Bildgebung: elektrische EEG-Quellenanalyse

Zusammenfassung

Quellenanalyse auf der Basis von Skalp-EEG, idealerweise von hochauflösendem EEG, hat sich etabliert als ein bildgebendes Medium, welches bestehende Verfahren ergänzt. Im Gegensatz zu anderen Techniken kann EEG-basierte Bildgebung die Quelle der neuronalen Aktivität millisekundengenau zu diesem Zeitpunkt abbilden, d.h es handelt sich nicht um indirekte Korrelate der elektrischen Aktivität wie Blutfluss oder Glucosekonsum. Prospektive Studien konnten zeigen, dass Quellenanalyse in einer Mehrheit der Patienten, die sich einer epilepsiechirugischen Therapie unterzogen, den Fokus korrekt im strukturellen MRI des Patienten lokalisiert. Bis dato konnte dies in mehreren Hundert Patienten gezeigt werden: die Wahrscheinlichkeit, nach einer resektiven Intervention anfallsfrei zu sein, ist 10 x höher wenn die elektrische Quelle zusammen mit der strukturellen Anomalie reseziert wurde als wenn dies nicht der Fall war. Studien in operierten Patienten und/oder mit intrakraniellem EEG konnten zeigen, dass es eine hohe Konkordanz zwischen der errechneten Quelle und dem intrakraniellem Fokus gibt. Weitere Anwendungen finden sich in der Lokalisierung von vitalem Kortex mithilfe von evozierten Potenzialen. Insgesamt ist die EEG-basierte Bildgebung relativ einfach zu akquirieren, kann auch bei Kindern und anderen Personen mit begrenzter Kollaboration durchgeführt werden, kann mit fMRI kombiniert werden und ist, vergleichen mit anderen Bildgebungsverfahren, relativ billig. Mögliche zukünftige Anwendungen betreffen die Ermittelung von epileptogener Aktivität bei vermeindlich normalem EEG und Netzwerkanalysen sowie die Netzwerk-Dysfunktionen in anderen neurologischen und psychiatrischen Erkrankungen.

Abstract

Source analysis on the basis of scalp EEG, ideally with high density EEG, has been established as an imaging tool, which complements existing tools. In contrast to other techniques EEG-based imaging visualizes neuronal activity with a resolution of milliseconds, i.e. it is does not measure indirect consequences of epileptic activity such as blood flow changes or glucose consumption. Prospective studies showed that electric source localization localizes the focus correctly in the vast majority of patients who underwent surgical treatment. Up to now, in several hundreds of patients it was found: the likelihood to benefit from epilepsy surgery is 10x higher if the electrical source is removed together with the structural anomaly if that was not the case. Studies in operated patients and/or intracranial EEG could show that there is a high concordance between the calculated source and the intracranial focus. Other applications include the localization of vital cortex with evoked potentials. Overall, EEG-based imaging is relatively easily acquired and can be done also in children or other persons with limited collaboration capacities, can be combined with fMRI and is relatively cheap compared to other imaging tools. Possible future application could be the identification of epileptogenic activity in presumably normal EEG and network analysis, as well as network dysfunctions in other neurological and psychiatric diseases.

Schlüsselwörter

EEG, hochauflösendes EEG, Epilepsiechirurgie, Erwachsene, Kinder

Key words

EEG, high-density EEG, epilepsy surgery, adults, children

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