Pertussis vaccine and injury to the brain.

A syndrome of pertussis vaccine encephalopathy was first reported 56 years ago. Analysis of the recent literature, however, does not support the existence of such a syndrome and suggests that neurologic events after immunization are chance temporal associations of neurologic conditions that occur in the target age group, even in the absence of immunization. Population-based studies do not prove a causal relationship with acute encephalopathy. There are no consistent neuropathologic findings suggesting a specific pathophysiologic process, and hypotheses concerning possible mechanisms of damage are not supported by reproducible studies in children. No acceptable animal model exists. There clearly is an increased risk of a convulsion after diphtheria-tetanus-pertussis immunization but no evidence that this produces brain injury or is a forerunner of epilepsy. Studies have also not linked immunization with either sudden infant death syndrome or infantile spasms.