3 pediatric patients with acute lymphoblastic leukemia received intrathecal chemotherapy. The 3 had toxic ( chemical) meningitis with in few hours after injection. This progressed to spinal cord affection next day in the form of urine retention, sensory level and lower limb weakness. 1 day later, they developed encephalopathy in the form of hallucination. Soon they developed respiratory failure, put on mechanical ventilation and died 10-21 days later ( from Intrathecal). We know that the usual intrathecals does not do that ( experience 7 years now). The most interesting thing that in the same day these 3 children received the intrathecal injection, another 4 children received intrathecal with no side effects what so ever. Can you help me.