Optic nerve hypoplasia, encephalopathy, and neurodevelopmental handicap

A major cause of loss of vision in childhood is hypoplasia (underdevelopment) of the optic nerve. This is a birth defect resulting from damage at any point along the developing visual pathways. Optic nerve hypoplasia may be associated with other important abnormalities in the nervous and endocrine systems. A study was undertaken to determine the factors involved when optic nerve hypoplasia and central nervous system disorders occur simultaneously, and to describe the association with vascular encephalopathies (brain abnormalities due to blood-vessel disorders). Forty-six children with bilateral optic nerve hypoplasia were studied; 32 children were born at full term, and 14 were born prematurely. Thirty-two of the 46 children (69.5 percent) had associated neurodevelopmental handicaps. A CT scan revealed that 90 percent of these neurodevelopmentally handicapped children had structural central nervous system abnormalities. Neurodevelopmental handicap occurred more often in the premature babies (86 percent) than in the full-term babies (62.5 percent). Full-term babies had a higher incidence of ventral developmental midline defects representing abnormalities in closure of the neural tube (precursor of the brain in the fetus), and they had fewer prenatal complications. The premature babies had a higher incidence of prenatal complications with resulting encephaloclastic lesions, indicating the residue of a destructive brain lesion. Four of the 12 babies had regression of retinopathy of prematurity, suggesting that inadequate blood supply may have been a contributing factor. It is suggested that all children with bilateral optic nerve hypoplasia receive a CT scan. Referral to a pediatrician should be made for assessment of other abnormalities. (Consumer Summary produced by Reliance Medical Information, Inc.)