Epilepsy in shunt-treated hydrocephalus

Although epilepsy is commonly associated with shunt-treated hydrocephalus, its relation to the shunting procedure and the criteria identifying postope rative epilepsy remain controversial. Of 283 patients shunted at Wurzburg U niversity Hospital over a 24-year period (1970 to 1994), 182 were followed up for a minimum of 1 year after shunt insertion and entered the study. The data were analyzed retrospectively in 1995 and 1996, Epilepsy was analyzed in relation to the etiology of hydrocephalus, functional status, time and site of shunt insertion, onset of seizures and seizure type, EEC; changes, sex, shunt systems, and shunt revisions. Of the 182 patients studied, 37 (2 0%) developed epilepsy. The incidence of epilepsy varied according to the e tiology of hydrocephalus: posthemorrhagic (5%), postinfectious (4%), connat al/miscellaneous/unknown (3%), myelomeningocele (2%), tumor/arachnoidal cys t/aqueduct stenosis (0%), Early shunting and poor functional status was ass ociated with a higher risk for epilepsy. Epilepsy was not influenced by sex , shunt systems, or number of shunt revisions. Twenty-two (12%) of 182 pati ents developed epilepsy (generalized N=13, focal N=9) after intracranial sh unting. Focal EEG; abnormalities (N=16) were located mainly at the anatomic al site of the shunt (N=14), but only three patients (2%) presented with fo cal seizures contralateral and focal EEG abnormalities ipsilateral to the s ite of the shunt. The presence of epilepsy was determined by the etiology o f hydrocephalus rather than by surgical intervention. The incidence of post operative epilepsy (12%) was low. Onset of epilepsy, clinical presentation of seizures, and EEG changes did not appear to be valid criteria for identi fying shunt-related epilepsy. Thus, epilepsy as a complication of intracran ial shunting might be overestimated in the literature.