Differentiating rhythmic high-amplitude delta with superimposed (poly) spikes from extreme delta brushes: limitations of standardized nomenclature and implications for patient management.

BACKGROUND: Following the standardized nomenclature proposed by the American Clinical Neurophysiology Society (ACNS), rhythmic high-amplitude delta activity with superimposed spikes (RHADS) can be reported as an extreme delta brush (EDB). The clinical implications of similar electrographic patterns being reported as RHADS versus EDB are important to highlight. We aim to review the electrographic characteristics of RHADS, evaluate whether RHADS is seen in other neurological disorders, and identify the similar and unique characteristics between RHADS and EDB to ultimately determine the most accurate way to differentiate and report these patterns. We believe that the differentiation of RHADS and EDB is important as there is a vast difference in the diagnostic approach and the medical management of associated underlying etiologies. DATA SOURCE: We conducted an extensive search on MEDLINE and Pubmed utilizing various combinations of keywords. Searching for "gamma polymerase and EEG", or "RHADS" or "Alpers syndrome and EEG" or "EEG" AND "Alpers-Huttenlocher syndrome". RESULTS: Three articles were found to be focused on the description of "RHADS" pattern in Alpers Syndrome. No publication to date were found when searching for the terms "EDB" AND "children", AND "infant" AND "adolescent" excluding "encephalitis" and "neonate". Although RHADS and EDB appear as similar EEG patterns, meticulous analysis can differentiate them. RHADS is not exclusive to patients with Alpers-Huttenlocher syndrome and may manifest in regions beyond the posterior head region. Reactivity to eye-opening and response to anesthesia can be two other elements that help in the differentiation of these patterns. CONCLUSION: RHADS is not exclusive to patients with AHS and may manifest in regions beyond the posterior head region. Reactivity to eye-opening and response to anesthesia are features that help in the differentiation of these patterns.

Generalized Rhythmic Delta Activity Frontally Predominant Differentiates Dementia with Lewy Bodies From Alzheimer's Disease and Parkinson's Disease Dementia: A Conventional Electroencephalography Visual Analysis.

Introduction. An easily accessible and inexpensive neurophysiological technique such as conventional electroencephalography may provide an accurate and generally applicable biomarker capable of differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) and Parkinson's disease-associated dementia (PDD). Method. We carried out a retrospective visual analysis of resting-state electroencephalography (EEG) recording of 22 patients with a clinical diagnosis of 19 probable and 3 possible DLB, 22 patients with probable AD and 21 with PDD, matched for age, duration, and severity of cognitive impairment. Results. By using the grand total EEG scoring method, the total score and generalized rhythmic delta activity frontally predominant (GRDAfp) alone or, even better, coupled with a slowing of frequency of background activity (FBA) and its reduced reactivity differentiated DLB from AD at an individual level with an high accuracy similar to that obtained with quantitative EEG (qEEG). GRDAfp alone could also differentiate DLB from PDD with a similar level of diagnostic accuracy. AD differed from PDD only for a slowing of FBA. The duration and severity of cognitive impairment did not differ between DLB patients with and without GRDAfp, indicating that this abnormal EEG pattern should not be regarded as a disease progression marker. Conclusions. The findings of this investigation revalorize the role of conventional EEG in the diagnostic workup of degenerative dementias suggesting the potential inclusion of GRDAfp alone or better coupled with the slowing of FBA and its reduced reactivity, in the list of supportive diagnostic biomarkers of DLB.

Increased delta power as a scalp marker of epileptic activity: a simultaneous scalp and intracranial electroencephalography study.

BACKGROUND AND PURPOSE: The purpose was to evaluate whether intracranial interictal epileptiform discharges (IEDs) that are not visible on the scalp are associated with changes in the frequency spectrum on scalp electroencephalograms (EEGs). METHODS: Simultaneous scalp high-density EEG and intracranial EEG recordings were recorded in nine patients undergoing pre-surgical invasive recordings for pharmaco-resistant temporal lobe epilepsy. Epochs with hippocampal IED visible on intracranial EEG (ic-IED) but not on scalp EEG were selected, as well as control epochs without ic-IED. Welch's power spectral density was computed for each scalp electrode and for each subject; the power spectral density was further averaged across the canonical frequency bands and compared between the two conditions with and without ic-IED. For each patient the peak frequency in the delta band (the significantly strongest frequency band in all patients) was determined during periods of ic-IED. The five electrodes showing strongest power at the peak frequency were also determined. RESULTS: It was found that intracranial IEDs are associated with an increase in delta power on scalp EEGs, in particular at a frequency ≥1.4 Hz. Electrodes showing slow frequency power changes associated with IEDs were consistent with the hemispheric lateralization of IEDs. Electrodes with maximum power of slow activity were not limited to temporal regions but also involved frontal (bilateral or unilateral) regions. CONCLUSIONS: In patients with a clinical picture suggestive of temporal lobe epilepsy, the presence of delta slowing ≥1.4 Hz in anterior temporal regions can represent a scalp marker of hippocampal IEDs. To our best knowledge this is the first study that demonstrates the co-occurrence of ic-IED and increased delta power.

A case of repetitive seizures following immune checkpoint inhibitor therapy as a feature of autoimmune encephalitis.

Pembrolizumab, an immune-checkpoint inhibitor (ICI), is a humanized monoclonal antibody that binds to programmed cell death-1 receptor (PD-1) and thereby inhibits binding to its ligand, which inhibits the suppression of activated T cells by cancer cells, resulting in enhancing antitumour immunity. Although several cases of encephalitis have been reported as immune-related adverse effects of ICIs, epilepsy has not been reported following ICI treatment. We describe the case of an elderly woman with bladder carcinoma who experienced two episodes of generalized seizures after treatment with pembrolizumab. The episodes were atypical of encephalitis, because the seizures were completely responsive to AEDs and the CSF parameters normalized completely without immunotherapy. Since interictal EEG revealed persistent epileptic discharges after the seizures, pembrolizumab was considered to have induced a chronic state of epileptogenicity as the possible pathology, with a clinical picture similar to that of autoimmune epilepsy. The possibility that ICIs may cause an immune-related adverse effect, such as a chronic epileptic condition, should be considered, since ICIs are used widely.

Stimulus-induced EEG-patterns and outcome after cardiac arrest.

OBJECTIVE: EEG 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. METHODS: In 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). RESULTS: Of 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. CONCLUSIONS: In 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. SIGNIFICANCE: Categorising the main EEG-pattern has important prognostic implications, but assessment of late appearing SIRPIDs does not seem to add prognostic information.

Occipital intermittent rhythmic delta activity (OIRDA) in pediatric focal epilepsies: A case series.

In this case series, we have identified an atypical pattern of OIRDA (Occipital intermittent rhythmic delta activity) on the electroencephalograms (EEGs) of three pediatric patients with self-limited focal epilepsies, including Childhood Epilepsy with Centrotemporal Spikes (CECTS), and Panayiotopoulos syndrome (PS). Previously, OIRDA was described as a symmetric sinusoidal occipital-maximal activity, often associated with childhood idiopathic generalized epilepsies, although it was also reported among other physiologic or pathological entities including focal epilepsy. We have observed in our case series that OIRDA, without prominent field effect, is lateralized or maximal on the hemispheric side ipsilateral to the more defining epileptiform discharges in these focal epilepsies. They also exhibit a notched morphology due to the intermixed sharp wave activities, although the sharp waves are not occurring repetitively. This report provides additional evidence that OIRDA can be associated with a spectrum of idiopathic focal epilepsies and may suggest a cortical origin of OIRDA in these patients as opposed to a hypothesized subcortical generator in patients with primary generalized absence epilepsy, even though further investigation is warranted for either hypothesis.

Functional neuroimaging in nonepileptiform electroencephalographic patterns in status epilepticus.

BACKGROUND: The diagnosis of nonconvulsive status epilepticus (NCSE) in patients with nonepileptiform EEG patterns remains a challenge. OBJECTIVE: To evaluate the usefulness of single photon emission computerized tomography (SPECT) and its quantification (QtSPECT) in the diagnosis of NCSE. METHODS: We retrospectively reviewed patients admitted with clinical suspicion of NCSE who underwent an HMPAO-SPECT simultaneously with scalp EEG showing nonepileptiform patterns, in a 5-year period. After a complete diagnostic workup, treatment, and clinical evolution, disregarding the SPECT results, patients were classified into confirmed NCSE (n = 11) and non-NCSE (n = 8). Then, we compared the EEG and SPECT results in both groups. RESULTS: Lateralized rhythmic delta activity (LRDA) was predominant in the NCSE group (45.4%, p = .045), while lateralized irregular slowing was observed equally in both groups. Patients with NCSE showed significant hyperperfusion compared with non-NCSE patients (p = .026). QtSPECT correctly classified 91% of patients in NCSE and 75% patients with non-NCSE (p = .006). CONCLUSIONS: Regional cerebral blood flow measured with SPECT could be useful in the diagnosis of NCSE in cases of an EEG pattern with lateralized slow activity and high clinical suspicion.

Hyperperfusion in the thalamus on arterial spin labelling indicates non-convulsive status epilepticus.

Non-convulsive status epilepticus describes the syndrome of unexplained impaired consciousness in critically ill patients. Non-convulsive status epilepticus is very likely to lead to delayed diagnosis and poor outcomes because of the absence of convulsive symptoms. EEG is essential for the diagnosis of non-convulsive status epilepticus to establish the association between periodic discharges and rhythmic delta activity in addition to ictal epileptiform discharges according to the Salzburg criteria. Arterial spin labelling, a type of perfusion MRI, has been applied for rapid and non-invasive evaluation of the ictal state. Ictal cerebral cortical hyperperfusion is the most common finding to demonstrate focal onset seizures. Hyperperfusion of the thalamus on single photon emission computed tomography was found in patients with impaired awareness seizures. We hypothesized that thalamocortical hyperperfusion on arterial spin labelling identifies non-convulsive status epilepticus and such thalamic hyperperfusion specifically associates with periodic/rhythmic discharges producing impaired consciousness without convulsion. We identified 27 patients (17 females; age, 39-91 years) who underwent both arterial spin labelling and EEG within 24 h of suspected non-convulsive status epilepticus. We analysed 28 episodes of suspected non-convulsive status epilepticus and compared hyperperfusion on arterial spin labelling with periodic/rhythmic discharges. We evaluated 21 episodes as a positive diagnosis of non-convulsive status epilepticus according to the Salzburg criteria. We identified periodic discharges in 15 (12 lateralized and 3 bilateral independent) episodes and rhythmic delta activity in 13 (10 lateralized, 1 bilateral independent and 2 generalized) episodes. Arterial spin labelling showed thalamic hyperperfusion in 16 (11 unilateral and 5 bilateral) episodes and cerebral cortical hyperperfusion in 24 (20 unilateral and 4 bilateral) episodes. Thalamic hyperperfusion was significantly associated with non-convulsive status epilepticus (P = 0.0007; sensitivity, 76.2%; specificity, 100%), periodic discharges (P < 0.0001; 93.3%; 84.6%), and rhythmic delta activity (P = 0.0006; 92.3%; 73.3%). Cerebral cortical hyperperfusion was significantly associated with non-convulsive status epilepticus (P = 0.0017; 100%; 57.1%) and periodic discharges (P = 0.0349; 100%; 30.8%), but not with rhythmic delta activity. Thalamocortical hyperperfusion could be a new biomarker of non-convulsive status epilepticus according to the Salzburg criteria in critically ill patients. Specific thalamic hyperexcitability might modulate the periodic discharges and rhythmic delta activity associated with non-convulsive status epilepticus. Impaired consciousness without convulsions could be caused by predominant thalamic hyperperfusion together with cortical hyperperfusion but without ictal epileptiform discharges.

Lateralized Rhythmic Delta Activity in Patients With Infectious or Autoimmune Insular Lesions.

INTRODUCTION: Lateralized rhythmic delta activity (LRDA) is a rare pattern on the ictal-interictal continuum (IIC) encountered in critically ill patients. Its association with acute seizures is yet to be fully explored. Insular involvement is a common finding in patients with infectious and autoimmune encephalitis. The association between acute insular lesions and the ictal-interictal continuum, particularly LRDA, has not been explored before. METHODS: A case series of 4 patients with either herpetic or autoimmune encephalitis and prominent insular cortex involvement who had LRDA when monitored on continuous EEG is being presented. RESULTS: Two patients had herpetic encephalitis and 2 patients had autoimmune encephalitis. All patients had either clinical or electrographic seizures with 1 patient progressing into new-onset refractory status epilepticus. CONCLUSION: LRDA can be seen in patients with insular cortex acute inflammation. In this group of patients, LRDA may be associated with a higher risk of acute seizures. The presence of this otherwise not clearly epileptiform pattern should raise the clinical suspicion for the development of acute seizures. Patients with LRDA and ipsilateral insular lesions should be carefully monitored for the development of recurrent electrographic or electroclinical seizures and status epilepticus.

Clinical Correlates of Frontal Intermittent Rhythmic Delta Activity Without Structural Brain Lesion.

Frontal intermittent rhythmic delta activity (FIRDA), rhythmic slow wave pattern lasting several seconds over the anterior leads of electroencephalography (EEG), has been reported in a wide variety of clinical conditions. We investigated the clinical significance of FIRDA without structural brain lesions. We reviewed 7689 EEGs between October 2017 and September 2019 at a university hospital. Patients (age >18 years) who were confirmed to have "nonsignificant neuroimaging" were examined. Clinical data were retrospectively collected, and the estimated cause was carefully decided. We found 83 FIRDA among 7689 EEGs (1.08%). After patients with any structural lesion identified on neuroimaging were excluded, 37 FIRDAs were reviewed. There were 20 (51.35%) patients of metabolic encephalopathy. Six patients showed FIRDA due to neurodegenerative disease (16.21%). In addition, we found 6 (16.21%) of neurodegenerative disease and 5 (13.51%) of hypoxic encephalopathy (cardiac arrest). Four (16.21%) patients were related to systemic infection (10.81%), whereas 2 were related to encephalitis (5.40%). We demonstrated several potential etiologies, including metabolic encephalopathy, neurodegenerative disease, hypoxic encephalopathy, and infections, which should be considered in the case of FIRDA without structural brain lesions.

Critical care EEG standardized nomenclature in clinical practice: Strengths, limitations, and outlook on the example of prognostication after cardiac arrest.

We discuss the achievements of the ACNS critical care EEG nomenclature proposed in 2013 and, from a clinical angle, outline some limitations regarding translation into treatment implications. While the recently proposed updated 2021 version of the nomenclature will probable improve some uncertainty areas, a refined understanding of the mechanisms at the origin of the EEG patterns, and a multimodal integration of the nomenclature to the clinical context may help improving the rationale supporting therapeutic procedures. We illustrate these aspects on prognostication after cardiac arrest.

A multimodal diagnostic approach for lateralised rhythmic delta activity in the ictal-interictal continuum.

The ictal-interictal continuum represents a diagnostic challenge even for expert neurrophysiologists, often requiring an additional multimodal diagnostic workup to understand its clinical significance. Lateralised rhythmic delta activity (LRDA) is an ictal-interictal continuum pattern that has only recently been investigated and recognised as potentially ictogenic or sometimes even ictal. We describe a patient who presented with acute-onset aphasia, initially suspected of having a stroke; advanced brain imaging with CT-perfusion showed features suggesting regional left temporo-parietal hyperperfusion and an EEG revealed LRDA with fluctuations and intermixed sharp waves in the same areas. Treatment with lacosamide caused both clinical and EEG improvement after a few hours, supporting the hypothesis that the EEG pattern represented an ictal/interictal phenomenon. In the literature, a correlation between metabolic/perfusion imaging and ictal-interictal continuum patterns is described regarding lateralised periodic discharges but less studied for LRDA. In this case, we adopted a multimodal approach, integrating advanced imaging, EEG, clinical features, and response to therapy, to consider the overall clinical presentation as focal NCSE.

Clinical correlates and electroencephalographic features of FIRDA in a tertiary center.

OBJECTIVES: We aimed to explore the diagnostic value, clinical correlates and electroencephalographic features of FIRDA (Frontal intermittent rhythmic delta activity). MATERIALS AND METHODS: We retrospectively reviewed reports from EEG studies done in adults at our tertiary center between January 2015 and May 2018. For cases demonstrating FIRDA, medical files were reviewed and each case was given a diagnostic category. EEG recordings were reviewed and electrophysiologic data were extracted including FIRDA characteristics (frequency, location, duration, and symmetry). Then, a statistical analysis was done to evaluate the relationship between the diagnostic categories and EEG variables. RESULTS: Ninety-four cases of FIRDA were found, with a frequency of 1.6% among inpatients. EEG recordings were available for review in 84 cases. FIRDA was asymmetric in 43 of these cases (49%), usually more prominent on the left (36/43, 84%). The diagnostic category groups included epilepsy (n = 39, 41%), other central nervous system (CNS) disease (n = 33, 35%), and systemic illness (n = 22, 23%). A significant difference in FIRDA location was found, as patients with epilepsy or other CNS disease, had a significantly higher probability for the delta activity to involve the temporal areas (frontotemporal location in 27/64 in these groups compared with 3/20 in the systemic illness group, P-value = .033). CONCLUSIONS: This study provides insights to the diagnosis underlying FIRDA, especially the high rate of epilepsy patients, and calls for further neurologic investigation of cases in which FIRDA involves the temporal areas since most of these cases were due to epilepsy or other CNS disease and not a systemic illness.

Electroencephalographic features associated with intermittent rhythmic delta activity.

OBJECTIVE: To investigate the clinical importance of intermittent rhythmic delta activity (IRDA) in terms of accompanying electrophysiological findings on EEG and their association with IRDA. METHODS: We retrospectively assessed all EEG studies recorded in our institution from 2011 to 2017. Patients with intermittent rhythmic delta activity (IRDA) in EEGs were included. Clinical data were collected from charts of the patients with IRDA. RESULTS: We identified 69 EEGs with IRDA in 58 patients from a total of 18,625 EEG recordings. The most common IRDA type was frontal IRDA (FIRDA; 55%), followed by temporal IRDA (TIRDA; 28.9%). Unilateral (UL) distribution was present in 36.8% of FIRDAs and 95% of TIRDAs. The frequency of focal epileptiform discharges (FED) was 78.5% in UL FIRDA group and 89.4% in UL TIRDA group. Among the EEGs with FEDs, in UL FIRDA group 90.9% and in UL TIRDA group 70.5% of the FEDs were ipsilateral. Concordance of focal structural brain lesions and FEDs with UL TIRDA was 30.7%, and with UL FIRDA was 50%. UL FIRDA had a 71.4% positive predictive value for ipsilateral focal epileptic focus and UL TIRDA had 63.1%. The frequency of focal structural lesions and FEDs were significantly higher in the UL FIRDA group than bilateral FIRDA group (P=0.03; P=0.01). Among the patients with focal structural lesions, ipsilateral FED association is significantly higher in the UL FIRDA group than BL FIRDA group (P=0.03). CONCLUSIONS: UL FIRDA is more likely to indicate a focal lesion and a focal epileptic focus compared to bilateral FIRDA, and it had similar characteristics to UL TIRDA. It can be considered that UL FIRDA has as good a lateralizing value for ipsilateral focal epileptic focus and focal lesion as UL TIRDA.

EEG analysis in anti-NMDA receptor encephalitis: Description of typical patterns.

OBJECTIVE: To describe different electroencephalogram (EEG) patterns and epileptic features in patients with anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE), their timeline in the course of the disease, their correlation with clinical data and outcome. METHODS: We retrospectively analyzed EEG recordings between November 2007 and June 2016 in 24 consecutive patients. RESULTS: Three EEG patterns were described: Excessive Beta Activity range 14-20 Hz (EBA) in 71% of patients, Extreme Delta Brush (EDB) in 58% and Generalized Rhythmic Delta Activity (GRDA) in 50%. They followed a chronological organization in the course of the disease: EBA appeared first, followed by EDB and then GRDA, as the median time of appearance for EBA, EDB and GRDA was respectively 10, 16.5 and 21.5 days. The presence of GRDA was strongly associated with concomitant abnormal movements (p < 0.001). CONCLUSION: This study focuses on EEG and epileptic abnormalities in anti-NMDARE. Beyond EDB that were already reported (Schmitt et al., 2012), GRDA seems to be a very frequent pattern. Its rhythmic aspect should not be misinterpreted as seizure or status epilepticus, to avoid antiepileptic treatments intensification. SIGNIFICANCE: This study comforts the importance of EEG in anti-NMDARE, with a better description of EEG abnormalities for a better treatment management.

[A case of painful seizure accompanying ictal paresis and homonymous hemianopia due to post-stroke epilepsy].

A 69-year-old female with an old infarct of the left parietotemporal lobe was admitted for the evaluation of suspected painful seizures accompanying ictal paresis. The painful seizure and ictal paresis involved her right extremities without convulsions, although intermittent tremulous movements were noted on the right upper extremity. She also showed right hemianopia during the seizure. Ictal scalp EEG demonstrated lateralized rhythmic sharply contoured delta activity intermingled with a large amount of spikes, sharp waves, and fast activity mainly on the posterior half of the left hemisphere. Ictal MRI showed restricted diffusion in the postcentral gyrus and dilatation of distal branches of the left middle cerebral artery (MCA). 99mTc-ECD SPECT revealed hyperperfusion on the left parietal cortex. Treatment with antiepileptic drugs successfully prevented seizure recurrence, then she was discharged home. On the follow-up SPECT after 1 month, the abnormal hyperperfusion disappeared. MRI demonstrated resolution of the restricted diffusion and the MCA dilatation. Taken together with the EEG abnormality and the transient abnormalities in SPECT and MRI, we concluded that her seizures were epileptic and that her painful seizures likely arise from the left primary somatosensory cortex. The mechanism of ictal paresis would be attributed to some disturbed functional architecture in the left primary motor cortex leading to loss of normal motor function through epileptic interference by ictal discharges. The same mechanism in the visual cortex could be assumed for her ictal hemianopia. Painful seizure and ictal paresis each is rarely encountered, even more so the combination thereof. These ictal manifestations might be difficult to differentiate from transient ischemic attack or postictal paresis, and thus EEG is essential to diagnose this treatable condition.

Ictal Interictal Continuum Patterns.

PURPOSE OF REVIEW: To present data available on the epidemiology and significance of rhythmic and periodic patterns that lie on the ictal interictal continuum and propose an algorithm for the clinical approach to patients exhibiting these patterns. RECENT FINDINGS: There is accumulating evidence on the prognostic implications of various rhythmic and periodic patterns in the critically ill population. These patterns are not only associated with increased seizure risk but have also been associated with worse outcome and increased long-term risk of epilepsy in recent studies. There is emerging evidence suggesting that certain EEG features as well as ancillary studies including serum, neuroimaging, and invasive multimodality monitory can assist in the risk stratification of neuronal injury associated with these patterns, allowing for a targeted approach to these patterns. We present a case illustrating the clinical nuances of these patterns. We propose an algorithm for a personalized and targeted approach to ictal interictal patterns based on risk stratification according to clinical, EEG, imaging, and invasive monitoring markers.

Frontal Intermittent Rhythmic Delta Activity (FIRDA) in the Neurological Intensive Care: Prevalence, Determinants, and Clinical Significance.

INTRODUCTION: Frontal intermittent rhythmic delta activity (FIRDA), a transient rhythmic slow wave pattern over the anterior EEG leads, has been reported in a wide variety of cerebral lesions and different metabolic disturbances. Few authors have analyzed the frequency and clinical significance of FIRDA in the critical care setting. We aimed to better understand these issues in our intensive care cohort and if possible, try to delineate its underlying mechanisms. METHODS: Video-EEG reports of consecutive adult patients in the neurological intensive care unit (NICU) since 2009 were retrospectively reviewed to identify cases with FIRDA. Demographic, clinical, and laboratory data were obtained from EEG reports and patient charts. Age- and sex-matched patients with acute stroke, hospitalized in NICU and no FIRDA on video-EEG monitoring served as the control group. RESULTS: Among 162 patients who underwent video-EEG monitoring, FIRDA was documented in 17%. Female prevalence was 50% and age ranged from 23 to 82 years. Twenty-three (82%) of patients with FIRDA had a diagnosis of stroke. Comparison of demographic characteristics, EEG findings, metabolic disturbances and prognoses revealed no differences between stroke cases with and without FIRDA, except for higher frequency of acute and chronic isolated posterior circulation infarcts in patients with FIRDA. CONCLUSION: FIRDA is more commonly encountered in the neurocritical care setting as compared with outpatient EEG clinics. Our findings in stroke patients indicate that involved vascular territories may be related to the generation of FIRDA.

Population of the ictal-interictal zone: The significance of periodic and rhythmic activity.

Seizures contribute to patient mortality and are usually treated aggressively. Rhythmic and periodic patterns - the "ictal-interictal continuum" - are often associated with seizures, yet the optimum method of treating these patterns is not known: should they be aggressively suppressed, or monitored without treatment? Understanding which patterns are more strongly associated with seizures and which are highly associated with mortality is important to help the clinician decide how to treat these findings. We present an overview of the etiologies, association with seizures, and mortality of periodic and rhythmic patterns, and one approach to treatment.

Ictal-interictal continuum: A proposed treatment algorithm.

The ictal-interictal continuum (IIC) is characterized by periodic and/or rhythmic EEG patterns that occur with relative high frequency in critically ill patients. Several studies have reported that some patterns seen within the continuum are independently associated with poor outcome. However there is no consensus regarding when to treat them or how aggressive treatment should be. In this review we examine peer-reviewed original scientific articles, guidelines and reviews indexed in PubMed and summarize current knowledge related to the ictal-interictal continuum. A treatment algorithm to guide management of critically ill patients with EEG patterns that fall along the IIC is proposed. The algorithm-based on best current practice in adults-takes into account associated clinical events, risk factors for developing seizures, response to medication trials and biomarkers of neuronal injury.