SIRPIDs: prevalence and outcome in critically ill patients

To determine the prevalence, associated factors, and outcomes of critically ill patients with stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) on long-term video-EEG (VEEG).

After IRB approval, we retrospectively reviewed patient characteristics and VEEG findings of all consecutive critical care unit patients who underwent VEEG monitoring between January 2012 and September 2012.

The prevalence of SIRPIDs was 12.1% (4 of 33 patients; exact 95% confidence interval, 3.4%-28.2%). Factors associated with SIRPIDs versus non-SIRPIDs patients included a higher prevalence of subclinical status epilepticus (100% vs. 17.2%, P = 0.003), longer total VEEG recording time (286 vs. 56.9 hours, P = 0.0004), and acute traumatic brain injury (75.0% vs. 17.2%, P = 0.036). Sex, age, a history of epilepsy, nonstatus epileptic seizures, other EEG periodic patterns, and background rhythm reactivity on VEEG did not correlate with the presence of SIRPIDs. The presence or absence of SIRPIDs had no bearing on outcome; however, the population studied was very small.

This small series suggests that the presence of subclinical status epilepticus and traumatic brain injury correlated with the presence of SIRPIDs signifying that SIRPIDs may be due to a more focal etiology and may represent a more ictal pattern than previously thought. Longer recording times in those patient populations may yield more cases of SIRPIDs in which to base further studies.