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Am Fam Physician. 1998;57(9):2175-2178

The etiology of stuttering is controversial. The prevailing theories point to measurable neurophysical dysfunctions that disrupt the precise timing required to produce speech. Stuttering is a common disorder that usually resolves by adulthood. Almost 80 percent of children who stutter recover fluency by the age of 16 years. Mild stuttering is self-limited, but more severe stuttering requires speech therapy, which is the mainstay of treatment. Delayed auditory feedback and computer-assisted training are currently used to help slow down speech and control other speech mechanisms. Pharmacologic therapy is seldom used, although haloperidol has been somewhat effective.

Stuttering is a disorder affecting the fluency of speech. The World Health Organization defines stuttering as “a disorder in the rhythm of speech in which the individual knows precisely what he or she wishes to say, but at the same time may have difficulty saying it because of an involuntary repetition, prolongation, or cessation of sound.”1 Stuttering may be divided into developmental dysfluency (which many children experience) and pathologic dysfluency.

Stutterers can display both repetitions and prolongations (primary symptoms), as well as avoidance and frustration (secondary symptoms). The primary symptoms of stuttering can be difficult to differentiate from those of normal developmental dysfluency. The secondary symptoms are often a response to the negative feedback a child receives from family and friends.

Almost 80 percent of children who stutter recover fluency spontaneously or with speech therapy by the age of 16 years.2 Even for children with more severe stuttering, the prognosis is favorable provided that treatment is started early. The outcome is less favorable for individuals who continue to stutter into adulthood.


The prevalence of stuttering varies with age. The disorder occurs in 3.0 to 5.0 percent of preschool-aged children and in 0.7 to 1.0 percent of the general population (excluding preschool-aged children).3 Stuttering is more prevalent in children because of the high incidence of developmental dysfluency in this population. Developmental dysfluency results in brief periods of stuttering that cease by the time a child enters school.

As with many behavioral disorders of childhood, stuttering occurs three to four times more often in boys than in girls.4 The reason for the difference between sexes is not known.

Stuttering is found in all cultures, races, languages and historical periods. The disorder has affected such notable figures as Winston Churchill, John Updike, King George VI and James Earl Jones. However, the incidence of stuttering does vary between cultures and socioeconomic groups. The disorder appears to occur more frequently in children from upper socioeconomic classes, although the higher incidence may represent an artifact of increased surveillance in this group.5


Over the years, numerous theories have been proposed to explain the etiology of stuttering. These theories have generally been representative of the prevailing beliefs of the time in which they were formulated. In ancient Greece, Hippocrates wrote that stuttering resulted from dryness of the tongue. As treatment, he recommended producing varices of the tongue by chemical or surgical means.6 In the 19th century, stuttering was widely believed to be caused by an anatomic defect in the oral cavity. Consequently, surgical procedures, often quite mutilating, were popular treatments. By the 20th century, the prevailing belief was that stuttering was a psychogenic disorder. Thus, operant conditioning and psychoanalysis became the treatments of choice. The psychogenic model went out of favor in the 1960s, in large part because these treatments proved ineffective (personal communication from B. Guitar, August 1997).

Today, the prevailing theory is that stutterers have subtle neurophysical dysfunctions that disrupt the precise timing required to produce speech.7 These abnormalities are not found in persons who do not stutter. Stutterers have also been shown to have difficulty coordinating airflow, articulation and resonance. In addition, small asynchronies have been found in even the fluent speech of stutterers.8

The role of genetics in stuttering has also been explored. Studies in twins have shown a higher concordance for stuttering in monozygotic twins than in dizygotic twins (77 percent versus 32 percent).5 Among first-degree relatives of stutterers, the risk of the disorder is more than three times that of the general population. More boys than girls are affected, and the sex ratio increases with age.9

Diagnosis, Evaluation and Referral

Differentiating between normal developmental dysfluency and stuttering is important (Table 1).10 In general, developmental dysfluency involves the repetition of whole words and phrases, whereas stuttering involves the repetition of word parts and the prolongation of sounds. In addition, stutterers frequently speak at a faster tempo, display silent pauses, have inappropriate articulating postures, become more dysfluent in response to stress and are more easily frustrated.11 Even though developmental dysfluency and stuttering have significant differences, the physician may find it difficult to distinguish between them.

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As part of the evaluation, the physician should assess the degree of dysfluency and the type of speech interruptions. Generally, there is cause for concern if a patient's speech has five or more breaks per 100 words. It is often helpful to find out about the stutterer's attitude toward the problem (and, in the case of children, the parents' attitude). The physician should also evaluate the dysfluent child's motor skills, auditory skills and language level.11

The physician needs to know when to refer a stutterer for speech therapy, which is the mainstay of treatment. In general, referral is indicated if a child is over four years old, has been stuttering for more than three months, shows consistent stuttering and demonstrates tension or struggle behavior when stuttering. Referral is also indicated if the child's parents show great concern about the problem.7

Psychologic and emotional issues must be addressed in the dysfluent child. Stutterers are often teased by their peers. They may not be able to participate fully in school activities, especially those that involve speaking in front of a group. They may be discriminated against when they apply for college entrance, and they frequently have difficulties in developing personal relationships and choosing a career. Stutterers may have a poor self-image, a sense of failure and a passive approach to life situations.11 It is important for the physician to be sensitive to these issues and to offer support and empathy when needed.


Mild stuttering is a self-limited condition, but patients with more severe stuttering require speech therapy and counseling (Table 2). Treatment should be tailored to the individual patient. To have a lasting effect, interventions should be aimed at the abnormal speech behavior, the emotional problems of the stutterer and negative parental attitudes.

Parental counseling on the importance of not criticizing or reprimanding the child who stutters
Environmental modifications to minimize frustrations and decrease stress in the stutterer
Psychologic counseling to improve self-image in the stutterer
Speech therapy
Timed syllabic speech: the stutterer is taught to speak syllable by syllable, with each syllable stressed evenly
Shadow method: the stutterer follows/repeats the words spoken by a speech therapist
Universal fluency initiating gestures: the stutterer is taught to use certain gestures that help to prevent dysfluent speech
Delayed auditory feedback: a tape-recording device distorts sound unless the stutterer slows his or her rate of speech
Edinburgh Masker: an apparatus is strapped across the larynx and then attached to a stethoscope-like system; as a result, the stutterer cannot hear his or her own words
STAR (structuring, targeting, adjustment and regulation) therapy: the four stages of this therapy are designed to identify the elements of the stuttering problem, to eliminate certain body and facial movements, and to help the patient adopt and regulate fluency-enhancing feelings, attitudes and behaviors
Computer-aided fluency establishment trainer: this is a computerized process that provides feedback and guidance to decrease stuttering

One of the keys to success is parental education. Parents should be advised to avoid criticizing their child, to remind the child to speak more slowly and to repeat words that are said indistinctly. Parents should talk to their child slowly and in a relaxed manner. They should allow the child to speak at his or her own pace. Bedtime reading is a good way for parents to model slow, fluent speech while fostering closeness and intimacy.

Frustrations experienced by the child should be kept to a minimum. The aim of treatment is to increase the child's confidence and to reduce the fear of stuttering. Stutterers should be encouraged to discuss the problem openly with friends and family and to explore their feelings about the disorder.

Speech therapy is widely available. Most approaches attempt to decrease the rate of speech either under the direction of the speech therapist or with the use of a metronome. The speech therapist encourages very young children to speak at a slower rate while playing games with them. Older children are taught “timed syllabic speech.” They are encouraged to speak syllable by syllable, with each syllable stressed evenly, spoken in a regular rhythm and separated equidistantly from the next syllable.12

Other treatment approaches are also used. In the shadowing method, the stutterer follows the words spoken by the therapist. The delayed auditory feedback technique uses a tape-recording device that reproduces the voice through earphones after a few milliseconds.12,13 To prevent distorted feedback, the stutterer must slow down his or her rate of speech. Another form of therapy uses the Edinburgh Masker. This therapy is based on the fact that stutterers speak fluently when they cannot hear their own voice. A small apparatus is strapped across the larynx and then attached to a stethoscope-like system. When the stutterer talks, the device is activated and prevents the stutterer from hearing his or her own speech.

In addition to teaching the stutterer how to speak fluently, the speech therapist must also assist with the development of appropriate speech gestures. Fluency initiating gestures (FIGs) help to prevent stuttering. The FIGs include, among others, slow, deep, loud and smooth. These gestures are first taught individually and then in combination.

Attempts have been made to treat stuttering with numerous drugs, including benzodiazepines, phenothiazines, calcium channel blockers, beta blockers and anticonvulsants. Only haloperidol (Haldol) has consistently produced improvement.14 However, most patients are unable to continue using this medication because of its unacceptable side effects. Therefore, haloperidol is not routinely used in the treatment of stuttering.

Much of the literature on stuttering emphasizes the behavioral, cognitive and affective aspects of treatment. The goal of treatment should be to establish and maintain the feeling of fluency control, rather than to attain an arbitrarily determined level of fluency.15 The feeling of control is the key variable in determining whether a patient maintains an acceptable level of fluency after treatment is completed.

One formal program for stuttering divides treatment into four different stages: structuring, targeting, adjustment and regulation (STAR).15 In the structuring stage, the patient identifies the feelings, attitudes and behaviors that constitute the stuttering problem. The targeting stage focuses on eliminating the distracting body and facial movements that occur during stuttering. In the adjusting stage, the speech therapist helps the patient to adopt fluency-enhancing feelings, attitudes and behaviors. In addition, the speech therapist assists the patient in becoming an effective self-reinforcer. During this stage, the patient learns to develop and use the universal FIGs. Finally, during the regulating stage, the speech therapist helps the patient to develop the feeling of fluency control and to regulate the use of FIGs outside of the therapy situation.

The computer-aided fluency establishment trainer is another formal program designed to change speech behavior in stutterers.16 This program has been shown to improve speech fluency through a computerized process that provides feedback and guidance to decrease stuttering.

Patients may obtain information on the prevention and treatment of stuttering from the Stuttering Foundation of America (telephone: 800-992-9392).

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