but in the US approximately one in four people consider their voice critical to their job.2
The cornerstone of management of a person with a voice disorder is to first exclude a malignancy. Early diagnosis and treatment improve prognosis no matter what the cause, but public awareness and knowledge about prevention and management is poor so consultation with healthcare professionals can be delayed. Identifying occupational groups at risk is therefore important for the practice nurse as this gives an opportunity to facilitate early assessment and treatment.
AT RISK GROUPS
Anyone who uses their voice professionally, such as singers and actors, is at risk of developing a voice problem caused by their work. But they are also at risk of experiencing disability - even if their problem is not caused by their job - as it is likely to affect their ability to perform at work.
Teachers and singers have been extensively studied and have been reported to have a higher frequency of voice disorders than the general population.3
Clearly, if a job has high vocal demands then anything that affects the voice will be noticeable to the individual and is more likely to lead to help seeking behaviour and positive reports on studies even if the job did not cause the condition in the first place.
Other less obvious groups at increased risk include obstetricians, lawyers, tour guides, telemarketers4 and people exposed to toxic agents such as allergens and chemical fumes.
THE VOICE
Voice is made, essentially, by the vibration of the vocal cords (a process known as phonation). This is then modified and resonated by the rest of the vocal tract to produce a recognisable voice quality. The lips, tongue and soft palate shape the sound source to make speech.
Speech and voice production requires precise co-ordination of muscle movements undertaken with accuracy and speed. The flexibility of the vocal tract and the numerous anatomical differences between people means that there is a huge range of voice and speech qualities and even in the same individual, it is possible to change the quality either consciously (for example, in an actor or impersonator) or unconsciously (for example, as a result of vocal fatigue or postural tension).
Vocal structures at rest
At rest the larynx is relaxed and respiration is quiet, the vocal folds are open and air moves in and out of the lungs without impediment. The whole of the larynx moves in sympathy with outflow and inflow of respiratory air. When about to speak we take a breath of air in, then, as we breathe out, the vocal folds come together in the midline. The air coming from the lungs meets the resistance below the closed vocal folds, this pressure increases until it is greater than the vocal fold resistance and then they peel apart and a puff of air is released. The negative pressure which results than closes the vocal folds quickly. The repetition of this is what we hear as vocal sound.
CAUSES OF VOICE LOSS
The majority of voice dysfunction is caused by abuse, misuse and psychogenic factors5 but consideration always needs to be given to the possibility of chemical and environmental causes.
Medical conditions
Neurological conditions such as myasthenia gravis, parkinsonism, and motor neurone disease can produce changes in voice but usually as part of more widespread problems, such as with swallowing. Gastro-oesophageal reflux disorder, and central and peripheral nerve lesions can also affect voice and speech.
Autoimmune, Infections and Endocrine Diseases
Conditions such as rheumatoid arthritis, systemic lupus erythematosis (SLE) and Sjogren's syndrome have well documented associations with voice dysfunction as have infections such as syphilis and TB. Changes in the voice occur related to menstruation, pregnancy and menopause and in association with thyroid dysfunction.
Neoplasms
Benign growths can grow on the cords or their surrounding structures. Vocal nodules, caused by misuse and abuse are also a benign form of tumour in this area.
Misuse
Habitual vocal behaviour involving speaking or singing with excessive loudness, yelling or screaming, speaking or singing with increased laryngeal muscle tension, forcing or straining the voice, excessive coughing or throat clearing all cause vocal dysfunction.
Poor postures such as slumping of the spine, raising the shoulders and hyperextension or hyperflexion of the neck and jaw, can also contribute to vocal misuse.
Laryngeal Irritants
Exposure to tobacco, marijuana smoke, chemical fumes and dusts, excessive dry air and allergens can all irritant the larynx and agents which cause dehydration such as alcohol, caffeine and several oral medications can exacerbate existing symptoms.
Psychological Issues
There is a strong link between voice abuse/misuse, personality and emotional status. A range of human emotions can be reflected in the human voice and so it is not surprising that heightened emotion can involve vocal strain and place excessive demands on the voice. Stress and anxiety can cause muscle tension generally and this can also affect the muscles of the larynx.
In many cases it is not one factor alone that causes or exacerbates a voice problem - many cases are multi-causal and contributory factors can include working conditions and the way the person compensates for their vocal condition.
DIAGNOSIS
Accurate diagnosis requires comprehensive assessment by a specialist voice clinic team, consisting of a laryngologist and a speech therapist but may also involve other professionals including psychologists.
Assessment includes a detailed history, perceptual evaluation of voice quality (listening to hear how the voice sounds - valuable for differential diagnosis), laryngeal endoscopy and vocal tract visualisation (including with a stroboscope) when the person is speaking to enable the diagnosis or exclusion of more subtle pathology at the edges of vocal cords.
If the patient presents with a history of loss of voice or hoarseness for more than 2 weeks, and especially if they are a smoker, than referral to exclude laryngeal cancer is needed. Once assessed and malignancy excluded, the patient is likely to come under the care of a speech therapist especially if the symptoms are prolonged or impacting on work ability.
PREVENTION AND TREATMENT
The prevention of voice problems involves the avoidance of excessive use. This can be achieved by use of microphones e.g. by tour guides or teachers, arrangement of audiences to facilitate low voice use e.g. by teacher arranging classes of pupils and by control of irritant agents at work to avoid exposure. Educating people in occupations who are reliant on their voice for their work (teachers, singers, actors, lawyers etc) is also essential.
Appropriate treatment depends on an accurate diagnosis and is best undertaken in a multi disciplinary setting. Essentially there are two groups of therapeutic approach:
1. Medical and surgical treatment
2. Voice (speech) therapy and other conservative treatments.
Conditions such as vocal nodules, polyps and cysts are treated surgically. Evidence for the many over-the-counter medications for hoarseness is poor but drugs affecting cough and viscosity of mucus can be beneficial, as can anti-allergic medication.
Voice Therapy
Speech therapists provide education, advice on vocal hygiene and voice conservation as well as providing insight into developing patients own auditory skills so they can better hear their voices themselves. They can also teach relaxation, advise on posture and provide more direct treatment such as improving control of breath flow, enhancing resonance, projection and amplification.
CONCLUSION
Voice disorders are common and can be disabling. While many are temporary and accompany common upper respiratory infections, chronic misuse of the voice through excessive shouting or prolonged use in an emotional state, can lead to chronic dysphonia. Voice disorders caused by work may occur due to inhalation of chemicals or be secondary to over-use but are relatively uncommon compared to disorders due to concurrent URTI. Nevertheless, no matter what the cause, problems with hoarseness, a weak voice or difficulty with voice projection, can significantly impact on the ability of a person to continue to work. Practice nurses have a valuable role in ensuring patients are referred early to multi disciplinary teams for diagnosis and treatment of their voice symptoms.
REFERENCES
1. Ramig LO, Verdolini K. Treatment efficacy: voice disorders. J Speech Lang Hear Res 1998;41:101-106
2.National Centre for Voice and Speech. Occupational Voice Data. National Centre. Iowa IA US 1993
3. Verdolini K, Ramig LO. Review; occupational risks for a voice problem. Log Phon Vocol 2001;26:37-46
4.Jones K et al. prevalence and risk factors for voice problems among telemarketers. Arch Otolaryngol Head Neck surg 2002; 128(5):571-577
5.Carding P. Voice pathology in the United Kingdom. BMJ 2003;327:514-515
