Sensory-motor rehabilitation in Rett syndrome: a case report.(Clinical report)

Rett syndrome (RS) is a severe neurodevelopmental disorder that mostly affects females. It is characterized by a regression of motor, cognitive, linguistic, and social abilities and by an inappropriate and stereotypical use of the hands. The purpose of the current study was to explore the possibility of rehabilitating purposeful use of the hands and hand-eye coordination in individuals with this syndrome. G.P., a child affected by RS, received experimental, computerized visual-motor coordination training and a sensory-motor rehabilitative program specifically designed for her based on Piaget's (1937) theory of cognitive development. After 3 years of therapy, G.P. partially regained the use of her hands as an instrument of object knowledge and as a means of communicating with people.

Keywords: Rett syndrome; cognitive development; sensory-motor rehabilitation; visual-motor coordination; rehabilitative treatment; computerized training; severe cognitive retardation; stereotypical hand movements

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Rett syndrome (RS) is a neurodevelopmental disorder that affects mainly females, with a prevalence of 1:10,000-20,000 (Percy, 2001). In this syndrome, seemingly normal infant development from 6 to 18 months is interrupted by a rapid or slow and gradual regression of cognitive development, including communication and socioemotional capacity, gross motor function, standing, ambulation, and transitional movements (Larsson & Witt Engerstrom, 2001; Rett, 1966). Children with RS show a very severe cognitive impairment, a loss of purposeful hand use, the appearance of stereotypical hand movements (hand washing and hand-mouthing movements), irregular breathing with apnea or hyperventilation, bruxism, sleep disturbances with unpleasant awakenings at night, frequent seizures, scoliosis, dystonia, ataxia, and autism (Kerr, 1992; Percy, Schanen, & Dure, 1998). Psychological features include anxiety and panic, occasionally self-injury (e.g., hand biting), reduced eye contact, and lack of interest in play (Coleman, Brubaker, Hunter, & Smith, 1988; Mount, Cass, & Charman, 2002; Mount, Hastings, Reilly, Cass, & Charman, 2001; Sansom, Krishan, Corbett, & Kerr, 1993). This pattern of symptoms can vary dramatically across individuals.

Recent studies have identified different mutations in the X-linked gene MECP2, encoding methyl-CpG binding protein 2 in several cases of RS. This suggests the genetic involvement of the Xq28 region of the X chromosome in this syndrome (Amir et al., 1999; Percy, 2001; Schanen, 1999; Willard & Hendrich, 1999). However, mutations in MECP2 are responsible for only 75% of cases RS submitted to genetic screening; 25% of cases are negative on the same test, suggesting that other genes may be involved in RS phenotype (Van Den Veyver, Subramanian, & Zoghbi, 1998).

Neuropathology studies show decreased brain growth beginning at 3 to 4 months, decreased size of dendrites of pyramidal neurons in the frontal and temporal lobes, and abnormalities in substantia nigra. This suggests deficient synaptogenic development, probably starting before birth (Armstrong, 1995; Belichenko, Hagberg, & Dahlstrom, 1997; Dunn, 2001; Kitt & Wilcox, 1995). Volumetric brain magnetic resonance imaging (MRI) studies reveal a selective reduction in gray and white matter volumes in prefrontal, posterior frontal, and anterior temporal regions (Percy et al., 1998; Subramanian, Naidu, & Reiss, 1997), along with general reduced thickness of the cortex (Naidu et al., 2001). However, brain weight does not continue to decrease with age.

According to diagnostic criteria (Hagberg, Goutieres, Hanefeld, Rett, & Wilson, 1985; Hagberg, Hanefeld, Percy, & Skjeldal, 2002; Trevathan et al., 1988), development is within the normal range in the first months of life. However, there is increasing agreement that subtle abnormalities (such as lack of vocalizations, communicative gestures, nonverbal play skills, and words) should be considered as early predictors of RS (Charman et al., 2002; Leonard & Bower, 1998). A developmental regression frequently occurs between 12 and 18 months of age, more rarely before 6 months or after 36 months. Age of regression may be considered a potential index of severity of neurological insult (Charman et al., 2002). A negative prognosis for individuals with RS relates to the severity of mental retardation. Individuals with RS generally achieve an average global cognitive development of 9 months, and their communication and verbal comprehension abilities are around 4 to 11 months of mental age. However, daily living abilities correspond to a mental age of 12 to 14 months (Perry, 1991). The loss of various skills is persistent and subtle. People with RS can grow old, but they are unable to regain hand ability or language (American Psychiatric Association, 1994).