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Chapter 31: Child Psychiatry
Available data indicate a prevalence of 6 to 7 cases of Rett
syndrome per 100,000 girls. Originally, it was believed that Rett
syndrome occurred only in females, but males with the disorder
or syndromes that are very close to this disorder have now been
described. Rett syndrome is not fully included within autism
spectrum disorder, and if present along with autism spectrum
disorder it should be diagnosed as an associated disorder.
Etiology.
The cause of Rett syndrome is unknown, although
the progressive deteriorating course after an initial normal
period is compatible with a metabolic disorder. In some patients
with Rett syndrome, the presence of hyperammonemia has led
to postulation that an enzyme metabolizing ammonia is defi-
cient, but hyperammonemia has not been found in most patients
with Rett syndrome. It is likely that Rett syndrome has a genetic
basis. It has been seen primarily in girls, and case reports so far
indicate complete concordance in monozygotic twins.
Diagnosis and Clinical Features.
During the first
5 months after birth, infants have age-appropriate motor skills,
normal head circumference, and normal growth. Social inter-
actions show the expected reciprocal quality. At 6 months to
2 years of age, however, these children develop progressive
encephalopathy with a number of characteristic features. The
signs often include the loss of purposeful hand movements,
which are replaced by stereotypic motions, such as hand-wring-
ing; the loss of previously acquired speech; psychomotor retar-
dation; and ataxia. Other stereotypical hand movements may
occur, such as licking or biting the fingers and tapping or slap-
ping. The head circumference growth decelerates and produces
microcephaly. All language skills are lost, and both receptive
and expressive communicative and social skills seem to pla-
teau at developmental levels between 6 months and 1 year. Poor
muscle coordination and an apraxic gait with an unsteady and
stiff quality develop.
Associated features include seizures in up to 75 percent of
affected children and disorganized EEG findings with some epi-
leptiform discharges in almost all young children with Rett syn-
drome, even in the absence of clinical seizures. An additional
associated feature is irregular respiration, with episodes of
hyperventilation, apnea, and breath holding. The disorganized
breathing occurs in most patients while they are awake; dur-
ing sleep, the breathing usually normalizes. Many patients with
Rett syndrome also have scoliosis. As the disorder progresses,
muscle tone seems to change from an initial hypotonic condi-
tion to spasticity to rigidity.
Although children with Rett syndrome may live for well over
a decade after the onset of the disorder, after 10 years, many
patients are wheelchair-bound, with muscle wasting, rigid-
ity, and virtually no language ability. Long-term receptive and
expressive communication and socialization abilities remain at
a developmental level of less than 1 year.
Dana was born as a full-term and healthy baby term after an
uncomplicated pregnancy. An amniocentesis had been obtained
because of advanced maternal age of 40 years, and findings were
normal. At birth, Dana received good Apgar scores and her weight,
height, and head circumference were all near the 50th percentile.
Her development during the first months of life was unremark-
able. At approximately 8 months of age, her development seemed
to wane, and her interest in the environment, including the social
environment, declined. Dana’s developmental milestones failed to
progress, and she became markedly delayed; she was just starting to
walk at her second birthday and had no spoken language. Evaluation
at that time revealed that head growth had decelerated. Self-stim-
ulatory behaviors emerged, and in addition, marked cognitive and
communicative delays were noted on formal testing. Dana began to
lose purposeful hand movements and developed unusual stereotypi-
cal hand-washing behaviors. By age 6, her EEG was abnormal and
abnormal hand movements were prominent. Subsequently, Dana
developed truncal ataxia and breath-holding spells, and motor skills
further deteriorated. (Adapted from Fred Volkmar, M.D.)
Differential Diagnosis.
Rett syndrome shares some fea-
tures with autism spectrum disorder; however, the two disorders
have some predictable differences. In Rett syndrome, there is
deterioration of developmental milestones, head circumference,
and overall growth, whereas in autism spectrum disorder, aber-
rant development is usually present from early on. In Rett syn-
drome, specific and characteristic hand motor movements are
always present; in autism spectrum disorder hand mannerisms
may or may not appear. Poor coordination, ataxia, and apraxia
are predictably part of Rett syndrome; however, individuals with
autism spectrum disorder may have unremarkable gross motor
function. In Rett syndrome, verbal abilities are usually lost com-
pletely, whereas in autism spectrum disorder language is widely
variable from markedly aberrant to relatively mildly impaired.
Respiratory irregularity is characteristic of Rett syndrome, and
seizures often appear early. In autistic disorder, no respiratory
disorganization is seen, and seizures do not develop in most
patients; when seizures do develop, they are more likely in ado-
lescence than in childhood. For autism spectrum disorder that
is associated with another neurodevelopmental disorder such as
Rett syndrome, the latter disorder is diagnosed in association
with autism spectrum disorder.
Course and Prognosis.
Rett syndrome is progressive, and
those individuals who live into adolescence and adulthood func-
tion at a cognitive and social level equivalent to that in the first
year of life.
Treatment.
Treatment is symptomatic. Physiotherapy has
been beneficial for the muscular dysfunction, and anticonvulsant
treatment is usually necessary to control the seizures. Behavior
therapy, along with medication, may help control self-injurious
behaviors, as it does in the treatment of autistic disorder, and it
may help regulate the breathing disorganization.
Childhood Disintegrative Disorder
The previous diagnosis of childhood disintegrative disorder,
now included in autism spectrum disorder, is characterized by
marked regression in several areas of functioning after at least
2 years of apparently normal development. Childhood disinte-
grative disorder, also called
Heller’s syndrome
and
disintegra-
tive psychosis,
was described in 1908 as a deterioration over
