SISCOM is a recently developed neuroimaging technique evaluating regional cerebral blood flow (rCBF) in both pediatric and adult patients with drug-resistant focal epilepsy during pre-surgical evaluation. Injection of a radiotracer (usually Tc-99m) during the ictus allows measure of local differences in rCBF between the ictal and interictal state of neuronal activation that occurs with seizures. Focal cerebral hyperperfusion noted on SISCOM (above) has been valuable for the identifying the seizure onset zone in 40-86% of patients in addition to assessing the extent of resection in temporal and extratemporal lobe epilepsy (1, 2). SISCOM findings may alter the decision to place or avoid pursuing invasive video-EEG (vEEG) in cases of successful outcomes (1) and complete resection of the area of involvement has been associated with a greater likelihood of becoming seizure-free after surgery. Rarely, discordant findings between invasive vEEG and SISCOM are reported in patients not seizure-free after surgery likely reflecting identification of a propagated rCBF pattern as opposed to the seizure onset zone (2). SISCOM will help restrict the iEEG electrode array and is anticipated to limit the extent of initial surgical resection for epilepsy in our patient.
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