Ataxic Dysarthria Flashcards
Definitions of Ataxic Dysarthria
Motor speech disorder often due to damage to cerebellum or its neural pathways
Speech errors in Ataxic Dysarthria
Results in speech errors that are primarily articulatory and prosodic, giving speech unsteady, slurred quality
Neurologic Basis of Ataxic Dysarthria
Caused by damage to cerebellum or neural pathways that connect cerebellum to other parts of central nervous system
Cerebellum
Primary function: coordinate timing and force of muscular contractions. Processes sensory information from all over body and integrates information into execution of movement
“Ataxia”
Widespread incoordination; Greek word for “lack of order”
Neural Pathways to and from the Cerebellum
Cerebellum
Attached to brainstem
Communicates with rest of CNS through three bundles of neural tracts called cerebellar peduncles
Inferior peduncle allows cerebellum to
Receive sensory information from entire body about position of body parts
Recognize what body is doing during movement and whether motor impulse to muscles is accomplishing intended result
Monitor timing and force of movements while performed
Middle peduncle allows cerebellum to
Receive preliminary information from cortex regarding planned movements
Coordinate planned movements by integrating sensory information from body with individual’s experience of what appropriate movement should be, smoothing and refining according to current conditions
Superior peduncle allows cerebellum to
Have main output to rest of CNS
Send its processed motor impulses to motor areas of cortex, completing corticocerebellar control circuit
Cerebellar control circuits
neurons that course through three cerebellar pathways
Not called upper motor neurons because do not synapse with lower motor neurons
Two ways cerebellum influences speech movements
- Through corticocerebellar control circuit
Planned motor impulses of planned speech act sent from cortex to cerebellum
Cerebellum coordinates and refines preliminary movements
Coordinated motor impulses then sent to thalamus for more refinement before sent to motor cortex and then to muscles
- Through its connections to extrapyramidal system
Makes rapid adjustments in timing and force of movements to compensate for unexpected changes in circumstances of movement
Causes of Ataxic Dysarthria
Damage to cerebellum or its control circuits causing difficulties coordinating voluntary movements
Cerebellar ataxia: movement deficits of timing, force, range, and direction
Vermis: midpoint of cerebellum between cerebellar hemispheres upon which speech coordination is highly dependent
Degenerative Diseases
Autosomal dominant cerebellar dysfunction of late onset
Hereditary disease usually beginning in middle age
Degenerative Diseases
Idiopathic sporadic late-onset cerebellar ataxia
Similar to autosomal dominant cerebellar dysfunction, but does not include as many neurologic symptoms
Degenerative Diseases
Friedreich’s ataxia
Progressive hereditary disease affecting spinal cord as well as cerebellum
Degenerative Diseases
Olivopontocerebellar degeneration
Progressive cerebellar disorder that runs in families
Stroke
Cerebellum has rich arterial blood supply
Arteries serving cerebellum:
Superior cerebellar, anterior inferior cerebellar artery
Ataxic dysarthria can result in:
Blockage to arteries serving cerebellum, ruptured aneurysms, arteriovenous malformations
Cerebellar signs: limb ataxia, problems with balance, visual deficits, ataxic dysarthria
Toxic conditions
Most treatable with ataxic dysarthria resolving as toxic levels decrease
Lead and mercury poisoning
Long- and short-term alcohol consumption
Exposure to chemicals such as acrylamide and cyanide
Toxic levels that may not be irreversible
Phenytoin (Dilantin): antiseizure drug
Metabolic conditions
Vitamin E or B12 deficiency
Severe cases of hypothyroidism
Hereditary disorders such as Wilson’s disease
Traumatic Head Injury
Trauma to cerebellum tends to be diffuse, as with most head injuries
Cerebellar peduncles especially vulnerable to twisting and rotational forces because cerebellum essentially an appendage attached to brainstem
Tumors
Extent of ataxic dysarthria depends on location and size of tumor
Tumor can affect cerebellar function by:
Growing in cerebellar tissue, perhaps directly destroying and compressing cerebellum
Growing near cerebellum, thereby compressing cerebellar tissue
Interfering with functions of cerebellar control circuits
Metastatic tumors
Among most common
Formed when primary tumor sheds cancerous cells that seed a secondary (metastatic) tumor
Low-grade actrocytoms
Slow-growing type of tumor appearing frequently in cerebellum, especially in children
Hemangioblastomas
Benign tumors of proliferated blood vessels found occasionally in cerebellum
Not common causes
Viral infections invading cerebellum
Infections such as trichinosis, typhus, and syphilis
Bacterial abscess near cerebellum that compresses surrounding brain tissue
Speech Characteristics of Ataxic Dysarthria
Movements appear poorly coordinated
Problems controlling timing/force for speech
Slurred, monotonous articulation
Primarily disorder of articulation and prosody
Scanning speech:
Term to describe ataxic dysarthria, describing slow, deliberate production of syllables, with each syllable in word receiving equal stress
Articulation
Articulation deficits significant problem
Imprecise consonant production is the most prevalent speech error
Distorted vowels
Imperfect articulation gives ataxic dysarthria slurred quality
Caused by cerebellar damage disrupting timing, force, range, and direction of movements
Irregular articulatory breakdowns: Imprecise consonant and vowel productions vary from utterance to utterance
Decomposition of movement: manifestations of cerebellar dysfunction, where instead of smooth coordinated movements, they are distinct and jerky
Prosody
Equal and excess stress is a distinguishing characteristic of ataxic dysarthria
Prolonged phonemes and prolonged intervals between phonemes
Slow movement on both single and repetitive motion tasks; hypotonia
Monopitch and monoloudness
Caused by hypotonia of speech muscles
Phonation
Few phonatory deficits noted in ataxic dysarthria
Harsh vocal quality
Caused by decreased muscle tone in laryngeal and respiratory structures, preventing full contraction of these muscle groups
Voice tremor
Resonance
Hypernasality
Seldom serious problem in ataxic dysarthria
Hyponasality
Intermittent
Caused by timing errors between muscles of velum and other muscles of articulation
Respiration
Uncoordinated movements in respiratory muscles, contributing to speech deficits
Paradoxical movements: movements that occur when muscles work against each other rather than in coordination
Paradoxical movements of intercostal muscles and diaphragm
Leads patient to speak on residual air, which can lead to increased rate of speech, decreased loudness, and harsh vocal quality
Key Evaluation Tasks for Ataxic Dysarthria
Speech alternate motor tasks
- Slower than normal, difficulty maintaining steady rhythm with repetition
- Severe cases: speed up abruptly then unexpectedly slow down
Reading, conversational speech, and repeating sentences containing numerous multisyllabic words
Treatment of Ataxic Dysarthria
Damage affects speed, force, and timing of movements of articulators, resulting in uncoordinated movement
Most evident speech errors related to articulation and prosody
Respiration Treatment
Do not need to address strengthening respiration
Concentrate on controlling airflow more accurately during speech, as uncoordinated movements of respiratory muscles cause speech on residual air, affecting prosody and phonation
Tasks to help improve breath control during speech
- Slow and controlled exhalation
- Speak immediately on exhalation
- Stop phonation early
- Optimal breath group: teaching how may syllables or words can be said clearly on one full inhalation
Prosody Treatment
Prosodic problems involve:
Rate, stress, and intonation
By slowing rate, can improve intelligibility
By incorporating more typical stress and intonation into utterances, speech may exhibit more natural quality
Rate control
Slow, irregular rate characteristic of ataxic dysarthria, but may attempt to speak too rapid for speech capabilities
Articulators are not given enough time to reach target positions
Listener not given enough time to assimilate spoken message
Articulation Treatment
May improve with slowed rate
Need to concentrate directly on improving production of phonemes
Articulation tasks
- Intelligibility drills
- Phonetic placement
- Exaggerating consonants (overarticulation)
- Minimal contrast drills
Speech characteristics include
Imprecise consonant production and irregular articulatory breakdowns
Ataxic dysarthria caused by
any process resulting in damage to cerebellum or cerebellar control circuits
Common causes include
degenerative diseases and stroke
Most significantly affected speech characteristics
Articulation and prosody
Treatment concentrates on:
- Controlling respiration for speech
- Increasing articulatory accuracy
- Developing optimal rate and intonation in -Connected speech
