Ictal asystole in a patient with posterior reversible encephalopathy syndrome (PRES) and seizures.

We describe a case of ictal asystole in a patient with posterior reversible encephalopathy syndrome (PRES), which has never been described previously. Ictal asystole is rare and has possible serious medical consequences, including syncope, and may be a potential mechanism for sudden unexpected death in epilepsy (SUDEP). Awareness that PRES may be observed with recurrent ictal asystole may aid in the recognition and treatment of seizures in this condition and the prevention of asystole-associated complications.

AR2, a novel automatic muscle artifact reduction software method for ictal EEG interpretation: Validation and comparison of performance with commercially available software.

Objective: To develop a novel software method (AR2) for reducing muscle contamination of ictal scalp electroencephalogram (EEG), and validate this method on the basis of its performance in comparison to a commercially available software method (AR1) to accurately depict seizure-onset location. Methods: A blinded investigation used 23 EEG recordings of seizures from 8 patients. Each recording was uninterpretable with digital filtering because of muscle artifact and processed using AR1 and AR2 and reviewed by 26 EEG specialists. EEG readers assessed seizure-onset time, lateralization, and region, and specified confidence for each determination. The two methods were validated on the basis of the number of readers able to render assignments, confidence, the intra-class correlation (ICC), and agreement with other clinical findings. Results: Among the 23 seizures, two-thirds of the readers were able to delineate seizure-onset time in 10 of 23 using AR1, and 15 of 23 using AR2 (p<0.01). Fewer readers could lateralize seizure-onset (p<0.05). The confidence measures of the assignments were low (probable-unlikely), but increased using AR2 (p<0.05). The ICC for identifying the time of seizure-onset was 0.15 (95% confidence interval (CI), 0.11-0.18) using AR1 and 0.26 (95% CI 0.21-0.30) using AR2.  The EEG interpretations were often consistent with behavioral, neurophysiological, and neuro-radiological findings, with left sided assignments correct in 95.9% (CI 85.7-98.9%, n=4) of cases using AR2, and 91.9% (77.0-97.5%) (n=4) of cases using AR1. Conclusions: EEG artifact reduction methods for localizing seizure-onset does not result in high rates of interpretability, reader confidence, and inter-reader agreement. However, the assignments by groups of readers are often congruent with other clinical data. Utilization of the AR2 software method may improve the validity of ictal EEG artifact reduction.

EEG Findings May Serve as a Potential Biomarker for Anti-NMDA Receptor Encephalitis.

Objective To determine if an electroencephalographic (EEG) characteristic, beta:delta power ratio (BDPR), is significantly higher for N-methyl-d-aspartate receptor encephalitis (NMDARE) patients than for non-NMDARE patients on presenting EEG. Identification of an additional EEG biomarker with significant specificity for NMDARE (in the absence of frank delta brush) could potentially allow for early identification of at-risk patients. Methods Single center retrospective comparison of NMDARE and non-NMDARE consecutive cases of encephalitis, collated over a 6-year period (from 2008 to 2014). Results None of the 10 NMDARE patients displayed the extreme delta brush pattern on EEG previously described, but the ratio of BDPR was significantly higher for NMDARE patients (P < .005). There was no significant relationship between BDPR and the time of recording from symptom onset. Additional analysis of clinical characteristics also indicated that the patients with NMDARE (median age 19.5 years) were younger than the 5 patients with non-NMDARE (median age 36 years). Encephalopathy, seizure, and psychiatric complaints were the most common diagnoses at time of first health care presentation and did not favor a single etiology, though the latter was present only in the NMDARE population (50% at T0). Prodromal illness featuring headache was more common in the non-NMDARE population. Outcomes, as measured by the Modified Rankin Scale, were globally better in the NMDARE group. Conclusions Patients with NMDARE had a significantly higher BDPR on EEG when compared with non-NMDARE patients even in the absence of extreme delta brush. This suggests that early EEG characteristics may be helpful in distinguishing NMDARE from non-NMDARE.

Parallel organization of contralateral and ipsilateral prefrontal cortical projections in the rhesus monkey.

BACKGROUND: The neocortical commissures have a fundamental role in functional integration across the cerebral hemispheres. We investigated whether commissural projections in prefrontal cortices are organized according to the same or different rules as those within the same hemisphere, by quantitatively comparing density, topography, and laminar origin of contralateral and ipsilateral projections, labeled after unilateral injection of retrograde tracers in prefrontal areas. RESULTS: Commissural projection neurons constituted less than one third of the ipsilateral. Nevertheless, projections from the two hemispheres were strongly correlated in topography and relative density. We investigated to what extent the distribution of contralateral projections depended on: (a) geographic proximity of projection areas to the area homotopic to the injection site; (b) the structural type of the linked areas, based on the number and neuronal density of their layers. Although both measures were good predictors, structural type was a comparatively stronger determinant of the relative distribution and density of projections. Ipsilateral projection neurons were distributed in the superficial (II-III) and deep (V-VI) layers, in proportions that varied across areas. In contrast, contralateral projection neurons were found mostly in the superficial layers, but still showed a gradient in their distribution within cortical layers that correlated significantly with cortical type, but not with geographic proximity to the homotopic area. CONCLUSION: The organization of ipsilateral and contralateral prefrontal projections is similar in topography and relative density, differing only by higher overall density and more widespread laminar origin of ipsilateral than contralateral projections. The projections on both sides are highly correlated with the structural architecture of the linked areas, and their remarkable organization is likely established by punctuated development of distinct cortical types. The preponderance of contralateral projections from layer III may be traced to the late development of the callosal system, whose function may be compromised in diseases that have their root late in ontogeny.