Objective We tested the hypothesis that there are readily classifiable electroencephalographic phenotypes of early post-anoxic multifocal myoclonus (PAMM) that develop after cardiac arrest. Methods We studied a cohort of consecutive comatose patients treated after cardiac arrest from January 2012 to February 2015. For patient with clinically evident myoclonus before awakening, two expert physicians reviewed and classified all EEG recordings. Major categories included: Pattern 1: Suppression-burst background with high-amplitude polyspikes in lock-step with myoclonic jerks; Pattern 2: Continuous background with narrow, vertex spike-wave discharges in lock-step with myoclonic jerks. Other patterns were subcortical myoclonus; and, unclassifiable. We compared population characteristics and outcomes across these electroencephalographic subtypes. Results Overall, 401 patients were included, of which 69 (16%) had early myoclonus. Among these patients, Pattern 1 was the most common, occurring in 48 patients (74%), whereas Pattern 2 occurred in 8 patients (12%). The remaining patients had subcortical myoclonus (n=2, 3%) or other patterns (n=7, 11%). No patients with Pattern 1, subcortical myoclonus or other patterns survived with favorable outcome (Table 2). By contrast, 4 of 8 patients (50%) with Pattern 2 on EEG survived, and 4 of 4 (100%) of survivors had favorable outcomes despite remaining comatose for 1–2 weeks post-arrest Interpretation Early PAMM is common after cardiac arrest. We describe two distinct patterns with distinct prognostic significances. For patients with Pattern 1 EEGs, it may be appropriate to abandon our current clinical standard of aggressive therapy with conventional antiepileptic therapy in favor of early limitation of care or novel neuroprotective strategies.

Scalp EEG is an essential component of epilepsy presurgical evaluation during the lateralization and localization of epileptogenic focus. Scalp EEG epileptiform discharges may either guide direct surgical intervention or provide necessary information to further localize the epileptic focus with intracranial EEG recording. Despite the importance and widespread use of scalp EEG epileptiform discharges, the cortical EEG substrates underlying these spikes and seizure discharges are mostly speculative. Misconceptions are therefore prevalent regarding the necessary cortical area, synchrony, and amplitude required to generate those that are recordable at the scalp. Using contemporary EEG recording techniques such as simultaneous scalp and intracranial EEG recording, the authors' recent studies have shown that the cortical area of epileptiform discharges required for the scalp recording is considerably larger than commonly thought. A cortical area of 10 to 20 cm is often required to generate a scalp recognizable interictal spike or ictal rhythm. Sufficient cortical source area and synchrony are mandatory factors for the corresponding scalp EEG epileptiform recording. The amplitude is primarily dependent on source area and synchrony; therefore it is a less important factor. The authors review the previous literatures in conjunction with their recent investigations on this topic.

Objective Hypoxic brain injury is the largest contributor to disability and mortality after cardiac arrest. We aim to identify electroencephalogram (EEG) characteristics that can predict outcome on cardiac arrest patients treated with targeted temperature management (TTM). Methods We retrospectively examined clinical, EEG, functional outcome at discharge, and in-hospital mortality for 373 adult subjects with return of spontaneous circulation after cardiac arrest. Poor outcome was defined as a Cerebral Performance Category score of 3–5. Pure suppression-burst (SB) was defined as SB not associated with status epilepticus (SE), seizures, or generalized periodic discharges. Results In-hospital mortality was 68.6% (N=256). Presence of both unreactive EEG background and SE was associated with a positive predictive value (PPV) of 100% (95% Confidence Interval: 0.96–1) and a false-positive rate (FPR) of 0% (95% CI: 0–0.11) for poor functional outcome. A prediction model including demographics data, admission exam, presence of status epilepticus, pure SB, and lack of EEG reactivity had an area under the curve of 0.92 (95% CI:0.87–0.95) for poor functional outcome prediction, and 0.96 (95% CI: 0.94–0.98) for in-hospital mortality. Presence of pure SB (N=87) was confounded by anesthetics use in 83.9% of the cases, and was not an independent predictor of poor functional outcome, having a FPR of 23% (95% CI: 0.19–0.28). Conclusions An unreactive EEG background and SE predicted poor functional outcome and in-hospital mortality in cardiac arrest patients undergoing TTM. Prognostic value of pure SB is confounded by use of sedative agents, and its use on prognostication decisions should be made with caution.

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Background and Purpose-Early vasospasm (EVSP), defined here as arterial narrowing seen on diagnostic angiography within the first 48 hours of aneurysmal rupture, is a rarely reported and poorly defined phenomenon in patients with subarachnoid hemorrhage (SAH). The purpose of this study was to characterize EVSP in a large database of such patients. Methods-We analyzed the relationship of EVSP to clinical characteristics, in-hospital complications, and outcome at 3 months among 3478 patients entered into 4 prospective, randomized, double-blind, placebo-controlled trials of tirilazad conducted in neurosurgical centers around the world between 1991 and 1997.