Febrile seizures represent the meeting point between a low seizure threshold (genetically and age determined) - some children have a greater tendency to have a seizure under certain circumstances - and a trigger: fever. The genetic causes of febrile seizures are still being researched. Some mutations that cause a neuronal hyperexcitability and could be responsible for febrile seizures have already been discovered.
Simple febrile seizures generally do not cause permanent brain injury; do not tend to recur frequently, as children tend to 'out-grow' them; and do not make the development of adult epilepsy significantly more likely (less than 3-5% which is similar to that of the general public). Children with febrile convulsions are more likely to suffer from afebrile epileptic attacks in the future if they have a complex febrile seizure, a family history of afebrile convulsions in first degree relatives (a parent or sibling), or a pre-convulsion history of abnormal neurological signs or developmental delay. Similarly, the prognosis after a simple febrile seizure is excellent, whereas an increased risk of death has been shown for complex febrile seizures (partly related to underlying conditions).
The UK's MHRA says that "there is no indication of an excess risk of febrile convulsions in children following seasonal flu vaccination".
Jan 15, 2011; The UK's MHRA says that "there is no indication of an excess risk of febrile convulsions in children following seasonal flu...