Objective To estimate the proportion of children with cerebral palsy (CP) and mild motor function impairment for different categories of neuroimaging findings.

Methods Children born in 1991–9 were included and described in the population-based register of cerebral palsy of Madrid following surveillance of cerebral palsy in Europe recommendations. Motor function was assessed with gross motor function classification system (GMFCS) and bimanual fine motor function (BFMF) scales. Motor function was considered mildly impaired when (GMFCS  =  1 and BFMF  =  1). Haemorrhage (I–III), parenchymal lesions (I–IV) and ventriculomegaly (I–III) were described in neonatal ultrasounds. Brain maldevelopment, parenchymal white matter lesions and grey matter lesions were described in magnetic resonance imaging (MRI). For each category of neuroimaging finding, the proportion of children with mild motor impairment is presented.

Results 89/103 (86%) children registered with cerebral palsy had neuroimaging examinations performed: ultrasound, 66%; computed tomography (CT), 54%; MRI, 62%. Neuroimaging abnormalities were reported in 76% of ultrasound; in 80% of CT; in 91% of MRI. Overall, 38% of CP children present a mild motor function impairment. The proportion of children with mild motor function was 11% when a ultrasound–haemorrhage was present (0% for II–III); 37% when ultrasound–parenchymal lesions; 23% when ultrasound–ventriculomegaly (0% for II–III); 29% when MRI–brain maldevelopment; 33% when MRI–grey matter lesions; 53% when MRI–white matter lesions were present.

Conclusions Most children with CP, but not all, have neuroimaging documented lesions. Mild motor function impairment is very unlikely when haemorrhage III is present.