Stuttering Notes

What We Know Thus Far

• Stuttering exists in all cultures throughout all time periods.
• Normal fluency requires the smooth integration between cognitive and motoric processes.
• Not all disfluencies equal stuttering.

The Respiration Process in Stuttering

• Attempts to speak during inhalation.
• Complete stoppage in respiration.
• Irregular (consecutive) respiratory cycles.
• Exhalation interrupted by inhalation.
• Higher incidence of thoracic breathing.
• Prolonged inhalations and exhalations.

The Phonatory Process in Stuttering

• Fluttering and abnormal vocal fold (VF) cycles (vibration).
• High levels of laryngeal muscular activation.
• Slow in the initiation of phonation.
• Vocal folds are abducted during part-word repetitions.

Articulation in the Stutter

• Increased muscular tension.
• Jumps or violent muscular activity.
• Synchronization between antagonistic muscle pairs is defective.

Aerodynamics of Stuttering

• A gradual elevation of air pressure.
• Increased intraoral pressure without airflow (silent blocks on stops).
• Prolonged airflow with breathy sounds.

Incidence and Prevalence

• Prevalence: The estimate of all the cases of the disorder at a given time.
• Incidence: The probability that new cases of any disorder will develop over a period of time.
• Importance for SLPs: Understanding the who, when, and length of stuttering.

Incidence Factors

• (a) Occurrence
• (b) Age
• (c) Gender
• (d) Genetics
• (e) Stressors
• (f) Concomitant disorders
• (g) Persistency-recovery
• (h) Subtypes
• National Institute on Deafness and Other Communication Disorders (NIDCD) - Ehud Yairi, Ph.D., University of Illinois.

Prevalence, Incidence, and Age

• Andrews (1984) (Incidence):
  • $0.50$ reduction in the risk of stuttering by age 4.
  • $0.75$ by age 6.
  • Most by age 12.
• Steady prevalence between 1st and 8th grade.
• Prevalence decreases with age.

Prevalence Details

• Lower than $1\%$ (Craig et al., 2002), with an actual incidence of approximately $5\%$, onsets mainly at the preschool age (Andrews & Harris, 1964; Manson, 2000).
• $1\%$ prevalence is an average for the population at large.
• Prevalence varies greatly according to age groups.
• More than 3,000 preschool children study:
  • Revealed a $2.43\%$ stuttering prevalence with no racial or ethnic differences (Proctor et al., 2002; Yairi & Ambrose, 2005).

Prevalence in Young Children

• Prevalence at any point in time: up to almost $2.5\%$ percent of children under age 5 stutter.

Prevalence Compared to Other Communication Disorders

• ADHD: $0.03-0.05$ in children and adults.
• Articulation Disorders:
  • Preschoolers: $0.10-0.15$
  • School aged: $0.06$
• ASD/Pervasive Developmental Disorder: $0.01-0.02$
• Aphasia: $(0.37)$
• Intellectual Disability: $0.01-0.03$
• Language Learning Disability: $0.15-0.20$
• Reading Disorders: $0.16$

Incidence vs. Prevalence

• Spontaneous recovery is not the same as sudden.
• Incidence encompasses all those who have stuttered.

Spontaneous Recovery Influences

• Age
• Family History
• Gender
• Secondary behaviors
• Severity
• Stimulability

Spontaneous Recovery Study

• Andrews & Harris study:
  • Longitudinal study found a $79.1\%$ spontaneous recovery rate.
  • Higher the age surveyed, the higher recovery rate.
  • Structured interview- and sentence-completion data were gathered (University of California, Berkeley).
  • Thirty-two spontaneously recovered stutterers were compared with 32 active stutterers and normal controls.
• Findings:
  • Four out of five recover from stuttering spontaneously.
  • Fewer of those who had received public school speech therapy recovered from stuttering.
  • There appear to be many different paths to recovery.

More Spontaneous Recovery Findings

• Fewer of those who had ever been severe recovered spontaneously.
• No familial incidence pattern with either group of stutterers as compared to controls.
• No differences in reported handedness in stutterers or their families.
• Improvement attributed to self-acceptance and role acceptance.
• There appear to be many different paths to recovery.

Spontaneous Recovery Estimates

• Other estimates vary from $0.36-0.83$ recover without treatment (Lankford and Cooper, 1974).
• Lankford and Cooper (1974):
  • 68 self-identified stutterers (high school students).
  • $0.66$ of the parents (telephone interview): their child never stuttered.
  • Those older than 15:
    • $0.25$ of those who stuttered at age 10 recovered by 16.
    • $0.50$ who stuttered at age 6 recovered by 16.
    • $0.75$ who stuttered at 4 had recovered by 16.

Groups/Disordered Populations or History

• Brain injury/not TBI: CP = $0.02$ & epilepsy: $3.2$
• Cleft Palate < $0.2$
• Down Syndrome $0.15-0.53$
• Familial incidence $0.46$ have family who stutters
• Hearing impaired $0.05$
• Intellectual disability $2.5$ to $0.17$
• Down Syndrome $0.15-0.53$
• Males more than females $0.75$
• Psychosis $0.28$

Impact

• Professional education and practice
  • Education and clinical practicum
• Clinical interventions
  • Most do not specialize in stuttering, as a rule
  • When do we intervene and provide treatment?
    • Mild or severe 3 year old?
    • An adult?
• Research results vary based on:
  • Age
  • Gender
  • Models
• Public awareness and education

What We Know Thus Far

• Factors that affect recovery:
  • Age
  • Gender
  • Onset date
  • Severity
  • Family History
• Recovery rates are studied by incidence and prevalence studies
  • Incidence
  • Prevalence
• General un-coordination of speech system