Stimulus-induced Rhythmic, Periodic, Or Ictal Discharges Research Articles

Stimulus-induced periodic discharges in response to low-frequency photostimulation in a female patient in recovery period after middle cerebral artery stroke

Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) represent a relatively common phenomenon recorded during a long-term electroencephalogram (EEG) monitoring allowing to capture the altered state and response to auditory, tactile or nociceptive stimulation in critically ill patients. It is a nosologically non-specific phenomenon, and its relation to ictal event remains debated. We present a clinical case in which SIRPIDs were recorded in the affected dominant hemisphere in response to low-frequency photostimulation in a 60-years-old woman recovering after middle cerebral artery stroke. No ictal events were recorded during routine EEG monitoring; the patient was not in critical condition.

Implications of stimulus-induced, rhythmic, periodic, or ictal discharges (SIRPIDs) in hospitalized patients.

Stimulus-induced electroencephalographic (EEG) patterns are commonly seen in acutely ill patients undergoing continuous EEG monitoring. Despite ongoing investigations, the pathophysiology, therapeutic and prognostic significance of stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) and how it applies to specific pathologies remain unclear. We aimed to investigate the clinical implications of SIRPIDs in hospitalized patients. This is a retrospective single-center study of hospitalized patients from May 2016 to August 2017. We included patients above the age of 18 years who underwent >16 h of EEG monitoring during a single admission. We excluded patients with cardiac arrest and anoxic brain injury. Demographic data were obtained as well as admission GCS, and discharge modified Rankin Score (mRS). EEGs were reviewed for background activity in addition to epileptiform, periodic, and rhythmic patterns. The presence or absence of SIRPIDs was recorded. Our outcome was discharge mRS defined as good outcome, mRS 0-4, and poor outcome mRS, 5-6. A total of 351 patients were included in the final analysis. The median age was 63 years and 175 (50%) were women. SIRPIDs were identified in 82 patients (23.4%). Patients with SIRPIDs had a median initial GCS of 12 (IQR, 6-15) and a length of stay of 12 days (IQR, 6-15). They were more likely to have absent posterior dominant rhythm, decreased reactivity, and more likely to have spontaneous periodic and rhythmic patterns and higher frequency of burst suppression. After adjusting for baseline clinical variables, underlying disease type and severity, and EEG background features, the presence of SIRPIDs was also associated with poor outcomes classified as MRS 5 or 6 (OR 4.75 [2.74-8.24] p ≤ 0.0001). In our cohort of hospitalized patients excluding anoxic brain injury, SIRPIDs were identified in 23.4% and were seen most commonly in patients with primary systemic illness. We found SIRPIDs were independently associated with poor neurologic outcomes. Several studies are indicated to validate these findings and determine the risks vs. benefits of anti-seizure treatment.

Nomogram for Early Prediction of Outcome in Coma Patients with Severe Traumatic Brain Injury Receiving Right Median Nerve Electrical Stimulation Treatment.

Accurate outcome prediction can serve to approach, quantify and categorize severe traumatic brain injury (TBI) coma patients for right median electrical stimulation (RMNS) treatment, which can support rehabilitation plans. As a proof of concept for individual risk prediction, we created a novel nomogram model combining amplitude-integrated electroencephalography (AEEG) and clinically relevant parameters. This study retrospective collected and analyzed a total of 228 coma patients after severe TBI in two medical centers. According to the extended Glasgow Outcome Scale (GOSE), patients were divided into a good outcome (GOSE 3-8) or a poor outcome (GOSE 1-2) group. Their clinical and biochemical indicators, together with EEG features, were explored retrospectively. The risk factors connected to the outcome of coma patients receiving RMNS treatment were identified using Cox proportional hazards regression. The discriminative capability and calibration of the model to forecast outcome were assessed by C statistics, calibration plots, and Kaplan-Meier curves on a personalized nomogram forecasting model. The study included 228 patients who received RMNS treatment for long-term coma after a severe TBI. The median age was 40 years, and 57.8% (132 of 228) of the patients were male. 67.0% (77 of 115) of coma patients in the high-risk group experienced a poor outcome after one year and the comparative data merely was 30.1% (34 of 113) in low-risk group patients. The following variables were integrated into the forecasting of outcome using the backward stepwise selection of Akaike information criterion: age, Glasgow Coma Scale (GCS) at admission, EEG reactivity (normal, absence, or the stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs)), and AEEG background pattern (A mode, B mode, or C mode). The C statistics revealed that the nomograms' discriminative potential and calibration demonstrated good predictive ability (0.71). Our findings show that the nomogram model using AEEG parameters has the potential to predict outcomes in severe TBI coma patients receiving RMNS treatment. The model could classify patients into prognostic groups and worked well in internal validation.

Stimulus Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs) and its Association with Non-convulsive Status Epilepticus in Critically Ill Patients.

Stimulus induced repetitive periodic or ictal discharges (SIRPIDs) are a commonly observed EEG pattern in critically ill patients. However, the epileptic significance of SIRPIDs remain unclear. We identified and reviewed 55 cases with SIRPIDs according to the ACNS criteria. SIRPIDs occurred after standardized painful stimuli during a standard 20-minute EEG. These cases were investigated regarding their relation to non-convulsive status epilepticus (NCSE) according to Salzburg Consensus Criteria and in-hospital mortality. In 37/55 patients (67.3%), SIRPIDs were associated with NCSE. In most patients (26/37 cases, 70.3%) with concurrent status epilepticus, SIRPIDs occurred after status epilepticus (on average 4.8 days later), but in 3/37 patients (8.1%) they were observed before a later status epilepticus. In four cases (4/37 cases, 10.8%), SIRPIDs appeared both before and after an episode of NCSE and in other four cases the two patterns coexisted in the same EEG. In 50% of the patients, status epilepticus was refractory, super-refractory or the patient died before its resolution. The overall mortality in the cohort was high at 58.2%. These findings corroborate the hypothesis that SIRPIDs might represent a state with increased epileptogenic potential, commonly co-occurring with NCSE. Furthermore, SIRPIDs are associated with therapy-refractory course of status epilepticus and high mortality.

A novel nomogram for early prediction of death in severe neurological disease patients with electroencephalographic periodic discharges

ObjectiveTo investigate death-related factors in patients with electroencephalographic (EEG) periodic discharges (PDs) and to construct a model for death prediction. MethodsThis case-control study enrolled a total of 80 severe neurological disease patients with EEG PDs within 72 h of admission to the neuroscience intensive care unit (NICU). According to modified Rankin scale (mRS) scores half a year after discharge, patients were divided into a survival group (<6 points) and a death group (6 points). Their relevant clinical and biochemical indicators as well as EEG characteristics were retrospectively analyzed. Logistic regression analysis was used to identify the risk factors associated with the death of patients with EEG PDs. A death risk prediction model and an individualized nomogram prediction model were constructed, and the prediction performance and concordance of the models were evaluated. ResultsMultivariate logistic regression analysis showed that the involvement of both gray and white matter in imaging, disappearance of EEG reactivity, occurrence of stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs), and an interval time of 0.5–4 s were independent risk factors for death. A regression model was established according to the multivariate logistic regression analysis, and the area under the curve of this model was 0.9135. The accuracy of the model was 87.01%, the sensitivity was 87.17%, and the specificity was 89.17%. A nomogram model was constructed, and a concordance index of 0.914 was obtained after internal validation. ConclusionThe regression model based on risk factors has high accuracy in predicting the risk of death of patients with EEG PDs. SignificanceThis model can help clinicians in the early assessment of the prognosis of severe neurological disease patients with EEG PDs.

Editors' Note: Prediction of Regaining Consciousness Despite an Early Epileptiform EEG After Cardiac Arrest

Neuroprognostication after cardiac arrest often remains reliant on neurophysiologic and serologic testing. To better prognosticate outcomes among patients with early epileptiform activity on EEG, Dr. Barbella et al. modeled various EEG predictors of favorable outcome using updated neurophysiologic criteria. Early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predicted favorable long-term outcomes in these patients after cardiac arrest (area under the curve 0.96, 95% CI 0.91–1.00). In a reader response, Dr. Sethi highlights that SIRPIDs may indicate brain reactivity, but they are not associated with cerebral hyperperfusion (as in the case of seizures). Both the investigators and Dr. Sethi agree that later SIRPIDs need not be treated aggressively in these patients. This study adds considerably to the neuroprognostication literature by showing early epileptiform activity may not always be a poor prognostic marker after cardiac arrest. Even in the presence of epileptiform activity, some features indicate a reasonable probability of functional recovery. As the investigators note in their methods—intensive care withdrawal was considered in patients with treatment-resistant myoclonus or status epilepticus, absent somatosensory-evoked potentials, incomplete return of brainstem reflexes, and elevated neuron specific enolase levels. Unsurprisingly, each of these findings strongly predicted poor outcomes. Therefore, the high sensitivity and specificity of the NEC2RAS score for predicting poor outcome does not disentangle it from the possibility of it contributing to the self-fulfilling prophecy. Neuroprognostication after cardiac arrest often remains reliant on neurophysiologic and serologic testing. To better prognosticate outcomes among patients with early epileptiform activity on EEG, Dr. Barbella et al. modeled various EEG predictors of favorable outcome using updated neurophysiologic criteria. Early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predicted favorable long-term outcomes in these patients after cardiac arrest (area under the curve 0.96, 95% CI 0.91–1.00). In a reader response, Dr. Sethi highlights that SIRPIDs may indicate brain reactivity, but they are not associated with cerebral hyperperfusion (as in the case of seizures). Both the investigators and Dr. Sethi agree that later SIRPIDs need not be treated aggressively in these patients. This study adds considerably to the neuroprognostication literature by showing early epileptiform activity may not always be a poor prognostic marker after cardiac arrest. Even in the presence of epileptiform activity, some features indicate a reasonable probability of functional recovery. As the investigators note in their methods—intensive care withdrawal was considered in patients with treatment-resistant myoclonus or status epilepticus, absent somatosensory-evoked potentials, incomplete return of brainstem reflexes, and elevated neuron specific enolase levels. Unsurprisingly, each of these findings strongly predicted poor outcomes. Therefore, the high sensitivity and specificity of the NEC2RAS score for predicting poor outcome does not disentangle it from the possibility of it contributing to the self-fulfilling prophecy.

Author Response: Prediction of Regaining Consciousness Despite an Early Epileptiform EEG After Cardiac Arrest.

We thank Dr. Sethi for his interesting comment on our study.1 The exact nature of stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) has been indeed unclear since their first description,2 and a retrospective multicenter study did not find any independent association between SIRPIDs and mortality.3 As hypothesized by Dr Sethi, it is possible that they may reflect a sort of brain reactivity; our finding that SIRPDs appearing after targeted temperature management (TTM) are linked to a possible good outcome goes in the same direction.1 However, in a previous study, we found that SIRPDs during TTM—thus occurring earlier after cardiac arrest—are rather related to poor prognosis.4 These observations likely reflect a complex interplay between SIRPIDs and prognostic implications that certainly deserve more attention in future works. Finally, we agree that current evidence does not suggest that SIRPIDs need to be treated aggressively in these patients.

Reader Response: Prediction of Regaining Consciousness Despite an Early Epileptiform EEG After Cardiac Arrest.

I read the study by Barbella et al.1 with great interest. The authors have put forth an easy to calculate EEG prognostic score, which correlates well with clinical outcome after cardiac arrest. Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDS) are commonly seen in the EEGs of these critically ill patients. Their clinical significance and how aggressively they should be treated has been debated vigorously. Functional imaging (SPECT) obtained at the time of SIRPIDS has shown no increase in cerebral blood flow, arguing against treatment as seizures.2 SIRPIDS likely reflect a form of brain reactivity and diffuse epileptogenic potential. Although they may regress on treatment with a benzodiazepine, it is likely that aggressive treatment of these discharges in these patients is not warranted and may even be harmful.

Stimulus-induced EEG-patterns and outcome after cardiac arrest

ObjectiveEEG is commonly used to predict prognosis in post anoxic coma. We investigated if stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) add prognostic information after cardiac arrest. MethodsIn the multicenter Targeted Temperature Management trial, routine-EEGs were prospectively recorded after rewarming (≥36 h). Presence and subtype of SIRPIDs and main EEG-pattern (benign, malignant, highly malignant) were retrospectively reported according to a standardised classification. Patients were followed up after 180 days. Poor outcome was defined as severe neurological disability or death (Cerebral Performance Category 3–5). ResultsOf 142 patients, 71% had poor outcome and 14% had SIRPIDs. There was no significant difference in outcome between patients with and without SIRPIDs, even when subgrouped according to underlying main EEG-pattern. Comparing subtypes of SIRPIDs, 82% of patients with stimulus-induced periodic discharges had poor outcome compared to 44% of patients with stimulus-induced rhythmic delta activity, but the difference was not significant. ConclusionsIn EEGs performed ≥36 h after cardiac arrest, SIRPIDs cannot be used to reliably predict poor outcome. Whether certain subtypes of SIRPIDs indicate worse prognosis needs further investigation. SignificanceCategorising the main EEG-pattern has important prognostic implications, but assessment of late appearing SIRPIDs does not seem to add prognostic information.

P09-T An extraordinary EEG phenomenon misdiagnosed as nonconvulsive status epilepticus: Subclinical ictal discharges interrupted by verbal stimuli

Background Triggering or modulation of seizures and rhythmic EEG patterns by external stimuli are well-known but an exclusive stopping effect by sound was not reported before. Here, we report a peculiar manifestation of stimulus-related ictal discharges, namely, subclinical ictal discharges interrupted by sudden verbal stimuli. Case The patient is a 20-year-old woman with recurrent febrile seizure history between the age of 4 months to one year and marked psychomotor developmental delay of unknown cause. She also had brief episodes of staring and sometimes bilateral tonic-clonic seizures. Neurological examination revealed strabismus and microcephaly. Brain MRI did not show any abnormality. At age of 8 years, self-mutilating and agitated behaviors were noted. First EEGs revealed bifrontal 2.5–3.5 Hz spike and waves with impaired background activity. Video-EEG showed frequent patterns of long-lasting (10–60 s) bilateral paroxysmal high-voltage slow waves with occasional spikes, misdiagnosed as non-convulsive status epilepticus. However, no apparent clinical change was noted by the technician, physician and mother during these subclinical ictal EEG recordings. Interestingly, these epileptic discharges were abruptly interrupted with sudden verbal stimuli. Lysosomal enzyme activities and metabolic screening tests were unremarkable. Molecular genetic investigations for ring 20 chromosome analysis and SLC2A1 gene analysis were also unremarkable. Her seizures were partly controlled with levetiracetam, valproic acid and primidone. Conclusion We report the “reverse” type of stimulus-induced, rhythmic, periodic or ictal discharges (SIRPIDS), that is stopped by the external sound in a patient with developmental delay. External modulation of ictal-appearing EEG patterns may show clues for hidden mechanisms of epileptogenesis.

Stimulus-Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs).

Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) are a relatively common phenomenon found on prolonged electroencephalogram (EEG) monitoring that captures state changes and stimulation of critically ill patients. Common causes include hypoxic injury, traumatic brain injury, and hemorrhage, as well as toxic-metabolic disturbances. Some studies have shown an association between SIRPIDs and the presence of spontaneous electrographic seizures. Although the degree to which SIRPIDs should be treated with antiepileptic medications is unknown, the rare cases of functional imaging obtained in patients with SIRPIDs have not shown an increase in cerebral blood flow to suggest an active ictal process. Stimulus-induced rhythmic, periodic, or ictal discharges may reflect dysregulation of thalamo-cortical projections into abnormal or hyperexcitable cortex.

Electroencephalographic Patterns During Common Nursing Interventions in Neurointensive Care: A Descriptive Pilot Study

Many patients with neurological insults requiring neurointensive care have an increased risk of acute symptomatic seizures. Various nursing interventions performed when caring for these patients may elicit pathological cerebral electrical activity including seizures and stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs). The aim was to explore changes in electroencephalogram (EEG) due to neurointensive care nursing interventions. A convenience sample was recruited between November 2015 and April 2016, consisting of 12 adult patients with impaired consciousness due to a neurosurgical condition. Continuous EEG and simultaneous video recordings of nursing interventions were collected 48 continuous hours for each patient. Two analysts categorized the video recordings for common nursing interventions, and a neurophysiologist analyzed the EEGs. In total, 976 nursing interventions were observed. Epileptiform activity was observed in 4 patients (33%), during 1 nursing intervention episode each (0.4%). The 4 observed episodes of epileptiform activity occurred during multiple simultaneous nursing interventions (n = 3) and hygienic interventions (n = 1). Stimulus-induced rhythmic, periodic, or ictal discharges were observed in 1 patient (8%), in 1 single nursing intervention (0.1%). The observed SIRPIDs occurred during repositioning of the patient. All patients had muscle artifacts, during 353 nursing interventions (36.3%). The duration of nursing interventions was longer for those with simultaneous muscle artifacts (median, 116 seconds) than those without muscle artifacts, epileptiform activity, or SIRPIDs (median, 89.0 seconds). With regard to epileptiform activity and SIRPIDs, the median durations of the nursing interventions were 1158 and 289 seconds, respectively. The results of this pilot study indicate that muscle artifacts seem prevalent during nursing interventions and may be a sign of stress. Nurses should be aware of the risk of inducing stress by performing regular nursing interventions in daily practice, consider shorter or fewer interventions at a time in sensitive patients, and administer sedation accordingly. Considering that this was a pilot study, more research that investigates correlations between EEG patterns and nursing interventions in larger samples is needed.

Termination patterns of stimulus-induced rhythmic, periodic, or ictal patterns and spontaneous electrographic seizures

ObjectiveTo investigate the ability of the evolution and termination patterns to distinguish stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) from spontaneous electrographic seizures, a challenge to the neurophysiologist and clinician. MethodsWe screened the prospectively collected database of patients undergoing continuous EEG (cEEG) and identified 25 cases of SIRPIDs. We compared patients with SIRPIDs to 25 patients with spontaneous seizures. Two experienced neurophysiologists graded the termination pattern of both on fast fourier transform (FFT) as “abrupt” or “sputtering.” ResultsThe identification of a “sputtering” or cyclical tapering pattern accurately discriminated SIRPIDs from spontaneous seizures with 88% sensitivity and 87% specificity, yielding a positive predictive value of 82% for SIRPIDs when the pattern was present (negative predictive value 87% when the sputtering termination was not seen). Similarly, the identification of an “abrupt” termination pattern identified clinically determined seizures with 84% sensitivity and 88% specificity. ConclusionsThe termination pattern quickly and accurately distinguishes SIRPIDs from spontaneous seizures, suggesting that at least some SIRPIDs have an underlying mechanism distinct from that of spontaneous seizures. SignificanceIf validated in other studies, the use of evolution and termination patterns to classify EEG patterns as epileptiform seizures versus SIRPIDs will help guide treatment of these patients.

Stimulus-Induced Rhythmic, Periodic, or Ictal Discharges in Coma-Incidence and Interrater Reliability of Continuous EEG After a Standard Stimulation Protocol: A Prospective Study.

Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) are often seen during continuous electroencephalographic (cEEG) monitoring in coma. Given their uncertain clinical significance, our prospective study evaluated incidence of SIRPIDs in comatose patients in the neuroscience intensive care unit (NSICU) who underwent a standard stimulation protocol and defined interreader reliability for cEEG. Of 146 patients prospectively screened who underwent cEEG during a 6-month period, 53 patients were included and 93 patients were excluded. Our protocol used a sequence of auditory, mild tactile, and painful stimuli tested in a quiet room. Continuous electroencephalogram were then reviewed offline by blinded experts, with interrater agreement assessed by kappa statistic. By Pearson χ and Wilcoxon rank-sum tests, we then compared binary and numerical clinical features between those with and without SIRPIDs. Of 53 patients who underwent our protocol, one patient with a corrupt cEEG file was excluded. Traumatic brain injury was the most common diagnosis. Moderate interrater agreement was observed for 66 total stimulations: 20 patients (38.5%) had possible or definite SIRPIDs by minimum one reviewer. For 19 stimulations reviewed by a third reviewer, consensus was reached in 10 cases making the incidence of SIRPIDs 19.3% in our cohort. There was a moderate interrate agreement with kappa of 0.5 (95% confidence interval: 0.1, 0.7). Median intensive care unit stay was 15 days in patients with SIRPIDs versus 6.5 days in those without (P = 0.021). Our prospective study of SIRPIDs in the neuroscience intensive care unit found a 19% incidence by cEEG using a standard stimulation protocol, most often rhythmic delta activity, and showed a moderate interrater agreement.

P.024 Stimulus-Induced Rhythmic, Periodic or Ictal Discharges (SIRPIDs): associated factors and prognostic implications

Background: SIRPIDS were first described in 2004 in patients admitted in an intensive care unit. Despite few studies attempting to better characterize SIRPIDS, their pathophysiology and clinical implication remain uncertain. Methods: Adult patients hospitalized in an intensive care unit with alteration of consciousness who underwent EEG recording in three separate centers were included in this retrospective study. Demographic data and EEG findings were noted. Characteristics of SIRPIDS were documented. The main outcome measures included the incidence of SIRPIDS, association of SIRPIDS with mortality and other EEG characteristics, EEG and clinical predictors of mortality. Results: 416 patients were included and SIRPIDs were identified in 43 patients (10.3%). The proportion of patients with SIRPIDs was not significantly different across the three sites (p=0.3351). Anoxia (p=0.0009), antiepileptic medications (p=0.0109), electrographic seizures (p=0.0259), triphasic waves (p=0.0012) and epileptiform discharges (p=0.0242) were independently associated with the presence of SIRPIDs. Older age (p=0.0050), anoxia (p=&lt;0.0001) and absence of EEG reactivity (p&lt;0.0001), but not SIRPIDs (p=0.1668), were independently associated with in-hospital mortality. Conclusions: In critically ill patients undergoing EEG, SIRPIDs occurred in 10% and were associated with other electrographic abnormalities previously reported to indicate poor prognosis. SIRPIDs were not independently associated with in-hospital mortality.

Associated Factors and Prognostic Implications of Stimulus-Induced Rhythmic, Periodic, or Ictal Discharges.

The implications of stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) sometimes found on prolonged electroencephalographic (EEG) recordings are uncertain. To evaluate the incidence of SIRPIDs and their clinical implications in critically ill patients. A multicenter, international retrospective study was performed from October 1, 2012, through September 30, 2014, of consecutive adult patients hospitalized in intensive care units with alteration of consciousness who underwent EEG recordings at 3 separate centers. Demographic data, including admission diagnosis, age, sex, history of epilepsy, and EEG findings, were noted. Characteristics of SIRPIDs were documented. Data were evaluated for predictors of SIRPIDs and in-hospital mortality. Data analysis was performed from January 16, 2015, to June 15, 2015. Incidence of SIRPIDs, association of SIRPIDs with mortality and other EEG characteristics, and EEG and clinical predictors of mortality. A total of 416 patients were studied. The median age of patients was 60 years (interquartile range, 46-71 years), and 252 (60.6%) were male. A total of 104 patients (25.0%) did not survive to hospital discharge. SIRPIDs were identified in 43 patients (10.3%). The proportion of patients with SIRPIDs was not significantly different across the 3 sites (P = .34). Anoxic brain injury (odds ratio [OR], 3.80; 95% CI, 1.73-8.33; P < .001), the use of antiepileptic medications (OR, 3.24; 95% CI, 1.31-8.00; P = .01), electrographic seizures (OR, 2.85; 95% CI, 1.13-7.19; P = .03), generalized periodic discharges with triphasic morphologic features (OR, 3.66; 95% CI, 1.67-8.02; P = .001), and sporadic sharp waves and periodic discharges (OR, 2.59; 95% CI, 1.13-5.92; P = .02) were independently associated with the presence of SIRPIDs. Older age (OR, 1.02; 95% CI, 1.01-1.04; P = .005), anoxic brain injury (OR, 3.49; 95% CI, 1.96-6.21; P ≤ .001), and absence of EEG reactivity (OR, 8.14; 95% CI, 4.20-15.79; P < .001) but not SIRPIDs (OR, 1.73; 95% CI, 0.79-3.78; P = .17) were independently associated with in-hospital mortality. In critically ill patients undergoing EEG recordings, SIRPIDs occurred in 43 (10.3%) and were associated with other electrographic abnormalities previously reported to indicate poor prognosis. However, SIRPIDs were not independently associated with in-hospital mortality.

SIRPIDs

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.

Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs): an intriguing EEG phenomenon

SIRPIDs, an acronym for stimulus-induced rhythmic, periodic, or ictal discharges, were first named in 2004. This is a pattern observed in continuous electroencephalogram (CEEG) consistently elicited by stimulation in comatose patients. The pathophysiology of SIRPIDs probably involves dysregulation of subcortico-cortical projections, particularly thalamocortical circuit, in a markedly abnormal brain with hyperexci-table cortex. This may explain some studies found an association of prolonged periodic epileptiform discharges (PEDs) activity and a higher incidence of concurrent electrographic seizures and SIRPIDs. An association of SIRPIDs and poor prognosis has already been described. However, it is not yet possible to assert whether these discharges can cause neuronal injury or if they are simply a marker of severe brain injury. Objective of this paper is to review clinical relevance and pathophysiology of SIRPIDs, as well as its role as a brain response in the critically ill patient.

Stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) in comatose survivors of cardiac arrest: Characteristics and prognostic value

ObjectivesTo analyze the prevalence of stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) in patients with coma after cardiac arrest (CA) and therapeutic hypothermia (TH) and to examine their potential association with outcome. MethodsWe studied our prospective cohort of adult survivors of CA treated with TH, assessing SIRPIDs occurrence and their association with 3-month outcome. Only univariated analyses were performed. Results105 patients with coma after CA who underwent electroencephalogram (EEG) during TH and normothermia (NT) were studied. Fifty-nine patients (56%) survived, and 48 (46%) had good neurological recovery. The prevalence of SIRPIDs was 13.3% (14/105 patients), of whom 6 occurred during TH (all died), and 8 in NT (3 survived, 1 with good neurological outcome); none had SIRPIDs at both time-points. SIRPIDs were associated with discontinuous or non-reactive EEG background and were a robustly related to poor neurological outcome (p<0.001). ConclusionThis small series provides preliminary univariate evidence that in patients with coma after CA, SIRPIDs are associated with poor outcome, particularly when occurring during in therapeutic hypothermia. However, survival with good neurological recovery may be observed when SIRPIDs arise in the post-rewarming normothermic phase. SignificanceThis study provides clinicians with new information regarding the SIRPIDs prognostic role in patients with coma after cardiac arrest.

Periodic electroencephalographic patterns: usefulness of definition and classification

identified a peri-odic and lateralized pattern, which they described as periodic lateralized epilepti-form discharges (PLEDs). The acronym encapsulates the essential characteristics of PLEDs, namely, wide distribution, polymorphism, one or more sharp components in a repeti-tive way (usually at the rate of one to two seconds), and localization over the hemisphere. Subsequent studies have described other variable periodic patterns as two independent PLED types in the same EEG (BIPLEDs), multifocal PLEDs, generalized periodic epileptiform dis-charges (GPEDs), and stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs)