Childhood apraxia of speech (CAS) is an uncommon speech disorder in which a child has difficulty making accurate movements when speaking.
In CAS, the brain struggles to develop plans for speech movement. With this disorder, the speech muscles aren't weak, but they don't perform normally because the brain has difficulty directing or coordinating the movements.
To speak correctly, your child's brain has to learn how to make plans that tell his or her speech muscles how to move the lips, jaw and tongue in ways that result in accurate sounds and words spoken with normal speed and rhythm.
CAS is often treated with speech therapy, in which children practice the correct way to say words, syllables and phrases with the help of a speech-language pathologist.
Children with childhood apraxia of speech (CAS) may have many speech symptoms or characteristics that vary depending on their age and the severity of their speech problems.
CAS can be associated with:
- Delayed onset of first words
- A limited number of spoken words
- The ability to form only a few consonant or vowel sounds
These symptoms are usually noticed between ages 18 months and 2 years, and may indicate suspected CAS.
As children produce more speech, usually between ages 2 and 4, characteristics that likely indicate CAS include:
- Vowel and consonant distortions
- Separation of syllables in or between words
- Voicing errors, such as "pie" sounding like "bye"
Many children with CAS have difficulty getting their jaws, lips and tongues to the correct positions to make a sound, and they may have difficulty moving smoothly to the next sound.
Many children with CAS also have language problems, such as reduced vocabulary or difficulty with word order.
Some symptoms may be unique to children with CAS and can be helpful to diagnose the problem. However, some symptoms of CAS are also symptoms of other types of speech or language disorders. It's difficult to diagnose CAS if a child has only symptoms that are found both in CAS and in other types of speech or language disorders.
Some characteristics, sometimes called markers, help distinguish CAS from other types of speech disorders. Those particularly associated with CAS include:
- Difficulty moving smoothly from one sound, syllable or word to another
- Groping movements with the jaw, lips or tongue to make the correct movement for speech sounds
- Vowel distortions, such as attempting to use the correct vowel, but saying it incorrectly
- Using the wrong stress in a word, such as pronouncing "banana" as "BUH-nan-uh" instead of "buh-NAN-uh"
- Using equal emphasis on all syllables, such as saying "BUH-NAN-UH"
- Separation of syllables, such as putting a pause or gap between syllables
- Inconsistency, such as making different errors when trying to say the same word a second time
- Difficulty imitating simple words
- Inconsistent voicing errors, such as saying "down" instead of "town"
Other characteristics are seen in most children with speech or language problems and aren't helpful in distinguishing CAS. Characteristics seen both in children with CAS and in children with other types of speech or language disorders include:
- Babbling less or making fewer vocal sounds than is typical between the ages of 7 to 12 months old
- Speaking first words late (after ages 12 to 18 months old)
- Using a limited number of consonants and vowels
- Frequently leaving out (omitting) sounds
- Using speech that is difficult to understand speech
Other speech disorders sometimes confused with CAS
Some speech sound disorders often get confused with CAS because some of the characteristics may overlap. These speech sound disorders include articulation disorders, phonological disorders and dysarthria.
A child who has trouble learning how to make specific sounds, but doesn't have trouble planning or coordinating the movements to speak, may have an articulation or phonological disorder. Articulation and phonological disorders are more common than CAS.
Articulation or phonological speech errors may include:
- Substituting sounds, such as saying "fum" instead of "thumb," "wabbit" instead of "rabbit" or "tup" instead of "cup"
- Leaving out (omitting) final consonants, such as saying "duh" instead of "duck" or "uh" instead of "up"
- Stopping the airstream, such as saying "tun" instead of "sun" or "doo" instead of "zoo"
- Simplifying sound combinations, such as saying "ting" instead of "string" or "fog" instead of "frog"
Dysarthria is a motor speech disorder that is due to weakness, spasticity or inability to control the speech muscles. Making speech sounds is difficult because the speech muscles can't move as far, as quickly or as strongly as normal. People with dysarthria may also have a hoarse, soft or even strained voice, or slurred or slow speech.
Dysarthria is often easier to identify than CAS. However, when dysarthria is caused by damage to certain areas of the brain that affect coordination, it can be difficult to determine the differences between CAS and dysarthria.
Childhood apraxia of speech (CAS) has a number of possible causes, but in many cases a cause can't be determined. Doctors often don't observe a problem in the brain of a child with CAS.
CAS may be the result of brain (neurological) conditions or injury, such as a stroke, infections or traumatic brain injury.
CAS may also occur as a symptom of a genetic disorder, syndrome or metabolic condition. For example, CAS occurs more frequently in children with galactosemia.
CAS is sometimes referred to as developmental apraxia. However, children with CAS don't necessarily grow out of CAS as they develop. In many children with delayed speech or developmental disorders, children follow usual patterns in development of speech and sounds, but they develop more slowly than usual.
Children with CAS don't make typical developmental sound errors. They need speech therapy to make maximum progress.
Abnormalities in the FOXP2 gene appear to increase the risk of childhood apraxia of speech (CAS) and other speech and language disorders. The FOXP2 gene may be involved in how certain nerves and pathways in the brain develop. Researchers continue to study how abnormalities in the FOXP2 gene may affect motor coordination and speech and language processing in the brain.
Many children with childhood apraxia of speech (CAS) have other problems that affect their ability to communicate. These problems aren't due to CAS, but they may be seen along with CAS.
Symptoms or problems that are often present along with CAS include:
- Delayed language, such as difficulty understanding speech, reduced vocabulary, or difficulty using correct grammar when putting words together in a phrase or sentence
- Delays in intellectual and motor development and problems with reading, spelling and writing
- Difficulties with gross and fine motor movement skills or coordination
- Hypersensitivity, in which the child may not like some textures in clothing or the texture of certain foods, or the child may not like tooth brushing
Diagnosing and treating childhood apraxia of speech at an early stage may reduce the risk of long-term persistence of the problem. If your child experiences speech problems, it's a good idea to have a speech-language pathologist evaluate your child as soon as you notice any speech problems.