Hydrocephalus and epilepsy.
Since the introduction of ventriculo-atrial and/or ventriculo-peritoneal shunting for hydrocephalic patients, controversies have developed regarding the likelihood of epileptic seizures developing as a result of the shunting itself and/or its complications. On the other hand, hydrocephalus is not commonly recognized as a cause of seizures in general, although epilepsy is reported to be frequently associated with shunt-treated hydrocephalus, especially in children. Several authors have reported an increased risk of epileptic seizures after shunt placement, but the underlying mechanisms are still controversial. The insult to the brain at the time of ventricular catheter insertion, the presence of the shunt tube itself as a foreign body, the burr hole location, the number of shunt revisions after malfunction, associated infection, the etiology of hydrocephalus, and associated mental retardation are thought to be related to the risk of epilepsy. Age at the time of initial shunt placement also seems to be an important factor. Early shunting is a well-known determinant of risk in shunt obstruction, and children less than 2 years old are consequently at a higher risk of developing epilepsy than older ones. It is reported that antiepileptic drug treatment is not so reliable as might be expected. Conscientious and more sophisticated EEG recording in those children may be beneficial during follow-up. The incidence of seizures in shunted children is reported to be quite high, ranging from 20% to approximately 50%, so that neurosurgeons should pay more attention to the issue of epilepsy in hydrocephalic children. Although ventriculo-extracranial shunts have been the standard treatment for hydrocephalus for decades, the long-term morbidity, including postshunt epileptic seizures, has to be taken seriously. The use of neuroendoscopic techniques when indicated may ameliorate this problem a great deal in the future.