Ictal direct current shifts contribute to defining the core ictal focus in epilepsy surgery.

Identifying the minimal and optimal epileptogenic area to resect and cure is the goal of epilepsy surgery. To achieve this, EEG analysis is recognized as the most direct way to detect epileptogenic lesions from spatiotemporal perspectives. Although ictal direct-current shifts (below 1 Hz) and ictal high-frequency oscillations (above 80 Hz) have received increasing attention as good indicators that can add more specific information to the conventionally defined seizure-onset zone, large cohort studies on postoperative outcomes are still lacking. This work aimed to clarify whether this additional information, particularly ictal direct-current shifts which is assumed to reflect extracellular potassium concentration, really improve postoperative outcomes. To assess the usefulness in epilepsy surgery, we collected unique EEG data sets recorded with a longer time constant of 10 s using an alternate current amplifier. Sixty-one patients (15 with mesial temporal lobe epilepsy and 46 with neocortical epilepsy) who had undergone invasive presurgical evaluation for medically refractory seizures at five institutes in Japan were retrospectively enrolled in this study. Among intracranially implanted electrodes, the two core electrodes of both ictal direct-current shifts and ictal high-frequency oscillations were independently identified by board-certified clinicians based on unified methods. The occurrence patterns, such as their onset time, duration, and amplitude (power) were evaluated to extract the features of both ictal direct-current shifts and ictal high-frequency oscillations. Additionally, we examined whether the resection ratio of the core electrodes of ictal direct-current shifts and ictal high-frequency oscillations independently correlated with favourable outcomes. A total of 53 patients with 327 seizures were analyzed for wide-band EEG analysis, and 49 patients were analyzed for outcome analysis. Ictal direct-current shifts were detected in the seizure-onset zone more frequently than ictal high-frequency oscillations among both patients (92% versus 71%) and seizures (86% versus 62%). Additionally, ictal direct-current shifts significantly preceded ictal high-frequency oscillations in patients exhibiting both biomarkers, and ictal direct-current shifts occurred more frequently in neocortical epilepsy patients than in mesial temporal lobe epilepsy patients. Finally, although a low corresponding rate was observed for ictal direct-current shifts and ictal high-frequency oscillations (39%) at the electrode level, complete resection of the core area of ictal direct-current shifts significantly correlated with favourable outcomes, similar to ictal high-frequency oscillation outcomes. Our results provide a proof of concept that the independent significance of ictal direct-current shifts from ictal high-frequency oscillations should be considered as reliable biomarkers to achieve favourable outcomes in epilepsy surgery. Moreover, the different distribution of the core areas of ictal direct-current shifts and ictal high-frequency oscillations may provide new insights into the underlying mechanisms of epilepsy, in which not only neurons but also glial cells may be actively involved via extracellular potassium levels.

A taxonomy of seizure dynamotypes.

Seizures are a disruption of normal brain activity present across a vast range of species and conditions. We introduce an organizing principle that leads to the first objective Taxonomy of Seizure Dynamics (TSD) based on bifurcation theory. The 'dynamotype' of a seizure is the dynamic composition that defines its observable characteristics, including how it starts, evolves and ends. Analyzing over 2000 focal-onset seizures from multiple centers, we find evidence of all 16 dynamotypes predicted in TSD. We demonstrate that patients' dynamotypes evolve during their lifetime and display complex but systematic variations including hierarchy (certain types are more common), non-bijectivity (a patient may display multiple types) and pairing preference (multiple types may occur during one seizure). TSD provides a way to stratify patients in complement to present clinical classifications, a language to describe the most critical features of seizure dynamics, and a framework to guide future research focused on dynamical properties.

Epileptic seizures have been recognized for centuries. But it was only in the 1930s that it was realized that seizures are the result of out-of-control electrical activity in the brain. By placing electrodes on the scalp, doctors can identify when and where in the brain a seizure begins. But they cannot tell much about how the seizure behaves, that is, how it starts, stops or spreads to other areas. This makes it difficult to control and prevent seizures. It also helps explain why almost a third of patients with epilepsy continue to have seizures despite being on medication. Saggio, Crisp et al. have now approached this problem from a new angle using methods adapted from physics and engineering. In these fields, "dynamics research" has been used with great success to predict and control the behavior of complex systems like electrical power grids. Saggio, Crisp et al. reasoned that applying the same approach to the brain would reveal the dynamics of seizures and that such information could then be used to categorize seizures into groups with similar properties. This would in effect create for seizures what the periodic table is for the elements. Applying the dynamics research method to seizure data from more than a hundred patients from across the world revealed 16 types of seizure dynamics. These "dynamotypes" had distinct characteristics. Some were more common than others, and some tended to occur together. Individual patients showed different dynamotypes over time. By constructing a way to classify seizures based on the relationships between the dynamotypes, Saggio, Crisp et al. provide a new tool for clinicians and researchers studying epilepsy. Previous clinical tools have focused on the physical symptoms of a seizure (referred to as the phenotype) or its potential genetic causes (genotype). The current approach complements these tools by adding the dynamotype: how seizures start, spread and stop in the brain. This approach has the potential to lead to new branches of research and better understanding and treatment of seizures.

Scalp EEG Could Record Both Ictal Direct Current Shift and High-Frequency Oscillation Together Even With a Time Constant of 2 Seconds.

Herein, the authors report for the first time, scalp-recorded (1) focal ictal direct current (DC) shifts (active DC shifts; that precede conventional pattern) from the chronic focus of focal epilepsy and (2) ictal high-frequency oscillation after ictal DC shifts (passive DC shifts; that follow both conventional and high-frequency oscillation ictal patterns) from the acute focus of acute symptomatic seizures (Szs) in a 77-year-old man. Sixteen episodes of clinical Szs were recorded by scalp EEG with a 2-seconds time constant. Among the 16 recorded episodes of Sz, four EEG Sz patterns originated from the left posterior temporal area (chronic focus), and all patterns (100%) exhibited active DC shifts preceding the conventional pattern by 12 seconds. Twelve EEG Sz patterns originated from the right parietal area (acute focus), and the high-frequency oscillations (five Szs) (41.6%) and DC shifts (six Szs) (50%) occurred first, followed by the conventional pattern 8 seconds later. Because both the active and the passive DC shifts were recorded with a time constant of 2 seconds, which was smaller than that reported previously for ictal DC shifts (e.g., time constant of 10 seconds), clinically useful ictal DC shifts could be routinely inspected with a time constant of 2 seconds.

Short "Infraslow" Activity (SISA) With Burst Suppression in Acute Anoxic Encephalopathy: A Rare, Specific Ominous Sign With Acute Posthypoxic Myoclonus or Acute Symptomatic Seizures.

OBJECTIVE: Slow wave with frequency <0.5 Hz are recorded in various situations such as normal sleep, epileptic seizures. However, its clinical significance has not been fully clarified. Although infra-slow activity was recently defined as activity between 0.01 and 0.1 Hz, we focus on the activity recorded with time constant of 2 seconds for practical usage. We defined short "infraslow" activity (SISA) less than 0.5 Hz recorded with time constant of 2 seconds and investigated the occurrence and clinical significance of SISA in acute anoxic encephalopathy. METHODS: This study evaluated the findings of electroencephalography in consecutive 98 comatose patients with acute anoxic encephalopathy after cardiac arrest. We first classified electroencephalography findings conventionally, then investigated SISA by time constant of 2 second and a high-cut filter of 120 Hz, to clarify the relationship between SISA and clinical profiles, especially of clinical outcomes and occurrence of acute posthypoxic myoclonus or acute symptomatic seizures. RESULTS: Short infra-slow activity was found in six patients (6.2%), superimposed on the burst phase of the burst-suppression pattern. All six patients showed acute posthypoxic myoclonus or acute symptomatic seizures (generalized tonic-clonic seizures) and its prognosis was poor. This 100% occurrence of acute posthypoxic myoclonus or acute symptomatic seizures was significantly higher than that in patients without SISA (39.1%; P < 0.05). CONCLUSIONS: Short infra-slow activity in acute anoxic encephalopathy could be associated with acute posthypoxic myoclonus and acute symptomatic seizures. Short infra-slow activity could be a practically feasible biomarker for myoclonus or seizures and poor prognosis in acute anoxic encephalopathy, if it occurs with burst suppression.

Recurrent diarrhea as a manifestation of temporal lobe epilepsy.

A woman with temporal lobe epilepsy manifesting with repeated episodes of sudden diarrhea and loss of consciousness is reported. A 63-year-old, right-handed female presented with chief complaints of sudden diarrhea and loss of consciousness for almost three decades. The first attack occurred in her 30s, and similar attacks repeated several times in a year. Her attacks comprised abrupt abdominal discomfort, diarrhea, sudden emergence of old memories relating to when she had played with her brother in her childhood, and loss of consciousness during defecation. She had no convulsion or automatism and fully recovered in a few minutes. Every time she was transferred to emergency hospital by ambulance, she had examinations such as blood test, head computed tomography, electrocardiogram, abdominal ultrasound, and electroencephalography (EEG), but no specific diagnosis was made. On admission to our hospital, vital signs, neurological examination, and blood tests did not show abnormal findings. During long-term video-EEG monitoring for 40 h, she had no habitual event. Interictal EEG showed intermittent irregular delta waves and sharp regional transients in the left anterio-midtemporal area. Sharp transients were not as outstanding from background activities as to be defined as epileptiform discharges, but they were reproducible in morphology and distribution and appeared not only in sleep but also in wakefulness. Brain magnetic resonance imaging was unremarkable. Single-photon emission computed tomography showed a decrease of blood flow in the left frontal and temporal lobes. Wechsler Adult Intelligence Scale-III showed a decline of verbal comprehension. We concluded that the patient was suffering from partial epilepsy originating from the left temporal lobe. Carbamazepine markedly improved her seizures. Temporal lobe epilepsy can manifest with diverse autonomic symptoms and signs. Abdominal sensations often herald the onset of epileptic seizures. Among them is an uncommon syndrome called abdominal epilepsy in which gastrointestinal complaints are the primary or the sole manifestation of epileptic seizures. In patients who present with diarrhea and other autonomic symptoms otherwise unexplained, a possible diagnosis of epilepsy should be considered.

A combined treatment for acute larger lacunar-type infarction.

Larger lacunar-type infarcts (LLIs), presumably caused by occlusion at the orifices or proximal portions of larger-caliber penetrating arteries by atheromatous plaque, are frequently associated with progressive motor deficits (PMD) and lead to poor functional outcome. This study was conducted to examine the efficacy of a combined treatment to prevent PMD or improve the functional outcome in patients with LLI. A total of 218 consecutive patients with LLI and motor lacunar syndrome were enrolled, including 138 patients with infarcts in the territory of the lenticulostriate artery and anterior choroidal artery (supratentrial group) and 80 patients with infarcts in the territory of the anterior pontine artery (pontine group). The prevalence of PMD and functional outcome represented by modified Rankin Scale (mRS) score at 1 month after ictus were compared between groups treated with a combined treatment approach consisting of cilostazol and edaravone (n = 100) and a conventional treatment approach (n = 118). The efficacy of the combined treatment provided in 2005-2009 was compared with conventional treatment provided in 2001-2005. There was no significant difference in the prevalence of PMD between the 2 treatment groups. The combined treatment group had significantly more favorable outcomes compared with the conventional treatment group in the total population (P = .0078, Wilcoxon Mann-Whitney test) and in the pontine group (P = .0042). Logistic regression analysis showed that an initial National Institutes of Health Stroke Scale score <4, the absence of PMD, and the novel combined treatment approach were independently associated with favorable functional outcome. The novel combined treatment approach was safe and effective in improving functional outcome in acute LLI, but not effective in preventing PMD.

The infarct location predicts progressive motor deficits in patients with acute lacunar infarction in the lenticulostriate artery territory.

BACKGROUND AND PURPOSE: Patients with acute lacunar infarction in the lenticulostriate artery (LSA) territory often show progression of motor deficits (PMD) after admission. The purpose of our study is to identify predictors for PMD using the findings of diffusion-weighted imaging (DWI) on admission. METHODS: From January 2005 to December 2008, we studied 60 consecutive patients with acute lacunar infarction in the LSA territory within 24h after onset. To identify predictors for PMD, clinical characteristics including vascular risk factors and DWI findings were evaluated. DWI findings included the size and location of the infarcts and the slice numbers of infarcts visible on DWI. For the location, posterior type was defined as an infarct located in the posterior part of corona radiata on the second slice from the top among slices including corona radiata. RESULTS: Twenty-six patients (43%) showed PMD. In univariate analysis, age >or=75 (P=0.03), female sex (P=0.04), infarct slice number >or=3 (P=0.04), and posterior type infarct (P<0.001) were more frequent in the PMD group than in the no PMD group. In multivariate analysis, posterior type infarct was the only independent predictor among DWI findings for PMD (odds ratio, 14.83; 95% confidence interval, 3.54-87.21, P<0.001). CONCLUSIONS: Posterior type infarct was the independent predictor in DWI findings for PMD in patients with lacunar infarction in the LSA territory. We postulate that the posterior type infarct may affect the corticospinal tract to a greater degree and cause PMD.