Childhood apraxia of speech

Overview

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

In CAS, the brain isn't able to direct the lips, jaw, and tongue to create speech sounds clearly or at the proper speed. The speech muscles aren't weak, but they are not able to form words the right way.

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

Symptoms

Children with childhood apraxia of speech, also called CAS, may have various speech symptoms. Symptoms vary depending on a child's age and whether their speech problems are severe.

Children usually talk more between the ages of 2 and 4. Signs that may indicate CAS include:

• Unclear vowels and consonants.
• Pauses between syllables or words.
• Voicing errors, such as the word "pie" sounding like the word "bye."

Symptoms that are unique to the speech of children with CAS help make a diagnosis. Some characteristics, called markers, help distinguish CAS from other types of speech disorders. Those markers may include:

• Trouble moving smoothly from one sound, syllable or word to another.
• Off-target movements of the jaw, lips or tongue as they search for the correct movements for speech sounds. This is called groping.
• Saying vowel sounds incorrectly.
• Using the wrong stress in a word, such as pronouncing the word "banana" as BUH-na-nuh instead of buh-NA-nuh.
• Using equal emphasis on all syllables, such as saying BUH-NA-NUH.
• Putting a pause or gap between syllables.
• Saying the same word differently when using it more than once.
• Having a hard time imitating simple words.
• Voicing errors, such as saying the word "down" instead of the word "town."

However, some CAS symptoms also are symptoms of other speech or language disorders. CAS may be hard to diagnose if a child has symptoms found in both CAS and other disorders.

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

CAS can result in:

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

These symptoms are usually noticed between the ages of 18 months and 2 years. Symptoms at this age may suggest a condition called suspected CAS. Suspected CAS means a child may develop CAS. The child should receive ongoing exams in addition to speech therapy.

Other speech disorders sometimes confused with CAS

Other speech sound disorders are often confused with CAS because some symptoms are similar, such as voicing errors and leaving out certain sounds. These other 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 movements to speak. Articulation and phonological disorders are more common than CAS.

Articulation or phonological speech disorder symptoms 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. For example, the child might say "ting" instead of string or fog instead of frog.

Dysarthria is a speech disorder that may be confused with CAS.  It happens because the speech muscles are weak. Making speech sounds is hard because the speech muscles can't move as far, as fast or as strongly as they need to for clear speech. People with dysarthria also may 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 may be hard to determine the differences between CAS and dysarthria.

Causes

Childhood apraxia of speech, also called CAS, has many possible causes. But often a cause can't be found. There usually isn't an obvious change in a child's brain with CAS. However, CAS can be the result of brain conditions or injuries. These may include stroke, infections or traumatic brain injury.

CAS also may be a symptom of a genetic condition or syndrome or a metabolic condition.

CAS is sometimes referred to as developmental apraxia. But children with CAS don't make typical developmental sound errors. CAS also does not go away as a child grows older. This is unlike what happens in children with delayed speech or developmental conditions who follow typical speech and sound development patterns but at a slower pace.

Risk factors

Childhood apraxia of speech, also called CAS, is linked to gene differences in about one-third of children with the condition. Sometimes, it's caused by a change in a single gene. For example, risk may increase due to a change in the FOXP2 gene. This gene helps the brain control muscles needed for talking, especially for planning how to move the mouth.

Other times, CAS is related to larger changes in chromosomes, such as parts being missing or repeated. These changes can affect many genes. For example, missing part of chromosome 22q11.2 can raise the risk of speech sound disorders, including CAS.

CAS also can be part of certain genetic syndromes that affect the whole body. One example is galactosemia, a condition that affects how the body breaks down certain sugars in the blood. Children with galactosemia have a higher chance of having CAS.

Complications

Many children with childhood apraxia of speech, also called CAS, have other conditions that affect their ability to communicate. These conditions aren't due to CAS but may happen along with CAS.

Symptoms 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 trouble with reading, spelling and writing.
• Trouble with motor movement skills or coordination.
• Trouble using communication in social interactions.

Prevention

You can't prevent childhood apraxia of speech, also called CAS. But early diagnosis and treatment of CAS may reduce the risk of long-term complications. If your child has trouble with speech, have a specialist, called a speech-language pathologist, evaluate your child as soon as you notice any issues.