Pediatric Speech Disorders

Dysarthria

Dysarthria is the result of muscle weakness or difficulty controlling the muscles of speech production. Common causes include neurologic disorders such as stroke, brain injury, brain tumors, and conditions that cause facial paralysis or tongue or throat muscle weakness. Children with dysarthria may produce speech that sounds slurred, with reduced rate, imprecise articulation, and impaired prosody (patterns of stress and intonation). A common childhood disorder that often results in dysarthria is cerebral palsy (CP). Children with CP can exhibit dysarthria ranging from minimal to severe, and this is often correlated with their overall level of physical function. A child’s degree of dysarthria is not correlated with language or cognitive impairment; a child with age-appropriate receptive language can have severe dysarthria that precludes oral communication. In these cases, it is important to refer children to assess their ability to use augmentative or alternative forms of communication (AAC).

Apraxia

Oral apraxia is an impairment of the voluntary ability to produce movements of the facial, labial, mandibular, lingual, palatal, pharyngeal, or laryngeal musculature in the absence of muscle weakness. A child might be unable to move their tongue from side to side on request or in imitation but may do it spontaneously.

Verbal apraxia (also called apraxia of speech, or AOS) is characterized by a diminished ability to program the positioning and sequencing of movements of the speech musculature for volitional production of speech sounds. AOS results in perceptual disturbances of breathing/speaking synchrony, articulation, and prosody.

Developmental verbal apraxia (also called childhood apraxia of speech, or CAS) refers to a speech disorder resulting from delays or deviances in those processes involved in planning and programming movement sequences for speech. The speech articulators have difficulty interpreting messages from the brain; children with apraxia know what they want to say but cannot execute the proper movements of the articulators to do so.

Associated characteristics of CAS include:

• phonemic errors (often, sound omissions) (e.g., “up” for “cup”)

• increase in errors with word/utterances of increased length and/or phonetic complexity

• inconsistent error patterns (might say “ba” for “boy” the first time, “be” for “boy” the second time)

• groping and/or trial-and-error behavior (appears to struggle to move tongue and lips to form sounds)

CAS is not related to a specific identifiable lesion (although a neurologic basis is presumed) and is defined primarily by speech symptoms. Children with motor speech disorders may demonstrate impaired phonologic systems. It is believed that their ability to acquire the sound system of their language is undermined by difficulties in managing the intense motor demands of connected speech.

Articulation Disorders

An articulation disorder exists when a child has difficulty physically producing a sound or sounds due to structural defects or difficulty with proper placement of articulators to create the target sound. For example, when a child substitutes a “w” for an “r” (“wed/”red”), or “y” for “l” (“yight” for “light”), they are exhibiting difficulty producing the “r” and “l” sounds.

Children with structural defects such as ankyloglossia (see Chapter 33) or cleft palate may exhibit obligatory and/or compensatory sound substitutions. A child with restricted tongue movement may be unable to produce interdental “th,” for example, and learns to substitute either a different sound (e.g., “vis” for “this”), or a different part of the tongue, protruding the mid tongue instead of the tongue tip to produce an interdental sound. A common compensatory behavior for children with limited tongue tip mobility is to use the mandible to bring the tongue into contact with the alveolar ridge. Unless ankyloglossia is very severe, these children typically learn to compensate for their restricted tongue movement and develop intelligible speech without need for frenulectomy.

Children with velopharyngeal insufficiency (see Chapter 10) secondary to cleft palate exhibit obligatory sound substitutions because of inability to close the velopharyngeal port. Substitution of a nasal for an oral sound (“m” for “b, p”; “n” for “t, d”; “ng” for “g, k”) is considered an obligatory substitution because of inability to close the palate. These children can also develop compensatory (mis)articulations, which are typically the result of attempts to valve the air stream in a different place of articulation, in the setting of palatal dysfunction. The most common compensatory articulation is glottal replacement, where a glottal stop (ʔ) is substituted for a stop consonant (e.g., ʔooʔie/“cookie”). Children with palatal dysfunction should be treated by SLP as early as possible—preferably as soon as they begin acquiring sounds—to facilitate accurate place of articulation for production of sounds, even if it promotes nasal air emission (obligatory sound substitution). These children will demonstrate significant improvement in speech intelligibility after palatal surgery. In contrast, palatal surgery may yield only minimal improvement in speech intelligibility in a child with compensatory misarticulations, because production of compensatory misarticulations will remain unchanged.

A less common articulation error is phoneme-specific nasal air emission (PSNAE). This is often mistaken for velopharyngeal dysfunction because of a structural or functional defect. In PSNAE, a child has learned to create frication (e.g., s, z) by putting air through their nose, and it is unrelated to palatal function. Most often, PSNAE is limited to fricative sounds, and can be easily corrected with speech-language therapy.

Certain genetic syndromes may cause speech sound disorders secondary to structural or neurologic deficits. Beckwith-Wiedemann syndrome is characterized by macroglossia associated with upper airway obstruction, feeding issues, and speech defects caused by the inability to produce consonants with more anterior location of articulation. Specifically, sounds produced by placing the tongue tip to the alveolar ridge (e.g., t, d, n) or teeth to lower lip (f, v) become interdentalized (tongue between teeth/lips).

Syndromes that include impairment of cranial nerves that affect speech production such as Moebius syndrome can also result in speech sound disorders. Some syndromes such as hemifacial macrosomia (Goldenhar syndrome) include both structural abnormalities and cranial nerve impairment, and most often result in significant disorders of speech production.

Phonologic Disorders

Phonology refers to the system of sounds in a language, including rules that specify how they interact with each other. Every language has its own set of speech sounds, or phonemes, and there are specific rules governing their use. For example, in English, the sound (or phoneme) “ng” never occurs at the beginning of a word. There are also certain phonemes that are not combined in English, such as “tm.” Phonologic disorders result from the inability to consistently apply these rules in everyday speech. The resulting errors are typically grouped into categories and referred to as phonologic processes. The cause of phonologic speech sound disorders in most children is unknown. Identified risk factors include otitis media with effusion, genetics (family history of speech and language disorders), and psychosocial involvement (e.g., lack of supportive learning environment, limited parental education). Current theory proposes that inherent processes present in the phonologic systems of all children as they develop language are systematically eliminated at predictable ages in a standard developmental progression. Failure to eliminate, or resolve, these immature processes results in a developmental phonologic processing disorder. An example of a developmental phonologic process is “velar fronting,” in which a child systematically substitutes an alveolar or tongue tip sound (t, d, n) for a velar sound (k, g, ng), producing words such as “tup” for “cup,” “dood” for “good,” or “sin” for “sing.” These sound substitutions are systematic and applied by the child in the same context each time that sound occurs. Nondevelopmental phonologic processes are not applied or eliminated systematically. An example of a nondevelopmental phonologic process is initial consonant deletion, in which a child deletes the initial sound in a word, such as “ee”/ “key” or “ake”/ “make.”