Hochfrequenzoszillationen (>80 Hz) als Marker für epileptogene Areale

Zusammenfassung

EEG-Frequenzen oberhalb von 80 Hz haben in den letzten Jahren zunehmend an Bedeutung gewonnen. Besonders im Bereich der prächirurgischen Epilepsidiagnostik bei Patienten mit therapierefraktärer Epilepsie verspricht die Analyse von physiologischen und pathologischen Hochfrequenzoszillationen (HFOs) zwischen 80–500 Hz die bisherigen diagnostischen Möglichkeiten zu verbessern. Im intrakraniellen EEG aufgezeichnete pathologische HFOs lassen sich klar von anderen EEG-Markern wie epileptischen Spikes unterscheiden. HFOs zeigen eine stärkere Verbindung zu epileptogenen Arealen und ihre intraoperative Entfernung korreliert mit der postoperativen Anfallsfreiheit. Zusätzlich hat die Analyse von Hochfrequenzoszillationen den entscheidenenden Vorteil, dass für ihre Erfassung 5 min intrakranielles EEG oder sogar intraoperativ aufgezeichnetem EEG-Abschnitte ausreichen. Hierdurch könnte die notwendige Zeit der EEG-Aufzeichnung im Sinne des Patienten verkürzt werden. Neuere Studien zeigen HFOs, die im Oberflächen-EEG aufgezeichnet wurden. Dies eröffnet die Möglichkeit zu Langzeitstudien und der Untersuchung von weniger komplizierten Epilepsien. Dieser Review fasst das bisherige Wissen zu physiologischen und pathologischen HFOs bei Epilepsien zusammen. Klinische Anwendungsmöglichkeiten und methodische Schwierigkeiten von HFOs als Marker für epileptogene Areale werden diskutiert.

Abstract

Frequencies above 80 Hz have gained importance in the analysis of EEG over the past few years. Especially in the presurgical evaluation of patients with refractory epilepsy, the analysis of physiological as well as pathological high frequency oscillations (HFO) may lead to improved diagnostic possibilities. Pathological HFOs recorded for intracranial EEG are distinct from other EEG markers, have been clearly linked to epileptogenicity and may improve the predictability of the postsurgical outcome patients with epilepsy. Moreover most of the analysis can be done from 5 min of interictal intracranial EEG and even intraoperative ECOG recordings. Thus the time needed for an investigation may be reduced in comparison to classical chronic EEG analysis. First studies discuss high frequency findings in the surface EEG which may allow extending the method to patients with less severe epilepsy and long-term studies. This review provides an overview over the knowledge of pathological and physiological HFOs in the field of epilepsy as well as discusses possible future clinical applications and methodological challenges of HFOs as markers of epileptogenicity.

Epilepsie - Ripple - Fast ripple - Hochfrequenzoszillationen

epilepsy - ripple - fast ripple - high frequency oscillations

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