chapter 12: motor speech disorders: apraxia and dysarthria

Chapter 6:

Motor Speech Disorders:Apraxia and Dysarthria

JusticeCommunication Sciences and Disorders: An Introduction

Copyright ©2006 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

Focus Questions

• What is a motor speech disorder?• How are motor speech disorders

classified?• What are the characteristics of prevalent

types of motor speech disorders?• How are motor speech disorders

identified?• How are motor speech disorders

treated?

6.1




Introduction• Speech production is one of the most

“impressive motor skills”

• Control of speech movements follows a course of development up to age 12; humans acquire adult-like speech motor control by adolescence

• Childhood motor speech problems most likely caused by neurological difficulties, and adults can experience also after injuries or illnesses

• Two major categories: apraxia and dysarthria

6.2




Case Study #1: Bob

• 42-year old bilingual, married with four children, travels, coaches soccer, involved in community activities

• Diagnosed with cerebellar tumor, removed successfully, but effects from surgery…

• Severely ataxic, difficulties coordinating voluntary movements, under- and over-shooting movements, and tremor

• Now requires wheelchair and only about 30% of speech is intelligible

6.3




Case Study #1 Questions

• What are some ways Bob’s communicative difficulties affect his participation in life?

• What types of strategies might you suggest to improve Bob’s participation in life?

6.4




Case Study #2: Walter

• 60-year old professor, likes to read, play tennis, improve the house, and play piano

• Age 59, left hemisphere stroke – now slow, effortful, and inconsistently distorted speech and weakness in right side of body, including oral structures (e.g. lips)

• SLP diagnosed him with mild aphasia and mild apraxia of speech – 95% intelligible

6.5




Case Study #2 Questions

• On which of Walter’s strengths might you attempt to capitalize in developing a treatment plan?

• Discuss some specific ways in which Walter’s participation in life is affected by his speech problems.

6.6




Case Study #3: Hikaru• 5-year old came to U.S. from Japan at 2, primarily

English speaker, but understands Japanese also

• Referred to evaluation by mother – fewer sounds during babbling stage, history of drooling and hypotonia, asymmetries between L and R hemispheres (cerebral palsy), delays in syntax and phonology, speech is imprecise and weak

• Weakness limited to articulatory system, and does not show characteristics consistent with apraxia of speech

• Mother wants to hold back in kindergarten

6.7




Case Study #3 Questions• Japanese is a language that does not

have consonant clusters and syllable-final consonants (“truck”). Why is this important information for evaluation and diagnosis? What other differences between Japanese and English might be relevant for fully understanding Hikaru’s problems?

• What are some pro’s and con’s of holding Hikaru back for a second year of kindergarten?

6.8




I. What is a Motor Speech Disorder?

• Speech production deficit that results from impairment of the neuromuscular and/or motor control system

• May co-occur with other language impairments

• Other oral movements (besides speech) may be impaired, including chewing and smiling

6.9




Terminology

Four Subsystems of Speech Production:• Respiratory• Phonatory• Resonatory• Articulatory

The muscles and muscle groups in these subsystems must be coordinated in time and space

6.10




Respiratory System• Speech production requires airflow• Pulmonary airstream mechanism: pushes air

out of lungs through trachea (windpipe) to produce airflow

• Ingressive – inhalation• Egressive – exhalation

-1:6 inhalation:exhalation ratio during speech production

• Exhalation cycle needs to be extended in time (for completion of utterance) and modulation (to reflect stress)

6.11




Phonatory System

• Includes various muscles and structures in the larynx, and regulates the production of voice and the intonational aspects of speech

• Vocal folds are brought closely together, and the airflow builds up to set the vocal folds into vibration

• Vocal folds are stretched lengthwise to manipulate the frequency or pitch of the voice

6.12




Resonatory System• Regulates the vibration of the airflow as it

moves from the pharynx into the oral and nasal cavity

• Manipulates shape and size of vocal tract for maintaining normal sound quality

• Manipulates the velo-pharyngeal port, (whether nasal cavity is used as a vibrating chamber) for determining nasality of sounds– oral vs. nasal sounds – b and p vs. m and n

6.13




Articulatory System• Control of the articulators within the oral

cavity to manipulate the outgoing airflow

• Major structures: lower jaw, lips, tongue (most important)

• Tongue: intrinsic muscles (fine-tuned movements) and extrinsic muscles (coarse movements – protrusion, retraction, elevation, depression)

• Muscles contract to create constrictions in the oral cavity to produce varying sounds

6.14




Motor Control

• To maintain speed and fluency, the sequences of movements are programmed together as a single movement unit– Degrees of freedom: the number of elements

that can be independently controlled– The greater the degrees of freedom, the greater

the challenge to the speaker

• Speakers reduce the number of degrees of freedom by organizing motor actions into motor units

6.15




Motor Units• Motor unit: single control mechanism that

controls more than one degree of freedom– Basic pattern of movement components remains

constant, while more specific aspects of movements are influenced by specific circumstances

• Producing speech involves producing both linguistic units and acoustic events– This requires coordination of muscle groups and

programming muscle activities into single motor units to ensure fluent and accurate articulation

6.16




Planning, Programming, and Execution

• Motor planning: processes that define and sequence articulatory goals (prior to initiation of movement)

• Motor programming: processes that establish and prepare the flow of motor info across muscle, as well as control timing and force of movement (prior to initiation of movement)

• Motor Execution: processes that activate relevant muscles (during and after initiation of movement)

6.17




Motor Learning• Extensive practice and experience

producing speech leads to motor learning (“permanent changes in capability of movement”)

• Schema Theory: memory representations of motor specifications needed to reach a desired speech outcome (schemas)– become stronger with experience– person uses stored schema to produce

desired speech outcomes

6.18




Prevalence and Incidence• Reliable estimates are rare, however…

– Among adults with acquired communication disorders, 51% have motor speech disorders (46% dysarthria, 5% apraxia of speech)

– Among children with developmental communication disorders, about 5% have motor speech disorders

-Difficulty to find estimates because of difficulties in identification and long standing debates about diagnosing motor speech problems in children

6.19




II. How are Motor Speech Disorders Classified?

ETIOLOGY:

• Acquired: damage to a previously intact nervous system

-caused by cerebrovascular accidents (strokes) degenerative diseases, brain tumors or traumatic brain injury

• Developmental: abnormal development of or damage to the nervous system

-caused by congenital diseases, or damage to the developing nervous system (different effects than damage to an already intact system)

6.20




MANIFESTATION:

• Impairments of Planning/Programming: coordination of relevant muscles and muscle groups is disrupted (muscle physiology and movement is intact)

• Impairments of Execution: disruptions in muscle physiology – affected by involuntary movements and reductions in movement abilities (whether speech is programmed normally or not)

6.21




SEVERITY:

World Health Organization (WHO):

• Disease: underlying physiological condition or psychological cause

• Activity: actual behavioral or performance deficits that result from the disease

• Participation in life: how the disease impacts upon quality of life of individual at home, school, work, and in the community

6.22




INDIVIDUAL DIFFERENCES:

• Differences occur between individuals in:

-ability to compensate

-ability to use unimpaired systems

-general life response

-response to treatment

6.23




III. Defining Characteristics of Prevalent Types of Motor Speech

Disorders• Motor Planning/Programming Disorders:

inability to group and sequence the relevant muscle with respect to each other-apraxia of speech (AOS) – acquired and developmental

• Motor Execution Disorders: deficits in physiology and movement abilities of muscles-dysarthria – acquired and developmental

6.24




Acquired AOS• Inability to transform an intact linguistic

representation into coordinated movements of the articulators

• Characteristics: slow speech, sound distortions, prolonged durations of sounds, reduced prosody, consistent errors within an utterance, difficulties initiating speech, groping of articulators

• Caused by neurological damage to the left frontal cortex surrounding Broca’s Area – due to stroke, brain injuries, illness, and infections

6.25




Childhood AOS• Salient characteristics of this disorder is

the same as acquired AOS• Considerable delay in speech production,

limited sound inventory, unintelligibility, and progress slowly in speech therapy

• Causes are not well understood; some research points to hereditary component, not clear there is specific neurological damage

• Some cases caused by stroke or traumatic brain injury

6.26




Acquired Dysarthria• Disruption in the execution of speech

movements resulting from neuromuscular disturbances to muscle tone, reflexes, and kinematic aspects of movement

• Speech sounds slow, slurred, harsh or quiet, or uneven depending on the type of dysarthria

• Three concepts: spasticity, dyskinesia, ataxia• Typically occurs because of a progressive

disease or trauma

6.27




Types of Acquired Dysarthria

• Spastic

• Flaccid

• Hypokinetic

• Hyperkinetic

• Ataxic

• Unilateral Upper Motor Neuron (UUMN)

6.28




Developmental Dysarthria

• Present at birth

• Usually occurs along with known disturbance to neuromotor functioning

• Can be caused by pre-, peri-, or post-natal damage to the nervous system

• Most common types:

-spastic

-dyskinetic

6.29




IV. How are Motor Speech Disorders Identified?

The Assessment Process:

-professionals consider how the disorder affects the individual’s life to determine the impairment and the course for treatment

-assessment of motor speech disorders should include measures of nonspeech oral motor skills and should isolate particular motor subsystems to determine impairment

6.30




Measurement Methods• Perceptual measures – perceptual

judgments of intelligibility, accuracy, and speed of speech production (most common)

• Acoustic measures – visual representation of the speech sound wave (e.g., spectogram) for more detailed and objective view of speech problems

• Physiologic measures – measurement of physiologic aspects of speech motor system not easily perceived otherwise (e.g., muscle strength)

6.31




Referral and Screening

• Referral – typically from a hospital, school, or parents of child – depending on whether acquired or developmental disorder

• Screening – includes interviews with patient and family and review of medical history

6.32




Comprehensive Motor Speech Evaluation

• Should involve motor control tasks that involve speech and nonspeech motor activities

• Should assess the motor speech problems at each of the levels of functioning – disease, activity, and participation in life

• Should include assessment of each of the subsystems separately – respiration, phonation, resonation, articulation, and also include prosody

6.33




Diagnosis

• After assessment, findings are interpreted to come up with a speech diagnosis

• In current practice, differential diagnosis is based largely on auditory perceptual measures (the professional’s perceptual observations), not yet on objective acoustic and physiologic indicators

• Diagnosis involves understanding the hit rate, miss rate, false positive rate, and the correct rejection rate

6.34




V. How are Motor Speech Disorders Treated?

• Treatment focuses on (re)learning motor aspects of speech production, which requires acquisition, retention, and generalization– Acquisition: temporary improvements during

treatment– Retention: lasting performance enhancements– Generalization: improvements in either related

but untrained behaviors (response) or in targeted behaviors in different contexts, tasks, or settings (stimulus)

6.35




Treatment Targets

• Use of nonspeech tasks (e.g., pursing the lips, smiling, moving the tongue) in assessment does not mean that nonspeech tasks should be used in treatment

• Little research supports “oral motor activities” to strengthen the articulators or improve their movements

• Focusing on more complex targets results in greater learning than focusing on simpler targets

6.36




Treatment Strategies

Primary Strategies: Two Approaches– Improve impaired subsystem – focus on

specific functions in relevant speech tasks• e.g., improve respiratory support for speech

– Compensatory strategies

… for the affected individual

… for the environment

… for the communication partners

6.37




Treatment Contexts

• Important indicator of treatment effectiveness is generalization

• Speech production in other tasks and with different conversational partners should be included the routine assessment process

6.38




The Treatment Plan

• Pre-practice considerations – several conditions should be considered and discussed prior to treatment:

-memory

-attention

-motivation

-goal setting

-establishing a reference of correctness

6.39




Treatment of Respiratory System

• Establishing respiratory support (e.g., making postural adjustments)

• Modifying inhalation (e.g., increasing duration of air intake)

• Modifying exhalation (e.g., vowel prolongation)• Improving inhalation/exhalation relationship• Increasing respiratory flexibility (e.g., producing

words with a variety of stress patterns)

6.40




Treatment of Phonatory System

• Improving voice quality (e.g., postural adjustments, relaxation therapy)

• Controlling vocal folds to enhance naturalness of speech

6.41




Treatment of Phonatory System

• Improvement of strength and control of velo-pharyngeal port (e.g., practicing nasal vs. oral airflow patterns)

• Might be necessary to use a palatal lift – a device that helps raise the velum – depending on severity of subsystem impairment

6.42




Treatment of Articulatory System

• Focus the patient’s attention to the accuracy, range, and direction of movement during speech

• Feedback from the clinician can include articulatory placement cues (e.g., modeling speech production)

6.43




Treatment of Prosody and Rate Control

• Prosody involves manipulation of three factors: loudness, pitch, and duration

• Each of these factors should be focused on during treatment

• Approaches to reducing the rate of speech:

-rigid control techniques

-non-rigid control techniques

6.44




chapter 12: motor speech disorders: apraxia and dysarthria

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