Acute and Long-Term Outcomes of Lateralized Rhythmic Delta Activity (LRDA) Versus Lateralized Periodic Discharges (LPDs) in Critically Ill Patients

Background To assess the acute and long-term outcomes for patients with lateralized rhythmic delta activity (LRDA) compared to patients with lateralized periodic discharges (LPDs). Methods A single-center retrospective study examining consecutive patients older than 10 years who had LRDA, LPDs, or both on continuous electroencephalographic (cEEG) between 12/01/2015 and 12/31/2017. Outcomes included inpatient mortality, functional outcome at follow-up, inpatient electrographic seizures, and the presence of new epilepsy at follow-up. Patients were classified into 4 groups: LRDA-only (without LPDs), LPDs-only (without LRDA), LRDA/LPDs, and control (without LRDA or LPDs). Results Twenty-nine patients (2.7%) were in the LRDA-only group, 76 (7%) patients were in the LPDs-only group, and 25 (2.3%) patients had both patterns (LRDA/LPDs group). 68 patients were identified as a control group. Only one patient (3%) in the LRDA-only group died during their hospitalization, compared to 21 patients (28%) in the LPDs-only group, 2 (8%) LRDA/LPDs group and 7 (10%) in the control group (p0.003). Patients in the LPDs-only group had three times higher odds of adjusted mortality compared to the control group (p0.05), while there was no difference in the mortality odds between the LRDA-only and control groups. Patients with LRDA-only had higher odds of good functional outcome at clinic follow-up (p0.04). When compared to control, patients with both IIC patterns (LRDA/LPDs group) had 24.3 higher odds of acute electrographic seizures (p < 0.001), followed by patients in LPDs-only (OR 12.6,p < 0.001) and then LRDA-only (OR 9.4,p = 0.002). The odds of developing epilepsy following discharge were not increased in patients with either LRDA or LPDs (p = 0.9). Conclusions Patients with LRDA had superior functional outcome compared to a higher mortality for patients with LPDs. Patients with both patterns had the highest odds of acute seizures, followed by those with only LPDs and then patients with only LRDA. There was no difference in the odds of developing new epilepsy compared to control with any IIC pattern. We hypothesize different underlying mechanisms of injury leading to the observed electrographic patterns.