Clinical Cases in Dysarthria

Margaret Walshe, Nick Miller, Margaret Walshe, Nick Miller

• Editore: Routledge
• Anno: 2021
• ISBN:
  9781000510607
• Edizione: 1
• Argomento: Medicine
• Categoria: Audiology & Speech Pathology

Through the medium of detailed clinical case reports, written by well-respected clinicians and researchers working internationally in the field, Clinical Cases in Dysarthria discusses the challenges, and rewards of applying evidence-based procedures to people with dysarthria in real-life busy routine clinical settings.

The text opens with an introduction to the latest research and practices within dysarthria treatment and sets the scene for the eight individual case reports which follow. These case reports form the core chapters of the text and cover themes that range from clinical diagnostic conundrums to applying popular, and/or novel intervention approaches to different populations where dysarthria presents. Each chapter has a specific argument drawing on theoretical principles of assessment and rehabilitation, incorporating latest research evidence to help readers problem-solve similar cases in their clinical practice. Throughout the text, readers are encouraged to 'think outside the box'.

This book will be essential for undergraduate and postgraduate student clinicians within speech and language therapy/pathology courses, as well as clinicians new to the field of dysarthria.

Chapter 1 Dysarthria Setting the scene

Nick Miller and Margaret Walshe

DOI: 10.4324/9781003172536-1

Introduction

Dysarthria denotes a neuromuscular disorder of speech. It represents probably the most prevalent speech-language disorder. It can be present from birth or be acquired at any age. Up to 53% of people after stroke may experience lasting dysarthria (Miller & Bloch, 2017); it constitutes a common long-term sequel of head injury. Dysarthria accompanies many progressive neurological disorders, with speech–voice changes reported in around 90% of people with Parkinson’s disease (Miller, 2017; Miller et al., 2007; Schalling, Johansson, & Hartelius, 2017), 80% of people with motor neurone disease (Vieira, Costa, Sousa, Reis, & Coelho, 2020), 45–50% with multiple sclerosis (Noffs et al., 2018) and approaching 100% of people with multiple system atrophy and progressive supranuclear palsy (Miller, Nath, Noble, & Burn, 2017). Myasthenia gravis, Huntington’s disease, Bell’s palsy, Ramsay Hunt syndrome, generalised and focal dystonias, muscular dystrophies and mitochondrial disorders (Read et al., 2012) can all involve dysarthria. More than 50% of children with cerebral palsy may be impacted by dysarthria, with many experiencing difficulties into adulthood (Coleman, Weir, Ware, & Boyd, 2015; Tan et al., 2020). Dysarthric sounding speech can be a presenting symptom of functional neurological disorders (see Chapter 2).

Manifestation of dysarthria varies enormously, by cause, course, voice–speech features and severity. This chapter gives a flavour of this variety, along with implications for assessment and rehabilitation. This sets the scene for the remaining chapters, which focus on specific issues of assessment and/or intervention.

Defining dysarthria

The heart of any definition of dysarthria is that speech changes because of neurophysiological alterations to centres and pathways in the central and peripheral nervous systems that play a role in speech production. Typically, this also covers disruption from alterations at the neuromuscular junction and the electrochemistry of muscles themselves. A common account is that the neuromuscular alterations alter tone, and/or power, and/or coordination of movements of the muscles for articulation, which in turn impair the force, range, rate, velocity, sustainability and differentiation of movements of speech. This tells only a fraction of the story.

One can describe dysarthric speech–voice according to changes in different subsystems (respiration, voice, resonance and articulation), sound classes (vowels–consonants, plosives, fricatives, etc.) and prosody (stress, intonation, rate and duration). This still represents a highly oversimplified sketch. The relationship between neuromuscular dysfunction and the range, rate and sustainability of movements is not straightforward. Neither is the relationship between these movement changes and intelligibility transparent (Chiu & Neel, 2020; McAuliffe, Fletcher, Kerr, O’Beirne, & Anderson, 2017; Miller, 2013). Consequently, levels of severity on instrumental clinical measures (e.g. force transducers, acoustics, and electromyography) may poorly reflect how severely communication is impacted, as experienced by the person with dysarthria and their family (see Chapter 7) (Gillivan-Murphy, Miller, & Carding, 2019; McAuliffe, Baylor, & Yorkston, 2017).

Dysarthria is not merely about not moving the articulators. Communication does not happen in a vacuum. It is a social act. Where people communicate, with whom, why and what about, makes immensely diverse demands on speech. Individuals come with a varied experience and lifetime’s set of habits around speaking, as do their partners regarding how they listen to and interact with the person with dysarthria. This signals key lessons for assessing and managing dysarthria (see Chapters 7 and 9).

Equally importantly, a speaker requires vigilance and constant monitoring to maintain attention to effort to keep speech intelligible, to integrate speech with language output and to make sure the correct emotional–affective tone of voice is conveyed. Participating in conversations demands sustaining and switching attention to keep up with content; sufficient speed and capacity of processing to comprehend what is said and compose one’s own responses. Conversations need appropriate non-verbal postural, facial and gestural communication to signal desire to take a turn and to maintain one’s turn; ability to initiate and sustain fluent, audible speech to maintain one’s turn; and so forth. All these facets may be affected in people with dysarthria. Even if someone sounds intelligible, these factors render attempts at communication cognitively and physically challenging for the speaker, again emphasising that understanding dysarthria entails far more than examination of distorted sounds.

Moreover, dysarthria exists, and assessment and rehabilitation take place, against the backdrop of diagnosis of a life-changing, possibly life-limiting condition. The individual’s and family’s dreams and reality have been turned upside down. They face a future of uncertainty or grim inevitability not just regarding physical, cognitive and mental health, but socially, financially and domestically too (Miller, Noble, Jones, Deane, & Gibb, 2011; Walshe & Miller, 2011; Wray & Clarke, 2017; Wray, Clarke, & Forster, 2019).

All these underline the repeatedly stressed imperative that a comprehensive, accurate characterisation of dysarthria must encompass all levels of measurement in the International Classification of Function (Hartelius & Miller, 2010). One may learn something from examining acoustic and articulatory aspects of pronunciation breakdown (impairment), but, if evaluation does not embrace activity (intelligibility and communicative ability) and psychosocial impact of dysarthria on participation in society (see Chapter 7) as well as environmental and cultural factors, one will only ever obtain a partial, distorted understanding. Without incorporating the views and roles of significant listeners in the person’s environment, one sees only half the picture. Furthermore, the same profile of impairment has a different impact on intelligibility and social interaction depending on the cultural-language context of the individual. Ignoring this also diminishes one’s completeness of understanding and assessment of dysarthria (Miller & Lowit, 2014).

The variety of dysarthria

Dysarthria arises in myriad ways. Dysarthria associated with cerebral palsy notwithstanding, it is mostly acquired after childhood. Onset may be sudden (e.g. stroke and head injury) or gradual (neoplasms and progressive neurological conditions).

In stroke and head injury, spontaneous improvement may occur. Resection of neoplasms may win benefits. However, the situation can be highly variable as regards whether (spontaneous) improvement happens, how long it takes or continues and whether speech ever returns to previous levels.

In degenerative conditions, progression may be rapid, gradual or stepwise, with possible periods of (partial) remission along the way. Decline can run over a few years or decades. Dysarthria may be an early severe, inevitable, relentless accompaniment to one condition, but a late occasional, mild sequel in another. For some aetiologies, alterations to voice, speech or resonance during a long prodromal period may signal the first inkling that something is amiss.

Dysarthria/dysphonia can arise as a sole manifestation of an isolated cranial nerve palsy. These cases are exceptional (see Chapter 3). Characteristically, speech alterations constitute but one element in a highly complex picture. Dysarthria exists alongside other physical (e.g. tremor, dystonia and hemiplegia), neuropsychological (e.g. aphasia and visual/auditory-perceptual dysfunction), cognitive and affective (e.g. apathy and depression) changes. Any or all of these might interact with speaking to impact on communication, complicate assessment and pose additional challenges in rehabilitation. In older people, physical, cognitive and psychosocial factors that affect communication in this age group may accompany neurological changes (Palmer et al., 2019).

The multiplicity of co-occurring conditions may colour priorities for intervention. One person is unconcerned that listeners struggle to understand what they say, their only wish is to fix their pain, disruptive dyskinesias, poor sleep, brain fog or whatever. Another person sounds as if they have nothing more than a mildly tremorous voice or hemifacial weakness scarcely impinging on speech, yet this is sufficient to cause a debilitating withdrawal from communicating (Miller, Noble, Jones, Allcock, & Burn, 2008; Walshe & Miller, 2011; Walshe, Miller, Leahy, & Murray, 2008).

Assessment

Why assess

Assessment is a sine qua non of evidence-based working, successful diagnosis and appropriately tailored intervention (Dobinson & Miller 2019; Lowit & Kent, 2011). It should answer why exactly the person is as they are, which factors are impacting their communication and which key elements if they can be modified will make a decisive difference to communication. Findings inform conversations between the person with dysarthria, their family and clinicians about what they want to do, where they want to be and how to get there.

What to assess

Systematic evaluation of dysarthria typically measures the pattern of performance within and across output subsystems – respiration, voice, resonance, articulation, prosody – to establish if and how any of them individually or jointly constitutes a source of reduced communicative ability.

That is a start. Since successful verbal communication is not the property of any single subsystem or articulator but emerges from interaction and coordination between all subsystems and between them and cognitive–affective variables, a vital step is to ascertain how well subsystems combine to produce viable speech/voice. For instance, respiratory support for speech may be satisfactory, but loss of air pressure due to velopharyngeal insufficiency tips the scales towards poor breath support for articulation; tongue tip to palate closure and vocal cord vibration may be independently competent, but poor timing between laryngeal and lingual subsystems leads to dysfluency or/and perceptually ambiguous voiced-voiceless realisations; lip strength may be sufficient for closure, but this is negated by inability to hold the mandible sufficiently raised. Ultimately, judging how well subsystems combine successfully comes from intelligibility evaluation (Lousada, Jesus, Hall, & Joffe, 2014; Miller, 2013; Sescleifer, Francoisse, & Lin, 2018; Wannberg, Schalling, & Hartelius, 2016).

Prosody components such as stress placement and intonation convey essential signals to listeners, not just meaning content but also emotional content. For some people with dysarthria, prosodic changes represent the chief factor undermining communication. Furthermore, a monoloud or monotone voice can contribute to negative perception of speakers. Therefore, inclusion of ability to convey differences in meaning dependent on stress and intonation and signalling different emotional content (sad, happy, tentative, etc.) is indispensable.

Because communication is a social act, assessment of the individual’s communicative environment, how communication changes have impacted on them, their views on where, when, why and how they wish to communicate and the roles and views of significant listeners are as important as any narrower focus on voice, speech and gesture examination (see Chapters 7 and 9). Given the non-linear relationship between physiological impairment, intelligibility and perceived impact on participation, meaningful assessment must combine all these strands. Attention, speed of processing, language, non-verbal and gestural communication and...