Abstracts

Rationale: Lateralized Periodic Discharges (LPDs) are a readily identifiable pattern. Whether LPDs themselves should be considered an ictal pattern remains a topic of ongoing controversy. It is well established that epileptic activity causes an increased metabolic demand in the involved cerebral cortex, which is accompanied by temporarily increased regional brain perfusion. Although ictal SPECT is a standard and reliable technique to assess brain perfusion changes, CT perfusion (CTP) is a faster imaging technique that also provides an active view of cerebral metabolic demand and perfusion. In our case, we found that CTP changes correlated with LPD abnormality on the EEG. With that information, we believe that CTP study can be helpful in differentiating ictal versus interictal LPD activity.   Methods: Clinical case report including EEG documentation, CT-perfusion scan, CT-angiography, and MRI.  Results: We report a case of a 70-year-old right-handed woman with a past medical history of Pulmonary Embolism on apixaban and Diffuse Large B-Cell Lymphoma (DLBCL) on R-CHOP therapy who presented as a stroke alert for new onset of left sided weakness. She was also found to have focal seizures involving rhythmic clonic movements of her left arm and face. Initial CTP study revealed hyperperfusion of the right posterior operculum and parieto-temporal lobe demonstrate by decreased MTT (mean transient time), increased CBF (cerebral blood flow), and CBV (cerebral bood volume) in those areas. Electroencephalogram (EEG) performed within 2 hour of the CTP studies showed lateralized, periodic discharges at 1-2 hertz seen over the right parietal area involving P4 electrode that, at times, were accompanied by focal seizures involving twitching of the left lower face. Her initial brain MRI showed restricted diffusion in the right insular region. Following adequate treatment with AEDs, her focal seizures resolved. Although repeat CT perfusion was not performed, restricted diffusion changes disappeared in the follow-up MRI done 3 days later, while her EEG showed persistent LPDs.    Conclusions: Because of its broad availability and short processing time, CT perfusion may qualify as a fast and complimentary diagnostic tool to help differentiate between ictal and interictal LPD pattern. In those patients who present with EEGs showing LPDs that are of uncertain etiology, a positive CTP may help determine if the LPDs are closer to an ictal pattern.  These patients may have had unrecognized seizures and CTP may help us determine if there is a need for a more aggressive AED therapy.  Funding: No funding