A 23-year-old woman was admitted for brief, recurrent spells of intense fear and visual hallucinations. During video-EEG study, one of the spells showed no definite ictal EEG changes on longitudinal bipolar montage for 26 seconds while evolving rhythmic discharges were readily visible on Cz reference. Because the pattern was evenly distributed in the temporal region at onset (figure), it “canceled out” in the bipolar montage.1 It is conceivable that a shorter seizure would have been missed if reviewed only in bipolar montage. Hence, this case is a reminder of why EEG should be reviewed in bipolar and referential montages before concluding that a spell has no EEG correlate.
Onset of evolving rhythmic discharges (red arrows) in Cz reference (A) and in anteroposterior bipolar (B) montages.
AUTHOR CONTRIBUTIONS
Rup K. Sainju: collection of data, interpretation of data, and drafting manuscript. Jeremy Moeller: interpretation of data and revision of the manuscript. Lawrence J. Hirsch: conceptualization of the study, interpretation of data, and revision of the manuscript.
STUDY FUNDING
No targeted funding reported.
DISCLOSURE
R. Sainju reports no disclosures relevant to the manuscript. J. Moeller reports speaker fees from UCB-Pharma and Serono and royalties from UpToDate, Inc. L. Hirsch reports research support for investigator-initiated studies from UCB-Pharma, Upsher-Smith, and Lundbeck; consultation fees for advising from Lundbeck, Upsher-Smith, Neuropace, Natus, and Allergan; and royalties for authoring chapters for UpToDate Neurology and for coauthoring Atlas of EEG in Critical Care, by Hirsch and Brenner, 2010. Go to Neurology.org for full disclosures.
Footnotes
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