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Paul Knox, Ian MacCormick, Ruairidh Watson, Macpherson Mallewa, Simon Harding; Cross-sectional Analysis of Pro- and Antisaccade Development in Retinopathy-Confirmed Cerebral Malaria. Invest. Ophthalmol. Vis. Sci. 2013;54(15):175. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Paediatric cerebral malaria (CM) continues to cause death and disability, particularly in sub-Saharan Africa. While survivors may suffer from long term cognitive impairment, interpretation of neuropsychological tests is problematic, since tests developed in a Western context may not be appropriate for children in developing countries. Pro-saccade (PS) and anti-saccade (AS) tests represent objective biological measurements of visuomotor reflexes that are related to the function of discrete brain circuits, attention, and working memory. AS error rate has a well-described developmental trajectory in which performance improves markedly between 8 and 12 years.
We compared PS and AS performance in children who had survived a single episode of retinopathy positive CM (n=45; mean±SD age 110±24months; 64%<120mo), and control (CON) children with no history of coma or seizure (n=43; 119±27mo; 72%<120mo), recruited from a prospective CM study in Blantyre, Malawi. Retinopathy is highly associated with pathologically confirmed CM, in contrast to current diagnostic criteria. Eye movements were recorded in a quiet room using an infrared reflectance eye tracker, which projected targets 10° to the left and right of a central fixation target. Participants completed 100 PS and 100 AS trials. Tests were explained to children in the local language, and comprehension of instructions was checked before data collection.
AS directional error rate was strongly related to age in both groups (CM: r=-0.53, p<0.0001; CON: r=-0.60, p<0.0001), and not statistically different between them (Fig). In children >12y, AS directional error rate was higher in the CM vs CON group (CM: 49±16%, n=9, mean age 163Mo vs CON: 32±22%, n=3, age 163Mo). PS, AS and error PS latencies all declined with age as expected, with no consistent difference between groups, although intersubject variability was higher in the CM group.
Both groups exhibited comparable age-related performance on both saccade tasks. However there was a preponderance of younger ages - relatively early in the period when AS performance begins to develop. Older CM participants did appear to have increased error rates. Longitudinal follow-up will demonstrate whether a previous episode of CM is associated with later impairment in AS performance. This finding would be consistent with reports of deficits in attention and working memory.
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