Kim Annink

99 The long-term effect of perinatal asphyxia on hippocampal volumes children, MRIs could not be obtained due to fear during or before the MRI (n=11), were of insufficient quality due to movement artefacts (n=31) or not available for segmentation (n=2). One additional child with HIE2 was excluded from volumetric analysis because of a perinatal arterial ischemic stroke, leading to total destruction of the hippocampus. There were no significant differences in baseline characteristics or the degree of HIE between the children whose MRI was used for volumetric analysis and the children of whom no MRI was obtained or whose MRI was of insufficient quality. Patient characteristics are shown in Table 1. The children with CP were able to perform all tests that were part of the protocol. On conventional imaging, none of the children had pathological lesions of the hippocampus, such as mesial temporal sclerosis. Table 1: Patient characteristics of the HIE1, HIE2 and control group. Characteristics Controls (n=37) HIE1 (n=26) HIE2 (n=26) p-value Gender, n (%) Male Female 19 (51.4) 18 (48.6) 13 (50) 13 (50) 12 (46.2) 14 (53.8) 0.92 CP, n (%) 0 (0) 2 (7.7) 2 (7.7) 0.23 Age at follow-up, mean years ±SDS 10.07 ±0.43 9.80 ±0.47 9.77 ±0.55 0.03* SES 5 categories**, median [range] 4 [2-5] 4 [1-5] 4 [1-5] 0.14 Incidence of epilepsy at school age, n (%) 0 (0.0) 0 (0.0) 1 (4.0) 0.30 * There was a significant trend towards a lower age in the HIE groups (p=0.03), but there were no significant differences in the post-hoc tests between the groups. ** Socioeconomic status (=educational level of mother): 1=no education or primary school, 2=lower technical or vocational training, 3=lower secondary education, 4=higher secondary education, 5=higher education e.g. university. Category 1, 2 and 3 were combined for multivariable linear regression analyses. Hippocampal volumes in HIE The total hippocampal volumes in HIE2 were significantly smaller than in controls, with a trend toward smaller volumes in HIE1 (controls: 8.7±0.8ml; HIE1: 8.2±0.9ml; HIE2: 7.6±1.3ml, p<0.001, Figure 2A). The hippocampal volume in HIE2 was 12.6% smaller than in the controls. No significant difference in volumes was observed between the HIE1 and HIE2 group. 5