Respiratory brain impulse propagation in focal epilepsy

Respiratory brain pulsations pertaining to intra-axial hydrodynamic solute transport are markedly altered in focal epilepsy. We used optical flow analysis of ultra-fast functional magnetic resonance imaging (fMRI) data to investigate the velocity characteristics of respiratory brain impulse propagation in patients with focal epilepsy treated with antiseizure medication (ASM) (medicated patients with focal epilepsy; ME, n = 23), drug-naive patients with at least one seizure (DN, n = 19) and matched healthy control subjects (HC, n = 75). We detected in the two patient groups (ME and DN) several significant alterations in the respiratory brain pulsation propagation velocity, which showed a bidirectional change dominated by a reduction in speed. Furthermore, the respiratory impulses moved more in reversed or incoherent directions in both patient groups vs. the HC group. The speed reductions and directionality changes occurred in specific phases of the respiratory cycle. In conclusion, irrespective of medication status, both patient groups showed incoherent and slower respiratory brain impulses, which may contribute to epileptic brain pathology by hindering brain hydrodynamics.

Automated summary

The study found that respiratory brain pulsations related to hydrodynamic solute transport are significantly altered in patients with focal epilepsy. Optical flow analysis of ultra-fast functional MRI data revealed significant changes in the velocity and direction of respiratory brain impulse propagation in both medicated and drug-naive patient groups compared to healthy control subjects. The slower and incoherent respiratory brain impulses observed in both patient groups, regardless of medication status, may contribute to epileptic brain pathology by hindering brain hydrodynamics.