Ictal-Postictal Temporal Evolution Of Cerebral Perfusion In Mesial Temporal Lobe Epilepsy

Background and objective:Recently, perfusion changes in the whole brain have received more attention. SPECT is a powerful approach to trace the dynamic cerebral blood change injected immediately periictal seizure onset. We aim to investigate the possible dynamic perfusion pattern after distinct injection time in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) to explore the epileptogenicity and propagation network in MTLE-HS with a longer follow-up and absolutely convencing data,Methods:Ictal or postictal and interictal SPECT scans were performed by using [99m]Tc-labeled hexamethyl-propylene-amine-oxime(HMPAO). Thirty SPECT scans of thirty cases injected with HMPAO during Vedio-EEG monitoring were studied in a voxel-based statistical mapping methods (SPM). We divided the 30 paired scans into 5 numerical injection time bins between ical injection pairs and postictal injection pairs separately. All the scans in one specific time bin were compared with the processed normal healthy cases to explore their dynamic perfusion pattern where they were injected ictally or postictally. The extent threshold (k) below which clusters were rejected was 125 voxels. This is equivalent to a volume of 1cc3 (with SPM voxel dimensions of 2×2×2 mm). Individual voxel level significance threshold p was 0.01, corresponding to a Z score of 2.65. Volumetric analysis of SPECT changes in individual patients has been apllied by calculating the mean percent change of [(ictal-interictal)/interictal]×100% in Region Of Interest. Correlation Analyses has been used for Linear Correlation in GRAPH PAD Prism 6.0 among temporal lobe region, subcortical regions and higher grade cortex of DMN with injection time.Results:The research reaveled significant dynamic perfusion change ofincreased cerebral blood change in epileptogenic temporal lobe. It tends to begin at the mesial temporal lobe (MTL) and propagate to lateral temporal lobe (LTL) and then extratemporal lobe such as superamarginal cortex (IPL). Spontaneously almost, bilateral mesial prefrontal cortex (MPFC), anterior cingulate cortex (ACC), ipsilateral posterior cingulate cortex (PCC) and inferior parietal lobe (IPL) illustrated decreased cerebaral blood perfusion patterns in ictal period and evolved to contralaterally increased pattern in postictal period. Cerebellum exited ictally contralaterally hyperperfusion and converted into hyperperfusion ipsilaterally postictally. The signal percent change increased gradually following time evolution ictally in ipsilateral MTL, LTL; on the contrary, the DMN declared simultaneously hypoperfusion changing trend especially in MPFC and ACC, the hypoperfusion converted into hyperperfusion postictally, markedly in PCC and IPL. Correlation analysis displayed strongly positive correlation between MTL and LTL, between LTL and PCC. We did not find out strong correlation among temporal lobe and other DMN areas.Conclusion:The research demonstrated the valuble perfusion evolution pattern in MTLE-HS without secondarily generalized tonic clonic seizure with distinct injection time. The epileptogenicity and propagation of epilepsy may involved in the interaction of peripheral seizure onset zone and DMN and cerebellum.