NEONATAL SOCIETY ABSTRACTS
Is hemiplegic cerebral palsy equivalent to "amblyopia" of the cortiospinal system and therefore preventable?
Presented at the Neonatal Society 2006 Summer Meeting (programme).
Eyre JA1, Smith M1, Dabydeen L1, Clowry GJ1, Petacchi E2,3, Battini R2, Guzzetta A2, Cioni G2
1 Developmental Neuroscience, School of Clinical Medical Sciences, University of Newcastle,
Newcastle upon Tyne, UK
2 Department of Developmental Neuroscience, Stella Maris Scientific Institute, Pisa, Italy
3 Division of Child Neurology and Psychiatry, University of Pisa, Pisa, Italy
Neonates initially have comparable ipsilateral and contralateral corticomotoneuronal projections from each cerebral hemisphere. Greater postnatal withdrawal of ipsilateral projections establishes the mature, contralateral-dominant pattern. In congenital hemiplegia the non-affected cortex maintains comparable ipsilateral and contralateral corticomotoneuronal projections in maturity. We hypothesised that during postnatal development its ipsilateral projections aren’t withdrawn but competitively take-over the synaptic space of less active contralateral projections from the damaged hemisphere. Longitudinal neurophysiological and anatomical studies were undertaken in 30 normal neonates, 14 with unilateral perinatal stroke and 25 with bilateral perinatal lesions of the cerebral hemispheres Our studies revealed postnatal loss of corticospinal projections from affected hemispheres, but only following unilateral and not bilateral perinatal lesions, and this loss was associated with progressive motor impairment. There was a significant relationship between loss of this projection and hypertrophy of the corticospinal tract from the non-affected hemisphere, with hypertrophy of ipsilateral axons and increased axonal number compared with normal subjects. We conclude that rather than representing “reparative plasticity”, an increased ipsilateral corticospinal projection from the non-affected hemisphere compounds disability by supplanting the residual corticospinal projection from the affected cortex.