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Definition: Means small head in which head circumference less than 2
standard deviations from normal distribution.
Etiology:
Primary (genetic ) Microcephaly
Exposure of the embryo to anoxious agent during the first weeks after
conception → impairment of neuronal development.
-Microcephaly vera :
AR inheritance ,small brain , slanted forehead, prominent nose and ear
,moderate to sever mental retardation , neurological abnormalities such
as spastic diplagia , seizures may be present
Diagnosis : Normal brain imaging
Management : Symptomatic
- Chromosomal disorders :Dysmorphism
#Down syndrome (triosomy 21): Abnormal rounding of occipital and
frontal lobes and other dysmophic features.
#Edward syndrome: low birth weight, microsomia, micrognathia, low set
malformed ears, and rocker bottom feet and may be congenital heart
diseases.
- Defective neurulation :
