CODI 555 Motor Speech Disorders
Lecture 4: Basal Ganglia Disorders: Hypokinetic/Hyperkinetic
Dysarthria
Basal Ganglia Control Circuits
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Consist of several intertwining loops among the basal ganglia nuclei
& thalamic nuclei
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Striatum (caudate & putamen) is receiver of input to basal ganglia
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Frontal cortex especially premotor area
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Thalamic nuclei
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Substantia nigra
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Striatum sends output to substantial nigra & globus pallidus
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Globus pallidus is site or origin for major efferent (output) from
basal ganglia
Basal Ganglia Pathways
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Loops
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Striatum to globus pallidus to thalamus to cortex to striatum
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Striatum to substantia nigra to striatum
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Globus pallidus to subthalamus to globus pallidus
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Efferent pathways - major pathway is from globus pallidus to ventrolateral
nucleus of the thalamus and then back to cortex
Functions of the Basal Ganglia Control Circuits
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Site for 2 influential neurotransmitters - dopamine and acetylcholine
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Balance between these two NT within the striatum is important for
motor control
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Regulation of amplitude, velocity and initiation of movement
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Probably aid in generating components of motor speech programs
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Modulate cortical discharges/ suppression of unwanted movements
Effects of Lesions within Basal Ganglia Circuits
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Hypokinesia - reduced mobility
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Increase in muscle tone
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Resistence to movement
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Movements are slow, stiff and difficult to initiate or stop
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Results from lack of dopamine in basal ganglia circuits
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Hyperkinesia - involuntary movements
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Excessive, unpredictable increases in muscle tone and movement
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Result of excessive activity in dopaminergic nerve fibers
Hypokinetic Dysarthria: Common Etiologies
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Degenerative diseases - Parkinson’s disease, nigrostriatal degeneration,
dementing diseases such as Alzheimer’s and Pick’s
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Multiple or bilateral strokes affecting basal ganglia
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Toxic-metabolic - antipsychotic medications, MPTP, chronic heavy
metal exposure, Wilson’s Diseas
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TBI - repeated head trauma as in boxers
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Infectious - viral encephalitis
Hypokinetic Dysarthria: Speech Musculature Deficits
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Resting tremor in jaw, lip, tongue
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Rigidity - cogwheel rigidity
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Bradykinesia - freezing
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Hypokinesia/akinesia - reduced frequency of swallow
Hypokinetic Dysarthria: Other Neuromuscular Deficits
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Resting tremors of head, limbs, pill-rolling
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Festinating gait
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Decrease in spontaneous movements such as arm swing, limb gestures
during speech, eye-blinking, head movements to accompany eye movement
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Micrographia
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Masked facies
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Loss of postural reflexes
Hypokinetic Dysarthria: Nonspeech Oral Mechanism Deficits
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Face masked or expressionless at rest
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Infrequent swallows resulting in drooling
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Tremor of jaw, lips, tongue at rest and in sustained postures
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Direction and rhythm of movements normal
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Rate of individual movements may be slow, repetitive movements may
be fast
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Range and force are reduced; tone is excessive
Hypokinetic Dysarthria: Patient Perceptions & Complaints
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Weak or quiet voice
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Can’t be heard in noise
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Rate is too fast- speech indistinct
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Trouble starting speech or “stutter”
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Voice lacks emotional tone
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Problems with drooling or swallowing
Hypokinetic Dysarthria: Distinguishing clusters
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Prosodic insufficiency (monopitch, monoloudness, reduced stress,
short phrases, variable rate, short rushes of speech and imprecise consonants)
Hypokinetic Dysarthria: Most Distinctive Speech Deviations
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Monopitch
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Monoloudness
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Reduced overall loudness
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Variable rate
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Short rushes of speech
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Some inappropriate silences
Hyperkinetic Dysarthria: Common Etiologies
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Damage to basal ganglia control circuits, portions of cerebellar
control circuits or indirect activation pathways
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Often result of neurochemical abnormalities rather than structural
lesions
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Degenerative diseases - Huntington’s
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Toxic-metabolic - neuroleptic or antipsychotic drugs, tardive dyskinesia
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Unknown etiologies - Tourette’s, Meige’s syndrome
Hyperkinetic Dysarthria: Neuromotor Deficits
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Abnormal involuntary movements occur at rest, during sustained postures
or during voluntary movement
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“hyper” refers to excessive or extra movements and does not imply
that the speed of the involuntary movements is fast
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Rate of movements can range from very fast to slow
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Pattern of Movements can be rhythmic or irregular
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Generally, voluntary movements of affected body parts is slow
Hyperkinetic Dysarthria: Types of Movement Disorders
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Dyskinesia
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Myoclonus
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Tics
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Chorea
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Ballism
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Athetosis
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Dystonia
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Spasm
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Tremor
Hyperkinetic Dysarthria: Patient Perceptions & Complaints
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Nonrhythmic hyperkinesias - slurred, slow or halting speech -“hard
to get out”
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Feelings of tightness, inability to move affected structure
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Laryngeal hyperkinesias - shaky voice, voice is tight or closes off,
“voice doesn’t want to come out”
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Shortness of breath/fatigue during speech but not in nonspeech activities
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Development of “sensory tricks”
Hyperkinetic Dysarthria: Chorea
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Possible drooling, chewing and swallowing problems
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Transient and unpredictable symptoms including hypernasality, strained-harshness,
breathiness, articulatory distortions, loudness variations and sudden forced
inspiration and expiration
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Above combined with attempts to avoid/compensate often result in
prolonged intervals and phonemes, variable rate, inappropriate silences,
voice arrest and disturbed stress
Hyperkinetic Dysarthria: Dystonia
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Complain of food getting stuck in throat; chewing difficulty
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Movements most evident at rest or during sustained postures
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Nearly all aspects of movement disturbed
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Imprecision and irregular articulatory breakdowns
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Inappropriate variations of loudness and rate
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Strained harshness, transient breathiness, audible inspiration
Hyperkinetic Dysarthria: Spasmodic torticollis
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Affects cervical neck muscles
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Effects on speech thought to be secondary to abnormal neck positions
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Usually articulatory and laryngeal in nature
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Slow initiation of speech, reduced maximum duration, reduced pitch
and pitch variability, dysphonia and reduced rate
Hyperkinetic Dysarthria: Palatopharyngolarygneal myoclonus
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Pt. May complain of earclicks but usually unaware of speech
symptoms
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Brief voice arrests or myoclonic beats
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Brief silent intervals
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Occasional, intermittent hypernasality
Hyperkinetic Dysarthria: Action Myoclonus
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Occasional voice arrests
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Slow rate, imprecision, marked irregularity of AMR’s with increased
rate
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Awareness of imprecise speech and reluctance to speak at normal or
rapid rates