Учебники / Voice Disorders and Their Management Freeman 2000

The voice of the individual with Huntington’s disease is characterized by irregular pitch fluctuations and voice arrests (Ramig, 1986). Darley et al. (1969) reported sudden forced inspiration or expiration, harsh voice quality, excess loudness variations, strained strangle phonation, monopitch, monoloudness, reduced stress, transient breathiness and voice arrests (Aronson et al., 1968b; Aronson, 1985b) in the voices of individuals with Huntington’s disease. The tremorous voice accompanying essential tremor is characterized by ‘quavering intonation’ (Brown and Simonson, 1963; Aronson, 1990; Colton and Casper, 1990) or rhythmic fluctuations in loudness. The pitch, loudness and regularity of vocal tremor has been reported to vary and there may be arrests of phonation. Laryngeal dystonia or spasmodic dysphonia is characterized by effortful, strain-strangle voice quality with frequent voice breaks as well as interruptions of breathy or whispered segments upon a normal or hoarse voice (Aronson, 1990). The former is considered as adductor spasmodic dysphonia and the latter as abductor spasmodic dysphonia.

The voices of individuals with ALS have been described in a number of studies. Carrow et al. (1974) studied 79 patients with ALS and reported that 80% had harsh voice quality; 65% were breathy, 63% had tremor, 60% were strain strangled; 41% had audible inhalation, 38% had excessively high pitch and 8% had excessively low pitch. Aronson et al. (1968a) reported voices in ALS patients that were harsh (79.75%), strained-stran- gled (59.5%) with some breathiness (64.5%), reduced loudness, audible inhalation, ‘wet hoarseness’ and hypernasality (74.7%). Rapid tremor or flutter was reported in 63.3% of the ALS patients studied by Aronson et al. (1992) on vowel prolongation. It was suggested that the specific profile of voice characteristics in ALS (e.g. more flaccid or spastic) depended upon the site of lesion. Darley et al. (1972) studied 168 MS patients and reported that of the 59% that were vocally disordered, their voices were characterized by the following: impaired loudness control (77%), harsh voice (72%), impaired intonation, inappropriate pitch and breathiness. Farmakides and Boone (1960) reported impaired loudness, harshness and hypernasality in individuals with MS.

Voice characteristics: endoscopic findings

Comprehensive endoscopic descriptive data sets do not exist on the majority of neurological voice disorders. Myasthenia gravis or myotonic dystrophy may reveal bilateral weakness of intrinsic laryngeal muscles. Sluggish vocal fold adduction and increasing weakness of arytenoid and vocal fold motion have been suggested in myasthenia gravis (Colton and Casper, 1990). Velopharyngeal inadequacy has been observed frequently

in both myasthenia gravis and myotonic dystrophy. Aronson (1980) suggests that the voice disorder accompanying spastic (pseudobulbar) dysarthria is caused by hyperadduction of the true and false vocal folds (i.e. glottal constriction and resistance to exhalatory flow). Aronson (1990) reports that the folds appear normal in structure.

Kitzing (1985) suggested that, when hyperadduction occurs, there would be reduced vocal fold amplitudes, diminished mucosal waves, and excessive glottal closure. Hanson et al. (1984) reported bowing and greater amplitude of vibration and laryngeal asymmetry in individuals with Parkinson’s disease. Smith and Ramig (1995) reported that 12 of 21 individuals with Parkinson’s disease had a form of glottal incompetence (bowing or anterior or posterior chink) on nasal fibreoptic views. Perez et al. (1996) reported visually-rated laryngeal tremor in 55% of the 29 individuals with Parkinson’s disease they studied; the primary site of tremor was vertical laryngeal motion. The most striking stroboscopic findings for these individuals were abnormal phase closure and phase asymmetry. Amplitude and mucosal waveform were essentially within normal limits in the majority of these patients.

Endoscopic descriptions of one individual with Huntington’s disease revealed adductory movements at rest and termination of phonation seemingly by adductory laryngospasm (Ramig and Wood, 1983). Endoscopic descriptions of vocal tremor have revealed multiple sites of tremor, including posterior tongue and/or the posterior pharyngeal wall as well as laryngeal structures (Ardran et al., 1966; Ludlow et al., 1986; Koda and Ludlow, 1992; Smith and Ramig, 1995).

Laryngeal endoscopic reports of ALS revealed that, if there is spastic involvement, patients may adduct normally or may hyperadduct with the false folds. If there is flaccid involvement, there is less abductory, adductory excursion (Aronson, 1990). Garfinkel and Kimmelman (1982) reported pooling of saliva.

Voice problems in speakers with dysarthria: treatment options

Course of treatment; options and outcomes

Treatment for neurological voice disorders must be considered in the context of treatment for the overriding neurological disorder. Frequently individuals with neurological voice disorders are receiving neuropharmacological treatment or may have had neurosurgical treatment. Either or both of these treatments may or may not influence their voice.

Surgical

Individuals with a neurological voice disorder may have systemic treatment (e.g. neurosurgical treatment such as pallidotomy for Parkinson’s disease or thymectomy for myasthenia gravis) or laryngeal surgical or injection treatment which may directly treat the disordered larynx (thyroplasty for vocal fold paralysis or Botox for laryngeal dystonia).

Various neurosurgical procedures have been used to treat Parkinson’s disease: adrenal cell transplant, fetal cell transplant (Freed et al., 1993) and pallidotomy (Iacono et al., 1994) as well as dystonia: pallidotomy (Vitek et al., 1998). Data on corresponding speech and voice changes following these procedures are accumulating. For example, Baker et al. (1997) reported that, while measures of limb movement improved following fetal cell transplant, measures of speech and voice did not show systematic changes.

Thalamectomy has been used for a number of years to successfully reduce limb tremor (Manen et al., 1984). However, reduced vocal volume, velopharyngeal incompetence and swallowing problems have been associated with bilateral thalamectomy (Allan et al., 1966). Recently, Countryman and Ramig (1993) reported pre-, post and follow-up data following an intensive voice treatment programme (Lee Silverman Voice Treatment; LSVT(CM)) administered to an individual with idiopathic Parkinson’s disease who had had bilateral thalamotomies. While the patient demonstrated statistically significant improvements following treatment on various measures of phonatory stability, intensity and fundamental frequency variation, in contrast to other individuals with IPD, she was unable to maintain these changes at 6 and 12 month follow-up. While data are variable in terms of the effects of surgical treatment on speech and voice production in Parkinson’s disease, it appears that the magnitude and consistency of these effects are not adequate to impact on functional communication.

Pharmacological

Neuropharmacological treatments can be very useful in treating general motor symptoms of the neurological condition.

For example, in myasthenia gravis, positive effects of tensilon/ pyridostigmine (Mestinon) have been documented on symptoms of myasthenia gravis including the voice (Rontal et al., 1978). Neuropharmacological treatment for Parkinson’s disease supports amelioration of general motor symptoms with, for instance, dopamine precursors or agonists (e.g. bromocriptine, pergolide mesylate). It has been suggested that Deprenyl may slow progression of disability (Shoulson and Fahn,

1989). However the impact of these drugs on speech or voice production is not established. While there are papers to support positive effects of medication on voices of individuals with Parkinson’s disease (Audelman et al., 1970; Mawdsley and Gamsu, 1971; Wolfe et al., 1975), the findings do not support consistent and significant effects of neuropharmacological treatment on voice production. For example, in a study of on–off effects of medication on acoustic and electroglottographic measures of vocal function in two individuals with Parkinson’s disease, Larson et al. (1994) reported no systematic or consistent relationship between drug cycle fluctuations and these measures. The medical treatment of Huntington’s disease involves pharmacological attempts to control the choreic movements with antidopaminergic agents, phenothiazines, benzodiazepines, or antiseizure medications (Brin et al., 1992). The effects of these on voice in Huntington’s disease has not been documented. Smith (personal communication) reports improved voice quality and ease of phonation in an individual with hyperadductory voice arrests associated with Huntington’s disease following Botox injections into the thyroarytenoid muscle. The neuropharmacological treatment of essential tremor has involved various drugs (e.g. propranolol, primidone, acetazolamide, alprazolam, phenobarbital) with mixed results (Koller et al., 1986). Recently, Stager and Ludlow (1994) reported positive findings on use of Botox for treatment of vocal tremor.

Since 1987 when Botox was first injected into laryngeal muscles of individuals with spasmodic dysphonia (laryngeal dystonia) (Brin et al., 1987; Miller et al., 1987), it has been considered an important medical treatment for this disorder. There is a large literature reviewing various aspects of Botox treatment (e.g. Ludlow, 1995; Brin et al., 1998).

Speech pathology

Behavioural treatment for neurological voice disorders has only recently been addressed systematically (Ramig and Scherer, 1992; Smith and Ramig, 1995; Ramig, 1995a). In contrast to previous approaches to speech treatment that have been directed to the aetiologic classification of disorders, the approach suggested by Ramig and colleagues presents a treatment framework in relation to the physical pathology in the laryngeal mechanism. Neurolaryngeal disorders have been classified as: disorders of glottal closure (hypoadduction and hyperadduction) and instability (short-term and long-term).

Hypoadduction

Certain neurological disorders are accompanied by inadequate vocal fold adduction or hypoadduction. The particular type and extent of

hypoadduction may be associated with the site and extent of the related neurological damage. Hypoadduction may accompany a variety of neurological disorders, but is often associated with lower motor neuron (flaccid) involvement, which is characterized by paresis (weakness) or paralysis (immobility), atrophy and fatigue. Recently the hypoadduction accompanying Parkinson’s disease has received attention (Smith and Ramig, 1995).

In treatment for individuals with reduced adduction, the primary treatment goal is to increase loudness and reduce breathy, hoarse voice quality by increasing vocal fold adduction. Procedures to accomplish this include pushing, pulling and lifting while phonating (Froeschels et al., 1955). The goal is to maximize adduction by ‘reinforcing the sphincter action of the laryngeal muscles engaged in phonation’ (Froeschels et al., 1955). Other techniques to increase adduction include hard glottal attack, digital manipulation of the thyroid cartilage and turning the head to one side or the other – to increase tension on the paralysed fold (Aronson, 1990).

To facilitate the goal of increased loudness and improved quality, the respiratory system is often a focus of treatment. The goal of respiratory treatment is to achieve a consistent subglottal pressure during speech that is produced with minimal fatigue and appropriate breath group lengths (Netsell and Daniel, 1979). Stabilization of posture may be considered first (Murphy, 1965; Collins et al., 1982; Rosenbek and LaPointe, 1985). This may be followed by training to increase subglottal air pressure to ‘5 cm. of water pressure for 5 sec’ (Netsell and Hixon, 1978). Other techniques include exercises against a resistive load and controlled exhalation (Putnam, 1988). To improve coordination of respiration and phonation, various techniques such as maximum duration vowel phonation (Stemple et al., 1994; Ramig et al., 1995b) and phonation with simultaneous respiratory and vocal feedback have been suggested (Yorkstonet al., 1988). The individual with hypoadduction may also be encouraged to maximize oral resonance in order to increase loudness and quality. Details of these approaches have been reported by Ramig and Scherer (1992), Smith and Ramig (1995), Ramig (1995a) and Ramig et al. (1995b).

Hyperadduction

Certain neurological diseases result in excess vocal fold adduction, or hyperadduction. In some cases, the ventricular (false) vocal folds may hyperadduct as well (Aronson, 1990). The particular type and extent of hyperadduction may be associated with the site and extent of the related neurological damage. Hyperadduction most frequently occurs in cases of upper motor neuron system disorders characterized by spasticity and

hypertonicity and extrapyramidal system diseases accompanied by abnormal involuntary movements (e.g. tics, chorea, dystonia) that may be focal or generalized. In addition, hyperadduction may be compensatory. For example, a patient may have weak respiratory support or velopharyngeal closure and hyperadduct in order to manage the air stream for adequate loudness (Putnam, 1988).

The primary focus of voice therapy for patients with hyperadduction is to decrease the pressed, strained voice by reducing vocal fold hyperadduction. Procedures to accomplish this include those designed to relax laryngeal musculature and facilitate easy voice onset. These techniques may begin with whole body relaxation (Jacobson, 1976; McClosky, 1977) and then focus on laryngeal musculature. Other approaches include laryngeal massage, chewing approach, the yawn-sigh, chanting and delayed auditory feedback (Froeschels, 1952; Boone, 1983; Pershall and Boone, 1986). These techniques are based upon the hypothesis that when phonation is produced in the context of these reflex-like (Aronson, 1990) or continuous phonation responses, it will be more relaxed and less hyperadducted.

To facilitate the goal of improved voice quality, the respiratory system is often a focus of treatment in individuals with hyperadduction. The goal of respiratory treatment is to achieve consistent, steady airflow with relaxed respiratory musculature (Aten, 1983). Once the patient’s posture is stabilized, relaxed abdominal breathing may be trained to provide the greatest respiratory support with the minimum muscle tension (Prater and Swift, 1984). These activities may be combined with progressive relaxation exercises. To encourage reduced hyperadduction and remove the laryngeal focus, some clinicians (Cooper and Cooper, 1977) encourage ‘placement’ of the vocal resonance in the frontal nasal area.

Instability

Certain neurological disorders are accompanied by increased phonatory instability. The particular type, extent and regularity of the instability may be associated with the site and extent of the related neurological damage. Long-term fluctuations and short-term changes can occur as well as random or continuous use of alternative modes of voicing such as ventricular phonation, glottal fry, or diplophonia (Ramig et al., 1988; Aronson, 1990). These forms of instability may occur singly or in combination and may be related to the problems of adduction discussed previously.

The main focus of therapy for individuals with phonatory instability is to reduce the unsteady, hoarse, rough voice quality by targeting steady, clear phonation. Patients are encouraged to maximize respiratory and laryngeal coordination, as discussed previously, in order to sustain steady

voicing with consistent good quality. Treatments discussed earlier to promote more efficient vocal fold adduction have been reported to have positive effects on phonatory stability as well. For example, improved phonatory stability has been measured in individuals with Parkinson’s disease after therapy designed to promote increased vocal fold adduction (Dromey et al., 1995).

Augmentative communication

In some cases the severity of the neurolaryngeal disorder in combination with breakdowns in other parts of the speech mechanism, as well as the neurological disorder, makes a form of augmentative communication the best choice to facilitate communication. These devices can range from a simple manual board up to sophisticated computer-based technology. The more advanced devices offer synthesized or digitized speech output which can be customized to the patient’s needs.

Prognosis

Recently, data have been presented on the efficacy of intensive voice treatment for individuals with neurolaryngeal disorders. These data have been generated primarily around an intensive voice treatment programme (LSVT) designed for individuals with Parkinson’s disease. Data from administration of this treatment (Ramig et al., 1995b; 1996) support improved sound pressure level, fundamental frequency variation, vocal fold adduction and subglottal air pressure as well as maintenance of these changes for 6–12 months. The rationale and techniques for this treatment have been summarized elsewhere (Ramig et al., 1995b). These data are consistent with data reported by others on the usefulness of intensive voice treatment for patients with Parkinson’s disease (Scott and Caird, 1983; Robertson and Thompson, 1984). Application of these treatment concepts to selected individuals with multiple sclerosis, stroke, ataxic dysarthria has generated positive findings as well.

Summary

The past few years have seen a great increase in academic and clinical interest in neurological voice disorders. Knowledge of the neural bases and physiology underlying these disorders continues to grow. Surgical, pharmacological and behavioural treatments offer the potential to enhance speech production in individuals with these disorders. The combined efforts of the speech–language pathologist, neurologist and otolaryngologist can provide optimal speech intelligibility for individuals with neurological disorders of the voice.

Acknowledgements:

Some of the material in this chapter has been modified from a previous review (Ramig et al., 1996). Supported in part by NIH R01 DC01150 and P60DC00976

adduction and abduction, as a difference in speed of movement between the two vocal folds and as some glottal incompetence. The only observable movement in a completely paralysed vocal fold is the aerodynamically induced motion described by Hirano (1977) as similar to that of a flag flapping in the wind. Both of these terms, paresis and paralysis, imply a disruption of the transmission of neural impulses and disruption of neuromuscular innervation. Vocal fold immobility, however, may result from fixation or dislocation of the cricoarytenoid joint or from posterior scar bands that restrict joint movement. These aetiologies have nothing to do with the integrity of the neuromuscular system. In this chapter the term paralysis will be used routinely in discussing the neurologically based impairment, unless it is important to specify a paresis. Immobility will be used in describing other than neurologically based vocal fold movement problems. Furthermore, because bilateral vocal fold paralysis typically has different aetiologies, presents unique problems and specific treatment, and is significantly less prevalent, it will be discussed in a separate section at the end of the chapter. The main focus of the chapter will address unilateral vocal fold mobility problems.

Neurolaryngology

It is not within the purview of this chapter to delve at length into neurolaryngology or phonatory physiology. (Those interested in pursuing these areas are referred to Titze, 1994 and Benninger and Schwimmer, 1995.) However, it is necessary to have a basic understanding of the innervation of the intrinsic laryngeal muscles and the nature of the disruption that results from their impairment.

The Xth cranial nerve, the vagus, innervates the intrinsic laryngeal muscles. The vagus exits the skull through the jugular foramen and divides into three branches. The pharyngeal branch supplies nerve fibres to the pharynx and much of the palate. The superior laryngeal nerve branches off at the level of the inferior ganglion and contains both sensory and motor fibres. It descends along the pharynx and the motor fibres innervate the cricothyroid muscle, which is active in tensing and relaxing the vocal folds. The third branch, the recurrent laryngeal nerve, also carries both sensory and motor fibres. It does not follow a bilaterally symmetric path. Indeed, it is this difference in anatomic course of the nerve that makes the left recurrent, whose course is convoluted and longer, more vulnerable to trauma and explains the higher incidence of left unilateral vocal fold paralyses over right-sided paralyses. The right recurrent nerve passes into the upper chest looping around the subclavian artery before entering the larynx. The left recurrent laryngeal nerve