Учебники / Voice Disorders and Their Management Freeman 2000

In infants, a particularly challenging problem is that of juvenile papillomatosis. Papillomata have a propensity to seed throughout the respiratory tract. Judicious use of the laser offers the best local control, to maintain a patent airway with minimal scarring to the larynx. A tracheotomy may be necessary, but this increases the risk of seeding to the lower airways. There is a natural tendency for the papillomata to regress, suggesting the development of immunological defences. Many alternative treatments to surgery have been evaluated, including chemotherapeutic agents having antibacterial, antiviral or cytotoxic properties and the use of prepared vaccines. These have proved successful in individual cases but none offer a universal solution.

Laryngeal trauma

Blunt and sharp trauma to the neck may involve the larynx and its nerve supply. Disruption of the cartilaginous framework requires early repair with stenting and preservation of as much mucosa as possible. The airway is maintained via a tracheotomy. It may be possible to approximate the ends of a severed recurrent laryngeal nerve. The management of an established stenosis after trauma is very difficult and some patients will remain with a tracheotomy and speaking valve.

Phonosurgery

Surgery that has its aim in the deliberate alteration of voice is termed phonosurgery. This involves microlaryngoscopy, injection techniques and laryngeal framework surgery (see also Chapter 17). Also considered in this section is surgical voice rehabilitation after laryngectomy.

Microlaryngoscopy

The advent of the CO2 laser, deliverable via the operating microscope, proved to be a false dawn in laryngeal microsurgery. It was used indiscriminately to treat vocal fold lesions previously excised with micro instruments. As more patients were assessed with stroboscopy, the scarring from laser surgery which inhibits the mucosal wave was recognized. In addition, lesions were more readily recognized as being submucosal, such as mucous and epithelial cysts, and therefore better excised via a cordotomy incision, which preserves the epithelial edge of the fold. Similarly, with vocal fold oedema, the practice of stripping the edge of the vocal fold should now be outlawed and be replaced by cordotomy and suction of the oedematous fluid, so preserving the vocal fold epithelium and promoting restoration of the mucosal wave.

Vocal fold medialization

In cases of unilateral adductor fold palsy, improvement in the quality of the voice may require positioning of the edge of the paralysed fold to the mid-line, in order to achieve glottic closure. This effect can be obtained by the injection of material to increase the bulk of the vocal fold. The substance that has been most associated with this procedure is a suspension of Teflon. It is injected deep into the muscle in the paraglottic space under general or local anaesthesia. It is essential to wait at least a year to allow for recovery of the paralysis before undertaking this procedure, unless there is certain knowledge of complete severance of the nerve by trauma or shown by EMG studies or where improvement in quality of life is sought in patients with terminal malignancy. Although uncommon, the risk of migration of the Teflon has led to the application of other materials. Collagen injection, apart from being very expensive, is not permanent and is a possible transmitter of disease. Autologous fat harvested from the patient does not suffer the latter risk but again is relatively temporary in its duration. A further development is the use of gelfoam (see Casper, Chapter 10; Bouchayer and Cornut, Chapter 17).

An alternative approach to the injection techniques is to push the vocal fold towards the midline, by cutting a window in the lamina of the thyroid cartilage at the level of the vocal fold and keeping it medialized by a plastic stent. This procedure is one of the types of thyroplasty.

Pitch alteration

Other types of thyroplasty have been devised, which aim to lengthen or shorten the vocal folds and thereby change the pitch of the voice. It is doubtful whether these procedures have any advantage over speech therapy.

Laryngeal reinnervation techniques

Attempts at re-establishing a nerve supply have met with limited success. The usual donor nerve is a branch of the ansa hypoglossi, which is anastomosed to the recurrent laryngeal nerve. Any return of innervation introduces tone to the paralysed muscle, but does return the power of abduction and adduction.

Surgery for spasmodic dysphonia

Injection of botulinum toxin into the vocalis muscle has improved the outlook for these unfortunate patients. Previously, surgical treatment had been by section of one recurrent laryngeal nerve. The transcutaneous

injection is monitored by EMG and laryngoscopic visualization. The benefit of the injection lasts between three and six months after which time it can be repeated (see Whurr, Chapter 11 for more details).

Surgical voice rehabilitation after laryngectomy

The methods which offer the best voice restoration with the least disadvantage involve the formation of a tracheo-oesophageal fistula maintained by a valve. The valve (e.g. Blom-Singer) acts to direct air from the lungs into the oesophagus, while preventing flow of saliva and ingested food and drink in the reverse direction into the trachea. To direct the air through the valve, the stoma is occluded temporarily by finger closure or by an outer casing valve assembly covering the stoma and which opens on inspiration and closes on expiration. The air vibrates the P-E segment in the same way as in acquired oesophageal speech, but has the advantage of greater volumes of air to increase loudness of phonation and length of continuous phonation.

The fistula can be established as a primary procedure at laryngectomy. The feeding tube is passed through the fistula, to maintain it, and replaced by the valve when oral feeding is established. Secondary puncture can be undertaken in previously performed laryngectomies. This may need to be combined with cricopharyngeal myotomy if hypertonicity is demonstrated at videofluoroscopy.

The future

As a footnote to this chapter it is now possible to say that the future has arrived, with the first laryngeal transplant successfully performed in the United States of America. We watch this exciting development with interest.

Causes of voice disorders

These three conditions will now be considered in more detail.

1.The larynx is vulnerable to physical stress which can result in the buildup of tissue reactions (vocal nodules, contact ulcers, or non-specific laryngitis). Physical vulnerability, upper respiratory tract infection and personality factors, as well as the demands of the situation, may all combine to produce a voice disorder. Where the vocal folds fail to present smooth vibrating edges, capable of full adduction along their total length, we may expect a voice characterized by air waste and a quality which may variously be described as ‘rough’, ‘hoarse’ or ‘husky’.

As indicated, such changes in the smooth appearance of the vocal folds may be a direct result of inappropriate voice use. In other cases there may be changes caused by physical trauma such as road traffic accidents or intratracheal intubation during general anaesthesia, causing haematoma or granuloma. Infection, benign or malignant new growths can also affect the structure of the vocal folds. In addition excessive alcohol consumption, smoking, chemical irritants, certain drugs, or hormone imbalance may also lead to tissue changes in the larynx. In many cases these factors occur in combination to have an adverse effect on voice quality.

2.The appearance of the vocal folds may be normal but the movement of the cords may be affected. Disturbed vocal function may be part of the dysarthrophonic syndrome (Peacher, 1949), where there is a disease process of the central nervous system, affecting both articulation and phonation. The dysarthrias associated with cerebellar, extrapyramidal, lower motor neuron and bilateral cortical lesions have associated voice problems involving all aspects of voice production (see Ramig, Chapter 9). At a peripheral level there may be interference with the nerve supply to one or both vocal folds. The most common of these is a unilateral recurrent laryngeal nerve lesion (see Casper, Chapter 10).

3.Voice disorders can exist in the apparent absence of any physical cause, although this may reflect the present state of investigation procedures rather than the true state of affairs. In some of these cases, more refined techniques such as laryngeal microscopy may reveal previously unidentified physical signs. This shift of emphasis from a psychogenic to a physical cause is demonstrated very clearly in the case of spasmodic dysphonia (see Whurr, Chapter 11). Generally speaking, however, wherever there are no apparent signs, the dysphonia is labelled as ‘functional’, ‘psychogenic’ or even ‘hysterical’. Freeman (Chapter 8)

and Oates (Chapter 7) have indicated the complexities of the situation and the need for a careful evaluation of the variables involved.

There are two other areas where the client has a normal voice mechanism but the voice is perceived as abnormal: in cases of significant hearing loss and in transsexualism. Increasing interest has developed in recent years in the indirect but often very marked effects of profound hearing loss for the frequencies of voice production (see Wirz, Chapter 12). The speaker has a potential for normal voice production which is never realized due to his severely impaired auditory feedback mechanism and, in the case of acquired profound hearing loss, the continuous auditory monitoring that enables us to maintain consistent and appropriate intensity, pitch and intonation patterns.

In the case of the transsexual individual (see Chaloner, Chapter 14), we may indeed challenge the concept of a voice disorder, since vocal pitch (the only aspect of voice with which the transsexual person is normally concerned) may be entirely in keeping with the physical constraints of the laryngeal structure. There is, however, a mismatch between the modal range and the desired gender which he or she wishes to convey.

We must now consider what we mean by a voice disorder in more detail, and examine the ways in which interested voice therapists, laryngologists, and phoniatrists have attempted to classify the aphonias and dysphonias.

A voice disorder exists [says Aronson (1980)] when quality, pitch, loudness or flexibility differs from the voice of others of similar age, sex, and cultural group.

It is on variants of these four perceived parameters of voice production that the listener judges the normality or otherwise of the voice he or she hears. Aronson considers that these judgements are made in relation to the listener’s expectations regarding sex and age within a given cultural group. We must also consider the listener’s individual preferences and biases, and his level of awareness of how voices sound and the differences between them. There is a continuum extending from the voice that is clear and audible to one which is unmistakably dysphonic.

Different listeners, asked to make a judgement about a speaker’s voice, will not always place that voice at the same point on the continuum. For one listener, a voice may be acceptably ‘normal’, while for another judge the same voice may be noted as frankly abnormal. Wynter (1974) has emphasized the subjectivity of listeners’ judgements, which has given rise to a confusing variety of terms to describe voice quality. ‘Typically they are

based on subjective auditory judgements rather than on objective observations of vocal function’ (Reed, 1980).

Prevalence of voice disorders

Rather little is known about the prevalence of voice disorder, and any figures available must be regarded with some caution: not all speakers with a hoarse voice would regard it as pathological, and would therefore not seek medical advice. Dysphonia may be regarded as a problem only if it causes discomfort or interferes in some way with their life style. We do, however, know rather more about the relative prevalence of the different causes of voice disorder.

Herrington-Hall et al. (1988) carried out a retrospective study of 1262 patients seen by eight otolaryngologists over a two-year period. The total population was approximately 2.3 million. The purpose of the investigation was to look at the occurrence of laryngeal pathologies across three variables: sex, age and occupation. They also looked at the residential environment of the patient population (rural or city). Herrington-Hall et al. identified 22 laryngeal pathologies (Table 4.1). Of these the most common was vocal nodules (21.6%) followed by oedema (14.1%), polyps (11.4%), carcinoma (9.7%), vocal fold paralysis (8.1%), and dysphonia with no apparent pathology (7.9%).

In taking the variable of age into account, it is clear that laryngeal pathologies occur most frequently in the older age group (carcinoma and vocal-fold paralysis being the most commonly found causes of vocal dysfunction in the elderly). Females presented with laryngeal pathologies at a slightly younger age. In the total population, nodules and oedema were more common in early adulthood (25–44 years), with polyps and dysphonia with a normal larynx occurring in middle age (45–64 years) (Table 4.2) .

It is interesting, but not altogether surprising, that nodules occur most frequently in males under the age of 14 years when we might well expect abusive vocal behaviour (ratio of males to females was 2.7:1). In contrast, nodules and oedema are found most commonly in females between the ages of 25 and 44 years. This is a period when many women are raising young children, and may also be facing the additional demands of being a working mother. Psychogenic voice disorders, perhaps for some of the same reasons, also showed an increased incidence in early adulthood.

When Herrington-Hall et al. looked at the influence of occupation, they found that the presence of laryngeal pathologies tended to reflect both the amount of voice use and the conditions under which voice was used (including noise and stress). Of the 73 occupations identified in the study,