Spectral entropy indicates electrophysiological and hemodynamic changes in drug-resistant epilepsy – A multimodal MREG study

Autor: T. Myllylä, Aleksi Rasila, Vesa Kiviniemi, Viola Borchardt, Janne Kananen, Heta Helakari, Tuija Keinänen, Lauri Raitamaa, Niko Huotari, Timo Tuovinen, Vesa Korhonen, Tuomo Starck, V. Raatikainen, Seppo Rytky, H. Ansakorpi, Osmo Tervonen, T. Hautaniemi
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Male
Drug Resistant Epilepsy
Entropy
Electroencephalography
lcsh:RC346-429
0302 clinical medicine
Nuclear magnetic resonance
Gyrus
Image Processing
Computer-Assisted
Medicine
EEG
Spectroscopy
Near-Infrared
medicine.diagnostic_test
05 social sciences
Parasympathetic
Regular Article
Human brain
Middle Aged
Magnetic Resonance Imaging
medicine.anatomical_structure
NIRS
Neurology
Cerebrovascular Circulation
lcsh:R858-859.7
Female
Adult
Cognitive Neuroscience
Inferior frontal gyrus
Neuroimaging
lcsh:Computer applications to medicine. Medical informatics
050105 experimental psychology
Young Adult
03 medical and health sciences
Irregularity
Humans
0501 psychology and cognitive sciences
Radiology
Nuclear Medicine and imaging
lcsh:Neurology. Diseases of the nervous system
Epilepsy
business.industry
Hemodynamics
Magnetic resonance imaging
Neurophysiology
Electrophysiology
Autonomic nervous system
Ultra-fast fMRI
Neurology (clinical)
business
030217 neurology & neurosurgery
Zdroj: NeuroImage: Clinical, Vol 22, Iss, Pp-(2019)
NeuroImage : Clinical
ISSN: 2213-1582
Popis: Objective Epilepsy causes measurable irregularity over a range of brain signal frequencies, as well as autonomic nervous system functions that modulate heart and respiratory rate variability. Imaging dynamic neuronal signals utilizing simultaneously acquired ultra-fast 10 Hz magnetic resonance encephalography (MREG), direct current electroencephalography (DC-EEG), and near-infrared spectroscopy (NIRS) can provide a more comprehensive picture of human brain function. Spectral entropy (SE) is a nonlinear method to summarize signal power irregularity over measured frequencies. SE was used as a joint measure to study whether spectral signal irregularity over a range of brain signal frequencies based on synchronous multimodal brain signals could provide new insights in the neural underpinnings of epileptiform activity. Methods Ten patients with focal drug-resistant epilepsy (DRE) and ten healthy controls (HC) were scanned with 10 Hz MREG sequence in combination with EEG, NIRS (measuring oxygenated, deoxygenated, and total hemoglobin: HbO, Hb, and HbT, respectively), and cardiorespiratory signals. After pre-processing, voxelwise SEMREG was estimated from MREG data. Different neurophysiological and physiological subfrequency band signals were further estimated from MREG, DC-EEG, and NIRS: fullband (0–5 Hz, FB), near FB (0.08–5 Hz, NFB), brain pulsations in very-low (0.009–0.08 Hz, VLFP), respiratory (0.12–0.4 Hz, RFP), and cardiac (0.7–1.6 Hz, CFP) frequency bands. Global dynamic fluctuations in MREG and NIRS were analyzed in windows of 2 min with 50% overlap. Results Right thalamus, cingulate gyrus, inferior frontal gyrus, and frontal pole showed significantly higher SEMREG in DRE patients compared to HC. In DRE patients, SE of cortical Hb was significantly reduced in FB (p = .045), NFB (p = .017), and CFP (p = .038), while both HbO and HbT were significantly reduced in RFP (p = .038, p = .045, respectively). Dynamic SE of HbT was reduced in DRE patients in RFP during minutes 2 to 6. Fitting to the frontal MREG and NIRS results, DRE patients showed a significant increase in SEEEG in FB in fronto-central and parieto-occipital regions, in VLFP in parieto-central region, accompanied with a significant decrease in RFP in frontal pole and parietal and occipital (O2, Oz) regions. Conclusion This is the first study to show altered spectral entropy from synchronous MREG, EEG, and NIRS in DRE patients. Higher SEMREG in DRE patients in anterior cingulate gyrus together with SEEEG and SENIRS results in 0.12–0.4 Hz can be linked to altered parasympathetic function and respiratory pulsations in the brain. Higher SEMREG in thalamus in DRE patients is connected to disturbances in anatomical and functional connections in epilepsy. Findings suggest that spectral irregularity of both electrophysiological and hemodynamic signals are altered in specific way depending on the physiological frequency range.
Highlights • Simultaneous imaging methods indicate spectral irregularity in neurovascular and electrophysiological brain pulsations in DRE. • Altered spectral entropy in EEG, NIRS and BOLD indicate dysfunctional brain pulsations in respiratory frequency in epilepsy. • Spectral irregularity (0-5 Hz) of BOLD in right thalamus supports previous structural and functional findings in epilepsy.
Databáze: OpenAIRE
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