Hemodynamic Changes Associated with Lateralized Periodic Discharges: A Near-Infrared Spectroscopy and Continuous EEG Study

Background Lateral periodic discharges (LPDs) have been recognized as a common electroencephalographic (EEG) pattern in critically ill patients. However, management decisions in these patients are still a challenge for clinicians. This study investigates hemodynamic changes associated with LPDs and evaluates if this pattern is likely to represent an ictal, interictal, or ictal–interictal continuum phenomenon via non-invasive near infra-red spectroscopy (NIRS) with concurrent with continuous EEG. Methods Seventeen patients admitted to the intensive care unit with LPDs on continuous electroencephalogram (EEG) were included. Participants engaged in NIRS recording—with scalp probes on right and left frontal regions simultaneously. Associations between LPDs laterality, primary frequency, NIRS a of cerebral oxygen saturation (SO 2 ), total hemoglobin concentration (tHb), oxygenated hemoglobin concentration (O 2 Hb), de-oxygenated hemoglobin concentration (HHb), and variables in participant medical history were studied. Results Hemispheres with LPDs showed higher overall SO 2 when compared to non-LPDs hemispheres (57% vs 52%, p = 0.03). Additionally, mildly increased tHb, O 2 Hb, and mildly decreased HHb concentrations were detected in the hemisphere showing LPDs, but changes were not statistically significant. A higher primary frequency of LPDs was associated with lower cerebral SO 2 (Pearson correlation r = − 0.55, p = 0.022) and O 2 Hb (Pearson correlation r = − 0.52, p = 0.033). In patients with seizure during their EEG recording (64.7%), lower tHb (28.2 μmol/L vs 37.8 μmol/L, p = 0.049) and O 2 Hb (15.5 μmol/L vs 24.2 μmol/L, p = 0.033) were recorded in the LPDs hemisphere. Conclusions This study demonstrates an increased cerebral SO 2 in the hemisphere with LPDs, and decreased SO 2 and O 2 Hb when the frequency of LPDs increases. The findings indicate that LPDs increase oxygen demand on the ipsilateral hemisphere. We infer that a threshold of LPDs frequency might exit, when the cerebral oxygen demand begins to supersede the ability of delivery, and saturation decreases.