Apraxia is a motor disorder caused by damage to the brain (specifically the posterior parietal cortex or corpus callosum[rx]) which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorder’s severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty.[rx] Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimer’s disease, brain tumor, or other neurodegenerative disorders.[rx] There are multiple types of apraxia, categorized by the specific ability and/or body part affected.
Apraxia of speech (AOS)—also known as acquired apraxia of speech, verbal apraxia, or childhood apraxia of speech (CAS) when diagnosed in children—is a speech sound disorder. Someone with AOS has trouble saying what he or she wants to say correctly and consistently. AOS is a neurological disorder that affects the brain pathways involved in planning the sequence of movements involved in producing speech. The brain knows what it wants to say, but cannot properly plan and sequence the required speech sound movements.
AOS is not caused by weakness or paralysis of the speech muscles (the muscles of the jaw, tongue, or lips). Weakness or paralysis of the speech muscles results in a separate speech disorder, known as dysarthria. Some people have both dysarthria and AOS, which can make a diagnosis of the two conditions more difficult.
The severity of AOS varies from person to person. It can be so mild that it causes trouble with only a few speech sounds or with the pronunciation of words that have many syllables. In the most severe cases, someone with AOS might not be able to communicate effectively by speaking and may need the help of alternative communication methods.
Types
There are several types of apraxia including:
- Apraxia of speech (AOS): Difficulty planning and coordinating the movements necessary for speech (e.g. Potato=Totapo, Topato).[5] AOS can independently occur without issues in areas such as verbal comprehension, reading comprehension, writing, articulation or prosody.[6]
- Buccofacial or orofacial apraxia: This is the most common type of apraxia and is the inability to carry out facial movements on demand. For example, an inability to lick one’s lips, wink, or whistle when requested to do so. This suggests an inability to carry out volitional movements of the tongue, cheeks, lips, pharynx, or larynx on command.[rx][rx]
- Constructional apraxia: The inability to draw, construct, or copy simple configurations, such as intersecting shapes. These patients have difficulty copying a simple diagram or drawing basic shapes.[rx]
- Gait apraxia: The loss of ability to have normal function of the lower limbs such as walking. This is not due to loss of motor or sensory functions.[rx]
- Ideational/conceptual apraxia: Patients have an inability to conceptualize a task and an impaired ability to complete multistep actions. This form of apraxia consists of an inability to select and carry out an appropriate motor program. For example, the patient may complete actions in incorrect orders, such as buttering bread before putting it in the toaster or putting on shoes before putting on socks. There is also a loss of ability to voluntarily perform a learned task when given the necessary objects or tools. For instance, if given a screwdriver, the patient may try to write with it as if it were a pen, or try to comb their hair with a toothbrush.[rx][rx]
- Ideomotor apraxia: These patients have deficits in their ability to plan or complete motor actions that rely on semantic memory. They are able to explain how to perform an action, but unable to “imagine” or act out a movement such as “pretend to brush your teeth” or “pucker as though you bit into a sour lemon.” However, when the ability to perform an action automatically when cued remains intact, this is known as automatic-voluntary dissociation. For example, they may not be able to pick up a phone when asked to do so, but can perform the action without thinking when the phone rings.[rx][rx]
- Limb-kinetic apraxia: The inability to perform precise, voluntary movements of extremities. For example, a person affected by limb apraxia may have difficulty waving hello, tying their shoes, or typing on a computer.[rx][rx] This type is common in patients who have experienced a stroke, some type of brain trauma, or have Alzheimer’s disease.[rx]
- Oculomotor apraxia: Difficulty moving the eye on command, especially with saccade movements that direct the gaze to targets. This is one of the 3 major components of Balint’s syndrome.[rx]
Causes
Apraxia is most often due to a lesion located in the dominant (usually left) hemisphere of the brain, typically in the frontal and parietal lobes. Lesions may be due to stroke, acquired brain injuries, or neurodegenerative diseases such as Alzheimer’s disease or other dementias, Parkinson’s disease, or Huntington’s disease. It is also possible for apraxia to be caused by lesions in other areas of the brain.[rx] Ideomotor apraxia is typically due to a decrease in blood flow to the dominant hemisphere of the brain and particularly the parietal and premotor areas. It is frequently seen in patients with corticobasal degeneration.[rx]
- Acquired AOS can affect someone at any age, although it most typically occurs in adults. Acquired AOS is caused by damage to the parts of the brain that are involved in speaking and involves the loss or impairment of existing speech abilities. It may result from a stroke, head injury, tumor, or other illness affecting the brain. Acquired AOS may occur together with other conditions that are caused by damage to the nervous system. One of these is dysarthria, as mentioned earlier.
- Childhood AOS is present from birth. This condition is also known as developmental apraxia of speech, developmental verbal apraxia, or articulatory apraxia. Childhood AOS is not the same as developmental delays in speech, in which a child follows the typical path of speech development but does so more slowly than is typical. The causes of childhood AOS are not well understood. Imaging and other studies have not been able to find evidence of brain damage or differences in the brain structure of children with AOS. Children with AOS often have family members who have a history of a communication disorder or a learning disability. This observation and recent research findings suggest that genetic factors may play a role in the disorder. Childhood AOS appears to affect more boys than girls.
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Blepharospasm or focal dystonia of the eyelids – idiopathic (also known as benign essential blepharospasm), infectious (keratitis, blepharitis, dacryocystitis, conjunctivitis), toxic exposure (extensive sunlight), autoimmune (keratoconjunctivitis sicca from Sjogren’s disease), neurodegenerative (Parkinson’s and Huntington’s disease)
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Face or eyebrow ptosis – severe levator palpebrae dysfunction from abnormal development, vascular injury, neuromuscular disease (myasthenia gravis), neuroimmunological (multiple sclerosis), trauma, iatrogenic (eye surgery). Ptosis can easily be corrected by tightening the muscle’s tendon that raises the eyelids.
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Dermatochalasis – refers to excess upper or lower eyelid skin, or both. These is merely baggy eyelids and can be fixed by removing the excess baggage and skin in the eyelids.
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Psychogenic – photophobia, fatigue
What are the symptoms of apraxia of speech?
People with either form of AOS may have a number of different speech characteristics or symptoms:
- Distorting sounds. People with AOS may have difficulty pronouncing words correctly. Sounds, especially vowels, are often distorted. Because the speaker may not place the speech structures (e.g., tongue, jaw) quite in the right place, the sound comes out wrong. Longer or more complex words are usually harder to say than shorter or simpler words. Sound substitutions might also occur when AOS is accompanied by aphasia.
- Making inconsistent errors in speech. For example, someone with AOS may say a difficult word correctly but then have trouble repeating it, or may be able to say a particular sound one day and have trouble with the same sound the next day.
- Groping for sounds. People with AOS often appear to be groping for the right sound or word, and may try saying a word several times before they say it correctly.
- Making errors in tone, stress, or rhythm. Another common characteristic of AOS is the incorrect use of prosody. Prosody is the rhythm and inflection of speech that we use to help express meaning. Someone who has trouble with prosody might use equal stress, segment syllables in a word, omit syllables in words and phrases, or pause inappropriately while speaking.
Children with AOS generally understand language much better than they are able to use it. Some children with the disorder may also have other speech problems, expressive language problems, or motor-skill problems.
There are a variety of speech-related symptoms that can be associated with apraxia, including:
- Difficulty stringing syllables together in the appropriate order to make words, or inability to do so
- Minimal babbling during infancy
- Difficulty saying long or complex words
- Repeated attempts at pronunciation of words
- Speech inconsistencies, such as being able to say a sound or word properly at certain times but not others
- Incorrect inflections or stresses on certain sounds or words
- Excessive use of nonverbal forms of communication
- Distorting of vowel sounds
- Omitting consonants at the beginnings and ends of words
- Seeming to grope or struggle to make words
Childhood apraxia of speech rarely occurs alone. It is often accompanied by other language or cognitive deficits, which may cause:
- Limited vocabulary
- Grammatical problems
- Problems with coordination and fine motor skills
- Difficulties chewing and swallowing
- Clumsiness
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
Childhood AOS symptoms
These are some childhood AOS symptoms:
- delayed first words
- only being able to produce a few different types of sounds
- syllables or sounds that aren’t put together in the right order
- saying the same word in different ways
- lengthy pauses between sounds or difficulty moving between sounds and syllables
- putting stress on the incorrect syllable of a word or using equal emphasis for all syllables
- putting stress on the incorrect syllable of a word or using equal emphasis for all syllables
- having more trouble with longer words
- having difficulties imitating what another person is saying
- having to move the lips, jaw, or tongue several times in order to make a sound
- appearing to understand spoken language better than they can speak it
Acquired AOS symptoms
Many of the symptoms of acquired AOS are similar to those of childhood AOS. Some of these symptoms can include:
- a slower rate of speech
- distortions of sounds, which can also include sound additions or substitutions
- long pauses between syllables
- placing an equal amount of stress on all syllables in a word
- having to move the lips, jaw, or tongue a few times before speaking
How is apraxia of speech diagnosed?
Professionals known as speech-language pathologists play a key role in diagnosing and treating AOS. Because there is no single symptom or test that can be used to diagnose AOS, the person making the diagnosis generally looks for the presence of several of a group of symptoms, including those described earlier. Ruling out other conditions, such as muscle weakness or language production problems (e.g., aphasia), can help with the diagnostic process.
In formal testing for both acquired and childhood AOS, a speech-language pathologist may ask the patient to perform speech tasks such as repeating a particular word several times or repeating a list of words of increasing length (for example, love, loving, lovingly). For acquired AOS, a speech-language pathologist may also examine the patient’s ability to converse, read, write, and perform nonspeech movements. To diagnose childhood AOS, parents and professionals may need to observe a child’s speech over a period of time.
Tests may include:
- Hearing tests. Your doctor may order hearing tests to determine if hearing problems could be contributing to your child’s speech problems.
- Oral-motor assessment. Your child’s speech-language pathologist will examine your child’s lips, tongue, jaw and palate for structural problems, such as tongue-tie or a cleft palate, or other problems, such as low muscle tone. Low muscle tone usually isn’t associated with CAS, but it may be a sign of other conditions.Your child’s speech-language pathologist will observe how your child moves his or her lips, tongue and jaw in activities such as blowing, smiling and kissing.
- Speech evaluation. Your child’s ability to make sounds, words and sentences will be observed during play or other activities.Your child may be asked to name pictures to see if he or she has difficulty making specific sounds or speaking certain words or syllables.
Your child’s speech-language pathologist may evaluate your child’s coordination and smoothness of movement in speech during speech tasks. To evaluate your child’s coordination of movement in speech, your child may be asked to repeat syllables such as “pa-ta-ka” or say words such as “buttercup.”
If your child can produce sentences, your child’s speech-language pathologist will observe your child’s melody and rhythm of speech, such as how he or she stresses syllables and words.
Your child’s speech-language pathologist may help your child be more accurate by providing cues, such as saying the word or sound more slowly or providing touch cues to his or her face.
How is apraxia of speech treated?
In some cases, people with acquired AOS recover some or all of their speech abilities on their own. This is called spontaneous recovery.
Treatment for individuals with apraxia includes speech therapy, occupational therapy, and physical therapy.[rx] Currently there are no medications indicated for the treatment of apraxia, only therapy treatments.[rx] Generally, treatments for apraxia have received little attention for several reasons, including the tendency for the condition to resolve spontaneously in acute cases. Additionally, the very nature of the automatic-voluntary dissociation of motor abilities that defines apraxia means that patients may still be able to automatically perform activities if cued to do so in daily life. Nevertheless, research shows that patients experiencing apraxia have less functional independence in their daily lives,[rx] and that evidence for the treatment of apraxia is scarce.[rx] However, a literature review of apraxia treatment to date reveals that although the field is in its early stages of treatment design, certain aspects can be included to treat apraxia.[rx]
Children with AOS will not outgrow the problem on their own. They also do not acquire the basics of speech just by being around other children, such as in a classroom. Therefore, speech-language therapy is necessary for children with AOS as well as for people with acquired AOS who do not spontaneously recover all of their speech abilities.
Speech-language pathologists use different approaches to treat AOS, and no single approach has been proven to be the most effective. Therapy is tailored to the individual and is designed to treat other speech or language problems that may occur together with AOS. Frequent, intensive, one-on-one speech-language therapy sessions are needed for both children and adults with AOS. (The repetitive exercises and personal attention needed to improve AOS are difficult to deliver in group therapy.) Children with severe AOS may need intensive speech-language therapy for years, in parallel with normal schooling, to obtain adequate speech abilities.
In severe cases, adults and children with AOS may need to find other ways to express themselves. These might include formal or informal sign language; a notebook with pictures or written words that can be pointed to and shown to other people; or an electronic communication device—such as a smartphone, tablet, or laptop computer—that can be used to write or produce speech. Such assistive communication methods can also help children with AOS learn to read and better understand spoken language by stimulating areas of the brain involved in language and literacy.
Additional studies have also recommended varying forms of gesture therapy, whereby the patient is instructed to make gestures (either using objects or symbolically meaningful and non-meaningful gestures) with progressively less cuing from the therapist.[rx] It may be necessary for patients with apraxia to use a form of alternative and augmentative communication depending on the severity of the disorder. In addition to using gestures as mentioned, patients can also use communication boards or more sophisticated electronic devices if needed.[rx]
No single type of therapy or approach has been proven as the best way to treat a patient with apraxia since each patient’s case varies. However, one-on-one sessions usually work best, with the support of family members and friends. Since everyone responds to therapy differently, some patients will make significant improvements, while others will make less progress.[rx] The overall goal for the treatment of apraxia is to treat the motor plans for the speech, not treating at the phoneme (sound) level. Research suggests that individuals with apraxia of speech should receive treatment that focuses on the repetition of target words and rate of speech. Research rerouted that the overall goal for the treatment of apraxia should be to improve speech intelligibility, rate of speech, and articulation of targeted words
Speech therapy
Your child’s speech-language pathologist will usually provide therapy that focuses on practicing syllables, words and phrases.
When CAS is relatively severe, your child may need frequent speech therapy, three to five times a week. As your child improves, the frequency of speech therapy may be reduced.
Children with CAS generally benefit from individual therapy. Individual therapy allows your child to have more time to practice speech during each session.
It’s important that children with CAS get a significant amount of practice saying words and phrases during each speech therapy session. Learning to say words or phrases takes children with CAS time and practice.
Because children with CAS have difficulties planning movements for speech, speech therapy often focuses your child’s attention to the sound and feel of speech movements.
Speech-language pathologists may use different types of cues in speech therapy. For example, your child’s speech-language pathologist may ask your child to listen carefully and watch him or her form the target word or phrase with his or her mouth.
Your child’s speech-language pathologist also may touch your child’s face as he or she makes certain sounds or syllables. For example, your child’s speech-language pathologist may use his or her hands to help your child round his or her lips to say “oo.”
No single speech therapy approach has been shown to be most effective for treating CAS. But, some important general principles of speech therapy for CAS include:
- Speech drills. Your child’s speech-language therapist will focus on speech drills, such as asking your child to say words or phrases many times during a therapy session.
- Sound and movement exercises. Your child will be asked to listen to the speech-language pathologist and to watch his or her mouth as he or she says the target word or phrase. By watching the speech-language pathologist’s mouth, your child also sees the movements that go along with the sounds.
- Speaking practice. Your child will most likely practice syllables, words or phrases, rather than isolated sounds, during speech therapy. Children with CAS need practice making the movements from one sound to another.
- Vowel practice. Because many children with CAS distort vowel sounds, your child’s speech-language pathologist may choose words for your child to practice that contain vowels in different types of syllables. For example, your child may be asked to say “hi,” “mine” and “bite,” or “out,” “down” and “house.”
- Paced learning. If your child has severe CAS, your child’s speech-language pathologist may use a small set of practice words at first, and gradually increase the number of words for practice as your child improves.
Speech practice at home
Because speech practice is very important, your child’s speech-language pathologist may encourage you to be involved in your child’s speech practice at home.
Your child’s speech-language pathologist may give you words and phrases to practice with your child at home that he or she has learned in speech therapy. Each home practice session can be short, such as five minutes in length, and you may practice with your child twice a day.
Children also need to practice words and phrases in real-life situations. Create situations where it will be appropriate for your child to say the word or phrase spontaneously. For example, ask your child to say “Hi, Mom” each time mom enters a room. Practicing words or phrases in real-life situations will make it easier for your child to say the practice words automatically.
Alternative communication methods
If your child has a severe speech disorder and can’t effectively communicate, alternative communication methods can be very helpful.
Alternative communication methods may include sign language or natural gestures, such as pointing or pretending to eat or drink. For example, your child could use signs to communicate he or she wants a cookie. Sometimes electronic devices, such as electronic tablets, can be helpful in communication.
It’s often important to use alternative communication methods early. Using these methods may help your child become less frustrated when trying to communicate. It may also help your child to develop language skills such as vocabulary and the ability to put words together in sentences.
As speech improves, these strategies and devices may no longer be necessary.
Therapies for coexisting problems
Many children with CAS also have delays in their language development, and they may need therapy to address their language difficulties.
Children with CAS who have fine and gross motor movement difficulties in their arms or legs may need physical or occupational therapy.
If a child with CAS has another medical condition, then effective treatment for that condition may be important to improving the child’s speech.
Some adults and children will make more progress during treatment than others. Support and encouragement from family members and friends and extra practice in the home environment are important.
What research is being done to better understand apraxia of speech?
Researchers are searching for
the causes of childhood AOS, including the possible role of abnormalities in the brain or other parts of the nervous system. They are also looking for genetic factors that may play a role in childhood AOS. Other research on childhood AOS aims to identify more specific criteria and new techniques to diagnose the disorder and to distinguish it from other communication disorders.
Research on acquired AOS includes studies to pinpoint the specific areas of the brain that are involved in the disorder. In addition, researchers are studying the effectiveness of various treatment approaches for both acquired and childhood AOS.
References