Incidence of seizures in patients with myelomeningocele: a multifactorial analysis.

To determine the role of ventricular shunts as a cause of seizures in children with hydrocephalus, 190 patients with myelomeningoceles were studied. There was a low incidence of seizures (2%) in the nonshunted patients in spite of a high incidence of ventriculomegaly, whereas the overall frequency of seizures in shunted patients was 22%. Further analysis indicated factors accountable for the increase. Only 9% of patients with shunts that had never required subsequent modification had seizures; however, 22% of the patients had seizures if they had required at least one modification for malfunction alone. Patients with a history of a shunt infection had a further increase in their likelihood of developing seizures to 47%. Information concerning the incidence of seizures by location of the shunt indicated no statistical difference between frontal and parietal entry points, with a frequency of 20% and 26%, respectively; however, there was a higher incidence of seizures in a small group of patients with shunts aberrantly placed in the posterior frontal lobe.