Focal Slow Waves Research Articles

EEG-patterns in sporadic Creutzfeldt–Jakob disease: From mild encephalopathy to epileptic hyperexcitability

Objectives As of today, clinical diagnosis of sporadic Creutzfeldt–Jakob disease (sCJD) remains a major challenge and needs to be corroborated by precision biomarkers. Despite moderate sensitivity, periodic electroencephalogram (EEG) abnormalities are of interest due to high specificity. However, their clinical yield could be much improved by a better understanding of their pathophysiological significance, their evolution in time and their overlap with epileptic discharge. Here we illustrate a typical EEG-evolution in sCJD, complicated in the end by prolonged electro-clinical seizures, and discuss the question of blurred boundaries between encephalopathic and epileptic patterns in sCJD. Methods Electro-clinical analysis of five successive video-EEG recordings in a patient with an initially dubious clinical presentation (ophthalmoplegia, preserved cognition, MRI and cerebrospinal fluid inconclusive). Within three months, she developed the full electro-clinical picture of sCJD. The findings are confronted with a review of the literature. Results Early recordings showed a regional encephalopathic pattern with focal slow waves attenuated by stimulation and sleep, localized in close vicinity to asymmetrical enhancement of diffusion signal on MRI. Concomitant to increasing cortical ribboning, EEG abnormalities became periodic, bilateral and finally evolved to prolonged individual electro-clinical seizures. EEG thus had a dual diagnostic role in this patient: early abnormalities helped to orient toward sCJD, late patterns revealed the presence of clinically ambiguous focal seizures. Conclusion Typical EEG changes in sCJD concern 60% of patients and seem to emanate from diverse pathophysiological mechanisms. Abnormalities evolve from early, rather non-specific encephalopathic patterns to unequivocal periodic sharp wave complexes and in 15–21% of cases, to seizures late in the disease. This evolution corresponds to an increasing degree of cortical hyperexcitability, with blurred transitions to non-convulsive status epilepticus. We propose that EEG patterns in sCJD represent diverse pathophysiological mechanisms with fluid boundaries and ultimately express an increasing burden of cortical hyperexcitability.

Contribution of EEG in transient neurological deficits.

Identification of stroke mimics and 'chameleons' among transient neurological deficits (TND) is critical. Diagnostic workup consists of a brain imaging study, for a vascular disease or a brain tumour and EEG, for epileptiform discharges. The precise role of EEG in this diagnostic workup has, however, never been clearly delineated. However, this could be crucial in cases of atypical or incomplete presentation with consequences on disease management and treatment. We analysed the EEG patterns on 95 consecutive patients referred for an EEG within 7days of a TND with diagnostic uncertainty. Patients were classified at the discharge or the 3-month follow-up visit as: 'ischemic origin', 'migraine aura', 'focal seizure', and 'other'. All patients had a brain imaging study. EEG characteristics were correlated to the TND symptoms, imaging study, and final diagnosis. Sixty four (67%) were of acute onset. Median symptom duration was 45min. Thirty two% were 'ischemic', 14% 'migraine aura', 19% 'focal seizure', and 36% 'other' cause. EEGs were recorded with a median delay of 1.6day after symptoms onset. Forty EEGs (42%) were abnormal. Focal slow waves were the most common finding (43%), also in the ischemic group (43%), whether patients had a typical presentation or not. Epileptiform discharges were found in three patients, one with focal seizure and two with migraine aura. Non-specific EEG focal slowing is commonly found in TND, and may last several days. We found no difference in EEG presentation between stroke mimics and stroke chameleons, and between other diagnoses.

Usefulness of EEG for the differential diagnosis of possible transient ischemic attack

ObjectiveEEG value in possible transient ischemic attacks (TIA) is unknown. We aim to quantify focal slow wave activity (FSWA) and epileptiform activity (EA) frequency in possible TIA, and to analyse its contribution to the final diagnosis of seizures and/or definitive TIA. MethodsProspective longitudinal study of possible TIA patients evaluated at a tertiary centre during 36 months and with 1–3 months follow-up. EEG was performed as soon as possible (early EEG) and one month later (late EEG). A stroke neurologist established final diagnosis after reassessing all clinical and diagnostic tests. Results80 patients underwent an early EEG (45.8 h after possible TIA): 52 had FSWA and 6 of them also EA. Early FSWA was associated with epileptic seizure or definitive TIA final diagnosis (p = .041). Patients with these diagnoses had more frequently early FSWA (19/23; 82.6%) than EA (6/23; 26.1%). 6/13 (46.2%) patients with epileptic seizure final diagnosis had EA.In the late EEG, 43 (58.1%) patients demonstrated persistent FSWA and 3 of them also EA. Persistent FSWA in the late EEG was more frequent in seizures than in TIA patients (91.7% vs. 45.5%). FSWA disappearance was associated with acute vascular lesion on neuroimage. ConclusionsFSWA was the commonest EEG abnormality found in the early EEG of patients with possible TIA, but did not distinguish between TIA and seizure patients. In patients with seizures, FSWA was more common than EA and its presence in the late EEG was more likely in patients with epileptic seizures than with TIA. SignificanceThe majority of possible TIA patients with the final diagnosis of epileptic seizures do not have EA in the early or late EEG.

The clinical phenotype of autosomal dominant lateral temporal lobe epilepsy related to reelin mutations.

ObjectiveTo describe the clinical phenotype of 7 families with Autosomal Dominant Lateral Temporal Lobe Epilepsy (ADLTE) related to Reelin (RELN) mutations comparing the data with those observed in 12 LGI1-mutated pedigrees belonging to our series.MethodsOut of 40 Italian families with ADLTE, collected by epileptologists participating in a collaborative study of the Commission for Genetics of the Italian League against Epilepsy encompassing a 14-year period (2000–2014), 7 (17.5%) were found to harbor heterozygous RELN mutations. The whole series also included 12 (30%) LGI1 mutated families and 21 (52.5%) non-mutated pedigrees. The clinical, neurophysiological, and neuroradiological findings of RELN and LGI1 mutated families were analyzed.ResultsOut of 28 affected individuals belonging to 7 RELN mutated families, 24 had sufficient clinical data available for the study. In these patients, the epilepsy onset occurred at a mean age of 20 years, with focal seizures characterized by auditory auras in about 71% of the cases, associated in one-third of patients with aphasia, visual disturbances or other less common symptoms (vertigo or déjà-vu). Tonic–clonic seizures were reported by almost all patients (88%), preceded by typical aura in 67% of cases. Seizures were precipitated by environmental noises in 8% of patients and were completely or almost completely controlled by antiepileptic treatment in the vast majority of cases (96%). The interictal EEG recordings showed epileptiform abnormalities or focal slow waves in 80% of patients, localized over the temporal regions, with marked left predominance and conventional 1,5T MRI scans were not contributory.By comparing these findings with those observed in families with LGI1 mutations, we did not observe significant differences except for a higher rate of left-sided EEG abnormalities in the RELN group.SignificanceHeterozygous RELN mutations cause a typical ADLTE syndrome, indistinguishable from that associated with LGI1 mutations.

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery.

ObjectiveIn this study, we use a novel automated method for localization and quantitative comparison of magnetoencephalographic (MEG) delta activity in patients with and without recurrent seizures after epilepsy surgery as well as healthy controls.MethodsWe identified the generators of delta activity by source location in frequency domain between 1 and 4 Hz in spontaneous MEG data. Comparison with healthy control subjects by z-transform emphasized relative changes of activation in patients. The individual results were compared to spike localizations and statistical group analysis was performed. Additionally, MEG results were compared to 1–4 Hz activity in invasive EEG (iEEG) in two patients, in whom this data was available.ResultsPatients with recurrent seizures exhibited significantly increased focal MEG delta activity both in comparison to healthy controls and seizure free patients. This slow activity showed a correlation to interictal epileptic activity and was not explained by consequences of the resection alone. In two patients with iEEG, iEEG analysis was concordant with the MEG findings.SignificanceThe quantity of delta activity could be used as a diagnostic marker for recurrent seizures. The close relation to epileptic spike localizations and the resection volume of patients with successful second surgery imply involvement in seizure recurrence. This initial evidence suggests a potential application in the planning of second epilepsy surgery.

Sleep EEG patterns in infants with congenital Zika virus syndrome.

To describe sleep EEG patterns of neonates, and infants with microcephaly due to congenital Zika virus (ZikV) syndrome. A descriptive case series of EEGs performed in a cohort of neonates with microcephaly monitored from October 2015 to February 2016 at a University Hospital in Northeast Brazil. Infants were investigated following an established protocol that includes EEG, neuroimaging studies, PCR and specific antibodies for ZikV detection. EEGs (n=37) from 37 infants were reviewed. Age at investigation varied from 1 to 5months (mean=2.6). Diffuse low voltage (n=7), background asymmetry (n=6) and modified hypsarrhythmia with or without burst-suppression (n=11), were the main background abnormalities identified. Interictal EEG abnormalities were identified in 23 recordings (62%) and localized as focal frontal (n=8) or occipital (n=2) spikes/sharp, multifocal spikes/sharp waves (n=13). Electrographic seizures without clinical manifestation were identified in 4 recordings and characterized as focal pseudo rhythmic pattern. Further findings were focal high amplitude slow waves that were registered in the frontal (n=3) or occipital (n=1) regions. Different types of EEG abnormalities were encountered with a predominance of interictal epileptogenic activity and hypsarrhythmia. Sleep EEGs in congenital Zika virus syndrome are consistently abnormal even in infants who have not yet developed epilepsy.

Clinical and electroencephalographic analysis of anti-N-methyl-D-aspartate receptor encephalitis in children

To study the clinical and electroencephalographic (EEG) characteristics of anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDAR encephalitis) in children. Retrospective analysis was performed on the clinical and EEG data of 105 patients with anti-NMDAR encephalitis treated in Beijing Children's Hospital (August 2011-March 2015). Of the 105 patients, 38 were male and 67 were female.The age of onset was from 6 months and 26 days to 15 years and 8 months (average (8±4)years). The time for confirmed diagnosis was from 4 days to 850 days (median 24.5 days). According to the modified Rankin scales, the patient's clinical conditions were assessed and underwent continuous EEG (cEEG) monitoring.The data were reviewed and analyzed. Based on the severity of the disease, the 105 patients were divided into three groups: mild group (12 cases), moderate group (65 cases), and severe group (28 cases). There were 91 cases(86.7%)with abnormal EEG patterns, including 28 cases (26.7%) with slow background activity in EEG, 25 cases (23.8%) with generalized or diffuse slow waves, 33 cases (31.4%) had focal slow waves, 41 cases (39.0%) had epileptic waves; 10 cases (9.5%) showed unilateral or diffuse alpha-theta band rhythms in nonrapid eye movement (NREM) sleep, 7 cases (6.7%) showed extreme delta brush waves (EDB). Accordingly, the number of patients with abnormal EEG in mild, moderate and severe groups was 5, 58 (89.2%) and 28(100.0%). Seven patients with EDB phenomenon were all in the severe group, and 10 patients with abnormal alpha-theta band rhythms were in the moderate group. In children with anti-NMDAR encephalitis, the EEG patterns are in line with the changes of EEG in general encephalitis.The extent of EEG abnormalities correlates with the clinical severity of the disease. Extreme delta brush and alpha-theta band rhythms may be suggestive of diagnosis and clinical assessment of the disease.

Clinical profile of seizure disorder in hospitalized patients

Background: Hughling Jackson in 1870 described first “seizures as intermittent derangement of central nervous system and abnormal and excessive discharge of central nervous tissue on muscles” and the same was refined further. Average incidence rate for epilepsy is 0.3 - 0.5% in patients. Methods: A total of 100 patients admitted with sign and symptoms suggestive of seizure disorder in tertiary care hospital during the period of 1 st December 2012 to 31 st July 2014. A detailed clinical history, examination and investigation with following patients were included in study; (1) age of the patients above 13 years; (2) patient present with history of seizure the cross sectional observational study was carried out at Dr. V. M. Government Medical College, Solapur, Maharashtra, India. Results: Generalized tonic clonic were the commonest type seen in 69 patients (69%) and cerebrovascular disease because seen in 25 patients (25%) is the second most common cause. Conclusions: ( 1) Ring enhancing lesion were seen in 15% patients, among most common was tuberculoma that is seen in 10 patients and neurocysticercosis was seen in 5 patients; (2) cerebral tumour was seen in 4 patients; (3) EEG was abnormal in 31% cases of seizure and most common EEG abnormality was focal slow waves and (4) CT scan abnormality was seen in 47 cases (47%).

V4. Focal slow wave in patients after epilepsy surgery with and without seizure recurrence

Background Recurrence of seizure after epilepsy surgery occurs in approx. 40% of operated patients ( Rosenow and Luders, 2001 ). Due to skull defects, the resection volume and scarification, reevaluation for potential epilepsy surgery is challenging. Conductivity differences caused by such alterations has an almost negligible effect on magnetoencephalography (MEG). MEG may thus provide valuable localizing information in this patient group. In addition to epileptic spikes, focal slow wave activity in the delta and theta frequency range have been utilized for epileptic focus localizations in patients without previous surgery only ( Kaltenhauser et al., 2007 ). In the presented study, we use an automatic procedure to investigate focal delta in patients with and without recurrent seizures after surgery to differentiate delta related to epilepsy from delta caused by surgery. Patients and methods We investigated 15 patients with recurrent seizures and 10 seizure free patients after surgery, as well as 15 healthy controls. MEG was recorded for 10 min in supine positions using a WHS3600 magnetometer system (4D Neuroimaging, San Diego, USA) with 248 channels. Distribution of delta activity (1–4 Hz) in source space was calculated (DICS) using the Fieldtrip ( Oostenveld et al., 2011 ) Matlab toolbox (The Mathworks, Natick, CA, USA). Source activity was morphed onto a common coordinate system (MNI). Delta activity in patients was then related to healthy controls by calculating location specific z-values. Results Both patient groups showed significantly increased delta activity compared to healthy controls (p 3) in all patients. Conclusions In patients with recurrent seizures after epilepsy surgery, focal delta may be utilized for epileptic focus localization and complement MEG spike analysis. Furthermore, the significant difference between patients with and without recurrent seizures indicates a potential role of focal delta activity in the relapse of epilepsy.

Anti-N-methyl-D-aspartate receptor encephalitis: three cases report and review of literature

Objective To study the clinical and laboratory features and diagnosis of the patient with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Methods The data of clinical features, laboratory findings, and radiological manifestations of 3 patients with anti-NMDAR encephalitis were reviewed and analyzed. Results Of the 3 patients, 2 were male and one was female. The age was from 33 to 34 years (33.30 years on average). Main symptoms included headache in 2 cases, psychiatric symptoms and speech disorder in 3 cases, different levels of movement disorder in one case and hallucinations in one case. The results of MRI examination revealed gyri swelling, abnormal signal and demyelination of temporal lobe. The EEG showed focal or diffuse slow waves. All cases were confirmed to have the disease by detection of anti-NMDAR antibodies. Both the white blood cell count (3 cases) and protein quantification (2 cases) elevated. No tumor was detected in any of the patients. All patients were coued after receiving immunotherapy with methylprednisolone and human immunoglobulin. Conclusions Anti-NMDAR encephalitis is a severe but treatable disorder. The syndrome is highly recognizable clinically and can be confirmed with the demonstration of anti-NMDAR antibodies. Timely diagnosis and treatment may yield a favorable prognosis. doi: 10.3969/j.issn.1672-6731.2014.07.005

LP31: EEG and MEG source localization of the epileptogenic foci in tuberous sclerosis complex: a pediatric case report

LP31: EEG and MEG source localization of the epileptogenic foci in tuberous sclerosis complex: a pediatric case report

Suggestive linkage of familial mesial temporal lobe epilepsy to chromosome 3q26

To describe the clinical findings in a family with a benign form of mesial temporal lobe epilepsy and to identify the causative genetic factors. All participants were personally interviewed and underwent neurologic examination. The affected subjects underwent EEG and most of them neuroradiological examinations (MRI). All family members were genotyped with the HumanCytoSNP-12 v1.0 beadchip and linkage analysis was performed with Merlin and Simwalk2 programs. Exome sequencing was performed on HiSeq2000, after exome capture with SureSelect 50 Mb kit v2.0. The family had 6 members with temporal lobe epilepsy. Age at seizure onset ranged from 8 to 13 years. Five patients had epigastric auras often associated to oro-alimentary automatic activity, 3 patients presented loss of contact, and 2 experienced secondary generalizations. Febrile seizures occurred in 2 family members, 1 of whom also had temporal lobe epilepsy. EEG showed focal slow waves and epileptic abnormalities on temporal regions in 1 patient and was normal in the other affected individuals. MRI was normal in all temporal lobe epilepsy patients. We performed single nucleotide polymorphism-array linkage analysis of the family and found suggestive evidence of linkage (LOD score=2.106) to a region on chromosome 3q26. Haplotype reconstruction supported the linkage data and showed that the majority of unaffected family members carried the haplotype at risk. Whole exome sequencing failed to identify pathogenic mutations in genes of the candidate region. Our data suggest the existence of a novel locus for benign familial mesial temporal lobe epilepsy on chromosome 3q26. Our failure to identify pathogenic mutations in genes of this region may be due to limitations of the exome sequencing technology.

Pediatric Seizures

On the basis of strong evidence, treatment is highly dependent on the seizure semiology results, electroencephalography (EEG) findings, and origin. • On the basis of moderate evidence and consensus, vigorous use of video EEG recordings and home video cameras should be used to delineate the epileptic syndromes. • On the basis of strong evidence, pediatric epilepsy syndromes have common comorbidities. As a consensus, some pediatric epilepsy centers consider referral to a neuropsychologist to be first-line care in these patients. • On the basis of strong evidence and consensus, antiepileptic drug therapy has its own complications and should be discontinued after an appropriate treatment course. • On the basis of moderate evidence and consensus, uncontrolled seizures put patients at risk for significant morbidity and mortality.

Quantitative Analysis of Simultaneous EEG Features during PET Studies for Childhood Partial Epilepsy

PurposeTo demonstrate the significance of simultaneous electroencephalography (EEG) recording during 2-deoxy-2-[18F] fluoro-D-glucose (FDG)-positron emission tomography (PET) in childhood partial epilepsy.Materials and MethodsWe included 46 children with partial epilepsy who underwent simultaneous EEG during PET. We compared the epileptogenic area of several EEG features including epileptiform discharges, focal polymorphic slow waves, and electrographic seizures, with the abnormal metabolic region on PET. We also compared the epileptogenic area of simultaneous EEG and PET with findings on magnetic resonance imaging (MRI) and video/EEG, as well as the histopathological diagnosis of the resected cortical area, in eight patients who underwent surgical resection of the epileptogenic area.ResultsHypometabolic regions on interictal PET were concordant with epileptogenic areas of epileptiform discharges and focal polymorphic slow waves, according to their frequency and/or severity, with odds ratios of 1.35 and 1.81, respectively (p<0.05). Hypermetabolic PET was also concordant with epileptogenic areas of ictal events longer than 20 seconds during the period of FDG uptake. Among the eight patients who underwent surgical resection, six patients, including two with non-lesional MRI, had concordant EEG and PET findings, were confirmed pathologically, and became seizure-free after surgery.ConclusionSimultaneous EEG is useful in identifying epileptogenic areas due to a high concordance with abnormal PET metabolic areas. Moreover, simultaneous EEG may also prevent false lateralization of PET from postictal and mixed metabolism during ictal events, as well as abnormal hypermetabolism, during frequent interictal epileptiform discharges.

Interictal electroencephalography in patients with epilepsy in northwestern Nigeria

Background: Different studies have reported various frequencies of electroencephalographic (EEG) abnormalities in patients with epilepsy. There is, however, a paucity of data on EEG in Nigeria; hence, the need for this study. Objective: The objective of the following study was to evaluate interictal EEG pattern in patients with epilepsy in Kano, Northwestern Nigeria. Subjects and Methods: A cross-sectional study involving the analysis of EEGs of consecutive patients with clinical diagnosis of epilepsy over a 5 year period at two diagnostic centers in Kano, northwestern Nigeria. Information on socio-demographic and seizure characteristics was obtained. The recordings from patients were obtained using the standard methods and interpreted by two of the investigators. The International Federation of Societies for Electroencephalography and Clinical Neurophysiology definition of interictal epileptiform discharges (interictal epileptiform activity [IEA]) was adopted for the study. Result: Out of 2219 patients referred for EEG at the two diagnostic centers during the study period, 2041 (92%) patients had a clinical diagnosis of epilepsy. Their age ranged between 0.04 and 75 years, with a mean age of 22.8 ± 14.9 years. Overall, EEG was abnormal in 1178 (57.7%) and 919 (45.1%) had an epileptiform pattern. A total of 1691 patients had hyperventilation (HV) and response to HV was unremarkable in 1286 (76%) of them. Out of 405 who had remarkable changes on HV; 302 had increase in epileptiform discharges, whereas 103 had abnormal discharges only on HV. Seventeen (89.5%) out of 19 patients with 3 Hz spike and wave complexes had activation by HV. The most common IEA were focal spike/sharp and wave and generalized spike/sharp and slow waves. More antiepileptic drug (AED) naive patients (678) than those that were on AED (500) had EEG abnormality and the difference was statistically significant, P < 0.001. Conclusion: The study showed that the occurrence of interictal EEG abnormality in patients with epilepsy was about 58%. The proportion of interictal epileptiform discharges was 45% in routine first EEG studies. Among those with epileptiform activity, generalized sharp and wave complexes and focal sharp and slow wave complexes were the most common findings.

Electroencephalographic Evaluation of Cerebral Hyperperfusion Syndrome Following Superficial Temporal Artery-Middle Cerebral Artery Anastomosis

Low-flow bypass, such as superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis, can result in cerebral hyperperfusion syndrome (CHS). The present study evaluated the pathophysiological conditions of CHS through the use of repeated electroencephalography (EEG). Among a total of 22 patients who underwent STA-MCA anastomosis over a course of 4 years, 3 patients were diagnosed with CHS based on clinical symptoms and neuroradiological examinations, including cerebral blood flow evaluation. Case 1 and Case 2 developed CHS on postoperative day 1, when EEG demonstrated focal slow waves on the frontal region of the operated side, indicating cortical dysfunction in these areas. Although prompt recovery of these EEG findings was noted with improvement of the clinical symptoms in Case 1, Case 2 developed an intracranial hemorrhage on postoperative day 5, when EEG clearly depicted persistent nonconvulsive status epilepticus (NCSE) after control of convulsive status epilepticus. In contrast, the clinical onset in Case 3 was delayed to postoperative day 6 and EEG revealed frequent ictal discharges in the operated hemisphere, although convulsive seizures were not apparent. Administration of anticonvulsants was performed after the diagnosis of NCSE, and complete recovery from CHS was achieved. Although the pathophysiology of CHS is cortical dysfunction, ictal hyperperfusion associated with NCSE could be included. The present findings emphasize the importance of repeated EEG examinations in the differential diagnosis of the various types of pathophysiological conditions of CHS.

Anti-N-methyl-D-aspartate receptor encephalitis in seven children

To study the clinical and laboratory features and diagnosis of the patient with anti-N-methyl-D-aspartate receptor(NMDAR)encephalitis in children. The data of clinical feature, laboratory findings, and radiological manifestation were reviewed and analyzed. Of the 7 patients, 4 were female and 3 were male. The age of onset was from 6.6 to 15.5 years (average 9.5 years). The onset of 4 cases started with convulsion. Six cases had seizures which was difficult to control by antiepileptic drugs. All patients had psychiatric symptoms and speech disorder. Six cases had different levels of decreased consciousness and dyskinesias. 6 cases had autonomic nerve instability, and 7 cases developed sleep disorders. The results of MRI examination were normal in all patients. The EEG of most patients showed focal or diffuse slow waves. Six cases had oligoclonal bands. All cases were confirmed to have the disease by detection of anti-NMDA receptor antibodies. No tumor was detected in any of the patients. All patients received immunotherapy. Anti-NMDAR encephalitis is a severe but treatable disorder that frequently affects children and adolescents. Pediatric patients had clinical manifestations similar to those of adult patients. But children have a lower incidence of tumors and hypoventilation also occurs less frequently in children. Most of children had a good prognosis.

Different quantitative EEG alterations induced by TBI among patients with different APOE genotypes

Although several studies have revealed the EEG alterations in AD and TBI patients, the influence of APOE (apolipoprotein E) genotype in EEG at the early stage of TBI has not been reported yet. We have previously studied EEG alterations caused by TBI among different APOE genotype carriers. In this study, we firstly investigated the relationship between APOE polymorphisms and quantitative EEG (QEEG) changes after TBI. A total of 118 consecutive TBI patients with a Glasgow Coma Scale (GCS) of 9 or higher were recruited, and 40 normal adults were also included as a control group. APOE genotype was determined by PCR-RFLP for each subject, and QEEG recordings were performed in rest, relaxed, awake and with eyes closed in normal subjects and TBI patients during 1–3 days after TBI. In the normal control group, both APOEɛ4 carriers and non-carriers had normal EEG, and no significant difference of QEEG data was found between APOEɛ4 carriers and non-carriers. But in the TBI group, APOEɛ4 carriers had more focal or global irregular slow wave activities than APOEɛ4 non-carriers. APOE gene did not influence brain electrical activity under normal conditions, but TBI can induce different alterations among different APOE gene carriers, and APOEɛ4 allele enhances the EEG abnormalities at the early stage of TBI.

Changes in cortical slow wave activity in healthy aging

A number of studies have demonstrated enhanced slow wave activity associated with pathological brain function e.g. in stroke patients, schizophrenia, depression, Morbus Alzheimer, and post-traumatic stress disorder. However, the association between slow wave activity and healthy aging has remained largely unexplored. This study examined whether the frequency at which focal generators of delta waves appear in the healthy cerebral cortex changes with age and whether this measure relates to cognitive performance. We investigated 53 healthy individuals aged 18 to 89years and assessed MEG during a resting condition. Generators of focal magnetic slow waves were localized. Results showed a significant influence of age: dipole density decreases with increasing age. The relationship between cognitive performance and delta dipole density was not significant. The results suggest that in healthy aging slow waves decrease with aging and emphasize the importance of age-matched control groups for further studies. Increased appearance of slow waves as a marker for pathological stages can only be detected in relation to a control group of the same age.

Childhood refractory focal epilepsy following acute febrile encephalopathy

We describe a group of previously normal children who developed severe focal epilepsy after an acute/sub-acute illness resembling encephalitis. This is a retrospective study. An acute phase (encephalitis/encephalopathy period) and a chronic phase (chronic focal resistant epilepsy) were defined. Eight patients were enrolled. The median age at onset was 6.6 years (range 8 months-17.6 years). In the acute phase, fever was the first symptom in all cases and was associated with seizures and status epilepticus. All patients had focal seizures arising in both hemispheres. Seizure onset occurred in the frontal and temporal regions. EEGs showed slowing background activity associated with focal or diffuse slow waves with rare epileptiform abnormalities. Cerebrospinal fluid oligoclonal bands were observed in four out of six patients tested. MRI images showed bilateral peri-insular hyperintensity in four cases. Five patients received corticosteroids, and in four cases, they were given along with intravenous immunoglobulins. The median duration of the acute phase was 19 days (range 15-30 days). During the chronic phase, which followed the acute phase without interval, patients presented with drug-resistant focal seizures and neuropsychological deficits, which ranged from hyperactivity and attention deficits to short-term verbal memory deficit, pervasive developmental disorders, and language delay. Considering the clinical presentations, EEG findings, and the associated occurrence of non-specific immunological activations, a possible immune-mediated pathogenesis can be hypothesized, although firm conclusions cannot be drawn out.