Defining the gap between electrographic seizure burden, clinical expression, and staff recognition of neonatal seizures

Deirdre M Murray ¹, Geraldine B Boylan ², Imhad Ali ³, C. Anthony Ryan ^4*, Brendan P Murphy ⁵ and Sean Connolly ⁶

¹ University College Cork, Republic of Ireland
² University College Cork, Eire
³ Unified Maternity Services, Cork, Republic of Ireland
⁴ Cork University Maternity Hospital, Republic of Ireland
⁵ University College Cork, Republic of Ireland
⁶ St Vincent's Hospital, Dublin, Republic of Ireland

^* To whom correspondence should be addressed. E-mail: ryant01{at}eircom.net.

Accepted 30 June 2007

Abstract

Background: Neonatal seizures are often sub-clinical, making accurate diagnosis difficult. The aim of this study was to describe the clinical manifestations of electrographic seizures recorded on continuous video-EEG, and to compare this to the recognition of clinical seizures by experienced neonatal staff.

Methods: Term infants, at risk of seizures, were monitored by continuous 12-channel video-EEG from < 6 hours of birth for up to 72 hours. All clinical seizures were recorded by experienced neonatal staff on individual seizure charts. Video-EEG recordings were subsequently analyzed. The number, duration, and clinical expression of electrographic seizures were calculated (in seconds), and compared to the seizures clinically suspected by the neonatal staff.

Results: Of 51 infants enrolled, 9 had electrographic seizures. A further 3 had clinically suspected seizures, without associated electrographic abnormality. Of the total 526 electrographic seizures, 179 (34%) had clinical manifestations evident on the simultaneous video recording. The clinical seizure activity corresponded to 18.7% of the total electrographic seizure burden. Over-diagnosis also occurred frequently. Of the 177 clinically-suspected seizure episodes documented by staff, 48(27%) had corresponding electrographic evidence of seizure activity Thus, only 9% (48/526) of electrographic seizures were accompanied by clinical manifestations, which were identified and documented by neonatal staff.

Conclusion: Only one third of neonatal EEG seizures display clinical signs on simultaneous video recordings. Moreover, two-thirds of these clinical manifestations are unrecognised, or mis-interpreted by experienced neonatal staff. In the recognition and management of neonatal seizures clinical diagnosis alone is not enough.

Keywords: hypoxic ischaemic encephalopathy, neonatal, seizure burden, seizures, video-EEG

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