The EEG changes and the frequency and type of epilepsy in patients with slit ventricles has been analyzed in 113 shunt-treated hydrocephalic children reported from the Department of Pediatrics, University of Oulu, Finland, and the Regional Pediatric Habilitation Center, Gothenburg, Sweden. Slit ventricles are caused by overdrainage of the cerebrospinal fluid and collapse of the ventricles following shunting of hydrocephalus. The incidence was 56% in this group of patients followed for a mean of 8.9 years. In patients who developed SLV the age at initial shunting was significantly lower (1.2 years) than for those who did not (2.7 years). Spike and sharp wave activity in the EEG developed more frequently in patients with SLV (81%) than in those without (54%). The severe generalized spike wave activity disappeared from the EEG after treatment of the slit ventricles. Epileptic seizures appeared after initial shunting in 44% of patients who developed SLV but in only 6% of the non-SLV group. Treatment of the SLV’s reduced the frequency of epilepsy to the level corresponding with the non-SLV group. 
COMMENT. This study demonstrates the value of repeated EEGs in shunt treated patients. If EEG abnormality appears after the initial shunting and especially severe spike wave activity, a shunt malfunction and overdrainage of the CSF should be suspected. The slit ventricle syndrome should be prevented or at least treated early to avoid permanent brain damage and long-term psychomotor retardation. Epileptic seizures have been reported in 10-40% of shunted hydrocephalic children. The position of the shunt, the frequency of the shunt revisions and epileptic seizures have been correlated in the present study. The ventricular size is also correlated with the frequency of epileptic seizures. Six patients suffering from West and Lennox syndromes associated with slit ventricle syndrome showed dramatic improvement and became asymptomatic after treatment for the slit ventricle syndrome. Anticonvulsant prophylactic therapy is warranted for at least a year after shunting and particularly in patients who develop slit ventricles. Raimondi AJ provides an editorial comment on shunts, indications, problems, and characteristics.