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different. Febrile convulsions that were focal, repeated or prolonged were strongly associated
with partial afebrile seizures, whereas only the number of febrile convulsions was
significantly associated with generalised-onset seizures. Verity and Golding14 also reported
an association between the occurrence of focal febrile convulsions and later afebrile complex
partial seizures.

However population-based studies have shown that the distribution of generalised and
complex partial seizures in those that have had febrile convulsions was similar to that in the
general population, i.e. there was no excess of complex partial seizures in the febrile
convulsion group2,14,53. This suggests that febrile convulsions do not contribute appreciably
to the occurrence of complex partial seizures.

Neurological impairment

No child in the population-based NCPP9 developed persisting hemiplegia or other motor
deficit during or immediately after an asymptomatic febrile convulsion10. In the CHES cohort
398 children had febrile convulsions. A total of 19 (4.8%) had lengthy febrile convulsions
(>30 minutes): in this group there was no evidence of neurological sequelae in those who had
been normal before the lengthy attacks, except for one atypical case  a child who became
very hyperpyrexial after he was put into a hot bath during a convulsion15.

Maytal and Shinnar54, in their study of ‘febrile status epilepticus’ (febrile convulsions lasting
longer than 30 minutes), reported that no child died or developed new neurological deficits
following the episodes of status.

Intellectual outcome

Ellenberg and Nelson8 identified 431 sibling pairs that were discordant for febrile
convulsions in the population-based NCPP and found that at seven years of age children who
were normal before any febrile convulsion did not differ in IQ from their normal seizure-free
siblings. Neither recurrent seizures nor those lasting longer than 30 minutes were associated
with IQ deficit. Population-based studies in Britain13,16 also found little difference in
intellectual outcome between children who had febrile convulsions and their peers, if the
children with febrile convulsions had no other known neurological abnormality. However
specific cognitive difficulties have been described – Martinos et al reported that recognition
memory is impaired in children after prolonged febrile seizures. When followed up after
about a year the children were still showing deficiencies in recognising a face after a five-
minute delay; this was associated with relatively small hippocampal volumes in those
children56.

Behaviour

Immediate and short-term effects on behaviour have been reported up to 35% of children
after febrile convulsions. In the CHES cohort a comprehensive assessment at ten years of age
found that the behaviour of children with febrile convulsions differed very little from their
peers16.

Outcome after febrile convulsions  conclusions

Authors who report a poor outcome tend to have studied selected groups of children attending
specialised hospitals or clinics. Sometimes they have included children who have suffered
with convulsions that complicate meningitis or encephalitis. Some have included children
that were known to be developmentally or neurologically abnormal before they had their first
febrile convulsion. In contrast population-based studies that have looked at a less selected