Poster No:
2437
Submission Type:
Abstract Submission
Authors:
Victoria Mosher1, Tefani Perera2, Laura Gill2, Ismael Gaxiola-Valdez1, Paolo Federico1
Institutions:
1University of Calgary, Calgary, Alberta, 2Univeristy of Calgary, Calgary, Alberta
First Author:
Co-Author(s):
Introduction:
Epilepsy is a serious neurological disease that affects millions of people worldwide and is characterized by recurrent, unprovoked seizures. Recently, it has been discovered that following a seizure, areas of the brain that are involved in the seizure onset become hypoxic due to a reduction in cerebral blood flow (CBF) for upwards of 60 minutes before returning to baseline (Farrell et al., 2016). Using perfusion imaging, we have generated CBF maps that detect hypoperfusion localizing to the region of seizure onset (Gaxiola-Valdez et al., 2017). While these postictal CBF maps can provide valuable localizing information for clinicians, it requires patients to be admitted to the hospital for 24-hour observation. For this reason, researchers have investigated the utility of baseline measures of hypoperfusion (i.e., hypoperfusion between seizures). Unfortunately, the utility of baseline hypoperfusion has not been established (Perera et al., 2020), possibly due to differences in seizure severity among the different seizure types. In this study, we measured baseline hypoperfusion in patients with epilepsy to determine whether the frequency of different focal seizure types influences the degree of hypoperfusion.
Methods:
Twenty patients with a confirmed diagnosis of epilepsy participated in this study. Baseline arterial spin labelling scans (3T GE Discovery MR 750 system; 3D fast-spin-echo pseudo-continuous arterial spin labeling with background suppression; TR=4725ms, TE=10.152ms, post label delay=2025ms, NEX=4 and spiral acquisition with 512 points and 8 arms) were collected from patients after a seizure-free period of ≥ 24 hours to generate CBF maps. Each CBF map was compared to CBF maps of 100 healthy controls to identify regions of hypoperfusion. The mean CBF value (mL/100g/min) of the area of maximal hypoperfusion was extracted from each patient's CBF map and correlated with the frequency of three different focal seizure types: focal aware (FAS), focal impaired awareness (FIAS) and focal to bilateral tonic-clonic (FBTCS).
Results:
Five patients did not display any baseline hypoperfusion and were excluded from further analysis. In the remaining 15 patients, mean disease duration was 17 years (range 6 months – 38 years), mean number of FAS was 14.5/month (range 0-135), mean number of FIAS was 8.1/month (range 0-40) and mean number of focal to bilateral tonic-clonic seizures was 0.5/month (range 0-5). There was a significant positive correlation between frequency of FBTCS and level of baseline hypoperfusion (r=0.558, p=0.031). No other significant correlations were found.
Conclusions:
FBTCS are considered the most severe type of focal seizure, with longer seizure duration and a greater involvement of brain tissue relative to other seizure types (Steriade et al., 2022). It is possible that FBTCS have more long-lasting effects on the vascular dynamics in the brain. These findings provide evidence that baseline hypoperfusion measures may be more useful in cases where the patient experiences a higher frequency of FBTCS. This relationship between hypoperfusion and frequency of FBTCS may help shed light on why studies investigating baseline hypoperfusion in patients with epilepsy have generated conflicting results.
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) 2
Novel Imaging Acquisition Methods:
Non-BOLD fMRI 1
Keywords:
ADULTS
Cerebral Blood Flow
Epilepsy
MRI
Other - Arterial Spin Labelling
1|2Indicates the priority used for review
Provide references using author date format
Farrell, J.S., Gaxiola-Valdez, I., Wolff, M.D., David, L.S., Dika, H.I., Geeraert, B.L., … Teskey, G.C. (2016), ‘Postictal behavioural impairments are due to a severe prolonged hypoperfusion/hypoxia event that is COS-2 depenedent, Elife, vol. 5, pp. e19352.
Gaxiola-Valdez, I., Singh, S., Perera T., Lie, E., Federico, P. (2017), ‘Seizure onset zone localization using postictal hypoperfusion detected by arterial spin labelling MRI’, Brain, vol. 140, no. 11, pp. 2895-2911.
Perera, T., Gaxiola-Valdez, I., Singh, S., Peedicail, J., Sandy, S., Lebel, R.M., Li, E., Milne-Ives, M., Szostakiwskyj, J., Federico, P. (2020), ‘Localizing the seizure onset zone by comparing patient postictal hypoperfusion to healthy controls’, Journal of Neuroscience Research, vol. 98, pp. 1517-1531.
Steriade, C., Sperling, M.R., DiVentura, B., Lozano, M., Shellhasss, R.A., Kessler, S.K., Dlugos, D., French, J. (2002), ‘Proposal for an updated seizure classification framework in clinical trials’, Epilepsia, vol. 63, pp. 565-572.