Authors :
Presenting Author: Addison Cavender, BS – Vanderbilt University Medical Center
Ghassan Makhoul, BS – Vanderbilt University Medical Center
Derek Doss, PhD – Vanderbilt University
Bruno Hidalgo, BS – Vanderbilt University Medical Center
Anas Reda, MS – Vanderbilt University Medical Center
Emily Liao, BE – University of Minnesota
Camden Bibro, BS – Vanderbilt University
Sarah Goodale, PhD – Vanderbilt University
Hernan Gonzalez, MD, PhD – University of California-San Diego
Graham Johnson, MD, PhD – Mayo Clinic
Laurie Cutting, PhD – Vanderbilt University
Sarah Bick, MD – Vanderbilt University Medical Center
Catie Chang, PhD – Vanderbilt University
Victoria Morgan, PhD – Vanderbilt University Medical Center
Dario Englot, MD PhD – Vanderbilt University Medical Center
Rationale:
Patients with temporal lobe epilepsy (TLE) exhibit deficits in functional connectivity (FC) of subcortical arousal structures compared to healthy controls. The nucleus basalis of Meynert (NBM), implicated in arousal, has been shown to have decreased FC in patients with TLE [1]. The unique NBM FC in patients suggests a disruption in FC due to epilepsy. However, it is unclear how NBM FC changes following surgery. Thus, using advanced patient-specific segmentations [2], we sought to analyze NBM FC before and after surgery in TLE patients who achieved seizure freedom and those who did not. We hypothesize that NBM FC will increase towards that of healthy controls in patients who achieve seizure freedom, suggesting that seizure cessation allows the affected NBM network to reorganize.
Methods:
We conducted FC analyses using resting-state fMRI of 35 pre- and post-operative TLE patients with known seizure outcomes and 35 age- and sex-matched controls. Patients were split into seizure-free (Engel IA) patients (n=18) and non-seizure free (non-Engel IA) patients (n=17). Using the Desikan-Killiany cortical atlas [3] and patient-specific NBM segmentations [2], we compared FC of the ipsilateral NBM to the whole-brain and frontoparietal association cortex (FPAC), an area specifically shown to have decreased FC to the NBM prior to surgery [1], across patients who achieved seizure freedom and patients who did not.
Results:
Prior to surgery, patients show robust differences in ipsilateral NBM FC compared to controls (cluster-corrected p< 0.05, Fig. A). Following surgery, non-seizure-free patients continue to show large differences in ipsilateral NBM FC to whole-brain compared to healthy controls, while seizure-free patients exhibit decreased differences (Fig. A). Additionally, ipsilateral NBM to FPAC FC significantly increases in seizure-free patients (p=0.021, Fig. B) and is no longer significantly different from controls.
Conclusions:
Our observations of NBM connectivity differences in patients with varying seizure outcomes before and after surgery suggest that connectivity of this region may reflect network disturbances due to recurrent seizures, and that NBM connectivity abnormalities may recover after seizure cessation. The unique connectivity of the NBM in patients achieving seizure freedom supports further exploration into its putative role in disease progression and the ability for neuroplasticity with improvement of disease.
Funding:
This work was supported by NIH grants NINDS R01NS112252, R01NS134625, R01NS108445, R01NS110130, F31NS131056, NIGMS T32GM007347, NIBIB T32EB021937, and Neil and Barbara Smit.