Ictal-Interictal Continuum: When to Worry About the Continuous Electroencephalography Pattern

Cormier, Justine; Maciel, Carolina B.; Gilmore, Emily J.

doi:10.1055/s-0037-1607987

Cited by 24 publications

(15 citation statements)

References 90 publications

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“…Repetitive or periodic epileptiform discharges less than 3 Hz can be considered ictal if associated with an improved clinical response with repeated short treatment with a benzodiazepine. Without a clear response, such EEG patterns fall along the ictal-interictal continuum without clear indication or consensus for continued treatment [ 26 ].…”

Section: Investigationsmentioning

confidence: 99%

Updates in Refractory Status Epilepticus

Marawar

Basha

Mahulikar

et al. 2018

Critical Care Research and Practice

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Refractory status epilepticus is defined as persistent seizures despite appropriate use of two intravenous medications, one of which is a benzodiazepine. It can be seen in up to 40% of cases of status epilepticus with an acute symptomatic etiology as the most likely cause. New-onset refractory status epilepticus (NORSE) is a recently coined term for refractory status epilepticus where no apparent cause is found after initial testing. A large proportion of NORSE cases are eventually found to have an autoimmune etiology needing immunomodulatory treatment. Management of refractory status epilepticus involves treatment of an underlying etiology in addition to intravenous anesthetics and antiepileptic drugs. Alternative treatment options including diet therapies, electroconvulsive therapy, and surgical resection in case of a focal lesion should be considered. Short-term and long-term outcomes tend to be poor with significant morbidity and mortality with only one-third of patients reaching baseline neurological status.

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Section: Investigationsmentioning

confidence: 99%

Updates in Refractory Status Epilepticus

Marawar

Basha

Mahulikar

et al. 2018

Critical Care Research and Practice

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“…On the other hand, generalized periodic discharges have been reported in patients with severe encephalopathy or coma and are thought to be more reflective of a global injury such as in our patient with GPD+R. While not reported as a pattern with increased seizure risk, GRDA can be seen in several brain pathologies, including metabolic encephalopathies (most commonly), as well as structural lesions …”

Section: Discussionmentioning

confidence: 63%

“…Bilateral independent periodic discharges (BIPDs) can emerge with various etiologies of acute and subacute brain injury, but are rarely seen in ICH and have not specifically been reported in patients with pIVH. Given the bilateral independent foci of periodic discharges, unilateral EVD placement in itself cannot fully account for this pattern.…”

Section: Discussionmentioning

confidence: 99%

Seizures, periodic and rhythmic patterns in primary intraventricular hemorrhage

Stretz

Sheikh

Maciel

et al. 2018

Ann Clin Transl Neurol

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ObjectivePrimary intraventricular hemorrhage (pIVH) uncommonly presents with seizures. There are no prior data regarding the frequency of seizures, periodic and rhythmic patterns on continuous electroencephalography (EEG), (cEEG) in these patients.MethodsWe retrospectively assessed frequency of seizures, periodic discharges, and rhythmic patterns in pIVH patients undergoing cEEG monitoring. We reviewed indications for cEEG, demographics, GCS at presentation and during cEEG, modified Graeb score (mGS), presence of hydrocephalus, cEEG duration, findings and use of antiseizure medications (ASM). cEEG patterns were classified according to location and morphology. All patterns were considered “hyperexcitable” except GRDA. The ictal‐interictal continuum (IIC) was defined as LRDA, PDs, and/or SW >1 Hz but <2.5 Hz, not meeting criteria for definite electrographic seizures.ResultsEleven patients had pIVH with median age of 81 (46–87) years and median mGS of 15 (9–23). Hydrocephalus was present in 7 (63.6%) and all underwent external ventricular drain (EVD) placement. Median cEEG recording was 19 (12–156) hours. Periodic or rhythmic EEG patterns were seen in 7 of 11 (64%), 5 of which were “hyperexcitable”. For the 5 patients with pIVH, EVDs, and hyperexcitable patterns, 4 (80%) were lateralized contralateral to the EVD and 1 (20%) was generalized to the EVD. The only significant difference between the hyperexcitable and non‐hyperexcitable group was duration of cEEG monitoring (P = 0.007).InterpretationHyperexcitable patterns were common in our cases. Further research is warranted to assess prevalence of hyperexcitable patterns, their risk factors, underlying pathophysiology, and association with neuronal injury in pIVH.

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“…LPDs are formerly referred to as PLEDs. They are the most commonly observed periodic pattern, seen in 4.7 to 8.6% of critically ill patients [9,[11][12][13][14]. These discharges have a sharp or spiky morphology, and are typically 100-300 μV in amplitude ( Fig.…”

Section: Lateralized Periodic Dischargesmentioning

confidence: 99%

“…Nevertheless, there is no consensus agreement on the definition of IIC. IIC commonly includes the rhythmic and periodic patterns occurring at a rate of 1-2.5 Hz without spatiotemporal evolution and clinical correlates [9]. Brief potentially ictal rhythmic discharges are > 4 Hz and < 10 s. They do not meet the criteria for an ictal pattern [10], and thus can be considered IIC patterns.…”

Section: Introductionmentioning

confidence: 99%

Ictal-interictal continuum: a review of recent advancements

Tao

Qin

Wang

2020

Acta Epileptologica

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Continuous electroencephalogram (cEEG) has become an indispensable technique in the management of critically ill patients for early detection and treatment of non-convulsive seizures (NCS) and non-convulsive status epilepticus (NCSE). It has also brought about a renaissance in a wide range of rhythmic and periodic patterns with heterogeneous frequency and morphology. These patterns share the rhythmic and sharp appearances of electrographic seizures, but often lack the necessary frequency, spatiotemporal evolution and clinical accompaniments to meet the definitive criteria for ictal patterns. They may be associated with cerebral metabolic crisis and neuronal injury, therefore not clearly interictal either, but lie along an intervening spectrum referred to as ictal-interictal continuum (IIC). Generally speaking, rhythmic and periodic patterns are categorized as interictal patterns when occurring at a rate of <1Hz, and are categorized as NCS and NCSE when occurring at a rate of >2.5 Hz with spatiotemporal evolution. As such, IIC commonly includes the rhythmic and periodic patterns occurring at a rate of 1-2.5 Hz without spatiotemporal evolution and clinical correlates. Currently there are no evidence-based guidelines on when and if to treat patients with IIC patterns, and particularly how aggressively to treat, presenting a challenging electrophysiological and clinical conundrum. In practice, a diagnostic trial with preferably a non-sedative anti-seizure medication (ASM) can be considered with the end point being both clinical and electrographic improvement. When available and necessary, correlation of IIC with biomarkers of neuronal injury, such as neuronal specific enolase (NSE), neuroimaging, depth electrode recording, cerebral microdialysis and oxygen measurement, can be assessed for the consideration of ASM treatment. Here we review the recent advancements in their clinical significance, risk stratification and treatment algorithm.

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Ictal-Interictal Continuum: When to Worry About the Continuous Electroencephalography Pattern

Cited by 24 publications

References 90 publications

Updates in Refractory Status Epilepticus

Updates in Refractory Status Epilepticus

Seizures, periodic and rhythmic patterns in primary intraventricular hemorrhage

Ictal-interictal continuum: a review of recent advancements

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