Is Iron Deficiency a Possible Risk Factor for Febrile Convulsions in Children?

Abstract

SUMMARY F ebrile seizures are one of the most common neurologic problems during infancy and childhood periods, occurring in 3-4% of the children, with an excellent prognosis. They occur rarely before 6 months and after 5 years of age, with a peak incidence between 14 -18 months of age. Febrile seizures are classified to simple (typical) and complex (atypical) types. A single seizure of <15 min duration in the presence of fever without focal features was defined as a simple FS, whereas seizures were defined as complex if they lasted >15 min, had focal features, or occurred more than once in 24 h. On the other hand, the etiology of febrile seizures is not clear. Different factors have been considered including familial (genetic) factors, prenatal factors, present acute illness, the highest degree of fever and finally, anemia. Iron deficiency is the most common cause of anemia in childhood. Prevalence of iron deficiency ranges from 5% to 29% of the population, with higher numbers seen in inner city and socioeconomically deprived populations. It is most common in toddlers and in the adolescent age groups (periods of rapid growth and higher potential for inadequate dietary iron. Iron deficiency anemia, the most common type of anemia during infancy and childhood, occurs usually between 9- 24 months of age and this period coincides with the peak incidence of febrile seizures. Iron has an important role in multiple physiological functions of neurotransmitters. Many of the nervous system enzymes are iron-dependent for their proper activities. It has been determined that iron depletion has negative effects on neurocognitive functions of children and supplemental iron can reduce breath-holding spells. On the other hand, fever can exaggerate the negative effects of anemia on brain. From the foregoing, the importance of febrile seizures and iron deficiency anemia cannot be ignored specially in our population. There are controversies regarding the positive and negative effects of iron on the occurrence of febrile seizures and so we decided to study the relationship between febrile seizures and iron deficiency anemia in 6-month to 5-year old children, the common age of febrile seizures. This study included 50 febrile seizures patients (20 males and 30 females with a male-to-female ratio 1:1.5) recruited from the emergency room, pediatric Hospital, Ain Shams University. Patients were compared with 50 age- and sex-matched children complaining from febrile illness without seizures (22 males and 28 females) enrolled as controls. All patients were subjected to detailed medical history and thorough clinical examination with special emphasis on seizure age of onset, duration, frequency and focality; peak temperature on admission; family history of febrile seizures and epilepsy. The underlying illness was recorded for all cases e.g. gastroenteritis, respiratory tract infections or non-specific illnesses. Neurological examination and developmental screening was done to exclude central nervous system abnormalities. The most common underlying cause of fever in febrile seizures patients is upper respiratory tract infections in 48% of studied patients with febrile seizures and other causes are gastroenteritis in 20%, lower respiratory tract infections 18%, urinary tract infections 10% and post-vaccination with DTP 4 % of studied febrile seizures patients. The mean body temperature in studied febrile seizures patients was 39.2 °C. The most significant risk factor for the development of a first febrile seizure is the degree of rising of the temperature; the higher the temperature, the higher the likelihood of febrile convulsions. As regards haemoglobin, it was found low in patients with febrile seizures (10.67±1.06) gm/dl compared to patients with febrile illness without seizures (11.47±0.63) gm/dl, In addition, serum ferritin, it was found low in patients with febrile seizures (48.20±21.33) ng/ml compared to patients with febrile illness without seizures (82.51±22.09) ng/ml. The mean levels of mean corpuscular volume and mean corpuscular haemoglobin was lower in febrile seizures patients than in control group but there was no statistically significant difference between the two groups. As regards the relation between serum ferritin, Hb level among febrile seizures patients and their relation with the frequency of seizures, there were significant negative correlations between serum ferritin, haemoglobin and frequency, duration and age of onset of seizures among febrile seizures patients. In studied febrile seizures patients, significant negative correlations were found between serum ferritin, haemoglobin and frequency, duration and age of onset of seizures among febrile seizures patients. Febrile seizures patients who had iron deficiency anemia have more frequent attacks and longer duration of seizures than those who are not anemic and the degree of anemia correlated with the frequency and duration of seizures are increased. And so, we concluded that children with febrile seizures are almost twice as likely to have iron deficiency as compared to children with febrile illness without seizures. Low level of plasma ferritin may lower the seizure threshold and increase frequency of seizures as iron is important for the function of various enzymes and neurotransmitters present in the central nervous system.