[1] Univ Witten Herdecke, Vodafone Fdn Inst, Childrens Hosp Datteln, D-45711 Datteln, Germany
[2] Univ Witten Herdecke, Chair Childrens Pain Therapy & Paediat Palliat Ca, Childrens Hosp Datteln, D-45711 Datteln, Germany
[3] Hosp Friedrichshafen, Childrens Hosp, Friedrichshafen, Germany
[4] Great Ormond St Hosp Sick Children, London WC1N 3JH, England