Stephen Hantus

American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology: 2012 version.

Continuous EEG Monitoring is becoming a commonly used tool in assessing brain function in critically ill patients. However, there is no uniformly accepted nomenclature for EEG patterns frequently encountered in these patients such as periodic discharges, fluctuating rhythmic patterns, and combinatio

Sensitivity of quantitative EEG for seizure identification in the intensive care unit

Objective: To evaluate the sensitivity of quantitative EEG (QEEG) for electrographic seizure identification in the intensive care unit (ICU). Methods: Six-hour EEG epochs chosen from 15 patients underwent transformation into QEEG displays. Each epoch was reviewed in 3 formats: raw EEG, QEEG + raw, and QEEG-only. Epochs were also analyzed by a proprietary seizure detection algorithm. Nine neurophysiologists reviewed raw EEGs to identify seizures to serve as the gold standard. Nine other neurophysiologists with experience in QEEG evaluated the epochs in QEEG formats, with and without concomitant raw EEG. Sensitivity and false-positive rates (FPRs) for seizure identification were calculated and median review time assessed. Results: Mean sensitivity for seizure identification ranged from 51% to 67% for QEEG-only and 63%–68% for QEEG + raw. FPRs averaged 1/h for QEEG-only and 0.5/h for QEEG + raw. Mean sensitivity of seizure probability software was 26.2%–26.7%, with FPR of 0.07/h. Epochs with the highest sensitivities contained frequent, intermittent seizures. Lower sensitivities were seen with slow-frequency, low-amplitude seizures and epochs with rhythmic or periodic patterns. Median review times were shorter for QEEG (6 minutes) and QEEG + raw analysis (14.5 minutes) vs raw EEG (19 minutes; p = 0.00003). Conclusions: A panel of QEEG trends can be used by experts to shorten EEG review time for seizure identification with reasonable sensitivity and low FPRs. The prevalence of false detections confirms that raw EEG review must be used in conjunction with QEEG. Studies are needed to identify optimal QEEG trend configurations and the utility of QEEG as a screening tool for non-EEG personnel. Classification of evidence review: This study provides Class II evidence that QEEG + raw interpreted by experts identifies seizures in patients in the ICU with a sensitivity of 63%–68% and FPR of 0.5 seizures per hour.

Ictal singing due to left frontal lobe epilepsy: A case report and review of the literature

Ictal singing has been rarely reported and the neural networks underlying this specific symptom remain unknown. We report a nineteen-year-old man with medically refractory seizures who exhibited ictal singing and laughing. He underwent intracranial stereotactic EEG recording which demonstrated ictal activity in medial and dorsolateral regions of the left frontal lobe in the generation of ictal singing. Thereafter, a left frontal resection of the superior and middle frontal gyri made him seizure-free. Among the previously reported cases of ictal singing, the symptomatogenic zones included bilateral frontal and temporal lobes. The wide variance of ictal onset zones suggests that the mechanism of ictal singing is probably related to the recruitment of music-related neural networks in different regions of both hemispheres rather than activation of a specific cortical region.

Electrographic Features of Lateralized Periodic Discharges Stratify Risk in the Interictal–Ictal Continuum

Purpose: To risk-stratify electrographic features of lateralized periodic discharges (LPDs) in acute structural brain lesions for predictors of electrographic seizures. Methods: This is a retrospective review of 100 consecutive patients with LPDs. Epileptiform features of LPDs were described based on electrographic features: blunt delta morphology, sharply contoured, overlying fast frequencies, and/or rhythmicity (loss of interdischarge interval lasting ≥1 second). EEG seizures were defined as evolving in frequency, distribution, or morphology at ≥2 Hz for ≥10 seconds. Results: Overall, electrographic seizures occurred in 55% of patients with LPDs. Lateralized periodic discharges with rhythmicity (odds ratio 13.91) were most significant for predicting status epilepticus and/or seizures. This was followed by LPDs with overlying faster frequencies (odds ratio 5.16) and then sharply contoured morphology (odds ratio 4.09). Blunt delta morphology (0.24) had the lowest risk for seizures. Conclusions: Electrographic features of LPDs may help determine seizure risk in patients with acute structural lesions. Sharply contoured morphology, overlying fast frequencies, or rhythmicity, showed progressively higher risk of seizures on continuous electroencephalography, whereas blunt delta morphology had the lowest risk of seizures.

Highly Epileptiform Bursts Are Associated With Seizure Recurrence.

Purpose: Pharmacologic sedation is often used to induce burst suppression in cases of refractory status epilepticus, but there is little evidence to guide the weaning of sedation. Similarly, the morphologic feature of bursts is of unknown clinical relevance. Recently, the standardized American Clinical Neurophysiology Society terminology of critical care EEG introduced the term highly epileptiform bursts (HEBs). Knowing the association of HEBs with seizure may direct the therapy for refractory status epilepticus. Methods: Consecutive adult patients classified as having burst suppression were identified in our EEG database. Those of an anoxic etiology were excluded. Available EEG records were reviewed, both visually and quantitatively, for the presence of burst suppression. Using the American Clinical Neurophysiology Society terminology, burst suppression was dichotomized into HEBs or nonepileptiform bursts. Periods of transition out of burst suppression were identified, and whether burst suppression was followed by seizure or a continuous slow EEG within 24 hours was determined. Results: Twenty-four patients were identified with a burst suppression pattern followed by either seizure or a continuous slow EEG within 24 hours, with some patients having multiple (maximal 5) transitions out of burst suppression, for a total of 33 examples of burst suppression. HEBs were associated with subsequent seizure (P = 0.0001), independent of medication exposure. Conclusions: Whether or not HEBs are indeed predictive of recurrent seizure or may be used to direct the therapy for status epilepticus, specifically the weaning of anesthetic medications, requires further prospective study in a larger cohort of patients.

De novo sustained refractory status epilepticus and encephalopathy: a retrospective case series.

Refractory status epilepticus is a devastating persistent seizure state with a poor prognosis that requires emergency medical management. Recent studies have reported de novo, idiopathic refractory status epilepticus of unclear etiology in healthy young patients followed by severe neurologic sequelae. We present a series of 7 cases of de novo sustained refractory status epilepticus. We found that all patients were young and previously healthy and that, prior to the onset of refractory status epilepticus, all had prodromal viral-like symptoms. The onset of refractory status epilepticus was explosive and intractable, resulting in prolonged hospital stay and dependence on multiple antiepileptic medications. Clinical outcome was poor in all 7 patients. The laboratory findings suggest a possible immune activation that can have persisted in the nervous system after a nonspecific infection. We report on these patients so as to raise awareness of this unique entity to facilitate early diagnosis and treatment.

Evaluating persistent altered mental status after status epilepticus

Autoimmune limbic encephalitis (LE)—either paraneoplastic or nonparaneoplastic—presents with neurobehavioral or focal changes. In more than 50% of patients with LE, seizures are observed.1 18F-FDG-PET may show focal hypermetabolism, especially in the mesial temporal region, suggestive of LE.2 Concomitant seizure activity must be excluded, emphasizing the role of continuous EEG (cEEG).

Interconnections in superior temporal cortex revealed by musicogenic seizure propagation

Musicogenic epilepsy (ME) is an intriguing epilepsy syndrome with estimated prevalence of 1 per million [1]. Seizures are precipitated by complex and usually highly specific stimuli. ME has been the topic of several excellent reviews [2, 3], but reports of comprehensively studied patients are scarce [1]. Notably, ME can provide insights in auditory processing and seizure-triggering mechanisms in humans. We present here a patient with non-lesional ME, whose seizure initiation and propagation shed light on interconnections within the superior temporal cortex. A 42-year-old right-handed professional composer started having seizures at 11 years. Seizures became difficult-to-control after he entered music school. Stereotyped auras were consistently triggered by songs with familiar melody and lyrics. ‘‘Happy Birthday’’ and songs by Elton John were especially provocative, whereas jazz/instrumentals had no effect. Auras consisted of buzzing or muffled sounds several times/week, evolving into dialeptic seizures with staring, unresponsiveness, and postictal dysphasia once/month. Interictal scalp-EEG showed intermittent left temporal slowing without epileptiform abnormalities. Ictal EEG localized to the left temporal region. High-resolution MRI was normal. Subtraction ictal SPECT showed discrete area of hyperperfusion within the left lateral superior temporal gyrus (STG) and contiguous supratemporal plane (Fig. 1a). Interictal FDG-PET showed small but congruent area of decreased fluoro-deoxy-glucose uptake (Fig. 1b). To further delineate the epileptogenic zone and its relationship to eloquent cortex, we performed invasive evaluation with subdural grids covering left lateral temporal and perisylvian cortex, and depth electrodes targeting Heschl’s, planum temporale and mesial temporal structures (Fig. 1c). This unique patient was also evaluated with simultaneous intracranial-EEG and MEG sampled at 1,000 Hz. For standard analysis intracranial-EEG and MEG were band-passed with low-frequency cutoff of 5 Hz, and highfrequency cutoff of 70 and 50 Hz, respectively. No epileptic spikes were found interictally on either modality. We then provoked an ictal event in the MEG suite by having the patient listen to ‘‘Happy Birthday’’ followed by his favorite Elton John song. Two minutes later he reported typical aura of muffled sound. Discrete onset (Fig. 2, red arrow) was then seen in the LPST depth electrode contacts located within planum temporale (red contacts in Fig. 1c, left), represented by sharply contoured rhythmic theta evolving into repetitive spiking with overriding paroxysmal fast activity. Similar activities (Fig. 2, blue arrow) were observed on adjacent LST depth electrode in Heschl’s gyrus (blue contacts in Fig. 1c, left) starting 1.5 s later (first propagation site). These activities Z. I. Wang Y. Kakisaka R. C. Burgess J. A. Gonzalez-Martinez S. Ito J. C. Mosher S. Hantus A. V. Alexopoulos (&) Cleveland Clinic Epilepsy Center, 9500 Euclid Avenue, Desk S-51, Cleveland, OH 44195, USA e-mail: alexopa@ccf.org

Electroclinical features of seizures associated with autoimmune encephalitis

PURPOSE We sought to characterize the electroclinical features of seizures associated with autoimmune encephalitis and their relevance to outcome. METHODS 19 patients with seizures and autoimmune encephalitis were identified from a database of 100 patients (2008-2017) with autoimmune neurological disorders. Clinical and electroclinical characteristics were collected. Persistent seizures at last follow-up were then correlated with electroclinical features. RESULTS Status epilepticus (53%) and early intractability to AEDs (median time to second AED 9.5 days) marked the onset of refractory seizures (median number of AEDs 3). Seizure semiology (abdominal (16%), psychic (42%), olfactory (6%) auras), interictal temporal epileptiform discharges (42%), and ictal onset in the temporal region (63%) mirrored radiologic involvement of the medial temporal regions (on MRI in 74% and/or FDG-PET in 75%). In addition, multimodal auras, with somatosensory (26%), autonomic (26%), gustatory (11%), and visual (16%), features were seen in 82% of patients with focal aware seizures, invoking broader involvement of the perisylvian regions. A change in seizure semiology and EEG findings was often seen. Electroclinical features were similar regardless of antibody type, with the exception of the association of faciobrachial dystonic seizures with LGI1 antibodies. Eight patients had medically intractable seizures at last follow-up and were more likely than patients with seizure remission to have generalized tonic-clonic seizures and temporal lobe involvement on the basis of semiological features, interictal EEG and MRI changes. CONCLUSIONS Seizures associated with autoimmune encephalitis exhibit common electroclinical features which show dynamic evolution over time. We propose a role for the temporo-perisylvian regions in their generation.

New onset epilepsy among patients with periodic discharges on continuous electroencephalographic monitoring

To evaluate the incidence of new onset epilepsy and associated risk factors in patients with periodic patterns on continuous electroencephalography (cEEG) during critical illness.