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More than 100 years of research have passed by and still the human electroencephalogram (EEG) remains a puzzle to be solved. Starting from his studies on plethysmography until his theories on brain thermodynamics, Hans Berger was able to refine his method of recording cortical signs with the apparatus at his disposal in an ordinary neuropsychiatric yard towards an early account of human EEG. This review is an appraisal of his contribution to the field of modern neurophysiology.

Mais de 100 anos se passaram e o eletroencefalograma humano (EEG) continua sendo um enigma a ser desvendado. A partir de seus estudos sobre pletismografia até suas teorias sobre termodinâmica cerebral, Hans Berger conseguiu refinar seu método de registro da atividade elétrica cortical com os equipamentos a sua disposição em uma ala psiquiátrica comum produzindo uma descrição acurada do EEG humano. Esta revisão é um breve resumo de sua contribuição para o campo da neurofisiologia moderna.

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Abstract More than 100 years of research have passed by and still the human electroencephalogram (EEG) remains a puzzle to be solved. Starting from his studies on plethysmography until his theories on brain thermodynamics, Hans Berger was able to refine his method of recording cortical signs with the apparatus at his disposal in an ordinary neuropsychiatric yard towards an early account of human EEG. This review is an appraisal of his contribution to the field of modern neurophysiology.

Resumo Mais de 100 anos se passaram e o eletroencefalograma humano (EEG) continua sendo um enigma a ser desvendado. A partir de seus estudos sobre pletismografia até suas teorias sobre termodinâmica cerebral, Hans Berger conseguiu refinar seu método de registro da atividade elétrica cortical com os equipamentos a sua disposição em uma ala psiquiátrica comum produzindo uma descrição acurada do EEG humano. Esta revisão é um breve resumo de sua contribuição para o campo da neurofisiologia moderna.

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OBJECTIVES: To determine the association of anti-seizure medication (ASM) treatment with outcomes in acute ischemic stroke (AIS) patients undergoing continuous electroencephalography (cEEG). METHODS: Retrospective analysis of AIS patients admitted between 2012 and 2019. The following are the inclusion criteria: age ≥ 18 years and ≥ 16 h of cEEG within the first 7 days of admission. ASM treatment exposure was defined as > 48 h of treatment after the first 24 h of cEEG. The primary outcome measure was 90-day mortality, and the secondary outcome was 90-day functional recovery (Modified Ranking Scale 0-3). Propensity scores were used to adjust for baseline covariates and presence of epileptiform abnormalities (seizures, periodic and rhythmic patterns). RESULTS: One hundred thirteen patients met the inclusion criteria; 39 (34.5%) were exposed to ASM. ASM treatment was not associated with 90-day mortality (propensity adjusted HR 1.0 [0.31-3.27], p = 0.999) or functional outcomes (adjusted HR 0.99 [0.32-3.02], p = 0.989), compared to no treatment. CONCLUSIONS: In our study, ASM treatment in AIS patients with cEEG abnormalities was not significantly associated with a change in 90-day mortality and functional recovery. Larger comparative effectiveness studies are indicated to identify which acute ischemic stroke patients with cEEG abnormalities benefit most from ASM treatment.

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SUMMARY: Zika virus (ZIKV) has been shown to be highly neurotropic; neurologic disorders are a common complication of this infection. Encephalitis-an inflammation of the brain parenchyma associated with neurologic dysfunction-is a rare complication of ZIKV infections. It affects patients from young to elderly ages. Clinical presentation of ZIKV encephalitis may be heterogeneous, including altered mental status (decreased or altered level of consciousness, lethargy, or personality change), seizures, and focal deficits. Complementary diagnostic investigation should include neuroimaging, lumbar puncture, and EEG. Neuroimaging findings in ZIKV encephalitis are not specific and may be diverse, including normal findings, hyperintense lesions on MRI involving cortical or subcortical structures, symmetric or asymmetric lesions involving supra or infratentorial regions, and more widespread involvement such as brain swelling. A remarkable scarcity of neurophysiological data on ZIKV encephalitis was found in the literature. In line with other diagnostic examinations, there are no neurophysiological findings suggestive or specific of the disease. EEG in ZIKV encephalitis showed different results: normal or diffuse disorganization of background activity, asymmetry with abnormal focal slow waves, focal epileptic discharges or generalized spike-wave and multispike-wave complexes, and periods of generalized voltage attenuation.

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PURPOSE: Self-limited epilepsy with centrotemporal spikes, formerly called benign epilepsy with centrotemporal spikes, or rolandic epilepsy, is an age-related and well-defined epileptic syndrome. Since seizures associated with rolandic spikes are infrequent and usually occur during sleep, and repetitive or prolonged EEG recording for diagnostic purposes is not necessary for diagnosis, reports of ictal video-electroencephalographic seizures in this syndrome are rare. We aimed to show ictal video-EEG of typical rolandic seizures. METHODS: We report the ictal video-EEG recordings of two children with rolandic epilepsy who presented typical rolandic seizures during routine recording. RESULTS: Case 1: A 9-year-old boy, with normal development, had his first seizure at 8 years old, characterized by paresthesia in his left face, blocking of speech, and drooling. Carbamazepine was started with seizure control. Case 2: A 10-year-old boy, with normal development, started with focal seizures during sleep, characterized by eye and perioral deviation, and speech arrest at age of 7. He started using oxcarbazepine. Both patients underwent routine electroencephalography for electroclinical diagnosis and presented a seizure. CONCLUSION: Although self-limited epilepsy with centrotemporal spikes is a very common epileptic syndrome, seizure visualization is very difficult, and these videos may bring didactical information for recognition of this usual presentation of benign childhood focal epilepsy.

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PURPOSE: In comatose patients, distinguishing between nonconvulsive status epilepticus and diffuse structural or metabolic encephalopathies is often challenging. Both conditions can generate periodic discharges on EEG with similar morphology and periodicity. We investigated the occurrence of high-frequency oscillations-potential biomarkers of epileptogenesis-on scalp EEG of comatose patients with periodic discharges in the EEG. METHODS: Fifteen patients were included. Patients were divided into three groups, according to underlying etiology: Group 1, seizure related; group 2, structural; group 3, nonstructural. EEG recordings were compared with respect to the presence and rates of gamma (30-80 Hz) and ripples (80-250 Hz). RESULTS: Patients were 23 to 106 years old (median, 68 years); 60% were female. 206 channels were eligible for analysis (median, 15 channels/patient). Overall, 43% of channels showed gamma, and 24% had ripples. Group 2 showed the highest proportion of channels with gamma (47%), followed by group 1 (38%) and group 3 (36%). Mean gamma rates were higher in group 2 (4.65 gamma/min/channel) than in group 1 (1.52) and group 3 (1.44) (P < 0.001). Group 2 showed the highest proportion of channels with ripples (29.2%), followed by group 1 (15%) and group 3 (24.2%). Mean ripple rates were higher in group 2 (5.09 ripple/min/channel) than in group 1 (0.96) and group 3 (0.83) (P < 0.001). CONCLUSIONS: Fast oscillations, including high-frequency oscillations, can be detected in scalp EEG of patients with altered consciousness. High rates of fast activity may suggest an underlying structural brain lesion. Future studies are needed to determine whether fast oscillations in the setting of acute/subacute brain lesions are a biomarker of subsequent development of human epilepsy.

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Myoclonic status epilepticus (MSE) in patients without epilepsy, or de novo MSE, is a rare condition associated with several acute symptomatic etiologies, including drugs and toxins. We describe a 94-year-old woman with Alzheimer dementia and long use of mirtazapine 30 mg/d and alprazolam 1 mg/d who developed MSE approximately 24 hours after abrupt discontinuation of alprazolam. The patient was taking sulfamethoxazole/trimethoprim for urinary tract infection, diagnosed 2 weeks before admission. She had no history of seizures. Routine laboratory examinations were normal and head computed tomography showed no acute injuries. She received a loading dose of 1000 mg of intravenous valproate (VPA). Continuous electroencephalogram monitoring revealed very frequent generalized spikes and polyspikes in a markedly slowed background activity. Intravenous VPA 500 mg thrice a day and alprazolam 0.5 mg twice a day were prescribed, and antibiotic was switched to piperacillin/tazobactam. Myoclonic jerks ceased completely and electroencephalogram showed no epileptiform discharges 2 days after VPA treatment onset, with recovery of baseline neurological status. This is, to the best of our knowledge, the first report of de novo MSE related to abrupt discontinuation of benzodiazepines. Seizures and status epilepticus are potential adverse events after abrupt withdrawal of chronically used benzodiazepines, especially in conditions with intrinsic epileptogenic susceptibility, such as Alzheimer disease.

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INTRODUCTION: Nonconvulsive seizures (NCS) are frequent in hospitalized patients and may further aggravate injury in the already damaged brain, potentially worsening outcomes in encephalopathic patients. Therefore, both early seizure recognition and treatment have been advocated to prevent further neurological damage. OBJECTIVE: Evaluate the main EEG patterns seen in patients with impaired consciousness and address the effect of treatment with antiepileptic drugs (AEDs), continuous intravenous anesthetic drugs (IVADs), or the combination of both, on outcomes. METHODS: This was a single center retrospective cohort study conducted in a private, tertiary care hospital. Consecutive adult patients with altered consciousness submitted to a routine EEG between January 2008 and February 2011 were included in this study. Based on EEG pattern, patients were assigned to one of three groups: Group Interictal Patterns (IP; EEG showing only interictal epileptiform discharges or triphasic waves), Group Rhythmic and Periodic Patterns (RPP; at least one EEG with rhythmic or periodic patterns), and Group Ictal (Ictal; at least one EEG showing ictal pattern). Groups were compared in terms of administered antiepileptic treatment and frequency of unfavorable outcomes (modified Rankin scale ≥3 and in-hospital mortality). RESULTS: Two hundred and six patients (475 EEGs) were included in this analysis. Interictal pattern was observed in 35.4% (73/206) of patients, RPP in 53.4% (110/206) and ictal in 11.2% (23/206) of patients. Treatment with AEDs, IVADs or a combination of both was administered in half of the patients. While all Ictal group patients received treatment (AEDs or IVADs), only 24/73 (32.9%) IP group patients and 55/108 (50.9%) RPP group patients were treated (p<0.001). Hospital length of stay (LOS) and frequency of unfavorable outcomes did not differ among the groups. In-hospital mortality was higher in IVADs treated RPP patients compared to AEDs treated RPP patients [11/19 (57.9%) vs. 11/36 (30.6%) patients, respectively, p = 0.049]. Hospital LOS, in-hospital mortality and frequency of unfavorable outcomes did not differ between Ictal patients treated exclusively with AEDs or IVADs. CONCLUSION: In patients with acute altered consciousness and abnormal routine EEG, antiepileptic treatment did not improve outcomes regardless of the presence of periodic, rhythmic or ictal EEG patterns.

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As opposed to focal epilepsy, absence seizures do not exhibit a clear seizure onset zone or focus since its ictal activity rapidly engages both brain hemispheres. Yet recent graph theoretical analysis applied to absence seizures EEG suggests the cortical focal presence, an unexpected feature for this type of epilepsy. In this study, we explore the characteristics of absence seizure by classifying the nodes as to their source/sink natures via weighted directed graph analysis based on connectivity direction and strength estimation using information partial directed coherence (iPDC). By segmenting the EEG signals into relatively short 5-sec-long time windows we studied the evolution of coupling strengths from both sink and source nodes, and the network dynamics of absence seizures in eight patients.

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PURPOSE: We conducted a retrospective study in order to investigate the clinical significance of temporopolar grey/white matter abnormalities (GWMA) in patients with temporal lobe epilepsy (TLE) and unilateral hippocampal sclerosis (HS) with a long post-surgical follow-up. METHODS: The study comprised 122 consecutive patients with medically refractory TLE and unilateral HS who underwent epilepsy surgery and had a minimum postoperative follow-up of 5 years. Patients were divided into two groups, based on findings of pre-surgical MRI: group 1 with GWMA and 2 with normal signal and grey/white matter definition in temporal pole. Demographic and clinical data were reviewed and compared between groups. RESULTS: GWMA were found in 52.5% of patients, always ipsilateral to HS. Compared with group 2, group 1 patients had earlier epilepsy onset (mean, 9.3 vs 14.4 years, P=0.001), a higher occurrence of first seizure ≤2 years of age (25.8% vs 10.5%, P=0.036; OR=2.96 [95% CI=1.07-8.19]), and greater prevalence of left HS (76.6% vs 43.1%, P<0.001; OR=4.31 [95% CI=1.98-9.38]). No differences were found in gender, presence or type of initial precipitating injury, history of secondary generalized seizures, duration of epilepsy, seizure frequency before surgery, neuropsychological evaluation and presence or lateralization of pre-surgical interictal epileptiform discharges. Postoperative follow-up varied from 5 to 11.5 years (mean 7.4) and was similar in both groups (P=0.155). The proportion of patients classified as seizure-free (Engel class I) at last follow-up in groups 1 and 2 were 73.4% and 69%, respectively (P=0.689). Similarly, the percentages of seizure-free patients with no antiepileptic drugs at last evaluation were not different between groups (P=0.817). In logistic regression analysis, left HS (P=0.001; OR=4.166 [95% CI=1.86-9.34]) and age at epilepsy onset ≤2 years (P=0.047; OR=3.885 [95% CI=1.86-17.50]) were independently associated with risk of having GWMA. CONCLUSION: GWMA are frequent findings in patients with TLE and HS, and may help lateralize the epileptogenic zone. Our data support the hypothesis that GWMA are caused by seizure-related insults during the critical period of cerebral myelination. GWMA did not influence the postoperative seizure outcome of patients with TLE and HS, even after an extended duration of post-surgical follow-up.

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OBJECTIVES: To investigate whether different protocols of sleep deprivation modify sleep perception. METHODS: The effects of total sleep deprivation (TD) and selective rapid eye movement (REM) sleep deprivation (RD) on sleep perception were analyzed in normal volunteers. Thirty-one healthy males with normal sleep were randomized to one of three conditions: (i) normal uninterrupted sleep; (ii) four nights of RD; or (iii) two nights of TD. Morning perception of total sleep time was evaluated for each condition. Sleep perception was estimated using total sleep time (in hours) as perceived by the volunteer divided by the total sleep time (in hours) measured by polysomnography (PSG). The final value of this calculation was defined as the perception index (PI). RESULTS: There were no significant differences among the three groups of volunteers in the total sleep time measured by PSG or in the perception of total sleep time at baseline condition. Volunteers submitted to RD exhibited lower sleep PI scores as compared with controls during the sleep deprivation period (P <0.05). Both RD and TD groups showed PI similar to controls during the recovery period. CONCLUSION: Selective REM sleep deprivation reduced the ability of healthy young volunteers to perceive their total sleep time when compared with time measured by PSG. The data reinforce the influence of sleep deprivation on sleep perception.

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PURPOSE: Gender differences are recognized in the functional and anatomical organization of the human brain. Differences between genders are probably expressed early in life, when differential rates of cerebral maturation occur. Sexual dimorphism has been described in temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS). Several voxel-based morphometry (VBM) studies have shown that TLE-MTS extends beyond mesial temporal structures, and that there are differences in the extent of anatomical damage between hemispheres, although none have approached gender differences. Our aim was to investigate gender differences and anatomical abnormalities in TLE-MTS. METHODS: VBM5 was employed to analyze gender and hemispheric differences in 120 patients with TLE-MTS and 50 controls. RESULTS: VBM abnormalities were more widespread in left-TLE; while in women changes were mostly seen in temporal areas, frontal regions were more affected in men. CONCLUSIONS: Our study confirmed that gender and laterality are important factors determining the nature and severity of brain damage in TLE-MTS. Differential rates of maturation between gender and hemispheres may explain the distinct areas of anatomical damage in men and women.

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The idea that magnetic fields could be used therapeutically arose 2000 years ago. These therapeutic possibilities were expanded after the discovery of electromagnetic induction by the Englishman Michael Faraday and the American Joseph Henry. In 1896, Arsène d'Arsonval reported his experience with noninvasive brain magnetic stimulation to the scientific French community. In the second half of the 20th century, changing magnetic fields emerged as a noninvasive tool to study the nervous system and to modulate neural function. In 1985, Barker, Jalinous, and Freeston presented transcranial magnetic stimulation, a relatively focal and painless technique. Transcranial magnetic stimulation has been proposed as a clinical neurophysiology tool and as a potential adjuvant treatment for psychiatric and neurologic conditions. This article aims to contextualize the progress of use of magnetic fields in the history of neuroscience and medical sciences, until 1985.

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PURPOSE: The aim of the study was to report the seizure outcome, motor skills and adaptive motor functions in a series of children and adolescents who underwent hemispheric surgery, analysing the risk-benefits of surgery. METHODS: The clinical course, seizure and motor function outcomes of 15 patients who underwent hemispheric surgery were reviewed. RESULTS: The mean age at surgery was 9.5, with 1-9 years follow-up. The underlying pathologies were Rasmussen encephalitis, vascular disorders, and hemimegalencephaly. All the patients presented with severe epilepsy and different degrees of hemiparesis, although motor functionality was preserved in 80% of the patients. At last follow-up, 67% were seizure free, and 20% rarely experienced seizures. Antiepileptic drugs were reduced in 60%, and complete withdrawal from such drugs was successful in 20% of the patients. The motor outcome following the surgery varied between the patients. Despite the motor deficit after surgery, the post-operative motor function showed unchanged for gross motor function in most (60%), while 27% improved. Similar results were obtained for the ability to handle objects in daily life activities. Sixty percent of the children were capable of handling objects, with somewhat reduced coordination and/or motor speed. CONCLUSION: Pre-surgical motor function continues to play a role in the pre-surgical evaluation process in order to provide a baseline for outcome. Hemispheric surgery, once regarded as a radical intervention and last treatment resource, may become routinely indicated for refractory hemispheric epilepsy in children and adolescents, with oftentime favourable motor outcomes.

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The long-term outcome of chronic epilepsy remains largely unknown, despite a long historical experience. We report the lifelong course of epilepsy of an historical cohort of 235 subjects who were in residential care at the Chalfont Centre for Epilepsy: 122 had comprehensive post-mortem examination. The populations admitted as resident to the centre over time followed the evolution of society's perception of epilepsy. 'Early residents' (before 1972) were admitted for sheltered employment, escaping stigmatization, whereas 'later' residents with more severe epilepsies were admitted for care. Subjects admitted before 1972 were similar to subjects followed nowadays as outpatients, whereas patients admitted later with a higher burden of disabilities are often those in residential care. This long follow-up allowed exploration of a wide spectrum of epilepsies, affecting both subjects who were otherwise healthy and those with co-morbidities. Age at death showed a bimodal distribution with an early peak of mortality between 45-50 years old, whilst the remainder had life expectancy comparable to the general population. As a group, subjects who had post-mortem examination were not significantly different from patients who did not have post-mortem examination, but post-mortem examination provided data that were otherwise unavailable. For those who had post-mortem examination, sudden unexpected death in epilepsy (SUDEP, 18% of all deaths) did not fully explain the early mortality, to which co-morbidities contributed. High seizure frequency was a significant independent predictor of early death even after excluding SUDEP (e.g. reduction in years of life for those who had >4 seizures/month compared with those who had <1 seizure/month: 13 years; 95% confidence interval: 6-19; overall P = 0.0006). Those who survived to older age increasingly went into spontaneous remission lasting until death (in the whole cohort, 38/166, 23% of those who died in or after sixth decade). In subjects who had post-mortem examination, older age (odds ratio = 1.13; 95% confidence interval: 1.06-1.20) and presence of neuropathologically confirmed degenerative changes (that were not the cause of epilepsy) (odds ratio 7.14; 1.95-26.2) were independent predictors of terminal remission. Epilepsy may cause premature death indirectly through co-morbid conditions. Terminal remission occurs even without prior remissions; ageing may improve epilepsy drug responsiveness although unknown factors related to the natural history may also play a role.

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This study aimed to analyze the impact of ictal dystonic posturing (DP) in postoperative seizure outcome and to assess the influence of DP in generalized tonic-clonic seizure (GTCS) occurrence during video-EEG monitoring of patients with temporal lobe epilepsy with mesial temporal sclerosis. The impact of DP on surgical outcome remains controversial. Moreover, DP has been recently associated with brain networks avoiding GTCS occurrence. Five hundred twenty-seven seizures of 171 patients who were submitted to standard anterior temporal lobectomy (ATL) between 2002 and 2010, with at least one year of post-surgical follow-up, were retrospectively analyzed and classified as with or without DP and as evolving or not to GTCS. The ictal semiologic correlates of DP, timing elapsed since precedent seizure and antiepileptic drug (AED) intake before each seizure were evaluated. Seizure outcome after ATL was assessed according to Engel's scale. Fifty-eight out of 171 patients (34%) exhibited ictal DP, of which 91.5% were always unilateral and contralateral to the operated side. DP was related to shorter seizures (p=0.007) and a much lower likelihood of the seizure evolving to GTCS (p=0.001), even during AED withdrawal (p=0.002). There was no association between DP and prognosis regarding seizure control as the result of the surgical resection, either in patients with shorter or in those with longer period of follow-up. Our data support the hypothesis that DP reflects a brain network activation that helps avoid GTCS, even during AED withdrawal.

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