Childhood apraxia of speech

Overview

Childhood apraxia of speech (CAS) is a rare speech disorder. Children with this disorder have trouble controlling their lips, jaws and tongues when speaking.

In CAS, the brain has trouble planning for speech movement. The brain isn't able to properly direct the movements needed for speech. The speech muscles aren't weak, but the muscles don't form words the right way.

To speak correctly, the brain has to make plans that tell the speech muscles how to move the lips, jaw and tongue. The movements usually result in accurate sounds and words spoken at the proper speed and rhythm. CAS affects this process.

CAS is often treated with speech therapy. During speech therapy, a speech-language pathologist teaches the child to practice the correct way to say words, syllables and phrases.

Symptoms

Children with childhood apraxia of speech (CAS) may have a variety of speech symptoms. Symptoms vary depending on a child's age and the severity of the speech problems.

CAS can result in:

• Babbling less or making fewer vocal sounds than is typical between the ages of 7 to 12 months.
• Speaking first words late, typically after ages 12 to 18 months old.
• Using a limited number of consonants and vowels.
• Often leaving out sounds when speaking.
• Using speech that is hard to understand.

These symptoms are usually noticed between ages 18 months and 2 years. Symptoms at this age may indicate suspected CAS. Suspected CAS means a child may potentially have this speech disorder. The child's speech development should be watched to determine if therapy should begin.

Children usually produce more speech between ages 2 and 4. Signs that may indicate CAS include:

• Vowel and consonant distortions.
• Pauses between syllables or words.
• Voicing errors, such as "pie" sounding like "bye."

Many children with CAS have trouble getting their jaws, lips and tongues to the correct positions to make a sound. They also may have a hard time moving smoothly to the next sound.

Many children with CAS also have language problems, such as reduced vocabulary or trouble with word order.

Some symptoms may be unique to children with CAS, which helps to make a diagnosis. However, some symptoms of CAS are also symptoms of other types of speech or language disorders. It's hard to diagnose CAS if a child has only symptoms that are found both in CAS and in other disorders.

Some characteristics, sometimes called markers, help distinguish CAS from other types of speech disorders. Those associated with CAS include:

• Trouble moving smoothly from one sound, syllable or word to another.
• Groping movements with the jaw, lips or tongue to try to make the correct movement for speech sounds.
• Vowel distortions, such as trying 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.
• Having a hard time imitating simple words.
• Voicing errors, such as saying "down" instead of "town."

Other speech disorders sometimes confused with CAS

Some speech sound disorders often get confused with CAS because some of the symptoms may overlap. These speech sound disorders include articulation disorders, phonological disorders and dysarthria.

A child with an articulation or phonological disorder has trouble learning how to make and use specific sounds. Unlike in CAS, the child doesn't have trouble planning or coordinating the movements to speak. Articulation and phonological disorders are more common than CAS.

Articulation or phonological speech errors may include:

• Substituting sounds. The child might say "fum" instead of "thumb," "wabbit" instead of "rabbit" or "tup" instead of "cup."
• Leaving out final consonants. A child with CAS might say "duh" instead of "duck" or "uh" instead of "up."
• Stopping the airstream. The child might say "tun" instead of "sun" or "doo" instead of "zoo."
• Simplifying sound combinations. The child might say "ting" instead of "string" or "fog" instead of "frog."

Dysarthria is a speech disorder that occurs because the speech muscles are weak. Making speech sounds is hard because the speech muscles can't move as far, as quickly or as strongly as they do during typical speech. People with dysarthria may also have a hoarse, soft or even strained voice. Or they may have slurred or slow speech.

Dysarthria is often easier to identify than CAS. However, when dysarthria is caused by damage to areas of the brain that affect coordination, it can be hard to determine the differences between CAS and dysarthria.

Causes

Childhood apraxia of speech (CAS) has a number of possible causes. But often a cause can't be determined. There usually isn't an observable problem in the brain of a child with CAS.

However, CAS can be the result of brain conditions or injury. These may include a stroke, infections or traumatic brain injury.

CAS also may occur as a symptom of a genetic disorder, syndrome or metabolic condition.

CAS is sometimes referred to as developmental apraxia. But children with CAS don't make typical developmental sound errors and they don't grow out of CAS. This is unlike children with delayed speech or developmental disorders who typically follow patterns in speech and sounds development but at a slower pace than usual.

Risk factors

Changes 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 changes in the FOXP2 gene may affect motor coordination and speech and language processing in the brain. Other genes also may impact motor speech development.

Complications

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. This may include trouble understanding speech, reduced vocabulary, or not 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.
• Trouble with gross and fine motor movement skills or coordination.
• Trouble using communication in social interactions.

Prevention

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, have a speech-language pathologist evaluate your child as soon as you notice any speech problems.