Page 37 - WNS 2024 -e-Program Edition_Neat

Functional / Pain

Resting state fMRI informs vigilance network properties in
patients undergoing epilepsy surgery
Abhijeet Gummadavelli, MD;
Neurosurgery One, AdventHealth Littleton
Derek J. Doss BE, 1,2,3 Graham W. Johnson MD PhD, 1,2,3 Ghassan S. Makhoul
BS, 1,2,3 Jared S. Shless BS, 5 Camden E. Bibro BS, 4 Monica L. Jacobs PsyD, 4
Hakmook Kang PhD, 6 Kevin F. Haas MD PhD, 7 Sarah K. Bick MD, 1,4 Douglas
P. Terry PhD, 4 Benoit M. Dawant PhD, 1,2,3,4,8,9 Catie Chang PhD, 1,2,3,9,10 Victoria L.
Morgan PhD, 1,2,3,4,7,8 Dario J. Englot MD PhD 1,2,3,4,7,8,9,10
1.Department of Biomedical Engineering, Vanderbilt University, Nashville
TN; 2.Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt
University Medical Center, Nashville, TN; 3. Vanderbilt Institute for Surgery
and Engineering (VISE), Vanderbilt University, Nashville, TN; 4. Department
of Neurological Surgery, Vanderbilt University Medical Center, Nashville,
TN; 5. Harvard Medical School, Harvard University, Boston, MA
6. Department of Biostatistics, Vanderbilt University Medical Center,
Nashville, TN; 7. Department of Neurology, Vanderbilt University Medical
Center, Nashville, TN; 8. Department of Radiology and Radiological Sciences,
Vanderbilt University Medical Center, Nashville, TN; 9. Department of
Electrical and Computer Engineering, Vanderbilt University, Nashville, TN
Introduction: Epilepsy is a common neurological disease affecting nearly
1% of the global population, and temporal lobe epilepsy (TLE) is the most
common type. Patients experience recurrent seizures and chronic cognitive
deficits that can impact their quality of life, ability to work, and
independence. These cognitive deficits often extend beyond the temporal
lobe and are not well understood. The extended network inhibition
hypothesis (ENIH) suggests that repeated spread of seizure activity to the
ascending reticular activating system (ARAS) may contribute to these
deficits.
Methods: Resting state functional magnetic resonance imaging (fMRI) data
were collected for 40 pre-operative TLE patients, 25 post-operative TLE
patients, and 40 age-matched healthy controls. Functional connectivity was
computed between all regions. Functional connectivity and segregation, a
graph-theory measure of network isolation, were compared across the age
spectrum in patients and controls.
Results: We found that increases in epilepsy duration were associated with
greater segregation of the ARAS and decreased functional connectivity
between the pedunculopontine tegmental nucleus and the frontoparietal
association cortex. Furthermore, patients with impaired neurocognitive
function were noted to have longer epilepsy duration and higher ARAS
segregation compared to patients with spared neurocognition. After surgery,
completely seizure-free patients demonstrated ARAS connectivity patterns
that resembled controls, whereas those with residual seizures had persistent
abnormal connectivity.
Conclusions: Recurrent seizures may contribute to the progressive
isolation of critical subcortical activating structures, possibly impacting
cognitive function. Furthermore, some ARAS functional connectivity
abnormalities can be reversed if seizure freedom is achieved after epilepsy
surgery.