Biomedical subjects

L Nobili

Publications and source records attributed to L Nobili.

At least 19 recordsLinked to original sources

PubMed2006

Surgical treatment of drug-resistant nocturnal frontal lobe epilepsy.

Of the cases with nocturnal frontal lobe epilepsy (NFLE) approximately 30% are refractory to antiepileptic medication, with several patients suffering from the effects of both ongoing seizures and disrupted sleep. From a consecutive series of 522 patients operated on for drug-resistant focal epilepsy, 21 cases (4%), whose frontal lobe seizures occurred almost exclusively (>90%) during sleep, were selected. All patients underwent a comprehensive pre-surgical evaluation, which included history, interictal EEG, scalp video-EEG monitoring, high-resolution MRI and, when indicated, invasive recording by stereo-EEG (SEEG). There were 11 males and 10 females, whose mean age at seizure onset was 6.2 years, mean age at surgery was 24.7 years and seizure frequency ranged from <20/month to >300/month. Nine patients reported excessive daytime sleepiness (EDS). Prevalent ictal clinical signs were represented by asymmetric posturing (6 cases), hyperkinetic automatisms (10 cases), combined tonic posturing and hyperkinetic automatisms (4 cases) and mimetic automatisms (1 case). All patients reported some kind of subjective manifestations. Interictal and ictal EEG provided lateralizing or localizing information in most patients. MRI was unrevealing in 10 cases and it showed a focal anatomical abnormality in one frontal lobe in 11 cases. Eighteen patients underwent a SEEG evaluation to better define the epileptogenic zone (EZ). All patients received a microsurgical resection in one frontal lobe, tailored according to pre-surgical evaluations. Two patients were operated on twice owing to poor results after the first resection. Histology demonstrated a Taylor-type focal cortical dysplasia (FCD) in 16 patients and an architectural FCD in 4. In one case no histological change was found. After a post-operative follow-up of at least 12 months (mean 42.5 months) all the 16 patients with a Taylor's FCD were in Engel's Class Ia and the other 5 patients were in Engel's Classes II or III. After 6 months post-surgery EDS had disappeared in the 9 patients who presented this complaint pre-operatively. It is concluded that patients with drug-resistant, disabling sleep-related seizures of frontal lobe origin should be considered for resective surgery, which may provide excellent results both on seizures and on epilepsy-related sleep disturbances. An accurate pre-surgical evaluation, which often requires invasive EEG recording, is mandatory to define the EZ. Further investigation is needed to explain the possible causal relationships between FCD, particularly Taylor-type, and sleep-related seizures, as observed in this cohort of NFLE patients.

Adolescent↗

PubMed2006

Stereo-EEG in children.

BACKGROUND: Stereotactic placement of intracerebral multilead electrodes for chronic EEG recording of seizures or stereoelectroencephalography (SEEG) was introduced 50 years ago at Saint Anne Hospital in Paris, France for the presurgical evaluation of patients with drug-resistant focal epilepsy. SEEG explorations are indicated whenever the noninvasive tests fail to adequately localize the epileptogenic zone (EZ). INDICATIONS: Currently, approximately 35% of our operated-on children require a SEEG evaluation. Arrangement of electrodes is individualized according to the peculiar needs of each child, to verify a predetermined hypothesis of localization of the EZ based on pre-SEEG anatomo-electro-clinical findings. Multilead intracerebral electrodes are designed to sample cortical structures on the lateral, intermediate, and mesial aspect of the hemisphere, as well as deep-seated lesions. Stereotactic stereoscopic teleangiograms and coregistered 3-D MRI are employed to plan avascular trajectories and to accurately target the desired structures. Pre-SEEG stereotactic neuroradiology and electrode implantation are usually performed in separate procedures. Electrodes are removed once video-SEEG monitoring is completed. INTRACEREBRAL ELECTRICAL STIMULATIONS: Intracerebral electrical stimulations are used to better define the EZ and to obtain a detailed functional mapping of critical cortical and subcortical regions. MORBIDITY: Surgical morbidity of SEEG is definitely low in children. SEEG-GUIDED RESECTIVE SURGERY: In 90% of evaluated children, SEEG provides a guide for extratemporal or multilobar resections. SEEG-guided resective surgery may yield excellent results on seizures with 60% of patients in Engel's Class I.

Brain Mapping↗

PubMed2005

Intracerebral recordings of minor motor events, paroxysmal arousals and major seizures in nocturnal frontal lobe epilepsy.

The clinical features of nocturnal frontal lobe epilepsy (NFLE) consist of a spectrum of paroxysmal motor manifestations ranging from minor motor events (MMEs) to paroxysmal arousals (PAs) and major seizures. During MMEs and PAs scalp EEG generally does not show definite ictal abnormalities. We describe the clinical and electrophysiological features of three patients affected by drug-resistant NFLE studied with intracerebral electrodes during a presurgical evaluation. The stereo-EEG (SEEG) investigation revealed that MMEs can be fragments of the major seizure and occur during a brief epileptic discharge or on the following arousal. PAs, in the same subject, do not show a definite stereotypy despite the morphological and topographic similarity of the epileptic discharges, thus indicating that other variables may influence the clinical features of PAs.

Adult↗

PubMed2005

Sleep-related hyperkinetic seizures: always a frontal onset?

Hyperkinetic seizures are considered a typical manifestation of nocturnal frontal lobe epilepsy (NFLE). Patients with temporal lobe epilepsy with mainly sleep-related seizures have been described; however they commonly lack hyperkinetic activity and seizure frequency is low. We retrospectively analysed our population of 442 consecutive patients surgically treated between January 1996 and January 2004. Among these there were 25 patients with sleep-related hyperkinetic epileptic seizures, with a frontal lobe onset in 18 cases and a temporal lobe onset in 7. Patients with sleep-related hyperkinetic seizures with temporal lobe origin had anamnestic and clinical features strikingly similar to those with a frontal onset, with agitated movements, high seizure frequency and no history of febrile convulsions. We confirm our previous findings that this kind of epileptic manifestation is not only peculiar to frontal lobe epilepsy.

Adolescent↗

PubMed2004

Sleep-related hyperkinetic seizures of temporal lobe origin.

Sleep-related hyperkinetic seizures are a common feature of nocturnal frontal lobe epilepsy. Although sleep-related seizures with a temporal lobe origin have been reported, they commonly lack hyperkinetic activity. The authors describe three patients with sleep-related seizures characterized by frenetic, agitated, hyperactive movements (bimanual/bipedal activity, rocking, axial, pelvic, and hemiballistic movements), in whom stereo-EEG investigation and surgical outcome demonstrated a temporal lobe origin of the attacks.

Adult↗

PubMed2001

The contributing role of sleepiness in highway vehicle accidents.

STUDY OBJECTIVE: To evaluate the contributing role of sleepiness in Italian highway vehicle accidents during the time span 1993-1997. DESIGN: We analyzed separately the hourly distribution of accidents ascribed by police officers univocally to sleepiness and the rest. PATIENTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS: Using a polynomial regression, we evaluated the relation between accidents (whether sleep-ascribed or not) and sleepiness as derived from a 24-hour sleep propensity curve. The relation between sleep-influenced and non-sleep influenced accidents was analysed using a linear regression. RESULTS: The rate of non-sleep ascribed accidents is closely related with sleep propensity and bears a strong similarity with the pattern of sleep-ascribed accidents. A close relationship between the curves of non-sleep ascribed accidents and sleep-ascribed accidents is confirmed. The regression coefficient, which can be seen as the ratio between the quota of accidents that can be considered as sleep affected and those actually ascribed to sleepiness, results in a value of 5.83. Considering that the rate of sleep ascribed accidents is 3.2%, we can calculate the quota of sleep influenced accidents out of those not officially ascribed to sleepiness as 18.7% reaching an estimate of accidents related in some way to sleepiness equal to 21.9%. CONCLUSIONS: Our indirect estimate of sleep influenced accidents approaches data reported by other European countries and highlights the importance of sleepiness as a direct and/or contributing factor in vehicle accident rates.

Accidents, Traffic↗

PubMed2001

Distribution of epileptiform discharges during nREM sleep in the CSWSS syndrome: relationship with sigma and delta activities.

PURPOSE: The EEG pattern of epilepsy with continuous spike-waves during slow wave sleep (CSWSS) is characterized by an almost continuous activation of spike-and-slow-wave complexes during nREM sleep with a marked reduction of EEG abnormalities during REM sleep and the awake state. Experimental studies indicate that normal sleep oscillations that during nREM sleep lead to the appearance of spindles and delta waves on scalp EEG might develop into paroxysmal synchronization. Spectral analysis enables the quantitative description of the dynamics of delta (Delta Activity, DA, 0.5-4.5 Hz) and sigma activity (SA, 12-16 Hz) and can be used to assess the relationship between SA, DA and epileptiform discharges (EDs) during sleep. METHODS: We analyzed the EDs distribution during sleep in five children affected by CSWSS. We used a model of the evolution of power of DA and SA to which the time series of EDs could be fitted. RESULTS: We found a high and positive correlation between EDs and SA. DA resulted negatively correlated with EDs. CONCLUSION: Our data suggest that neural mechanisms involved in the generation of sleep spindles facilitate EDs production in the CSWSS syndrome. Such a mechanism seems to be an age related phenomenon shared by other epileptic syndromes of childhood.

Child↗

PubMed2001

Factor structure and ammonia-related modulation of the human retinal oscillatory potentials.

OBJECTIVE: To investigate in man the factor structure of retinal oscillatory potentials (OPs) to full-field luminance stimulation (0.9-9.5 cd.s.m(-2)) and the correlation with the spontaneous fluctuations of plasma ammonia. METHODS: Six male healthy volunteers were studied. Five OP recordings and ammonia determinations (GLDH method) were obtained for each subject at 2 h interval during an 8 h experimental session. A standard factor analysis was applied on the OP latency (time from stimulus to peak) and amplitudes values. RESULTS: Two consecutive factors on latencies and two factors on amplitudes were identified, consistent with reported differences between the earlier and later OP waves. The model explained a large portion of the OP variance. Both factors on latencies and factor 1 on amplitudes were directly correlated to the stimulus intensity and the ammonia plasma concentration in the 15.8-39.5 micromol/l range. Factors 1 and 2 on latencies decreased and factor 1 on amplitude increased at increasing stimulus intensities. The latency factors decreased and the amplitude factor increased with increasing ammonia concentration. Factor 2 on amplitudes did not correlate with the stimulus intensity or ammonia concentration. CONCLUSIONS: The factor structure further supports the evidence of functional differences between early and late OP waves. The observed correlation conceivably reflects a role of ammonia in the modulation of retinal electrophysiology in physiological conditions and potentially accounts for spontaneous variability in otherwise controlled electrophysiological studies.

Adult↗

PubMed2001

Hypersomnia in the Prader Willi syndrome: clinical-electrophysiological features and underlying factors.

OBJECTIVE: Excessive daytime sleepiness is a common symptom in Prader Willi syndrome (PWs). Sleep disordered breathing (SDB) and narcoleptic traits such as REM sleep onsets (SOREMPs) have been reported in these subjects. We evaluated nighttime and daytime sleep patterns in patients with PWs in order to clarify the nature of their hypersomnia. DESIGN AND METHODS: We performed overnight continuous EEG-polysomnographic studies (with breathing monitoring included) in 14 subjects (6 M,8 F; mean age 17 years, range 8-37) affected by PWs unselected for sleep disturbances. Ten patients underwent a Multiple Sleep Latency Test (MSLT) the day following the nocturnal sleep studies. Patients assessment was completed by means of immunogenetic characterization. RESULTS: Nocturnal polysomnographic investigation documented sleep related breathing abnormalities such as central apneas, hypopneas or hypoventilation which mainly occurred during REM sleep in 8 subjects and did not cause sleep disruption. Only 4 subjects presented an increase in the Respiratory Disorder Index (RDI) slightly above the normal limits. In 8 subjects out of 10, with and without SDB, the mean daytime sleep latency could be considered abnormal according to the Tanner staging of pubertal development. Five patients showed at least two SOREMPs at MSLT. Subjects with and without SOREMPs had, respectively, a mean age of 18.6 SD 7.9 (4 M, 1 F) and 14.5 SD 2.9 (4 F, 1 M). The paternal deletion:uniparental dysomy ratio at genotypic characterization was 4:1 and 3.5:1 in subjects with and without SOREMPs, respectively. No patient presented DR-15 nor Dq-6. CONCLUSIONS: Excessive sleepiness is a frequent disturbance in PWs. Subgroups of PW patients show hypersomnolence and SOREMPs. Sleep disordered breathing appears to have a limited role in the genesis of hypersomnia which not seems on the other hand attributable to the coexistence of narcolepsy phenotype. Hypersomnia in PW syndrome is likely to mainly be attributable to a primary hypothalamic dysfunction. The potential interacting role of other factors such as subjects age, sex and genetic pattern is suggested and deserve further investigation.

Adolescent↗

PubMed2001

Absence of sleep EEG markers in fatal familial insomnia healthy carriers: a spectral analysis study.

OBJECTIVES: Fatal familial insomnia (FFI) is linked to a mutation at codon 178 (C178) of the prion protein gene (PRNP). FFI is pathologically characterized by selective atrophy of the anteroventral and mediodorsal thalamic nuclei and clinically by loss of sleep, dysautonomia and motor signs. A key early polysomnographic sign of the disease onset is the loss of sleep spindling (sigma activity, SA). In FFI the loss of SA leads to the spectral representation of a sudden slow wave activity (SWA) increase from an awake state, the reaching of a stable plateau without oscillations, followed by abrupt fall down to REM sleep. We evaluated the presence of differences in the spectral sleep EEG pattern in FFI relatives carriers (C178(pos)) or non-carriers (C178(neg)) of the C178 mutation. METHODS: Seventeen healthy relatives of FFI patients, 8 carriers of the C178 FFI mutation in a preclinical condition and 9 non carriers, underwent two-night polysomnography. The absolute and relative EEG power of the 4 main bands (delta: SWA, 0.5-4.0 Hz; theta: TB, 4.5-8 Hz; alpha: AB, 8.5-12 Hz; sigma: SA, 12.5-16 Hz) has been studied for the total sleep time, the period of delta increase after sleep onset, and the period of delta plateau. Multiple regression has been applied to investigate relations between the power of the bands studied and 3 parameters: age, the gender of the subjects and the C178 genotype. RESULTS: Our study could not show evidence of differences in the sleep EEG composition between carriers and non-carriers of the C178 FFI mutation. CONCLUSIONS: The spectral analysis techniques we used were not able to disclose sleep EEG markers linked to the FFI C178(pos) in the preclinical condition. Key sleep EEG alteration become evident only at the clinical onset of the disease.

Adult↗

PubMed2001

Temporal relationship of generalized epileptiform discharges to spindle frequency activity in childhood absence epilepsy.

OBJECTIVE: The hypothesis that the two main synchronizing mechanisms (spindle and delta oscillations) acting during non-rapid eye movement sleep show opposite relationship with the distribution of generalized epileptiform discharges (GEDs) during sleep was evaluated. METHODS: We studied the temporal relationship between the distribution of sleep GEDs and the dynamics of Sigma Activity (SA, 12-16 Hz) and Delta Activity (DA, 0.5-4.5 Hz) in 5 children affected by childhood absence epilepsy. RESULTS: Using correlation techniques, we found a high and positive correlation between GEDs and SA, while DA resulted negatively correlated with GEDs. CONCLUSION: Sleep generalized spike-and-slow-waves seems to be produced when spindle synchronizing mechanisms are active while DA production seem to exert an inhibiting role. Such a feature seems to be common to other childhood partial and undetermined epileptic syndromes.

Child↗

PubMed2001

Neuropsychological disorders related to interictal epileptic discharges during sleep in benign epilepsy of childhood with centrotemporal or Rolandic spikes.

Nine children (five males, four females; age range 6 years 1 month to 11 years 1 month) affected by benign epilepsy of childhood with centrotemporal or Rolandic spikes (BECRS) with EEG evidence of marked activation of interictal epileptic discharges (IEDs) during sleep, and nine unaffected control children matched for age, sex, and socioeconomic status, were enrolled in a prospective study. At the time of detection of IED activation during sleep, patients showed a mean Full-Scale IQ score within the normal range, but significantly below that of control participants; neuropsychological assessment revealed disorders in visuospatial short-term memory (Corsi's Block Tapping Test), attention, and cognitive flexibility (Trail Making Test and Stroop Color-Word Test), picture naming, and fluency (Benton's Naming Test and Word Fluency), visuoperceptual skill (Ghent-Poppelreuter and Street Gestalt Completion Tests) and visuomotor coordination (Bender Test). After detection of IED activation during sleep, children were followed up for 2 years. At the time of IED remission (T1), neuropsychological re-evaluation showed a notable increase in IQ score and a significant improvement (t-test: p<0.007) in visuomotor coordination, non-verbal short-term memory, sustained attention and mental flexibility, picture naming, and visual-perceptual performance. At T1, patients' performance did not differ from the controls (Mann-Whitney U test).

Anticonvulsants↗

PubMed2001

Benign parasomnias and nocturnal frontal epilepsy: differential diagnosis in a case report.

We report the case of a 13-year-old boy who complained of complex motor episodes during sleep characterized by sudden arousal followed by deambulation associated with automatic movements and vocalization. His family history included both epileptic and psychiatric disorders. The patient himself presented psychopathologic traits and adaptive difficulties. In support of an epileptic origin of these phenomena were the stereotyped fashion in which they appeared and their responsiveness to carbamazepine. We classified the present case as a nocturnal frontal epilepsy with variable manifestations that can be classified as paroxysmal arousals, paroxysmal dystonia, and epileptic nocturnal wanderings. It was possible to differentiate such events from the most common parasomnias on the basis of videopolysomnographic studies.

Adolescent↗

PubMed2001

Nocturnal sleep features in narcolepsy: a model-based approach.

The internal structure of night sleep in subjects with narcolepsy significantly differs as compared to the controls. The differences consist in the presence of sleep onset REM periods (SOREMPs) and in a longer duration (120 minutes versus 90 minutes) of the NREM-REM cycles. Another difference consists in the lack of increase in REM sleep duration during the night, cycle after cycle. These characteristics, taken as a whole, suggest that the sleep structure of narcoleptic patients is due to an imbalance between the homeostatic process and the enhanced pressure of REM inducing mechanisms. With regard to the intrasleep dynamics the current extension of the Two-process model cannot give a satisfactory explanation because REM sleep is included as an external trigger with no intrinsic rhythmic property. Neurobiologic studies lead to consider the REM cyclic occurrence as the result of reciprocal interaction between two populations of REM-ON and REM-OFF cells. The introduction in the Two-process-model extended to the intra-night dynamics of an ultradian oscillator, based on a REM-ON--REM-OFF reciprocal interaction, allows the theoretical possibility to simulate a SOREMP. This revised model accounts for the progressive extension of REM sleep-periods duration in the course of the night. The sleep structure of narcoleptic patients can be simulated leaving unaltered the pressure of the homeostatic process and enhancing the REM inducing pressure. Such an enhanced REM pressure can be achieved by increasing the value of the numerical coefficient, which represents the strength of connection between the two types of REM-ON and REM-OFF cells. This modification allows not only to obtain a stronger ultradian oscillator but also a longer periodicity of REM sleep occurrence. By coupling the homeostatic process, considered as normal, to such a modified ultradian oscillator, our model can explain the intra-night sleep dynamics of narcoleptic subjects. A REM-ON REM-OFF dysregulation can be hypothesized to explain the pathophysiological basis of nocturnal sleep features in narcolepsy.

Activity Cycles↗

PubMed2001

Sleepiness in a population of Italian shiftwork policemen.

The aim of this study was to evaluate the effects of shiftwork on sleepiness, sleep disorders and sleep related accidents in a population of policemen. Data concerning age and physical characteristics, working conditions, sleep problems and accidents were collected by a questionnaire. Sleepiness was evaluated by the Epworth Sleepiness Scale (ESS) while the presence of sleep disorders was evaluated by a score (SD-score) drawn from indicators of insomnia, breathing disorders, periodic limb movements-restless leg syndrome and hypersomnia. The effects of age, gender, body mass index, working condition and seniority on ESS, SD-score and accidents were analysed by linear and logistic regression. Participants were 1280 policemen: 611 shiftworkers and 669 non-shiftworkers. The ESS scores were not higher in shiftworkers than in non-shiftworkers, but the SD-score was found to be significantly influenced by shiftwork condition and seniority. The occurrence of sleep-related accidents was found to have been significantly increased for shiftworkers and related to the presence of indicators of sleep disorders. The sleepiness could be underestimated or even overcome by the influence of stressing conditions. However our data should alert occupational health physicians for the diagnosis and prevention of possible lurking intrinsic sleep disorders likely to influence health problems and risk of accidents in shiftworkers.

Accidents, Occupational↗

PubMed2000

Relationship of sigma activity to sleep interictal epileptic discharges: a study in children affected by benign epilepsy with occipital paroxysms.

INTRODUCTION: By applying spectral analysis techniques we recently showed that Interictal Epileptic Discharges (IEDs) are modulated by sleep spindle synchronization mechanisms (sigma activity, SA, 12. 0-16.0 Hz). This finding applies to both benign epilepsy of childhood with rolandic spikes (BECRS), to symptomatic epilepsy of childhood strongly activated by sleep and to the Landau-Kleffner syndrome. These results are quite different from those found in adult partial epileptic patients where slow wave activity (SWA, 0. 5-4.5 Hz) plays the main role in the modulation of IEDs during sleep. This finding could suggest that the activation of IEDs by spindle activities could be an age-related feature of epilepsy. In order to verify this hypothesis we studied a group of epileptic children performing a polysomnographic study on five patients with BEOP strongly activated by sleep. METHODS: We performed overnight continuous EEG-polysomnographic studies in five patients (mean age 6. 0+/-2.5). The IEDs count was performed on the most active occipital lead. The temporal series of SWA and SA values, derived from spectral analysis, were obtained from a spike-free central, controlateral lead. Relationships between SA, SWA and time series of IEDs were tested by means of correlation techniques after data normalization. RESULTS: Our results revealed a significantly higher correlation between IEDs and SA with respect to SWA in all subjects, in total sleep time. When the analysis was limited only to NREM sleep the correlation between sigma and IEDs was even more impressive. CONCLUSIONS: Data suggest that also in BEOP the spindle generating mechanism modulates the IEDs during sleep. This mechanism seems to be an age-dependent phenomenon with no relation whatsoever either with the type of epilepsy or with the brain region.

Child↗

PubMed2000

Sleep-EEG modulation of interictal epileptiform discharges in adult partial epilepsy: a spectral analysis study.

INTRODUCTION: In order to define accurately the relationship between EEG components (spindles, delta and theta frequencies) and the occurrence of interictal epileptiform discharges (IED) during sleep in partial epilepsy, a correlation study between spike overnight distribution and EEG spectral power time series was performed. METHODS: Eighteen patients (mean age: 24.7+/-5.5 years) affected by partial epilepsy underwent continuous EEG-polysomnography. The temporal series of Slow Wave Activity (SWA), Sigma Activity (SA) and Theta Band (TB), derived from spectral analysis, were obtained from a spike-free and pathologic alteration-free derivation, contralateral to the most active lead, where the IED count was performed. Relationships between SA, SWA and TB and time series of IED were tested by means of correlation techniques after data normalization. RESULTS: Our results revealed a significantly higher correlation between IED and SWA in 12 subjects; a significantly higher correlation between IED and SA in three subjects and a significant correlation with TB in three cases. CONCLUSIONS: Data suggest that in most adult patients with partial epilepsy IED production during sleep is facilitated by the action of synchronizing mechanisms which are active during NREM sleep and lead to the appearance of EEG delta waves. Nevertheless evidence is given of two smaller groups of patients. In one of them IED are more sensitive to the promoting action of the spindle generating mechanism, active during stage 2 of NREM sleep. In the other one the promoting action of TB, characterizing EEG during stage 1 and REM sleep, is evident.

Adult↗

PubMed2000

Sleep EEG synchronization mechanisms and activation of interictal epileptic spikes.

OBJECTIVE: The temporal course of sleep interictal epileptic discharges (IEDs) has been studied focusing their relationship with the temporal course of the main sleep-EEG frequency bands that is thought to reflect the action of different synchronization neural mechanisms. The existence of a mutually exclusive mechanism between spindles and delta waves should be reflected in a mutually exclusive facilitation of IEDs activation by slow wave activity (SWA) and sigma activity (SA) during synchronized NREM sleep. METHODS: We reanalyzed data from 19 children and 15 adult patients affected by different partial epileptic syndromes. The temporal series of SWA, SA and theta band (TB), derived from spectral analysis, were obtained from a spike-free and pathologic alteration-free derivation, controlateral to the most active lead, where the IEDs count was performed. Relationships between SA, SWA and TB and time series of IEDs were tested by means of correlation techniques after data normalization. RESULTS: A positive correlation of spike distribution with SWA time course has been found in the majority of adults. Only a few adult patients showed IEDs that were correlated with SA or TB. Conversely SA was shown to be positively correlated with spiking in many different epileptic syndromes of childhood. Moreover, in the contest of the NREM sleep cycle an inverse relationship between the SWA and SA mode of spike activation has been detected. CONCLUSIONS: Overall results give evidence that 3 main rhythmic spectral components that characterize sleep EEG can exert positive influences on IEDs production. Our studies demonstrate that within NREM sleep the facilitating influences on IEDs production exerted separately by either spindle activity or delta synchronization mechanisms can be detected. Moreover, a mutually exclusive mechanism between SA and SWA oscillations is detectable in the opposite relationship of the correlation between IEDs and the two bands in the central part of the NREM cycle.

Brain↗