MRI findings in children with cerebral visual impairment

The classical definition of cortical blindness in both adults and children refers to complete loss of vision, including appreciation of light and dark, loss of OKN with preservation of pupillary responses, normal eye motility and normal retina on examination. Cerebral visual impairment (CVI) is now recommended as a better term. Complete blindness is rare in these patients. Most of them have some residual vision, which it is often difficult to test because they show inattention and variability in their visual performance. Secondly, ‘cerebral’ seems to be a more appropriate term than ‘cortical’. Visual impairment is secondary to a cerebral disease from multiple causes (e.g. infection, trauma, cerebrovascular disease, etc.), involving retrochiasmatic visual pathways but not necessarily the visual cortex. According to the timing of the cerebral injury, CVI in children can be classified as congenital or acquired. The latter can be caused by meningitis, encephalitis, head trauma, hydrocephalus, or metabolic derangements. Occipital infarctions are often observed in these cases. Congenital CVI includes visual loss caused by malformations, intrauterine infections or perinatal hypoxic ischaemic encephalopathy (HIE). HIE is the most common cause of CVI, and is often accompanied by other motor and cognitive impairment owing to the diffuse nature of this pathology.