Myotonic dystrophy MD is an autosomal dominant, progressive, neuromuscular disease with congenital,

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Neuropsychological Outcomes in Children with
Myotonic Dystrophy and the Neurodevelopmental
Factors that Contribute to Variability Dawn
Ilardi, Ph.D. Kathleen OToole,
Ph.D.Childrens Healthcare of Atlanta,
Department of Neuropsychology

• INTRODUCTION
• Myotonic dystrophy (MD) is an autosomal
  dominant, progressive, neuromuscular disease with
  congenital, child, and adult onset. Neurological
  abnormalities are variable. For congenital MD,
  onset is prenatal, transmission is maternal, and
  the adult literature indicates more severe
  medical (e.g., muscle weakness, cardiovascular
  and respiratory problems) and cognitive
  challenges. For child onset, transmission is
  maternal or paternal, motor symptoms are mild,
  but reports indicate significant cognitive and
  behavioral challenges. With regard to specific
  neurocognitive deficits, these have been clearly
  documented for adults only (i.e.,
  attention/executive, motor, visuospatial,
  language, and social-emotional functioning). The
  sparse research on neurodevelopmental course in
  children indicates average to deficient
  intellectual functioning, symptoms of ADHD, and
  internalizing behaviors (e.g., anxiety and
  depression). One study reported childhood
  difficulty with reading and spelling. These
  studies repeatedly recommended that comprehensive
  neuropsychological findings be used to more
  thoroughly understand developmental outcomes.
  The purpose of the current study was to review a
  series of pediatric cases with MD who received
  comprehensive neuropsychological testing. It was
  hypothesized that the modal profile for pediatric
  neurocognitive deficits in MD would be similar to
  those in adults when biological risk, time since
  onset, development, and reserve are considered.
• A NEURODEVELOPMENTAL MODEL
• (Dennis, 2000)

• Table 1 Summary of Spared and Impaired (SS
  85) Test Results Across Cases
• Case 1 Case 2 Case 3 Case 4 Case 5
• Intelligence strength Verbal Verbal
• Nonverbal Nonverbal
• weakness Nonverbal Verbal Verbal
  
• Nonverbal Nonverbal
• Language strength Naming Naming Naming,
  Fluency
• Vocabulary
• weakness Naming, Fluency Fluency E
  xpressive
• Listen Comp Expressive
  Listen Comp
• Motor/ strength Visuomotor Dexterity D
  exterity
• Visuospatial Visuomotor
• weakness Dexterity Visuospatial Dexter
  ity Visuomotor
• All Visuospatial Visuomotor Visuo
  spatial
• Memory strength Visual Word lists Visual Wo
  rd lists Word lists
• Verbal Pictures Verbal Visual
• weakness Designs Visual
• Stories
• Academic strength Pre-academic Spelling All
  areas All areas

Medical Condition Myotonic Dystrophy
Biological Insult
Development of the Child

• DM1 or DM2
• Severity of CNS involvement
• Treatment side-effects
• Secondary effects of other medical
• conditions (e.g., prematurity epilepsy)
• Neurodegeneration and Abnormality
• Cell loss and atrophy
• Neuronal intranuclear inclusions
• Neurofibrillary tangles

• onset interferes with acquisition of skills at
  critical
• stages in developmental course (e.g., executive
• functioning)
• Congenital onset more severe than childhood onset
• Rate of progression more rapid in congenital
  onset

Outcome Algorithm
Reserve
Time Since Onset

• Socioeconomic, cognitive, and physical factors
• prior to onset
• Mental health (e.g., internalizing symptoms)
• Family and school resources

• stability, attenuation, and
• exacerbation of deficits across
• the lifespan depending on age of
• onset

Cognitive Phenotype
Overall results suggest that intellectual
functioning is variable within the range of
average to mildly deficient Verbal IQ 82 to 108
Nonverbal IQ 68 to 98 Full Scale 73 to 102.
This is consistent with the current research in
adult and child studies. Language functioning is
variable for receptive and expressive measures.
Research suggests that oral motor deficits in MD
affect language production, and it is likely that
attentional deficits affect listening
comprehension. Motor functioning is variable
for simple dexterity tasks and visual tasks that
required a motor component. Visuospatial/perceptua
l functioning is generally a weakness. Verbal
and visual memory are strengths. Academic
functioning is generally a strength, with the
exception of two children who have reading
difficulties. Reading and spelling difficulties
have been previously reported in children with
MD. Attention/executive functioning weaknesses
are consistent across all cases, and this
supports the existing literature in adults and
children suggesting a high prevalence of AD/HD.
Adaptive functioning is delayed in the one case
it was assessed (4 year old). Finally,
socioemotional functioning is a weakness in the
older children (ages 11-18). These children
exhibited social difficulties and internalizing
symptoms related to anxiety and depression, which
is consistent with child and adult research.
Impairment in visuospatial, attention/executive,
and socio-emotional functioning, as well as
reading difficulties, appears to be the cognitive
phenotype of childhood MD, and is generally
consistent with adult research. Variability is
evident for language and motor functioning, but
likely related to increased biological risk due
to possible secondary effects.
References are available upon request
18 years
Cognitive Phenotype for MD
Progression of neuromuscular disease Progression
of development
11 years
4 years
Attention/Executive Functioning
Visuospatial Functioning
Internalizing Symptoms
Reading Problems
Social Functioning
Biological risk, despite buffer of Reserve
Motor and Language Weaknesses