Altered physiological brain variation in drug-resistant epilepsy.

Area of Science:

• Neuroimaging
• Epilepsy Research
• Physiological Signal Analysis

Background:

• Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG-fMRI) are key tools for epilepsy source localization.
• Resting-state fMRI can reveal intrinsic brain alterations even without detectable epileptiform activity.

Purpose of the Study:

• To investigate physiological variance differences between healthy controls and drug-resistant epilepsy (DRE) patients using ultra-fast fMRI.
• To explore the potential of critically sampled fMRI for identifying intrinsic brain pulsations in DRE.

Main Methods:

• Utilized coefficient of variation (CV) of 10 Hz ultra-fast fMRI (magnetoencephalography, MREG) signals.
• Compared physiological variance in 10 healthy controls and 10 DRE patients.

Main Results:

• Significantly increased voxel-level physiological variance (p < 0.01) was observed in DRE patients compared to controls.
• Elevated variance in DRE patients ranged over three standard deviations above the control mean, allowing for patient-specific mapping.
• Group-level analysis revealed the most significant differences in white matter, brainstem, and cerebellum, particularly affecting respiratory and very-low-frequency signal variances.

Conclusions:

• The observed increase in CV_MREG is likely linked to intrinsic physiological pulsations, not head motion or cardiorespiratory activity.
• Intrinsic brain pulsations may play a significant role in DRE.
• Critically sampled fMRI shows promise as a powerful tool for identifying these pulsations in epilepsy patients.