Asthma and epilepsy: are they related? A retrospective study.

Numerous studies have suggested that epilepsy and asthma may be related conditions. There has, however, been little epidemiologic data published to support this association. We conducted a retrospective study to determine whether the prevalence of epilepsy is increased among children with asthma, and the prevalence of asthma is increased among children with epilepsy, in comparison with the general pediatric population. We reviewed the medical records, at a large city hospital, of two groups of pediatric outpatients: (1) 400 consecutive patients with asthma followed regularly at the asthma and allergy clinic; and (2) 201 consecutive patients with idiopathic epilepsy followed regularly at the pediatric neurology clinic. Patients with a history of birth prior to 36 weeks' gestational age were excluded. Among the 400 cases of asthma, there were three patients with idiopathic epilepsy (prevalence of 0.75%). The prevalence of epilepsy was similar in mild (0.79%) and moderate-to-severe (0.73%) asthma. Among the 201 cases of idiopathic epilepsy, there were 12 patients with asthma (prevalence of 5.97%). Similar percentages of epilepsy patients with and without asthma reported generalized tonic-clonic, complex partial, simple partial, and myoclonic seizures as their predominant type. The prevalence values in this study are consistent with the prevalence of epilepsy and asthma in the general pediatric population. Our findings therefore suggest that idiopathic epilepsy and asthma are not etiologically related or mutually predisposing conditions. Small samples, failure to exclude patients born prematurely, and the equation of electroencephalographic (EEG) abnormalities with epilepsy may account for the results of previous studies.