Microcephaly is defined as head circumference _________: (A) < 1SD for age and sex, (B) < 2SD for age and sex, (C) < 3SD for age and sex, (D) < 4SD for age and sex
Answer is C. *Microcephaly is defined as an occipitofrontal circumference more than 3 standard detions (SD) below the mean for given age, sex and gestation. *Causes are structural brain malformations, inherited syndromes, congenital or acquired infections, hypoxic ischemic insults and rarely metabolic disorders. Isolated inherited microcephaly is autosomal recessive. Reference : page 36 Ghai Essential Pediatrics 9 th edition