M Haers

The variety of visual perceptual impairments in pre-school children with perinatal brain damage

To study the selectivity of visual perceptual impairment in children with early brain injury, eight visual perceptual tasks (L94), were administered to congenitally disabled children both with and without risk for cerebral visual impairment (CVI). The battery comprised six object-recognition and two visuoconstructive tasks. Seven tasks were newly designed. For these normative data are presented (age 2.75-6.50 years). Because the recognition tasks required object naming, each item included a canonical control drawing and visual perceptual ability was evaluated relative to the non-verbal intelligence level, instead of chronological age. In 22 multiple disabled children with no indications of CVI, the frequency of impairment did not exceed that in the reference sample for any L94 task. In contrast, in 57 5-year-old children who were at risk for CVI due to pre-maturity or birth asphyxia, a significant increase in the frequency of impairment was seen on six L94 tasks (range 12-38%). However, only five children had more than two impairments, indicating that the deficits were selective, not pervasive. We conclude that early brain lesions interfere with the functioning of particular visual subsystems, yet leave other subsystems intact and functioning within the normal range.

Relation between visual perceptual impairment and neonatal ultrasound diagnosis of haemorrhagic-ischaemic brain lesions in 5-year-old children

Visual‐perceptual abilities were assessed in 5‐year‐old children with the following neonatal neurological conditions: born preterm with normal ultrasound scan (NL, n=17); born preterm with ultrasound diagnosis of intraventricular haemorrhage (IVH, n=17); born preterm with ultrasound diagnosis of periventricular leukomalacia (PVL, n=12); born term with hypoxic‐ischaemic encephalopathy (HIE, n=11). Visual‐perceptual ability was evaluated with the L94: eight visual‐perceptual tasks designed to evaluate different aspects of visual perception at the preschool level in children with multiple disabilities. Impairment was established in comparison to the performance age obtained on non‐verbal intelligence subtests, instead of chronological age. Frequency of L94 impairment was highest in children with PVL, while children with IVH did not differ from the NL control group. Impairment rates were increased also in children with transient periventricular echodensities, and in children with HIE. Impairments were only moderately related to the delay of visual acuity maturation in infancy.

Performance of 5-Year-Old Children on Seven Visual Perceptual Tasks in Relation to Neonatal Ultrasound Abnormalities

We investigated whether neonatal brain damage can give rise to visual perceptual deficits, in addition to the well-documented impairments in visual acuity. To this end, forty-one children (age 5.02 to 5.89 years) were given four visual object identification tasks and three visuo-constructive tasks. These subjects were neonatal at risk owing to prematurity or birth asphyxia. From neonatal ultrasound scans, the occurrence of intracranial hemorrhage (ICH, N = 17), periventricular leukomalacia (PVL, N = 15), and/or white matter damage due to either of these conditions (WMD, N = 9) was determined for each subject. Scans were normal in fourteen of them. The number of subjects performing at or below Pc10 of same-age normal children was significantly above 10% for each task (range 27% – 49%). This was still true when mental instead of chronological age was used for comparison, as shown by the results of nine subjects for which intelligence data were available. This high incidence of impairment is not attributable to loss of visual acuity, since grating acuity was reduced in only four subjects (14 – 19 cycles deg−1). The frequency of scores < Pc10 correlated significantly with WMD in six tasks, with PVL in 4 tasks, but not with ICH. We conclude that neonatal at risk children are more likely to develop impaired visual perceptual skills, independent of mental disability and visual acuity loss. On ultrasound permanent white matter abnormalities are most strongly associated with visual perceptual deficit, whereas intracranial hemorrhage is unrelated.