Lesser Known Disorders
Each issue of this series contains at least three lesser known disorders. Some of these disorders may contain subtypes which will also be presented. You will also notice that each disorder has a code. These codes represent the coding system for all disabilities and disorders listed in the Educator’s Diagnostic Manual(EDM) Wiley Publications.
Disorders in this issue:
- Rett Syndrome
- Mental Retardation due to Prader-Willi Syndrome
- Apraxia of Speech (Verbal Apraxia or Dyspraxia)
AU 7.00 – Rett Syndrome
Disability Category – Autism
Definition
Rett Syndrome (RS) is a neurological disorder seen almost exclusively in females, and found in a variety of racial and ethnic groups worldwide (International Rett Syndrome Association, 2005).
Diagnostic Symptoms
An inability to perform motor functions is perhaps the most severely disabling feature of Rett syndrome, interfering with every body movement, including eye gaze and speech. Other diagnostic symptoms of Rett Syndrome include (International Rett Syndrome Association, 2005; National Institute on Neurological Disorders and Stroke, 2005c):
- An early period of apparently normal or near normal development until 6–18 months of life.
- A period of temporary stagnation or regression follows during which the child loses communication skills and purposeful use of the hands.
- stereotyped hand movements
- gait disturbances
- slowing of the rate of head growth become apparent
- Seizures
- Disorganized breathing patterns which occur when awake
- Compulsive hand movements such as wringing and washing follow the loss of functional use of the hands
Further Key Points
When diagnosing Rett Syndrome, it is important to recognize that there are four stages to this syndrome. According to the National Institute for Neurological Disorders and Stroke (2004c), these are the following:
Stage I – called early onset, generally begins between 6 and 18 months of age. Quite frequently, this stage is overlooked because symptoms of the disorder may be somewhat vague, and parents and doctors may not notice the subtle slowing of development at first. The infant may begin to show less eye contact and have reduced interest in toys. There may be delays in gross motor skills such as sitting or crawling. Hand-wringing and decreasing head growth may occur, but not enough to draw attention. This stage usually lasts for a few months but can persist for more than a year.
Stage II – or the rapid destructive stage, usually begins between ages 1 and 4 and may last for weeks or months. This stage may have either a rapid or a gradual onset as purposeful hand skills and spoken language are lost. The characteristic hand movements begin to emerge during this stage and often include wringing, washing, clapping, or tapping, as well as repeatedly moving the hands to the mouth. Hands are sometimes clasped behind the back or held at the sides, with random touching, grasping, and releasing. The movements persist while the child is awake but disappear during sleep. Breathing irregularities such as episodes of apnea and hyperventilation may occur, although breathing is usually normal during sleep. Some girls also display autistic-like symptoms such as loss of social interaction and communication. General irritability and sleep irregularities may be seen. Gait patterns are unsteady and initiating motor movements can be difficult. Slowing of head growth is usually noticed during this stage.
Stage III – also called the plateau or pseudo-stationary stage, usually begins between ages 2 and 10 and can last for years. Apraxia, motor problems, and seizures are prominent during this stage. However, there may be improvement in behavior, with less irritability, crying, and autistic-like features. An individual in stage III may show more interest in her surroundings, and her alertness, attention span, and communication skills may improve. Many girls remain in this stage for most of their lives.
Stage IV – called the late motor deterioration stage—can last for years or decades and is characterized by reduced mobility. Muscle weakness, rigidity (stiffness), spasticity, dystonia (increased muscle tone with abnormal posturing of extremity or trunk), and scoliosis (curvature of the spine) are other prominent features. Girls who were previously able to walk may stop walking. Generally, there is no decline in cognition, communication, or hand skills in stage IV. Repetitive hand movements may decrease, and eye gaze usually improve.
AMR 1.06- Intellectual Disability due to Prader-Willi Syndrome
Disability Category II – Intellectual Disability
Definition
Prader-Willi syndrome is chromosomal disorder caused by inheriting from one’s father a lack of genetic material on the fifteenth pair of chromosomes (Dykens, Hodapp, & Finucane, 2000). It is a complex genetic disorder that typically causes low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to excessive eating and life-threatening obesity (Hallahan & Kaufmann, 2003; National Center for Biotechnology Information, 2005). Children who have Prader-Willi Syndrome have mild or moderate intellectual disability, and some of them have abilities in the low average range (Prader-Willi Syndrome Association, 2003).
Explanation
Prader-Willi syndrome is a complex genetic condition that affects many parts of the body. This condition is due to the effects of the loss of active genes in a specific region of chromosome 15. People normally have two copies of this chromosome in each cell, one copy from each parent. Some genes on this chromosome, however, are only active when they are inherited from a person’s father (the paternal copies). Prader-Willi syndrome occurs when the region of paternal chromosome 15 containing these genes is missing (National Center for Biotechnology Information, 2005g).
The condition is characterized in infancy by weak muscle tone (hypotonia), feeding difficulties, poor growth, and delayed development (Taylor, Richards, & Brady, 2005)
Beginning in childhood, features of the disorder include excessive eating (hyperphagia), obesity, short stature, scoliosis, intellectual disability or learning disabilities, and behavioral problems. Some affected individuals also have unusually fair skin and light-colored hair (Taylor, Richards, & Brady, 2005; U.S. National Library of Medicine, 2005g).
SL 1.00 Apraxia of Speech (Verbal Apraxia or Dyspraxia)
Disability Category III – Speech and Language Impaired
Definition
Apraxia of speech, also known as verbal apraxia or dyspraxia, is a speech disorder in which a person has trouble saying what he or she wants to say correctly and consistently. It is characterized by a disruption of motor planning and programming so that speech is slow, effortful, and inconsistent (Hallahan and Kauffman, 2006).
Apraxia is a motor disorder in which volitional or voluntary movement is impaired without weakness or paralysis of the speech muscles, such as the muscles of the face, tongue, and lips (National Institute on Deafness and Other Communication Disorders, 2002a). It is a motor speech disorder that affects the way in which a student plans to produce speech (Turnbull et al., 2004) even though they have no paralysis or weakness of the muscles involved in speech.
Oral apraxia indicates that the child has difficulty with volitional control of nonspeech movement. For instance, perhaps the child will have difficulty sticking out and wagging his/her tongue when requested to do so. Or the child may have difficulty sequencing movements for the command, “Show me how you kiss, now smile, now blow”.
Verbal apraxia indicates that the child has difficulty with volitional movement for the production of speech. This can be at the level of sounds, syllables, words, or even phrases (connected speech). The motor struggle is most typically seen with sounds sequencing (Childhood Apraxia of Speech Association, 2005).
Diagnostic Symptoms
Apraxia is a motor planning disorder in the absence of muscle weakness (Hedge & Maul, 2006). People with apraxia of speech may have a number of different speech characteristics, or symptoms. One of the most notable symptoms is difficulty putting sounds and syllables together in the correct order to form words. Longer or more complex words are usually harder to say than shorter or simpler words. People with apraxia of speech also tend to make inconsistent mistakes when speaking (National Institute on Deafness and Other Communication Disorders, 2002a). For example, they may say a difficult word correctly but then have trouble repeating it, or they may be able to say a particular sound one day and have trouble with the same sound the next day. People with apraxia of speech often appear to be groping for the right sound or word, and may try saying a word several times before they say it correctly.
Another common characteristic of apraxia of speech is the incorrect use of “prosody”—that is, the varying rhythms, stresses, and inflections of speech that are used to help express meaning (National Institute on Deafness and Other Communication Disorders, 2002a).
Children with apraxia of speech generally can understand language much better than they are able to use language to express themselves. Some children with the disorder may also have other problems. These can include other speech problems, such as dysarthria; language problems such as poor vocabulary, incorrect grammar, and difficulty in clearly organizing spoken information; problems with reading, writing, spelling, or math; coordination or “motor-skill” problems; and chewing and swallowing difficulties (Anderson and Shames, 2006)
Apraxia is evident when the child cannot position articulators correctly for speech production even though there is no muscular problem (Hedge and Maul, 2006). The severity of apraxia of speech varies from person to person. Apraxia can be so mild that a person has trouble with very few speech sounds or only has occasional problems pronouncing words with many syllables. In the most severe cases, a person may not be able to communicate effectively with speech, and may need the help of alternative or additional communication methods (National Institute on Deafness and Other Communication Disorders, 2002a).
Individuals with speech apraxia may have a number of different symptoms, which may include (Golisano Children’s Hospital, 2005):
- A tendency to grope for words or sounds
- A tendency to say a word several times before saying it the right way
- Demonstrate poor language skills, including poor vocabulary and grammar
- Difficulty putting sounds or syllables together in the correct order to form words
- Errors using vowels
- Experience problems with reading, writing, spelling, or math
- Have difficulty organizing spoken information clearly
- Have other speech disorders, coordination or “motor-skill” problems
- Inconsistent or improper use of rhythms, stresses, and inflections of speech that are used to convey meaning
- Inconsistent speech errors, even when repeating a word that’s just been said
- Incorrect timing of speech movements and their accompanying sounds
- Increased tendency to make errors as the length of words or sentences increases
- Limited ability to make speech sounds automatically
- Suffer from chewing and swallowing difficulties.
- Understand language better than they are able to use it
Further Key Points
Researchers are searching for the causes of apraxia of speech, including the possible role of abnormalities in the brain or other parts of the nervous system. Students with apraxia need frequent therapy that focuses on repetition, sound sequencing, and movement patterns (Caruso & Strand, 1999).Generally, treatment for individuals with apraxia includes physical, speech, or occupational therapy. If apraxia is a symptom of another disorder, the underlying disorder should be treated. The prognosis for individuals with apraxia varies and depends partly on the underlying cause. Some individuals improve significantly while others may show very little improvement (National Institute on Deafness and Other Communication Disorders, 2002a).
Types of Apraxia of Speech
SL 1.01-Acquired Apraxia of Speech
Definition
A type of apraxia of speech specifically associated with damage to the parts of the brain that are involved in speaking and/or the loss or impairment of existing speech abilities (Hallahan & Kauffman, 2006). The disorder may result from a stroke, head injury, tumor, or other illness affecting the brain (National Institute on Deafness and Other Communication Disorders, 2002a). Acquired Apraxia may occur together with muscle weakness affecting speech production (dysarthria) or language difficulties caused by damage to the nervous system (aphasia).
Explanation
Acquired Apraxia of Speech can affect a person at any age. It is due to the effects of damage to the parts of the brain that are involved in speaking, and involves the loss or impairment of existing speech abilities. The disorder may result from a stroke, head injury, tumor, or other illness affecting the brain (National Institute on Deafness and Other Communication Disorders, 2002a).
Acquired Apraxia of Speech is a condition in which strength and coordination of the speech muscles are unimpaired but the individual experiences difficulty saying words correctly in a consistent way (Anderson & Shames, 2006). This type of disorder can create tremendous anxiety and tension for students diagnosed with it. For example, a student may repeatedly stumble on the simple word “tomorrow” when asked to repeat it, but then be able to say it in a statement such as, “I’ll try to say it again tomorrow” (National Institute on Deafness and Other Communication Disorders, 2002a).
SL 1.01a-Acquired Apraxia of Speech with Aphasia
Acquired Apraxia of speech may occur together with language difficulties due to the effects of damage to the nervous system (aphasia). Aphasia is a total or partial loss of the ability to use or understand language; usually due to the effects of recent insult to the brain (e.g., stroke, brain disease, or injury) (Hedge & Maul, 2006).
SL 1.01b-Acquired Apraxia of Speech with Dysarthria
Acquired Apraxia of speech may occur together with muscle weakness affecting speech production (Dysarthria). Dysarthria is a complex set of communication problems due to impaired neural control of muscles involved in speech production (Shames & Anderson, 2006; Hedge & Maul, 2006).
SL 1.02-Developmental Apraxia of Speech (also known as DAS, Developmental Verbal Dyspraxia, Developmental Verbal Apraxia, Articulatory Dyspraxia, Childhood Apraxia of Speech)³
Definition
A type of apraxia of speech specifically associated with a child’s ability to plan and sequence speech sounds for clear and intelligible speech (Hallahan & Kauffman, 2006). Children with Developmental Apraxia of Speech (DAS) have difficulty preparing and coordinating their muscles for speech production (Hearing, Speech & Deafness Center, 2005).
Explanation
Developmental Apraxia of Speech (DAS) occurs in children and is present from birth (Anderson & Shames, 2006). It is neurologically based communication disorder that interferes with a child’s ability to correctly pronounce sounds, syllables, and words (Hearing, Speech & Deafness Center, 2005). There are no specific lesion sites in the brain in cases of developmental apraxia (whereas acquired apraxia can be linked to specific lesion sites).
DAS goes by several other names, including developmental verbal Apraxia, developmental verbal dyspraxia, articulatory Apraxia, and childhood Apraxia of speech. DAS is different from what is known as a developmental delay of speech, in which a child follows the “typical” path of speech development but does so more slowly than normal. It appears to affect more boys than girls. (National Institute on Deafness and Other Communication Disorders, 2002a).
Typical speech characteristics of children with DAS include (Anderson & Shames, 2006; Hearing, Speech & Deafness Center,2005):
- Additions of sounds
- Difficulties with sound sequencing
- Distortions of sounds
- Disturbances in timing of movements and accompanying sounds
- Inconsistent speech errors, even on repetitions of the same word
- Increased errors as word / sentence length increases
- Intelligibility of connected speech may be significantly impaired
- Limited speech sound repertoire (very few speech sounds that a child can use automatically) Multiple speech sound errors present:
- Omissions of sounds (very common)
- Substitutions of one sound for another
- Vowel errors
The cause or causes of DAS are not yet known. Some scientists believe that DAS is a disorder related to a child’s overall language development. Others believe it is a neurological disorder that affects the brain’s ability to send the proper signals to move the muscles involved in speech. However, brain imaging and other studies have not found evidence of specific brain lesions or differences in brain structure in children with DAS(National Institute on Deafness and Other Communication Disorders, 2002a).
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