High kurtosis of intracranial electroencephalogram as a marker of ictogenicity in pediatric epilepsy surgery

Objective

We determined whether kurtosis analysis of intracranial electroencephalogram (EEG) can estimate the localization of the epileptogenic zone.

Methods

We analyzed 29 pediatric epilepsy patients who underwent intracranial EEG before focal resective surgery. We localized the brain regions with high kurtosis, the seizure onset zone (SOZ) and the regions with high-rate, high-amplitude and long-duration interictal paroxysms ?20 Hz. We tested correlations between the surgical resection of those regions and post-surgical seizure outcome, and correlations between kurtosis and the rate/amplitude/duration of interictal paroxysms.

Results

The resection of the regions with high kurtosis correlated with 1-year post-surgical seizure outcome (p = 0.028) but not with 2-year outcome. Kurtosis showed more significant correlation with 1-year seizure outcome than the SOZ and the rate/amplitude/duration of interictal paroxysms. Kurtosis showed positive, independent correlations with the amplitude and duration of interictal paroxysms (p < 0.0001) but not with the rate (p = 0.4).

Conclusions

The regions with high kurtosis provide more reliable information to predict seizure outcome than the SOZ and the regions with high-rate/amplitude and long-duration interictal paroxysms. Kurtosis reflects combined effects of the amplitude and duration of the interictal paroxysms.

Significance

High kurtosis suggests the regions with acquired ictogenicity within the irritative zone.     

Clinical Utility of Interictal High-Frequency Oscillations Recorded with Subdural Macroelectrodes in Partial Epilepsy

Background and Purpose

There is growing interest in high-frequency oscillations (HFO) as electrophysiological biomarkers of the epileptic brain. We evaluated the clinical utility of interictal HFO events, especially their occurrence rates, by comparing the spatial distribution with a clinically determined epileptogenic zone by using subdural macroelectrodes.

Methods

We obtained intracranial electroencephalogram data with a high temporal resolution (2000 Hz sampling rate, 0.05-500 Hz band-pass filter) from seven patients with medically refractory epilepsy. Three epochs of 5-minute, artifact-free data were selected randomly from the interictal period. HFO candidates were first detected by an automated algorithm and subsequently screened to discard false detections. Validated events were further categorized as fast ripple (FR) and ripple (R) according to their spectral profiles. The occurrence rate of HFOs was calculated for each electrode contact. An HFO events distribution map (EDM) was constructed for each patient to allow visualization of the spatial distribution of their HFO events.

Results

The subdural macroelectrodes were capable of detecting both R and FR events from the epileptic neocortex. The occurrence rate of HFO events, both FR and R, was significantly higher in the seizure onset zone (SOZ) than in other brain regions. Patient-specific HFO EDMs can facilitate the identification of the location of HFO-generating tissue, and comparison with findings from ictal recordings can provide additional useful information regarding the epileptogenic zone.

Conclusions

The distribution of interictal HFOs was reasonably consistent with the SOZ. The detection of HFO events and construction of spatial distribution maps appears to be useful for the presurgical mapping of the epileptogenic zone.     

Intracerebrally recorded high frequency oscillations: Simple visual assessment versus automated detection

Objective

We compared the possible contribution (in the detection of seizure onset zone – SOZ) of simple visual assessment of intracerebrally recorded high-frequency oscillations (HFO) with standard automated detection.

Methods

We analyzed stereo-EEG (SEEG) recordings from 20 patients with medically intractable partial seizures (10 temporal/10 extratemporal). Independently using simple visual assessment and automated detection of HFO, we identified the depth electrode contacts with maximum occurrences of ripples (R) and fast ripples (FR). The SOZ was determined by independent visual identification in standard SEEG recordings, and the congruence of results from visual versus automated HFO detection was compared.

Results

Automated detection of HFO correctly identified the SOZ in 14 (R)/10 (FR) out of 20 subjects; a simple visual assessment of SEEG recordings in the appropriate frequency ranges correctly identified the SOZ in 13 (R)/9 (FR) subjects.

Conclusions

Simple visual assessment of SEEG traces and standard automated detection of HFO seem to contribute comparably to the identification of the SOZ in patients with focal epilepsies. When using macroelectrodes in neocortical extratemporal epilepsies, the SOZ might be better determined by the ripple range.

Significance

Standard automated detection of HFO enables the evaluation of HFO characteristics in whole data. This detection allows general purpose and objective evaluation, without any bias from the neurophysiologist’s experiences and practice.     

Frequency-independent characteristics of high-frequency oscillations in epileptic and non-epileptic regions

Objective

The purpose of the presented study is to determine whether there are frequency-independent high-frequency oscillation (HFO) parameters which may differ in epileptic and non-epileptic regions.

Interictal high-frequency oscillations (80-500 Hz) are an indicator of seizure onset areas independent of spikes in the human epileptic brain

Purpose: High‐frequency oscillations (HFOs) known as ripples (80–250 Hz) and fast ripples (250–500 Hz) can be recorded from macroelectrodes inserted in patients with intractable focal epilepsy. They are most likely linked to epileptogenesis and have been found in the seizure onset zone (SOZ) of human ictal and interictal recordings. HFOs occur frequently at the time of interictal spikes, but were also found independently. This study analyses the relationship between spikes and HFOs and the occurrence of HFOs in nonspiking channels. Methods: Intracerebral EEGs of 10 patients with intractable focal epilepsy were studied using macroelectrodes. Rates of HFOs within and outside spikes, the overlap between events, event durations, and the percentage of spikes carrying HFOs were calculated and compared according to anatomical localization, spiking activity, and relationship to the SOZ. Results: HFOs were found in all patients, significantly more within mesial temporal lobe structures than in neocortex. HFOs could be seen in spiking as well as nonspiking channels in all structures. Rates and durations of HFOs were significantly higher in the SOZ than outside. It was possible to establish a rate of HFOs to identify the SOZ with better sensitivity and specificity than with the rate of spikes. Discussion: HFOs occurred to a large extent independently of spikes. They are most frequent in mesial temporal structures. They are prominent in the SOZ and provide additional information on epileptogenicity independently of spikes. It was possible to identify the SOZ with a high specificity by looking at only 10 min of HFO activity.     

Interictal ripples nested in epileptiform discharge help to identify the epileptogenic zone in neocortical epilepsy

Objective

This study aimed to identify the subtype of interictal ripples that help delineate the epileptogenic zone in neocortical epilepsy.

Oxytocin does not modify GH, ACTH, cortisol and prolactin responses to Ghrelin in normal men

Background

In order to test the possible effect of Oxytocin (OT) on Ghrelin-stimulated GH, PRL, ACTH and cortisol, ten healthy normal men were studied.

Methods

Tests: Ghrelin (0.2 μg/kg body weight (BW)) as an iv bolus; Ghrelin plus OT (2 IU as bolus plus 0.07 IU/min administered for 90 min).

Results

The administration of OT did not change GH, PRL, ACTH and cortisol release induced by Ghrelin.

Conclusions

The data suggests that in humans OT did not modulate the GH, PRL, ACTH and cortisol response to Ghrelin.     

Co-occurrence of high-frequency oscillations and delayed responses evoked by intracranial electrical stimulation in stereo-EEG studies

Objective

To perform a side-by-side comparison of two epileptogenicity biomarkers, high frequency oscillations (HFOs) and delayed responses (DRs), as a result of single-pulse electrical stimulation.

Scalp-recorded high-frequency oscillations in childhood epileptic encephalopathy with continuous spike-and-wave during sleep with different etiologies

Objective

To investigate high-frequency oscillations (HFOs) in epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) with different etiologies.

Relationship between lunar phases and serious crimes of battery: a population-based study

Objective

The hypothesis of a lunar influence on human abnormal behavior is still widespread, although research has led to conflicting findings. Therefore, a population-based study to assess the influence of lunar phases on violent crimes was conducted.

Methods

The study included all serious crimes of battery (aggravated assaults) committed in Middle Franconia (Bavaria, Germany) between 1999 and 2005 (n = 23?142). Data were analyzed regarding lunar phase, sex, and place of crime scene (outdoor vs indoor).

Results

No significant associations between full, absent, and the moon's interphases and serious crimes of battery could be detected. Furthermore, a Fourier analysis was conducted that failed to produce an association between violence and the moon's phases.

Discussion

Several possible explanations for the presented results are discussed including biological and social mechanisms.

Conclusions

The present study fails to find a significant association between lunar phases and crimes of battery.     

High-frequency (80-500 Hz) oscillations and epileptogenesis in temporal lobe epilepsy

High-frequency oscillations (HFOs), termed ripples (80-200 Hz) and fast ripples (250-600 Hz), are recorded in the EEG of epileptic patients and in animal epilepsy models; HFOs are thought to reflect pathological activity and seizure onset zones. Here, we analyzed the temporal and spatial evolution of interictal spikes with and without HFOs in the rat pilocarpine model of temporal lobe epilepsy. Depth electrode recordings from dentate gyrus (DG), CA3 region, subiculum and entorhinal cortex (EC), were obtained from rats between the 4th and 15th day after a status epilepticus (SE) induced by i.p. injection of pilocarpine. The first seizure occurred 6.1 ± 2.5 days after SE (n = 7 rats). Five of 7 animals exhibited interictal spikes that co-occurred with fast ripples accounting for 4.9 ± 4.6% of all analyzed interictal spikes (n = 12,886) while all rats showed interictal spikes co-occurring with ripples, accounting for 14.3 ± 3.4% of all events. Increased rates of interictal spikes without HFOs in the EC predicted upcoming seizures on the following day, while rates of interictal spikes with fast ripples in CA3 reflected periods of high seizure occurrence. Finally, interictal spikes co-occurring with ripples did not show any specific relation to seizure occurrence. Our findings identify different temporal and spatial developmental patterns for the rates of interictal spikes with or without HFOs in relation with seizure occurrence. These distinct categories of interictal spikes point at dynamic processes that should bring neuronal networks close to seizure generation.     

Effect of sleep stage on interictal high-frequency oscillations recorded from depth macroelectrodes in patients with focal epilepsy

Purpose :  To investigate the effect of sleep stage on the properties of high-frequency oscillations (HFOs) recorded from depth macroelectrodes in patients with focal epilepsy.
Methods :  Ten-minute epochs of wakefulness (W), stage 1–2 non-REM (N1-N2), stage 3 non-REM (N3) and REM sleep (R) were identified from stereo-electroencephalography (SEEG) data recorded at 2 kHz in nine patients. Rates of spikes, ripples (>80 Hz), and fast ripples (>250 Hz) were calculated, as were HFO durations, degree of spike–HFO overlap, HFO rates inside and outside of spikes, and inside and outside of the seizure-onset zone (SOZ).
Results :  Ripples were observed in nine patients and fast ripples in eight. Spike rate was highest in N1-N2 in 5 of 9 patients, and in N3 in 4 of 9 patients, whereas ripple rate was highest in N1-N2 in 4 of 9 patients, in N3 in 4 of 9 patients, and in W in 1 of 9 patients. Fast ripple rate was highest in N1-N2 in 4 of 8 patients, and in N3 in 4 of 8 patients. HFO properties changed significantly with sleep stage, although the absolute effects were small. The difference in HFO rates inside and outside of the SOZ was highly significant (p < 0.000001) in all stages except for R and, for fast ripples, only marginally significant (p = 0.018) in W.
Conclusions :  Rates of HFOs recorded from depth macroelectrodes are highest in non-REM sleep. HFO properties were similar in stages N1-N2 and N3, suggesting that accurate sleep staging is not necessary. The spatial specificity of HFO, particularly fast ripples, was affected by sleep stage, suggesting that recordings excluding REM sleep and wakefulness provide a more reliable indicator of the SOZ.     

Uncovered primary seizure foci in Lennox-Gastaut syndrome after corpus callosotomy

Purpose

Corpus callosotomy (CC) is a palliative surgical procedure to control atonic, tonic, or generalized tonic-clonic seizure in Lennox-Gastaut syndrome (LGS). Here, we report patients with LGS who underwent resective surgery, following CC better delineating the presumed seizure foci localized in one hemisphere.

Methods

We retrospectively reviewed seven patients with LGS who underwent CC and subsequent cortical resection. The median follow-up duration after lobectomy was 20 months (range, 15-54 months) and three patients had follow-up periods over 24 months. The findings of video electroencephalography (EEG) monitoring, structural and functional neuroimagings were compared between pre- and post-CC.

Results

Four patients had Engel class I and one patient had Engel class II outcomes following cortical resection; post-CC, compared to pre-CC, showed better localized ictal/interictal epileptiform discharges in the unilateral frontal area in two patients, in the unilateral parieto-temporo-occipital areas in one patient and in the unilateral fronto-temporal areas in the remaining two patients. Two patients had Engel Class III outcome following cortical resection; post-CC EEG continued to show multifocal epileptiform discharges but predominantly arising from a unilateral frontal area. Following CC, positron emission tomography showed localized glucose hypometabolism of which location was concordant with post-CC EEG abnormalities in all patient. Similarly, ictal/interictal single photon emission computed tomography also showed localized abnormalities concordant with post-CC EEG abnormalities in five of the six patients. Pathological assessment revealed cortical dysplasia in six patients, whereas no pathological abnormality was found in the remaining patient, who obtained Engel Class I outcome following cortical resection.

Conclusion

CC could change EEG findings, glucose metabolisms and cerebral blood flows, and it is sometimes helpful in delineating the primary seizure focus in patients with LGS.     

Prevalence of psychiatric disorders in patients with polycystic ovary syndrome

Objective

To investigate the prevalence of psychiatric disorders among women in ambulatory treatment for polycystic ovary syndrome (PCOS) and to correlate its clinical and demographic aspects with mental disorders.

Methodology

Seventy-two patients in ambulatory treatment at the Endocrinal and Gynaecological Institute of the Federal University of Rio de Janeiro were evaluated using Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition criteria by means of MINI (Mini International Neuropsychiatric Interview, version 4.4). Polycystic ovary syndrome was confirmed according to the ultrasonographic criteria of Adams and by clinical parameters.

Results

Forty-one patients (57%) presented at least one psychiatric diagnosis. Among them, the prevalence of mood disorder reached 78%. The most prevalent diagnostics were major depression (26.4%) and bipolar disorder (11.1%).

Conclusion

A high prevalence of mental disorders was observed, especially major depression and bipolar disorder. The data obtained regarding the relationship between PCOS and mood disorders in a Brazilian sample is in accordance with recent research findings in the same area.     

Hippocampal volume in borderline personality disorder with and without comorbid posttraumatic stress disorder: A meta-analysis

Background

Several studies have found a reduction in hippocampal volume in borderline personality disorder (BPD) patients.

Methods

In order to investigate the degree to which comorbid posttraumatic stress disorder (PTSD) could account for reduction in hippocampal volume in these patients, we conducted a systematic review and meta-analysis of studies that compared hippocampal volume in BPD patients with and without PTSD relative to healthy controls.

Results

Seven articles, involving 124 patients and 147 controls, were included. We found a statistically significant reduction for the left and right hippocampus. Data from the four studies that discriminated BPD patients with and without PTSD indicate that hippocampal volumes were reduced bilaterally in BPD patients with PTSD, relative to healthy controls, but that results were mixed for BPD patients without PTSD, relative to healthy controls.

Conclusions

Results from this meta-analysis suggest that hippocampal volumes are reduced in patients with BPD, relative to healthy controls, but particularly in cases in which patients are diagnosed with comorbid PTSD.     

Utilization of independent component analysis for accurate pathological ripple detection in intracranial EEG recordings recorded extra- and intra-operatively

Objective

To develop and validate a detector that identifies ripple (80–200?Hz) events in intracranial EEG (iEEG) recordings in a referential montage and utilizes independent component analysis (ICA) to eliminate or reduce high-frequency artifact contamination. Also, investigate the correspondence of detected ripples and the seizure onset zone (SOZ).

Microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm: naunces of the technique based on experiences with 100 patients and review of the literature

Background

Microvascular decompression (MVD) surgery for trigeminal neuralgia and hemifacial spasm offers a relatively low-risk opportunity to treat cranial nerve hyperactivity-compression syndromes, which are associated with severe, disabling facial pain and spasm. Although a number of publications have described the technique in detail, combining the technical nuances from different schools of thought or neurosurgical training in an effort to increase the safety and efficacy of this procedure would be beneficial to the surgeon.

Methods

The nuances of technique and operative findings from performing this procedure for the last 100 cases have been reviewed and combined. The author has reflected on his experience performing microvascular decompression operation.

Findings

The specifics of operating room set-up, positioning, craniotomy, and intradural microsurgical methods are provided, including managing postoperative care and complications.

Conclusion

In the presence of alternative methods of therapy, microvascular decompression operations should be performed with low risk to the patient. There is a learning curve involved with this operation and the surgeon should remain always critical of his/her performance and aspire for a “perfect” result.     

Non-harmonicity in high-frequency components of the intra-operative corticogram to delineate epileptogenic tissue during surgery

Objective

We aimed to test the potential of auto-regressive model residual modulation (ARRm), an artefact-insensitive method based on non-harmonicity of the high-frequency signal, to identify epileptogenic tissue during surgery.

Left mesiotemporal lesions and anterograde memory impairement: a case of neurosyphilis

Introduction

Neurosyphilis has become uncommun in the developed countries.

Observation

We report a case of neurosyphilis with limbic presentation, left mesiotemporal lesions on MRI and severe anterograde amnesia.

Discussion

Pathogeneses of MRI findings are unknown. We suggest the implication of arteritis wich affects small vessels, parenchymatous and excitotoxic lesions. The absence of mesiotemporal lesion in immunodeficient patients, the limbic systematization of pathology underlines the involvement of probably auto-immune process. Neurosyphilis should always be considered in the differential diagnosis of limbic encephalitis in order to initiate treatment and to prevent cognitives sequelaes. At last, partial status epilepticus should be diagnosed and excitotoxicity lesions prevents with antiepileptic treatment.     

Differences in findings of nocturnal polysomnography and multiple sleep latency test between narcolepsy and idiopathic hypersomnia

Objectives

To compare differences in nocturnal and daytime polysomnographic findings between narcolepsy (NA) with and without cataplexy (CA) and idiopathic hypersomnia without long sleep time (IHS w/o LST).

Methods

Nocturnal polysomnography (n-PSG) and multiple sleep latency test (MSLT) findings were compared among subjects with NA with CA (n = 52), NA without CA (n = 62), and IHS w/o LST (n = 50).

Results

The NA with CA group had significantly more disrupted and shallower nocturnal sleep than the other groups. On MSLT, the IHS w/o LST group had significantly longer sleep latency (SL) compared with the two NA groups. The latter two groups did not show statistical differences in diurnal variation of SL.

Conclusions

The IHS w/o LST group had milder objective daytime sleepiness compared with the NA groups. In patients with NA, nocturnal sleep disturbances appeared only in cases with CA, despite a similar trend in diurnal changes in sleep propensity between the two NA groups.

Significance

Objective nocturnal sleep disturbances are specific to NA patients with CA, whereas diurnal variations of sleep propensity are observed irrespective of the presence of CA among NA patients. These findings could be helpful for choosing optimal treatment plans for patients with these disorders.