Stereo-EEG features of temporal and frontal lobe seizures with loss of consciousness.

The loss of consciousness (LOC) during seizures is one of the most striking features that significantly impact the quality of life, even though the neuronal network involved is not fully comprehended. We analyzed the intracerebral patterns in patients with focal drug-resistant epilepsy, both with and without LOC. We assessed the localization, lateralization, stereo electroencephalography (SEEG) patterns, seizure duration, and the quantification of contacts exhibiting electrical discharge. The degree of LOC was quantified using the Consciousness Seizure Scale. Thirteen patients (40 seizures) with focal drug-resistant epilepsy underwent SEEG. In cases of temporal lobe epilepsy (TLE, 6 patients and 15 seizures), LOC occurred more frequently in seizures with mesial rather than lateral temporal lobe onset. On the other hand, in cases of frontal lobe epilepsy (7 patients; 25 seizures), LOC was associated with pre-frontal onset, a higher number of contacts with epileptic discharge compared to the onset count and longer seizure durations. Our study revealed distinct characteristics during LOC depending on the epileptogenic zone. For temporal lobe seizures, LOC was associated with mesial seizure onset, whereas in frontal lobe epilepsy, seizure with LOC has a significant increase in contact showing epileptiform discharge and a pre-frontal onset. This phenomenon may be correlated with the broad neural network required to maintain consciousness, which can be affected in different ways, resulting in LOC.

Dancing epilepsy: A stereo encephalography case report.

Ictal semiology is essential to identify the epileptogenic zone (EZ), especially in drug-resistant focal epilepsy (DRE), as its accurate identification determines the surgical prognosis. Dancing is highly unusual ictal semiology, and its underlying neural networks remain somehow unclear since both temporal and frontal lobe (FL) have been implicated in its generation. We present a 21-year-old male with DRE characterized by dancing seizures. Homemade videos were obtained. Through a non-invasive pre-surgical evaluation, the epileptogenic zone was localized within a gross lesion in the left FL. Using stereo electroencephalography (SEEG), we successfully identified the ictal-onset zone in the mesial middle, inferior, and orbito-frontal cortex, with rapid propagation of ictal activity extending backward and laterally to the precentral regions. Subsequently, a left frontal middle and inferior gyrectomy was performed, resulting in seizure freedom for the patient. Pathology results revealed a mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE). Atypical seizure semiology, such as dancing, provides an interesting starting point for the analysis of the areas involved in the EZ. Further intracranial recordings are required to fully comprehend the underlying networks and interactions of cerebral areas during dancing seizures.

Time- and frequency-resolved covariance analysis for detection and characterization of seizures from intracraneal EEG recordings.

The amount of power in different frequency bands of the electroencephalogram (EEG) carries information about the behavioral state of a subject. Hence, neurologists treating epileptic patients monitor the temporal evolution of the different bands. We propose a covariance-based method to detect and characterize epileptic seizures operating on the band-filtered EEG signal. The algorithm is unsupervised and performs a principal component analysis of intra-cranial EEG recordings, detecting transient fluctuations of the power in each frequency band. Its simplicity makes it suitable for online implementation. Good sampling of the non-ictal periods is required, while no demands are imposed on the amount of data during ictal activity. We tested the method with 32 seizures registered in 5 patients. The area below the resulting receiver-operating characteristic curves was 87% for the detection of seizures and 91% for the detection of recruited electrodes. To identify the behaviorally relevant correlates of the physiological signal, we identified transient changes in the variance of each band that were correlated with the degree of loss of consciousness, the latter assessed by the so-called Consciousness Seizure Scale, summarizing the performance of the subject in a number of behavioral tests requested during seizures. We concluded that those crisis with maximal impairment of consciousness tended to exhibit an increase in variance approximately 40 s after seizure onset, with predominant power in the theta and alpha bands and reduced delta and beta activity.

Two types of ictal phase-amplitude couplings in epilepsy patients revealed by spectral harmonicity of intracerebral EEG recordings.

OBJECTIVE: Spectral harmonicity of the ictal activity was analyzed regarding two clinically relevant aspects, (1) as a confounding factor producing 'spurious' phase-amplitude couplings (PAC) which may lead to wrong conclusions about the underlying ictal mechanisms, and (2) its role in how good PAC is in correspondence to the seizure onset zone (SOZ) classification performed by the epileptologists. METHODS: PAC patterns observed in intracerebral electroencephalography (iEEG) recordings were retrospectively studied during seizures of seven patients with pharmacoresistant focal epilepsy. The time locked index (TLI) measure was introduced to quantify the degree of harmonicity between frequency bands associated to the emergence of PAC during epileptic seizures. RESULTS: (1) Harmonic and non harmonic PAC patterns coexist during the seizure dynamics in iEEG recordings with macroelectrodes. (2) Harmonic PAC patterns are an emergent property of the periodic non sinusoidal waveform constituting the epileptiform activity. (3) The TLI metric allows to distinguish the non harmonic PAC pattern, which has been previously associated with the ictal core through the paroxysmal depolarizing shifts mechanism of seizure propagation. CONCLUSIONS: Our results suggest that the spectral harmonicity of the ictal activity plays a relevant role in the visual analysis of the iEEG recordings performed by the epileptologists to define the SOZ, and that it should be considered for the proper interpretation of ictal mechanisms. SIGNIFICANCE: The proposed harmonicity analysis can be used to improve the delineation of the SOZ by reliably identifying non harmonic PAC patterns emerging from fully recruited cortical and subcortical areas.

Seizure localization using pre ictal phase-amplitude coupling in intracranial electroencephalography.

Understanding changes in brain rhythms provides useful information to predict the onset of a seizure and to localize its onset zone in epileptic patients. Brain rhythms dynamics in general, and phase-amplitude coupling in particular, are known to be drastically altered during epileptic seizures. However, the neural processes that take place before a seizure are not well understood. We analysed the phase-amplitude coupling dynamics of stereoelectroencephalography recordings (30 seizures, 5 patients) before and after seizure onset. Electrodes near the seizure onset zone showed higher phase-amplitude coupling. Immediately before the beginning of the seizure, phase-amplitude coupling dropped to values similar to the observed in electrodes far from the seizure onset zone. Thus, our results bring accurate information to detect epileptic events during pre-ictal periods and to delimit the zone of seizure onset in patients undergoing epilepsy surgery.

[Validation of the Montreal Cognitive Assessment (MoCA) as a screening tool for mild cognitive impairment in the population of Buenos Aires, Argentina]. / Validez de la prueba de Evaluación Cognitiva de Montreal (MoCA) como una herramienta de screening para detectar Deterioro Cognitivo Leve en población de Buenos Aires, Argentina.

INTRODUCTION: The Montreal Cognitive Assessment (MoCA) test is a brief tool for neuropsychological assessment. OBJECTIVE: to validate the MoCAin the population of Buenos Aires, Argentina, to allow for the use of the test for the detection of Mild Cognitive Impairment (MCI). METHODS: The sample consisted of 269 adults over 60 years old and of schooling of more than 6 years (healthy adults n = 115 and MCIn = 154). Receiver operating characteristic (ROC) analysis was used to establish the relationship between the diagnoses of the patients and the scores obtained at MoCA. The optimal cut-off points were selected, and the positive and negative predictive value were calculated for them. RESULTS: The area under the curve (AUC) was 0,741 (p <0001, 95% CI:.682 -.800) for the MMSE and 0.810 (p <0001, 95% CI:.759 -. 861) for the MoCA test. The cut point suggested using the MoCA test is 26 points, which throws .727 of sensitivity and a specificity of. 748. CONCLUSION: The MoCA test is a useful test for clinical consultation. Its brevity and simplicity place it as an interesting instrument for neuropsychological screening in the Argentinian population.

Subjective and objective characteristics of altered consciousness during epileptic seizures.

BACKGROUND: Conscious states are inner states and processes of awareness. These states are by definition subjective. METHODS: We analyzed subjective and objective characteristics of alteration of consciousness (AOC) during epileptic seizures, including its involvement in both the level of awareness and subjective content of consciousness. We evaluated AOC using the Consciousness Seizure Scale, the Ictal Consciousness Inventory, and a new structured survey developed by our group: the Seizure Perception Survey, which incorporates patients' subjective experiences before and after they watch a video-electroencephalographic recording of their own seizure. RESULTS: We included 35 patients (105 seizures) with drug-resistant epilepsy. Most seizures caused profound AOC. The content of consciousness was lower during temporal seizures with profound AOC. We uncovered a correlation between the subjective perception and objective duration of a seizure using the Seizure Perception Survey regarding memory; the patients had a better recall of ictal onset during wakefulness regardless of the epileptogenic zone, laterality, or magnitude of AOC. Nonetheless, the recovery of memory at the end of a seizure took more time in patients who showed greater AOC, less vivid content of consciousness, or a longer seizure. For 85% of the patients, this was the first time they were able to view their own seizures. The majority of the patients requested to view them again because this procedure allowed them to compare the recordings with their own memories and emotions during a seizure and to verify the real duration of the seizure. DISCUSSION: Alteration of consciousness is one of the most dramatic clinical manifestations of epilepsy. Usually, practitioners or relatives assume that the patients with AOC may not have any knowledge on their seizures. In this study, however, we found that most patients with AOC had a fairly accurate perception of the duration of a seizure and retained their memory of ictal onset. In contrast, for the majority of the patients, watching their own seizure was an extremely positive experience, and most patients stated that they were surprised as well as glad to view what really happened, without expressing negative opinions. Inclusion of subjective characteristics of AOC into the analysis yielded complete assessment of various dimensions of consciousness and therefore allowed us to gain a more detailed understanding of consciousness.

Cardiovascular risk factors and frontotemporal dementia: a case-control study.

Cardiovascular risk factors (CRF) were widely described as related to dementia. There are very few studies regarding this association in FTD. The objective of the study was to compare the frequency of CRF in our population with FTD and controls. 100 consecutive subjects with FTD diagnosis according to Lund-Manchester clinical criteria and 200 controls matched by age and sex were included between January 2003 to February 2007 at the Cognitive and Behavior Unit of Hospital Italiano de Buenos Aires. Clinical evaluation, laboratory tests, brain images (CT/MRI), neuropsychological and neuropsychiatric assessment were performed. Multiple regression analysis was performed to analyze the association in CRF between FTD patients vs. controls. The mean age in FTD was 69.7 ± 0.9 vs. 70.1 ± 0.8 in controls (p 0.12). No difference in gender was observed between cases and controls. No differences were identified between patients and controls regarding hypertension (HTA) (65% vs. 67,3% p 0.44); dyslipidemia (57% vs. 54.7% p 0.74); obesity (39% vs. 27.6% p 0.14) and hypothyroidism (26% vs. 17.1% p 0.1). A significant difference was observed for Diabetes Mellitus (39% vs. 22.6% p 0.001). In our population, Diabetes Mellitus was associated as an independent risk factor for FTD. To our knowledge this is the first report in which CRF were evaluated prospectively in FTD patients. More studies are needed to confirm this finding in larger populations.