[1] Univ Bristol, Dept Clin Sci N Bristol, Bristol BS10 5NB, Avon, England
[2] Univ Bristol, Dept Clin Sci S Bristol, Bristol BS10 5NB, Avon, England
[3] Southmead Hosp, Neonatal Intens Care Unit, Bristol, Avon, England
[4] Frenchay Hosp, Dept Neurosurg, Bristol BS16 1LE, Avon, England
[5] Med Univ Silesia, Dept Neonatal Intens & Special Care, Katowice, Poland
[6] Med Univ Silesia, Div Pediat Neurosurg, Katowice, Poland
[7] Queen Mothers Hosp, Neonatal Intens Care Unit, Glasgow, Lanark, Scotland
[8] Royal Hosp Sick Children, Dept Paediat Surg, Glasgow G3 8SJ, Lanark, Scotland