Video-EEG telemetry: apparent manifestation of both epileptic and non-epileptic attacks causing potential diagnostic pitfalls

Video-EEG telemetry is often used to support the diagnosis of non-epileptic seizures (NES). Although rare, some patients may have both epileptic seizu res (ES) and NES. It is crucially important to identify such patients to av oid the hazards of inappropriate anticonvulsant withdrawal. To delineate th e electroclinical characteristics and diagnostic problems in this group of patients, we studied the clinical, EEG and MRI features of 14 consecutive p atients in whom separate attacks, considered to be both NES and ES were rec orded using video-EEG telemetry. Only two patients were drug-reduced during the telemetry. Most patients had their first seizure (ES or NES) in childh ood (median age 7 years; range: 6 months-24years); 8/14 patients were femal e. Brain MRI was abnormal in 10/14 patients. Interictal EEG abnormalities w ere present in all patients; 13/14 had epileptiform and 1/14 only backgroun d abnormalities. Over 70 seizures were recorded in these 14 patients: in 12 /14 patients, the first recorded seizure was a NES (p < 0.001), and 7 of th ese patients had at least one more NES before an ES was recorded. Only 3/14 patients had more than 5 NES before an ES was recorded. Recording a small number of apparently NES in an individual by no means precludes the possibi lity of additional epilepsy. Particular care should be taken, and multiple (> 5) seizure recording may be advisable, in patients with a young age of s eizure onset, interictal EEG abnormalities, or a clear, potential aetiology for epilepsy.