Neurodevelopment of Children Under 3 Years of Age With Smith-Magenis Syndrome

Abstract

Systematic data regarding early neurodevelopmental functioning in Smith-Magenis syndrome is limited. Eleven children with Smith-Magenis syndrome less than three years of age (mean = 19 months; range 5-34) received prospective multidisciplinary assessments using standardized measures. The total sample scored in the moderately to severely delayed range in cognitive functioning, expressive language, and motor skills, and exhibited generalized hypotonia, oral-motor abnormalities, and middle ear dysfunction. Socialization skills were average and significantly higher than daily living, communication, and motor abilities, which were below average. Mean behavior ratings were in the non-autistic range. Exploratory analyses revealed the toddler subgroup scored significantly lower than the infant subgroup in cognition, expressive language, and adaptive behavior suggesting that the toddlers were more delayed than the infants relative to their respective peers. Infants aged approximately one year or younger exhibited cognitive, language, and motor skills that ranged from average to delayed but age-appropriate social skills and minimal maladaptive behaviors. At ages two to three years, the toddlers consistently exhibited cognitive, expressive language, adaptive behavior, and motor delays and mildly to moderately autistic behaviors. Combining age groups in studies may mask developmental and behavioral differences. Increased knowledge of these early neurodevelopmental characteristics should facilitate diagnosis and appropriate intervention.

Concrete and relational vocabulary: Comparison between Williams and Smith–Magenis syndromes

“…Although this is the first report on concrete and relational vocabulary in SMS, these results are in line with evidence showing relatively preserved receptive language when compared with expressive language, and with relatively preserved spatial perception skills in SMS (Garayzá bal-Heinze et al, 2011;Gropman et al, 2006;Sarimski, 2004;Udwin et al, 2001;Wolters et al, 2009). As hypothesized, performance on relational space concepts was significantly poorer among individuals with WS, in comparison to the SMS group.…”

Neurodevelopmental features of Smith–Magenis syndrome: strengths and weaknesses

“…Regarding motor development, such as walking and crawling, delays when compared to typical development varied from 4 to 6 months. This result is consistent with previous evidence (Wolters et al, 2009) and may be a consequence of infantile hypotonia, a symptom that is often present in SMS (Udwin et al, 2001;Wolters et al, 2009). Bladder and bowel control also seems to have occurred in the normal sequence, with bowel control at night being attained first, followed by bowel control during the day, then by bladder control also during the day and finally by night time bladder control.…”

Autism spectrum features in Smith–Magenis syndrome

“…The striking neurobehavioral phenotype that characterizes the syndrome emerges over time, beginning between 18-36 months of age, when head-banging and autistic-like behaviors are seen [Gropman et al, 2006; Wolters et al, 2009]. Mild gross and fine motor delays with age-appropriate social skills and minimal maladaptive behaviors can be observed in infants <18 months; however, at ages 2-3 years, global psychomotor, expressive language delays and mild to moderate autistic behaviors begin to emerge [Wolters et al, 2009].…”

“…Mild gross and fine motor delays with age-appropriate social skills and minimal maladaptive behaviors can be observed in infants <18 months; however, at ages 2-3 years, global psychomotor, expressive language delays and mild to moderate autistic behaviors begin to emerge [Wolters et al, 2009]. Initially, infants are sociable and are frequently described as a “perfect baby” who “never cries” [Gropman et al, 2006].…”