Saline activation of pseudoepileptic seizures: clinical EEG and neuropsychiatric observations.

Twenty patients with suspected pseudoseizures underwent saline infusion during prolonged sleep deprived EEG with video monitoring and nasopharyngeal electrodes. No patients had definite clinical evidence of epilepsy, but 35% had abnormal EEGs, 10% with epileptiform activity. Patients with epileptiform discharges did not experience pseudoseizures with saline infusion. Patients with generalized EEG slowing responded to saline infusion with characteristic seizures. Three groups of patients were differentiated. Eight patients had characteristic attacks with saline infusion, and in these patients females predominated, mean age was lower, and somatoform disorder was common. Six patients each either failed to respond to saline or had episodes different from their characteristic spells. These patients were more often male and more often had diagnoses of personality disorders. The findings suggest that, although saline infusion may identify pseudoseizures and confirm their non-epileptic nature, some patients may not be sufficiently suggestible to respond to saline infusion, while others may have non-epileptic attacks which are different from the spells under evaluation. Psychiatric and neuropsychological features suggestive of pseudoseizures may be more readily identified by psychiatric interview or psychometric testing. Ethical issues regarding saline infusion in the guise of a potent convulsant should also be considered.