Should prophylactic anticonvulsants be administered to patients with newly-diagnosed cerebral metastases? A retrospective analysis.

We analyzed a retrospective series of 195 patients with documented intracerebral metastases (ICM) to assess the frequency of late seizure development and the impact of prophylactic anticonvulsants. Eighteen percent of the patients presented with seizures. Of the remaining patients, 40% received prophylactic anticonvulsants (diphenylhydantoin [DPH] in greater than 90%). Ten percent developed late seizures at an interval from the diagnosis of ICM ranging from 1 to 59 weeks. No patient with a posterior fossa lesion developed seizure; conversely, patients with evidence on initial examination of cerebral hemispheric dysfunction had a higher incidence of late seizure development. The incidence of seizure was virtually identical in patients who received DPH compared with those in whom it was withheld, although two thirds of patients who developed seizure while on DPH had a serum anticonvulsant level that was subtherapeutic. Based on the above findings and until prospective data become available, we recommend that anticonvulsants be withheld in newly-diagnosed patients with ICM until the first seizure.