Etiology, Evaluation, and Treatment of Stuttering

Etiology of Stuttering: Historical Perspective and Contemporary Views

Theories of Stuttering: Changing Perspectives

Johnson's Diagnosogenic Theory (1942)

3 dimensions of the stuttering problem:
- X: The behavior called stuttering.
- Y: Listener reactions to these behaviors and to the speaker who exhibits it.
- Z: Speaker's reaction to the listener's reaction and to his own feelings about stuttering and himself as a person.
Stuttering is caused by parents' misdiagnosis of "normal disfluencies" as "stuttering."
Stuttering is an anxiety-motivated avoidance response that becomes conditioned to the cues or stimuli associated with its occurrence.
- "The things the stutterer does to keep the expected stuttering from occurring."

Orton-Travis Theory (1920s – 1930s)

Stuttering is a symptom of incomplete cerebral lateralization of language-related skills.

Bloodstein's Anticipatory Struggle Hypothesis (1960-1970)

Wingate's (1987) "Fault-Line" Hypothesis

Stuttering is caused by slowness in formulating or retrieving the rime constituent of the syllable.

Covert Repair Hypothesis

Postma and Kolk (1993)
Impairment (slowness) in phonological encoding.
- Speaker is prone to errors in phonetic plan.
Detection and repair planning of errors prior to speaking.
Stutter-like disfluencies: symptomatic of attempts to repair planning errors.

Perkins, Kent, and Curlee (1991) Neuropsycholinguistic Theory

Theory assigns roles to:
- Prosodic/paralinguistic factors
- Linguistic factors
- Awareness and emotional factors
PWS have difficulty integrating supra-segmental "slots" with phonetic "fillers."
When integration problems are accompanied by a feeling of time pressure, the speaker perceives it as "I'm stuttering."

Multifactor Models: Levels of Causality

Predisposing cause: which people?
Precipitating cause: trigger
Perpetuating cause: maintenance
A dynamic, multifactorial model of stuttering (Smith and Kelly, 1997)
- Interactions
  - Environmental + constitutional factors
- Multiple risk factors in etiology
  - Across individuals
    - Factors: varying degrees of impact
  - Within individuals
    - Factor impact varies with time
$P= (family \ incidence + sex + speech \ motor \ coordinative \ ability + language \ skills + proneness \ to \ anxiety + reactivity \ to \ communicative \ stress + intelligence)$
- $P$ = probability for stuttering

Buchel & Sommer (2004) What Causes Stuttering?

Buchel & Sommer (2004): a genetically-based dysmyelination of key white matter tracks
Diffusion tensor imaging (DTI)
- Fractional anisotropy (FA differences)
- Inferences about white matter integrity
Consistently replicated – 4 studies
- Dysmyelination of fiber tract in left ventral perisylvian area
Role of ventral subdivision of superior longitudinal fasciculus
- Runs from premotor area to inferior parietal lobule
  - Premotor area: articulatory planning
  - Inferior parietal lobules: somatosensory representations of articulatory targets (corrective feedback to guide movement)
Myelination starts postnatally, at age 4 to 6 months post-natal age.
- Evidence of disruption in myelination process in speakers who stutter
Predictions
- Difficulty producing certain types of speech fluently:
  - Low frequency words
  - Motorically complex (phonological words)
  - Effects of degradation if auditory models supplied

Impact of Quality of Life

Impact of Stuttering
- Feeling and Emotions
  - Hindering emotions
    - Anxiety and embarrassment
      - State
      - Trait
      - Driven by expected reactions and difficulty, based on past experiences
    - Guilt
      - It's wrong to stutter
      - I'm letting parent/boss down
    - Shame
      - I'm no good
- Effects on communication
  - Activity limitations
    - Negative emotion -> more severe stuttering
  - Participation restrictions
    - Negative emotion -> avoid situation or expected difficulty
    - Say as little as possible
- Self-awareness
  - Emergent during preschool
    - Some children are aware of fluency impairment near onset of symptoms
    - Other show more gradual awareness
    - Situational awareness
  - Evidence of awareness
    - Word substitution or avoidance
      - Active attempts to avoid words that are about to be stuttered
    - Physical concealment behaviors
      - Covering mouth
    - Compensatory types of vocalization
      - Singing
      - Whispering
    - Verbal remarks
      - "I can't say it, mom"
      - Sighs
- Consequences of stuttering
  - Employment
    - Others views on suitable careers
    - Speakers views on suitable careers
    - Underemployment
  - Societal views of stuttering
    - Movie depictions
  - Mental health and sense of suffering
    - More problems, on average, among adults who stutter versus nonstuttering adults

Cluttering: Etiology & Associated Difficulties

Etiology of Cluttering
- Weiss (1964)
  - A "Central Language Imbalance"
- Alm (2010)
  - Core area of impairment
    - Medial wall of left frontal lobe
      - This is the "bank" of the superior longitudinal fissure
      - Anterior cingulate cortex
      - Pre supplemental motor area (assembly of phrases, word selection, word order)
      - Supplemental motor area: retrieval of linguistic information from Wernicke's and Broca's area
      - Basal ganglia: word selection too "winner takes all"
        Disinhibition of basal ganglia circuits
        Leads to hyperactivation and dysregulation of medial frontal cortex
- Associated Disorders
  - Learning disability
    - Language-based deficits affecting
      - Oral language
      - Literate language (reading, writing)
  - Motor problems
    - Lack of coordination
    - Poor handwriting
  - Attention deficits
    - Task focus
    - Poor problem awareness
    - Attention deficit hyperactivity disorder (ADHD)

Cluttering and Stuttering

Stuttering and cluttering sometimes co-exist
- Fruend (1952) 22% of 513 subjects who stutter show cluttering
- Preus (1981) 35% of 100 subjects who stutter show cluttering
- Daly (1981): 24% of 138 subjects who stutter show cluttering, of these 85% have history of articulation disorder, 97% have history of language delay

Acquired Stuttering: Classification and Etiologies

Causes
- Most often nervous system damage
  - A symptom of brain injury or neurological dysfunction
    - TBI
    - Stroke
    - Degenerative CNS diseases
    - Brain tumor, brain surgery
    - Drug-induced brain dysfunction
  - Transient or persistent
  - Diffuse lesion sites
    - Usually L, but R hemisphere too
    - Frontal, parietal, temporal lobes
    - Subcortical, as well
  - Males affected most
  - Relationship with developmental stuttering is unclear
General Characteristics
- Onset usually sudden and in adulthood
- In 68% of cases, occurs with concomitant disorders
  - Aphasia
  - Dysarthria
  - Apraxia of speech
- Fluency symptoms
  - Similar to developmental stuttering
    - Word and part word repetitions are most common
    - Prolongations and blocks occur
    - Disfluency on both function and content words
    - Occasionally, stutter-like interruptions are limited to specific sounds
  - Sometimes we see atypical disfluency patterns
    - Repetition of word-final consonants
    - Extremely long disfluencies
    - Stuttering during singing, choral reading, rhythmic stimulation, slowed articulation
    - Bursts of rapid, unintelligible speech
    - Lack of adaptation effect, neurodegenerative patients
- Secondary Behaviors
  - Some may not have secondary behavior
  - May include:
    - Excessive eye blinking
    - Facial grimacing
    - Foot tapping
    - Extraneous limb and head movements
- Attitudes and Emotions
  - Classic view: many acquired cases show little apparent reaction
Acquired Stuttering vs. Developmental Stuttering Classifications and Etiologies
- Developmental Stuttering
  - Stutter-like speech emerges in the context of neurological and speech-language development
  - No evidence of trauma, injury, illness or other factors that might lead one to acquire stuttering
  - Remember, developmental stuttering usually
    - Onset typically in childhood
    - Gradual onset
    - Often is a family history
    - Cases with onset beyond age 12 or so should be viewed cautiously
- Continuity
  - Acquired stuttering is often more severe than developmental stuttering
    - Some acquired cases may have disfluency associated with 50% of syllables
- Rate & Rhythm
  - Rate
    - Often linked to the number of continuity interruptions
      - More disfluencies= slower speech rate
    - Acquired cases may have slower speech rate, as a group
  - Rhythm
    - Associated with disfluency duration, speech timing
      - More disfluencies = less rhythmic speech
      - More lengthy disfluencies = less rhythmic speech
    - Acquired cases may have less rhythmic speech, as a group
- Effort & Talkativeness
  - Effort
    - Mental effort is tied to awareness of impairment and attempts to self-correct or control
      - Acquired cases less likely to be aware of fluency problems
      - So, less likely as a group to experience "excessive mental effort"
  - Talkativeness
    - Acquired stuttering may coincide with aphasia or TBI and other such disorders
    - In such cases, the person's talkativeness may be affected by factors associated with these disorders
- Recovery/Remission
  - Developmental stuttering
    - Among preschoolers
      - About 75% of all cases seem to resolve
      - Severity is not good predictor of severity
  - Acquired stuttering
    - Among acquired cases
      - Unclear exactly how many cases recover, but recovery is fairly common
      - Severity is not good predictor of recovery

Evaluating Fluency

Basic Strategy: Describe Patient functioning Across Various Fluency Domains
- Continuity
  - Disfluency
  - Frequency
- Rate/rhythm
  - Articulation rate
  - Speech rate
  - Disfluency duration
- Effort
  - Physical
  - Mental
- Naturalness
  - Self rating
  - Other rating
- Talkativeness
  - # of situations engage in
  - Output per situation
- Stability
  - Variation over time/task
- Step 1: Elicit Speech Samples
  - Elicit representative sample
    - Over time, across contexts
  - Elicit standard samples
    - Conversational speech
    - Narrative tasks
    - Sentence production tasks
    - Oral reading tasks
    - Rapid naming tasks
- Step 2: Transcribe Samples
  - How to transcribe
    - Verbatim transcripts
      - Exactly what the speaker says
    - Coded transcripts
      - Fluent words coded with dot or dash
      - Other code entered for words that contain or are preceded by a disfluency
  - When to transcribe
    - On-line transcription
      - As the person speaks
    - Off-line transcription
      - Reviewing a recording of the person's speech
- Step 3: Describe Disfluency (Type and Frequency)
  - Detailed analysis
    - # of disfluencies per 100 words for each of the various types of disfluency
  - Broad analysis
    - # of disfluent segments per 100 words
    - Or by other broad subcategories
    - Duration of disfluency segments
- Typical Types of Speech Disfluency
  - Repetitions
    - Part-word
    - Monosyllable word
    - Multiple words
  - Prolongations
    - Audible
    - Inaudible
  - Revisions
    - Word choice errors
    - Syntactic errors
    - Phonologic errors
    - Semantic appropriateness
  - Interjections
  - Pauses
- Less Typical Types of Disfluency
  - Simple forms
    - Final sound or word repetitions
  - Complex forms
    - Repeating while interjecting
    - Interjecting before repeating
    - Prolonging while repeating
    - Repeating or prolonging sound during a multi-word repetition
    - Repeating or prolonging in a word that is later revised
- Step 4: Measure Rate & Rhythm of Speech
  - Unit of measurement
    - Syllables per minute
  - Methods
    - Time the beginning to end of randomly selected conversational utterances
    - Time the start to finish of a passage reading
  - Instrumentation
    - Stop watch
    - Spectrogram
  - Formulas
    - # of words in fluent stretches of speech/speaking time = wps
    - # of words in fluent stretches of speech/speaking time x 60 = wpm
Measuring duration of disfluencies
- M duration (in seconds) of randomly selected disfluencies
  - Stopwatch
  - Spectrogram
- M # of extra iterations for randomly selected repetitions
  - [B-b]boy = 2 iterations
- Assessing Effort & Talkativeness
  - Effort
    - Self-rating and reports of mental effort
      - How much work goes into talking?
    - Self-ratings and reports of physical effort
      - How much muscle activation is evidenced?
  - Talkativeness
    - Verbal output
      - Standard situations
      - Important situations
    - Coping strategies
      - Avoidance vs. Participation
Step 5: Look for Other Signs of Fluency Difficulty (Associated Behaviors)
- Unusual rate patterns
  - Rapid bursts of speech?
- Atypical respiration
  - Quickly audible inhalation before speaking?
  - Forced audible exhalation before/during speech?
  - Speaking near end of vital capacity?
- Atypical phonation
  - Abrupt pitch changes during disfluencies?
  - Highly variable inflection? (sing-song)
  - Intermittent phonation, excessive vocal tension?
  - Whispered speech?
- Excess physical tension or tremor:
  - Tongue, lip, jaw, respiratory or laryngeal musculature
- Extraneous movement:
  - Head, facial, eye, trunk, limb muscle movements
- Unusual prosody, inflection, intensity:
  - Use of irregular or sing song prosody
Monopitch
- Reduced/increased loudness
- Altering/avoiding communication
  - Saying "um" when word is known
  - Starting word with inappropriate sound
  - Changing or abandoning words
  - Rearranging sentence syntax
  - Saying "I don't know"
Step 6: Assessing Impact of Stuttering
- Self-reporting instruments
  - Stuttering prediction instrument
  - S-24 Scale
Behavioral Assessment Battery
- Other quality of life instruments
  - Overall assessment of speakers experience of stuttering
Step 7: Describe Activity Limitations and Performance Restrictions
- Activity Limitations
  - Fluency disability across contexts
    - Reading
    - Conversing
    - Public speaking
    - Narrating
    - Restating
    - Phone conversations
Participation restrictions
* Patient based
* Avoiding words
* Avoiding situations?
* Saying "as little as possible"
* Listener based
* Intentional exclusion
* Unintentional exclusion
Step 8: Assess Effect of Contextual Factors
- Environmental factors
  - Behaviors, contexts, policies that foster fluency
  - Behaviors, contexts, policies that hinder fluency
- Personal factors
  - Attitudes, beliefs, behaviors, and thoughts that foster fluency
  - Attitudes, beliefs, behaviors, and thoughts that hinder fluency
Step 9: Make Diagnosis – Does person stutter?
- Disfluencies per unit of speech
  - Ratio of "reps & pro" to "interjections & revisions"
    - Is one category more common than another?
Types of disfluencies
- Length of disfluencies
- Tempo/tension
Formal Tests of Fluency
- Test of Childhood Stuttering – TOCS
  - Population
    - Children, aged 4 to 12 years, suspected of stuttering
  - Purpose
    - To identify developmental stuttering
    - To determine stuttering severity
    - To determine extent to which stuttering impacts child
TOCS Part 1: Speech Fluency Measure (normed)
- Rapid picture naming: label pictures as quickly as possible
  - Modeled Sentences: produce sentences that incorporate syntax of examiner model
- Structured Conversation: respond to various requests for information about 8 sequenced pictures
  - Narration: tell a story about the 8 sequences pictures
Part 2: Observational Rating Scales (normed)
- Part A: Speech fluency rating
  - Parents, teachers, SLP report on frequency of various stuttering-related behaviors
- Part B: Disfluency-related consequences
  - Parents, teachers, SLP report on how child reacts to stutter-like speech and how others react to the child
Part 3: Supplemental Clinical Assessment Activities (informal not normed)
- Procedures for clinical interviews
  - Comprehensive analysis of disfluency
  - Speech rate analysis
  - Disfluency duration analysis
  - Repetition unit analysis
  - Associated behaviors checklist
  - Stuttering frequency analysis
  - Speech naturalness analysis
TOCS Scoring
- Stuttering Severity Instrument – IV (SSI-4): Riley (2008)
  - Purpose:
    - To determine the severity of a person's stuttering
  - Ages
    - Preschool to adult
  - Norms
    - Preschoolers, school-ages, adults
Ratings
* Very mild, mild, moderate, severe, very severe
* Note
* No diagnostic component; SLP must make diagnosis of stuttering using other means
* SSI – 4 Tasks
* Speech elicitation
* Oral reading
* Oral narratives
* Topic prompts
* Picture prompts
Recommended sampling contexts
* Clinic
* Home
* Tools/materials
* Picture booklet
* Computer software
* Used for fluency analysis
* Tap one keep to count syllables
Tap another key to count stuttered disfluencies
- SSI – 4 Weighted Scores
  - Stuttering frequency
  - Stuttering duration
  - Physical concomitants
    - Distracting sounds, facial grimaces, head movements, movements of the extremities
Treating Stuttering: Selected Treatment Goals
- When to Treat Developmental Stuttering
  - Communication functioning
    - Activity limitations
    - Participation restrictions
  - Personal factors
    - Distressed by speech impairment? Affected by environmental factors
    - Interest, motivation
  - Time since onset & developmental trend
    - Preschoolers: usually "recovery" occurs within 12 to 18 months of onset
    - No better getting worse after 6 to 8 months?
Conceptualizing Treatment
- Build capacity for
  - Speaking fluently
Coping with disfluency
* Address contextual factors
* Manage environmental factors
* Address personal factors, e.g., coping strategies; attitudes, feelings, and beliefs
Improve Performance
* Real-world fluency
* Performance in various daily contexts
Participation in various daily contexts