Is there a Predictive Value of EEG and MRI after a First Afebrile Seizure in Children?

Abstract

Background: After a first afebrile seizure, EEG in addition to cMRI is recommended for pediatric patients. Once indications requiring immediate treatment are excluded, it is of interest to determine if the results provide a prognostic tool for seizure relapses.

Methods: Patients aged between 1 month and 18 years who had a first afebrile seizure between 2006 and 2008 were retrospectively studied and monitored for another 48 months.

Results: Out of 248 patients, 62.5% had generalized and 36.3% focal seizures. 34.7% of the EEG results were pathological. 176 patients had a cMRI that showed in 23.3% probable epileptogenic lesions. 3 patients with benign cerebral tumours needed surgical therapy. In the following 48 months 29.4% of the children showed seizure relapses. There was a correlation between epileptic patterns in the EEG and further seizures (p=0.0001). However, the sensitivity of the EEG based diagnoses was 0.6, the specificity 0.78 and the positive predictive value 0.52. There was no correlation between epileptogenic lesions and the probability of seizure relapses. The sensitivity of the cMRI to this effect was 0.36, the specificity 0.74 and the positive predictive value 0.34.

Discussion: The EEG is superior to cMRI for predicting seizure relapses. The percentage of noticeable cMRI findings is high but this has low therapeutic relevance and is assumed to largely represent "incidental findings". It is important to question the value of MRI investigations for sedated small children except in the case of emergencies. The key question is whether the cMRI should be deployed to diagnose epilepsy, the probability of seizure recurrences or to classify the entity of a most likely epilepsy.

Zusammenfassung

Hintergrund: Nach ersten afebrilen Krampfanfall wird neben einer EEG-Untersuchung ein cMRT empfohlen. Außerhalb von Notfällen ist von Interesse, ob sich dadurch eine Aussage über das Risiko von Anfallsrezidiven machen lässt.

Methoden: Patienten im Alter zwischen 1 Monat und 18 Jahren, die zwischen 2006 und 2008 einen ersten afebrilen Krampfanfall hatten, wurden für 48 Monate retrospektiv analysiert.

Ergebnisse: Von 248 Patienten hatten 62,5% generalisierte, 36,3% fokale Anfälle. 34,7% der EEG-Befunde waren pathologisch. 176 Patienten erhielten ein cMRT, das in 23,3% der Fälle wahrscheinlich epileptogene zerebrale Läsionen zeigte. 3 Patienten mit benignen zerebralen Tumoren wurden operiert. 29,4% der Kinder bekamen in den folgenden 48 Monaten Anfallsrezidive. Zwischen epileptogenen Mustern im EEG und weiteren Anfällen besteht ein Zusammenhang (p=0,0001). Die Sensitivität der EEG-Diagnostik lag bei 0,6, die Spezifität bei 0,78 und der positiv prädiktive Wert bei 0,52. Es gab keine Korrelation zwischen epileptogenen Läsionen und der Wahrscheinlichkeit von Anfallsrezidiven. Die Sensitivität des cMRT lag bei 0,36, die Spezifität 0,74 und der positiv prädiktive Wert 0,34.

Diskussion: Das EEG ist dem cMRT überlegen hinsichtlich der Prognose von Anfallsrezidiven. Der Anteil auffälliger cMRT-Befunde ist hoch, aber von geringer therapeutischer Relevanz und großteils als „incidental finding” zu sehen. cMRT-Untersuchungen sind außer in Notfällen im Kleinkindesalter wegen der notwendigen Sedierung kritisch zu hinterfragen. Wichtig ist die Frage, ob das cMRT die Diagnose Epilepsie stellen soll, die Wahrscheinlichkeit von Anfallsrezidiven oder die Entität einer wahrscheinlichen Epilepsie angeben soll.

Key words

epileptogenic lesion - cMRI - EEG - first afebrile seizure - seizure relapse - incidental finding

Schlüsselwörter

epileptogene Läsion - cMRT - EEG - erster afebriler Anfall - Anfallsrezidiv - incidental finding

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