Cerebrospinal fluid shunt malfunction signaled by new or recurrent seizures.

We have observed two patient groups with seizure activity as the primary presentation of shunt malfunction. Eight patients had a first-time seizure, and seven patients had a history of prior seizures, none more recently than 1 year prior to the seizure recurrence. Five of seven patients with prior seizures who seized were on anticonvulsant medication, three of these seven patients had therapeutic anticonvulsant levels. Shunt malfunction was diagnosed via a combination of tests. The electroencephalograms of nine patients were diffusely abnormal with regions of slowing and focal spike activity. Seizure activity stopped in all patients after preoperative stabilization with anticonvulsant medication and shunt revision. These 15 patients represent 2% of all patients treated for shunt malfunction during a 3-year period. The assessment of new or recurrent seizure activity in a previously stable shunted patient should include evaluation of shunt function whatever the anticonvulsant levels.