Perfusion network shift during seizures in medial temporal lobe epilepsy.
BACKGROUND
Medial temporal lobe epilepsy (MTLE) is associated with limbic atrophy involving the hippocampus, peri-hippocampal and extra-temporal structures. While MTLE is related to static structural limbic compromise, it is unknown whether the limbic system undergoes dynamic regional perfusion network alterations during seizures. In this study, we aimed to investigate state specific (i.e. ictal versus interictal) perfusional limbic networks in patients with MTLE.


METHODS
We studied clinical information and single photon emission computed tomography (SPECT) images obtained with intravenous infusion of the radioactive tracer Technetium- Tc 99 m Hexamethylpropyleneamine Oxime (Tc-99 m HMPAO) during ictal and interictal state confirmed by video-electroencephalography (VEEG) in 20 patients with unilateral MTLE (12 left and 8 right MTLE). Pair-wise voxel-based analyses were used to define global changes in tracer between states. Regional tracer uptake was calculated and state specific adjacency matrices were constructed based on regional correlation of uptake across subjects. Graph theoretical measures were applied to investigate global and regional state specific network reconfigurations.


RESULTS
A significant increase in tracer uptake was observed during the ictal state in the medial temporal region, cerebellum, thalamus, insula and putamen. From network analyses, we observed a relative decreased correlation between the epileptogenic temporal region and remaining cortex during the interictal state, followed by a surge of cross-correlated perfusion in epileptogenic temporal-limbic structures during a seizure, corresponding to local network integration.


CONCLUSIONS
These results suggest that MTLE is associated with a state specific perfusion and possibly functional organization consisting of a surge of limbic cross-correlated tracer uptake during a seizure, with a relative disconnection of the epileptogenic temporal lobe in the interictal period. This pattern of state specific shift in metabolic networks in MTLE may improve the understanding of epileptogenesis and neuropsychological impairments associated with MTLE.
Comprehensive Epilepsy Center, Division of Neurology, Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA.
Karen M
KM
Sequeira
Ali
A
Tabesh
Rup K
RK
Sainju
Stacia M
SM
DeSantis
Thomas
T
Naselaris
Jane E
JE
Joseph
Mark A
MA
Ahlman
Kenneth M
KM
Spicer
Steve S
SS
Glazier
Jonathan C
JC
Edwards
Leonardo
L
Bonilha
D000328:Adult; D002648:Child; D002675:Child, Preschool; D003710:Demography; D004833:Epilepsy, Temporal Lobe / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D010477:Perfusion; D011877:Radionuclide Imaging; D012640:Seizures / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D019690:Technetium Tc 99m Exametazime; D055815:Young Adult
D019690:Technetium Tc 99m Exametazime