0131722514 pp6

Chapter 6:
Motor Speech Disorders:
Apraxia and Dysarthria
Justice
Communication 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?
identified?
treated?
6.1
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

• 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
Justice
Introduction

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
Justice
Introduction

• 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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

INDIVIDUAL DIFFERENCES:
• Differences occur between individuals in:
-ability to compensate
-ability to use unimpaired systems
-general life response
-response to treatment
6.23
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

Types of Acquired Dysarthria
• Spastic
• Flaccid
• Hypokinetic
• Hyperkinetic
• Ataxic
• Unilateral Upper Motor Neuron (UUMN)
6.28
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

Treatment of Phonatory System
• Improving voice quality (e.g., postural
adjustments, relaxation therapy)
• Controlling vocal folds to enhance
naturalness of speech
6.41
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

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
Justice
Introduction

0131722514 pp6

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