Nearly 30% of children with FS have recurrences after their first episode, and 50% are likely to have recurrences after two or more episodes. In recent years, there have been many studies on risk factors for recurrence of FS.
The risk factors predicting recurrence of FS are.
(1) Age at first seizure ≤ 15 months or 18 months. Those with age of first attack <12 months have at least 50% of subsequent recurrences; those with age of first attack over 12 months have a 30% probability of recurrence.
(2) The probability of recurrence is high in children with a history of FS in first-degree relatives, especially in those with a maternal relative with FS.
(3) Relatively low body temperature at the time of the first episode. The higher the body temperature at the time of FS, the lower the recurrence rate. The recurrence rate of FS within 1 year was 42%, 29% and 12% for children with FS who had convulsions at 38.3°C, 39.4°C and 40.5°C, respectively.
(4) The fever duration before the FS attack was shorter. The shorter the fever duration before the convulsion, the higher the recurrence rate of the convulsion. It has been shown that the recurrence rate of FS was 44%, 23% and 13% for those who had FS within 1h, 1-24h and after 24h of fever, respectively.
Risk factors in the AAP practice guidelines that predict FS recurrence are.
(1) Young age at first presentation (≤15 months);
(2) History of FS in first-degree relatives;
(3) CFS;
(4) Seizures occurring at hypothermia;
(5) Short duration of fever (≤1 h) before the attack.
The recurrence rate was 14% for those without the above risk factors; 23% and 32% for those with one or two risk factors; and 80% to 100% for those with three and four risk factors.
Among the major factors are.
(1) Age <1 year;
(2) duration of fever <24 h;
(3) fever temperature 38-39°C. Secondary factors were.
(1) Family history of FS ;
(2) Family history of G epilepsy;
(3)CFS;
(4) Daycare children ;
(5) Male ;
(6) reduced serum sodium level.
The risk of recurrence in children with no risk factors was approximately 12%, in those with one risk factor it was approximately 25% to 50%, in those with two risk factors it was 50% to 59%, and in those with three or more risk factors it was 73% to 100%.