How is Rett syndrome diagnosed?
Before 2010, Rett syndrome was considered to be an autism spectrum disorder, and was listed in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-4) under the autism spectrum umbrella. With the publication of the DSM-5 in 2013, Rett syndrome was deleted from the DSM because it is primarily caused by a genetic mutation. The diagnosis is made clinically and the mutation is confirmed through a blood test. There are typically two kinds of Rett syndrome: there is classic Rett syndrome, where someone meets all of the required criteria, and there is a less severe version called atypical or variant Rett.
Focusing on Classic Rett, the main criteria are listed below. All four of these are required in order to meet the diagnosis of classic Rett syndrome:
- Partial or complete loss of functional hand skills
- Partial or complete loss of spoken language skills
- Impaired apraxic gait or absence of ability to ambulate
- Stereotypic, repetitive, nonfunctional hand movements
There is an early period of typical development, and then a regression will most likely begin before the third birthday and last up to two years. People can still be regressing at ages four or five, but usually there is a stabilization between ages three and five, followed by a regaining of skills. We used to think this was a degenerative disorder, but it is no longer considered to be so.
Starting with the four required criteria, there must be a partial or complete loss of functional hand skills. This means that someone with Rett syndrome is unable to engage in the hand skills that are part of daily activities. An example of this is bringing things to the mouth, which can become evident as they get older and begin using utensils. If you start to see these kinds of features, it may be classic Rett syndrome. There is also partial or complete loss of spoken language skills. Some individuals never begin to speak. Others will begin to speak within their first year and then will usually lose most or all of their spoken words. The individuals who retain verbal skills usually meet the atypical or variant Rett and tend to have a less severe presentation. That is important to remember because most individuals with Rett syndrome are almost completely nonverbal. If a young child is on your caseload, it is important to introduce augmentative communication because it is unlikely that they are going to be able to use spoken language in a functional way.
The third criteria is impaired apraxic gait or the complete lack of ability to ambulate. Many individuals with Rett are completely unable to stand or walk. If they are able to walk, there are balance issues. They might have a wide, apraxic-like gait, where their acquisition of motor skills is most likely delayed.
The fourth criteria is stereotypic, repetitive, non-functional hand movements. These usually look like bilateral hand movements and can take different forms. It could be hand-wringing, clasping the hands together, or doing something with one hand and something else with the other. These are not generally under the individual's volitional control, but with appropriate intervention, you can get some girls to use their hands in a functional way. That is where working with occupational therapists is helpful.
Along with the required main criteria, there are supportive criteria. They can be observed but are not required. These are conditions that frequently accompany Rett syndrome:
- Respiratory disturbances, such as rapid breathing or breath-holding
- Teeth grinding
- Impaired sleep patterns; frequent sleeping during the day, frequent night waking
- Abnormal muscle tone
- Peripheral vasomotor disturbances
- Scoliosis and/or kyphosis
- Growth retardation
- Small cold hand and feet
- Laughing and/or screaming spells, not appropriate for the context
- Lessened response to pain
- Intense eye communication – often referred to as “eye pointing
These criteria are important for us to know because they affect how we assess, as well as what we use as an intervention program.
Please refer to the SpeechPathology.com course, Back to Basics: Guidelines for Management of Communication in Rett Syndrome, for more information on best practices for assessment and intervention of communication in individuals with Rett syndrome.