Psychiatric non-epileptic seizure: diagnostic utility of density spectral array

Abstract

© BMJ Publishing Group Limited 2021. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A 40yearold woman with a history of insomnia admitted to the emergency room for generalised convulsion lasting for more than 30 min. The attack was characterised by bilateral asynchronous hyperkinetic prolonged jerking with loss of responsiveness. The serial intravenous diazepam (10 mg) had a limited effect. As the attack was accompanied by a decrease in the oxygen saturation due to the apnoea, she was intubated followed by deep sedation with barbiturates for almost 24 hours. Continuous electroencephalography (EEG) monitoring revealed a suppressionburst pattern during the sedation. However, after the discontinuation of sedation, the hyperkinetic attack reappeared immediately. The ictal EEG during this attack was obscured by the motion artefacts (figure 1). Given the unresponsiveness, she seemed to be impaired awareness. However, density spectral array (DSA) 2 that was analysed from the data of O1 and O2 electrodes during the prolonged attack clearly showed preserved alphaband activity (figure 2). This activity was consistent with the posterior dominant rhythm, that is, the presence of this preserved background alpha activity suggested that she was aware during the attack. Thus, she was diagnosed with psychiatric nonepileptic seizure (PNES). The attack of PNES gradually disappeared after a liaison psychiatry therapy with drugs for anxiety and insomnia. While EEG waves that were recorded during a hyperkinetic attack were often obscured by motion artefacts, DSA was occasionally useful to