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2. HC measures >3SD below the mean for age and sex.
This condition is relatively common, ** in children with developmental delay.
In microcephaly there are abnormalities in
neuronal migration during fetal development.
Including:-
• Heteropias of neuronal cells
• Cyto-architectural derangements
Primary (genetic) Secondary
Usually has no associated
malformations.
Follow a mendelian pattern.
Or are associated with specific
genetic syndromes.
1. Syndromes.
2. Congenital infections.
3. Other causes.
Microcephaly
3.
4. Primary (genetic) Microcephaly
Usually have no associated malformations.
Follow a mendelian pattern of inheritance.
Or are associated with specific genetic syndromes.
Affected infants are usually identified at birth.
--Most commonly familial & AD (autosomal dominant).
--A series of chromosomal disorders
--AR (autosomal recessive): MCPH (microcephaly primary hereditary).
At least 7 gene loci are present.
X-linked microcephaly, caused by gene mutations that lead to
severe structural brain malformations as:
Lissencephaly
Holoprosencephaly
Polymicrogyria
Cobblestone dysplasia
Pontocerebellar hypoplasia
Neuronal heteropia
10. Neuronal heterotopia is a condition in which
nerve cells (neurons) do not migrate properly
during the early development of the fetal
brain, Heterotopia means "out of place.
18. Cri-du-chat (cat's cry) syndrome, also known as 5p- (5p minus)
syndrome, is a chromosomal condition that results when a piece
of chromosome 5 is missing. Infants with this condition often have
a high-pitched cry that sounds like that of a cat.
Round face
Prominent epicanthic folds
Low-set ears
hypertelorism
35. ** before 15 weeks of gestation (1st trimester)
Meningitis/encephalitis
Cerebral infarcts.
Cystic cavitation.
Diffuse loss of neurons.
Maternal D.M.
Maternal hyperphenylalaninemia.
Significant fever during the 1st 4-6 weeks after birth
Initially
Diffuse cerebral edema
Late
Cerebral atrophy
Is a controversial cause.
RMHOther causes of microcephaly:
36.
37. History & clinical examination
A thorough family history should be taken , seeking additional cases
of microcephaly or disorders affecting the nervous system.
It’s important to measure the patient’s head circumference (HC) at
birth to diagnose microcephaly as early as possible.
The HC of each parent and sibling should be recorded.
38. • A very small HC implies a process than began
early in embryonic or fetal development.
• An insult to the brain that occurs later in life,
particularly beyond the age of 2 years, is less
likely to produce severe microcephaly.
Serial HC measurements are more meaningful
than a single determination, particularly when
the abnormality is minimal.
40. Imaging
MRI CT
Can show:-
Lissencephaly. Intracerebral
calcification.
Pachygyria
Polymicrogyria.
Laboratory
1-Mother’s serum
phenylalanine
High phenylalanine serum levels in
an asymptomatic mother can
produce marked brain damage in
an otherwise normal non-
phenylketonuric infant.
2-Karyotyping
& comparative genome hybridization study
3-Whole genome sequence.
Additional studies
Amino acid analysis Fasting.
Plasma & urine.
Serum ammonia
--TORCH
--HIV
Tests in the mother & child.
CMV culture From urine sample
Investigations for a cases of microcephaly