Motor Speech Disorders Samantha Shune, PhD, CCC-SLP sshune@uoregon.edu

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

Introduction

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

Cognitive-Communication Disorder Aphasia Apraxia of Speech Dysarthria

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

Motor speech disorders are a significant proportion of acquired communication disorders

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)

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

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

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

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)

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.

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

(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

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

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…

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

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

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

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.

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

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

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]

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

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

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

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

Video/Audio samples

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