1. What causes ataxic dysarthia?
Damage to the cerebellum or to the neural pathways that connect the cerebellum to other parts of the CNS.
2. What is the primary function of the cerebellum?
To coordinate the timing and force of muscular contractions so that skilled, voluntary movements are appropriate for an intended task. It processes sensory information from all over the body and integrating that information into the execution of a movement
3. Explain how the cerebellum is able to monitor ongoing movements
and communicate with the cortex concerning planned upcoming movements.
There are three neural tracts through which the cerebellum communicates. The inferior, middle and superior peduncles
Inferior: transmits sensory information from the entire body to the cerebellum
-receives sensory information from the entire body: position, vestibular system, joints, skin, tendons, and muscles.
-provides cerebellum with position of body before, during and after a movement
-monitors whether the impulse to the muscles is achieving the intended results.
-monitors the timing and force of movements while they are being performed
middle peduncle: transmits planned movements from the association cortex
to the cerebellum
-largest of the cerebellar peduncles
-connects cortex with the cerebellum
-cerebellum receives preliminary information from the cortex regarding planned movements
-cerebellum coordinates these planned movements by integrating sensory information it receives from the entire body with the individual’s experience of what the appropriate movement should be. The intended movements are refined according to the current conditions of the body and sent back to the cortex via the thalamus. The refined motor commands are then sent (via superior peduncle) to the motor areas of the cortex where they are transmitted to the appropriate muscles.
superior peduncle: transmits cerebellar commands to the cortex and the
-cerebellum’s output channel to the rest of the CNS.
-destinations: cerebral cortex or the neurons of the extrapyramidal tract
-cortex: sends processed motor impulses to the motor areas of the cortex completing the cortiococerebellar control circuit.
Neurons of extrapyramidal tract: cerebellar commands course through the extrapyramidal system to the appropriate lower motor neurons and thus, coordinate and adjust the movements of the voluntary muscles according to the changing positions and circumstances of the body by stimulating or inhibiting the actions of the voluntary muscles.
4. What is the corticocerebellar control circuit? Information starts in the cortex and courses down into the cerebellum through the middle peduncle. The fibers of this neural circuit exit the cerebellum through the superior peduncle and travel back up to the cortex after passing through the thalamus.
5. Are the cerebellar control circuits upper motor neurons? Explain. No. because they do not synapse with lower motor neurons.
6. How does the cerebellum influence speech movements?
The cerebellum coordinates and refines the planned motor impulses sent from the cortex based on the sensory information about the positions and conditions of the articulators and on prior practice on what the skilled target movement should be.
Adjustment in the timing and force of the movements to compensate for unexpected change in the circumstances of a movement may be influenced by connections of the cerebellum to the extrapyramidal system.
Therefore the cerebellum is able to coordinate and modify both planned and ongoing speech movements.
7. Does damage to the cerebellum or its control circuits affect speech? Significantly
8. Define cerebellar ataxia: movement deficits of timing, force, range, and direction.
9. Describe some of the symptoms of cerebellar damage.
Impairment of equilibrium during walking
Deficits in voluntary eye movements
Hypotonia of the muscles
Problems with motor learning
10. What are some of the causes of ataxic dysarthria
a. Autosomal dominant cerebellar ataxia of late onset:
-cerebellar ataxia, number of neurological features: retinal degeneration, muscle rigidity, deafness, balance and dementia
b. Idiopathic sporadic late-onset cerebellar ataxia: similar to above but not as many neurological symptoms
-cerebellar ataxia, ataxic dysarthria, balance
c. Friedreich’s ataxia: affects spinal cord also (spinocerebellar disease); affects gait, dexterity, dysarthria and vision; also affects lower motor neuron and extrapyramidal system (Mixed dysarthria)
d. Olivopontocerebellar degeneration caused by atrophy of middle cerebellar peduncle, cerebellum, can also affect basal ganglia and some of the corticospinal tract. Exhibits cerebellar ataxia, parkinsonian symptoms of rigidity, reduced range of movement (Mixed dysarthria)
Stroke: sudden onset of cerebellar signs: limb ataxia, balance, vision, ataxic dysarthria
-blockage of flow to cerebellar artery; anteriorinferior cerebellar artery
-intercerebral hemorrhages (affect cerebellum or the neurons in the cerebellar control circuits.
Toxic Conditions: Lead, mercury poisoning; alcohol, exposure to chemicals; medicines (Dilantin)
Deficiency E or B12, hypothyroidism, Wilson’s disease
a. metastatic tumors: tumors that seed a secondary tumor
b. Low-gade astrocytoma:slow growing tumors
c. Hemangioblastomas benign tumors of proliferated blood vessels
11. Define scanning speech.
Speech that is slow and there is a deliberate production of the syllables with each syllable in a word receiving equal stress.
12. What are the defining speech characteristics of Ataxic Dysarthria?
Primary are articulatory “drunken quality”; irregular breakdown
Prosody: prosody is monotonous due to equal stress; scanning speech; equal and excess stress
13. What is another hallmark of cerebellar damage: slow movement on both single and repetitive motion task probably caused by decreased muscle tone
14. How are the processes of speech affected by Ataxic Dysarthria?
a. imprecise consonant articulation
b. distorted vowels (slurred quality)
c. irregular articulatory breakdown: imprecise consonant and vowel productions that can vary from utterance to utterance. Primarily in multisyllabic words. Breakdowns give the appearance that the syllables are compressed during the production of a word.
d. hyperkinetic and ataxia are the only dysarthrias that have irregular breakdown (with other dysarthrias, errors are consistent during speech.
a. Equal and excess stress
b. Prolonged phonemes
c. Prolonged intervals between phonemes
f. Slow rate.
Harsh vocal quality caused by decreased muscle tone which prevents full contraction of the muscles
Resonance: seldom a problem
Respiration: Cerebellar damage can cause uncoordinated movements; respiration during speech can contain exaggerated or paradoxical movments
Exaggerated movements can lead to excessive loudness;
Pardoxical movement can limit subglottic air available for speech which causes the person to speak on residual air which can lead to an increased rate of speech, decreased loudness and a harsh voice
15. What happens when an individual speaks on residual air?
leads to an increased rate of speech, decreased loudness and a harsh voice
16. What are some key evaluation tasks for ataxia dysarthria?
1. AMR’s rate is slower than normal with an unsteady rhythm; sometimes they speed up abruptly and then unexpectedly slow down during the speech production task. Difficulty maintaining a regular rhythm highlights how cerebellar damage can affect the timing of movements by different muscle groups.
2. Reading, conversational speech, repeating sentences containing multisyllabic words: reveal inaccurate speech movements: irregular articulatory breakdowns; reveal prosodic errors.
17. What is the TX for ataxia dysarthria?
Respiration:Uncoordinated movements of the respiratory muscles result in speaking on residual air which affects prosody and phonation
a. speak immediately on exhalation
b. stop phonation early (before speaking on residual air)
c. determine optimum breath group (how many syllable to speak before taking another breath)
a. Rate control: slow rate down
-finger or hand tapping to set the pace for syllable production
-cued readings (finger pointing or marking pauses)
b. Stress and Intonation:
-contrastive stress drills
- intonational drills using printed material with pitch markings
- chunking information into syntactic units (using marked inhalation cues in written passages)
-intelligibility drills (clinician doesn’t look)
-minimal contrast drills