1. Motor Speech Disorders
Samantha Shune, PhD, CCC-SLP

2. Preview Brief introduction to motor speech disorders
Brief neuroanatomy primer
Video samples

3. Introduction

4. Neurogenic Communication Disorders
Neurogenic communication disorders can be defined as impairments in speaking, listening, reading, and writing skills that result from damage in different parts of the nervous system.
These impairments include:
Aphasia
Cognitive-Communication Disorders
Motor Speech Disorders
Dysarthria
Apraxia of Speech

5. Cognitive-Communication Disorder
Aphasia
Apraxia of Speech
Dysarthria

6. Motor Speech Disorders
Motor speech disorders can be defined as disorders of speech resulting from neurologic impairments affecting the:
Motor planning,
Motor programming, or
Neuromuscular execution of speech
Dysarthria and apraxia of speech
MSDs encompass the dysarthrias and apraxia of speech
MSDs are NOT: anatomic/structural abnormalities; articulation/phonological disorders; dysphonia; dysfluency; psychogenic impairments; language impairments; cognitive impairments; normal aging changes

7. Motor speech disorders are a significant proportion of acquired communication disorders

8. Etiologies of Motor Speech Disorders
VITAMIN D (Dworkin, 1991)
V vascular accidents
I infectious processes
T traumatic insults
A allergic or anoxic
M metabolic disorders
I idiopathic
N neoplasms
D degenerative demyelinating
Vascular is probably the most common (embolism, thrombosis, hemorrhage)
These will differ based on localization (focal versus diffuse), the course or temporal profile (acute - minutes, sub-acute - days, or chronic - months), and evolution of the disease (transient, improving, progressive, exacerbating remitting, stationary)

9. Major types of MSDs Type Localization Neuromotor basis
Flaccid Dysarthria
Lower motor neuron
Weakness
Spastic Dysarthria
Bilateral upper motor neuron
Spasticity
Ataxic Dysarthria
Cerebellum
Incoordination
Hypokinetic Dysarthria
Basal ganglia control circuit
Rigidity/reduced range of movement
Hyperkinetic Dysarthria
Involuntary movements
Unilateral Upper Motor Neurons (UUMN) Dysarthria
Unilateral upper motor neurons
Weakness, incoordination, or spasticity
Mixed
More than one
Apraxia of Speech
Left (dominant) hemisphere
Motor planning
Looking at where the neurologic impairment is this should make sense:
Flaccid and Spastic are generally disorders of execution
Ataxic, Hypokinetic, Hyperkinetic are issues with control
UUMN execution and control
Apraxia motor planning/programming

10. Distribution of MSDs Type Percentage Flaccid Dysarthria 8%
Spastic Dysarthria 7%
Ataxic Dysarthria 9%
Hypokinetic Dysarthria
Hyperkinetic Dysarthria
19%
Unilateral Upper Motor Neurons Dysarthria
Mixed
28%
Apraxia of Speech
Dysarthria, type undetermined 4%
From Duffy, 2012

11. Methods for Studying & Categorizing MSDs
Perceptual
Eyes, ears, and hands
Examples
Prolonged /a/
Diodokinetic task /pataka/
Read grandfather passage
Oral motor examination
Multidimensional Classification System (DAB 1969, 1975): disease process, anatomical areas, cranial nerves, speech process, perceptual characteristics
They are the gold standard for clinical differential diagnosis, judgments of severity, many decisions about management, and the assessment of meaningful temporal change. DAB’s perceptually based classification scheme really is the framework in which MSDs are commonly discussed.
Rarely have I had access to equipment in clinical practice…
Of course, that means they can be highly subjective and difficult to quantify – this will be a focus of this class, but of course this is a skill that you will continue to develop and hone in your clinical practice.
But, these are the starting point for evaluation. Everyone will undergo a perceptual evaluation if they have a suspected MSD

12. Methods for Studying & Categorizing MSDs
Instrumental
Acoustic methods
Same data as perceptual = speech signal
Provides quantification, description, and confirmation of human (clinical) perception
As mentioned though, instrumental methods are not widely used in the clinical evaluation and management of MSDs
Instrumentation can also be used therapeutically (feedback methods)

13. Methods for Studying & Categorizing MSDs
Instrumental
Physiologic methods
Study of movements of speech structures, air flow and air pressure, muscle contraction, nervous system, CNS and PNS activities in relationship to biomechanical activity and and CNS activity during speech planning and execution.
Ex.
Electromyography and aerodynamic measures
Before we focused on the sounds emitted from the vocal tract – these measures are more “upstream”. Thus these are crucial to establishing the relationships between pathophysiology (e.g., weakness, spasticity, and incoordination) and the acoustic and perceptual attributes of MSDs.

14. Methods for Studying & Categorizing MSDs
Instrumental
Visual imaging methods
Allows visualization of upper aerodigestive tract during speech
Ex.
Videofluoroscopy
Nasoendoscopy
Videostroboscopy

15. (Re)visiting neuroanatomy
The diagnosis and treatment of motor speech disorders really relies on a strong understanding of neuroanatomy and neurophysiology. Perceptual evaluation will also be guided by understanding the underlying deficits and etiologies…
(Re)visiting neuroanatomy

16. Speech Motor System The final common pathway
Lower motor neurons
Cranial and spinal nerves
The direct activation pathway
Upper motor neurons (pyramidal system)
Corticobulbar and corticospinal tracts
The indirect activation pathway
Upper motor neurons (extrapyramidal system)
The control circuits
Basal ganglia and cerebellar

17. Final Common Pathway Lower motor neuron system
Brainstem and spinal cord  muscles
Includes: cranial nerves supplying muscles for phonation, resonance, articulation, and prosody; spinal nerves for respiration and prosody
CN V (trigeminal), VII (facial), IX (glossopharyngeal), X (vagus), XI (accessory), XII (hypoglossal)
The cranial nerves we are particularly interested in for speech are…

18. Damage to lower motor neuron system
Weakness
Paralysis
Diminished reflexes
Decreased muscle tone
Atrophy
Fasciculations
Flaccid dysarthria

19. Direct Activation Pathway
Upper motor neurons with direct, fast connection and influence on lower motor neurons
Includes: corticobulbar tract (cortex to brainstem/cranial nerves); corticospinal tract (cortex to spine/spinal nerves)
UMNs are encased in the brain and spinal cord. These DIRECTLY innervate the motor neurons
Activities lead to movement (not inhibition of movement) and generally finely controlled, skilled, and voluntary movement

20. Damage to direct activation pathway
Loss or reduction of skilled movement
Unilateral upper motor neuron lesion = contralateral weakness
Particularly of tongue, lower face
Bilateral upper motor neuron lesion = bilateral weakness and alterations in muscle tone (spasticity)
Normal reflexes
UUMN, spastic dysarthria

21. Indirect Activation Pathway
Upper motor neurons with indirect influence on lower motor neurons
Effects of damage:
Increased muscle tone (spasticity)
Hyperreflexia
UUMN, spastic dysarthria
Complex and its functions for speech are poorly understood. Made up of lots of different pathways connecting relevant parts of the system – a number of different, interconnected descending motor pathways. Many of the tracts begin in the brainstem region and travel down to the spinal cord – lots of communication with the spinal cord
Is a source of input to LMNs like the direct pathway and has anatomical and functional similarities to the basal ganglia and cerebellar control circuits
Thus, while they do connect higher levels of the nervous system and the cranial or spinal nerves, usually we are talking about paths here that originate in the brainstem. But they are influenced by the cortex, BG, cerebellum as all have neural connections to this system.
Control the postural support needed by the fine motor movements in the pyramidal tracts. Responsible for modulation and regulation of motor activity.

22. Control Circuits Basal ganglia and cerebellum Effects of damage
Coordinate, integrate, control movement activites
Effects of damage
Cerebellar control
Ataxia, incoordination
Intention tremor
Dysdiodokinesia
Ataxic dysarthria
Basal ganglia control
Hypokinesia (too little movement)
Hyperkinesia (too much movement)
Hypokinetic, hyperkinetic dysarthria

23. What does this damage look like in speech?
Flaccid (‘weakness’)
Articulation: imprecise consonant production
Phonation: breathy/hoarse voice quality, diplophonia, short phrases, weak cough or glottal coup, vocal flutter, audible inhalations (stridor)
Prosody: monopitch, monoloudness
Resonance: hypernasality, nasal emissions, weak pressure consonants
Respiration: reduced loudness, short phrases, strained vocal quality

24. Spastic (‘spasticity’)
Articulation: imprecise consonant production, labored and slow production
Phonation: harsh and/or strained-strangled vocal quality, low pitch, short phrases, pitch breaks
Prosody: monopitch, monoloudness, slow rate
Resonance: hypernasality
Respiration: [shallow, slow inhalation]

25. Ataxic (‘incoordination’)
Articulation: imprecise consonant production, distorted vowels (slurred), irregular breakdowns
Phonation: harsh vocal quality, voice tremor
Prosody: equal and excess stress, prolonged phonemes and intervals between phonemes, monopitch, monoloudness, slow rate
Resonance: [intermittent hyponasality]
Respiration: exaggerated and/or paradoximal mvmt

26. Hypokinetic (‘diminished movement’)
Articulation: imprecise consonants, repeated phonemes, palilalia
Phonation: harsh or breathy voice, low pitch
Prosody: monopitch, monoloudness (low), reduced stress, inappropriate pauses, short rushes of speech
Resonance: [mild hypernasality]
Respiration: faster breathing rates, incoordination of muscles, shallow breath support, poor control of exhalation for speech

27. Hyperkinetic (‘extraneous movement’)
Articulation: imprecise consonants, distorted vowels, prolonged phonemes
Phonation: harsh, strain-strangled, or breathy voice, excess loudness variation, voice stoppage
Prosody: prolonged intervals between syllables/ words, variable rate of speech, monopitch, inappropriate silences, monoloudness
Resonance: hypernasality and hyponasality
Respiration: unexpected inhalations and exhalations

28. Motor System Actions Motor Planning Motor Programming Motor Execution
Higher level
Goal-oriented
What to do
Plans are inflexible
Sets the plan for place & manner of articulation
Premotor cortex
Insular cortex
Lower level
Procedure-oriented
How to do it
Modifiable via sensory feedback
Detailed program of motor acts across 5 speech systems
Basal ganglia
Cerebellum
Lowest level
Muscle oriented
Do it
Executes muscle movements
Upper motor neurons
Lower motor neurons
Apraxia of Speech
Dysarthrias

29. Video/Audio samples

30. Questions/comments?