Electroencephalographic studies in children with autism spectrum disorders

An important factor in the diagnosis and treatment of Autism spectrum disorder (ASD) is prescribed Electroencephalography (EEG). EEG changes may show the following: slowing, asymmetry, sharp waves or spikes, sharp and slow waves, generalized sharp and slow waves, or generalized polyspikes in a distributed or general area, multifocal or focal, unilateral or bilateral, and they may be located in many different areas of the brain. There is a need to look for a EEG phenotype typical of patients with ASD. The importance of gamma waves, rhythm mu, mirror neurons, and their role in patients with ASD was discussed. Epilepsy is reported to occur in one third of ASD patients. In ASD, seizures and EEG paroxysmal abnormalities could represent an epiphenomenon of a cerebral dysfunction independent of apparent lesions. This article reviews ASD and EEG abnormalities and discusses the interaction between epileptiform abnormalities and cognitive dysfunction.     

Juvenile myoclonic epilepsy: non-classic electroencephalographical presentation in adult patients.

Although diagnosis of juvenile myoclonic epilepsy (JME), a common form of idiopathic generalized epilepsy, is based on clinical and electroencephalogram (EEG) criteria, at times clinical symptoms may be misleading, like the occurrence of asymmetric myoclonic jerks. Thus EEG assumes an important role in these cases, it can fail to show the classical polyspike and slow wave (PSW) discharges of JME, specially in a routine evaluation in older patients. We analyzed retrospectively EEG results of 35 patients with JME [Commission on Classification and Terminology of the International League Against Epilepsy (ILAE) Epilepsia 1989; 30: 389] aged 12-44 years. (mean 22.7 years) at first medical evaluation. EEG findings of 35 patients (19 females, 16 males) with JME consisted of normal tracings in 22.9 and 54.3% had at least one normal exam. EEG abnormalities present in 27 patients (77.1%) consisted of isolated generalized slowing in two and generalized discharges in 25: irregular spike and wave complexes (SWC) in 76%; PSW in 48%; SWC faster than 3 Hz in 20%; spikes, sharp waves, and irregular slow waves in 24%; asymmetric generalized epileptiform discharges in 40%; and associated focal paroxysms in 12%. Thus JME is classically associated to PSW on EEG, the most frequent abnormality was irregular SWC. Generalized paroxysms could occur in an asymmetric fashion and rarely associated to focal activity.     

Electroencephalographic and seizure manifestations of pyridoxal 5'-phosphate-dependent epilepsy

We describe the electroencephalographic and clinical seizure manifestations of pyridoxal 5'-phosphate-dependent epilepsy (PLP-DE) in two patients [diagnosis confirmed by low cerebrospinal fluid (CSF) PLP, complete resolution of previously intractable seizures with PLP supplementation, negative pyridoxine-dependent epilepsy CSF biomarkers, and/or positive disease causing pyridox(am)ine 5'-phosphate oxidase gene mutation] along with a comprehensive review of the literature. One patient presented with neonatal tonic status epilepticus with subsequent generalized tonic-clonic seizures, and the second, with refractory complex partial seizures starting at 2 years of age. The pretreatment EEG revealed, interictally, burst suppression, multifocal independent sharp waves, and electrical status epilepticus in sleep. Ictally and interictally, it revealed runs of unilateral spike/slow waves. Previously reported features include burst suppression, myoclonus, tonic seizures, clonic seizures, and spasms. In the appropriate clinical scenario, the aforementioned features should raise the possibility of PLP-DE and appropriate treatment should be initiated. The first late-onset case (at 2 years) of PLP-DE is reported.     

The Electroencephalogram in Attention Deficit-Hyperactivity Disorder: Emphasis on Epileptiform Discharges

This study dealt with the electroencephalograms (EEGs) of 176 children with attention deficit-hyperactivity disorder (ADHD). Of special interest were the patients who had in their EEG some type of spike activity (spike group), in contrast with those without such activity (control group). In the entire group, 27.8% were completely normal and an additional 18.8% had positive spikes as their only finding. Definite noncontroversial, epileptiform activity was seen in 30.1%, mainly focal (usually occipital or temporal), less often generalized, with bilaterally synchronous spike and waves complexes seen in 11 children. Extreme spindles or diffuse slow waves occurred only in the spike group (one exception in each) and slow wave abnormalities (mainly frontal or temporal), nearly always mild in degree, were seen mainly in the spike group. These different findings suggest that ADHD is a condition often with organic changes in the form of EEG abnormality, at times with epileptiform activity that could contribute to a deficit in attention or a plethora of movements.     

Infantile epileptic encephalopathy with late‐onset spasms: Report of 19 patients

Purpose: Late‐onset spasms (LOS) are epileptic spasms starting after the first year of life. Our aim was to assess the electroclinical features and the follow‐up of the patients with this particular type of epileptic seizure. Methods: We retrospectively included all patients with LOS confirmed by electroencephalography between 1989 and 2008. Clinical and electroencephalographic findings at diagnosis and during follow‐up were collected. The Vineland scale was used to evaluate the neuropsychological outcome. Results: We report 19 patients with LOS of 240 patients with recorded epileptic spasms. Eighteen patients had an epileptic encephalopathy with late‐onset spasms. The ictal electroencephalography (EEG) showed a focal or generalized discharge of triphasic slow‐waves, slow‐spikes, or slow spikes‐waves with fast activities. The interictal EEG usually showed focal or generalized slow‐waves or slow spikes‐waves without hypsarhythmia. LOS were controlled in only six patients. Three developed typical Lennox‐Gastaut syndrome and 10 had a severe epileptic encephalopathy. Neuropsychological outcome was evaluated in 15 patients with the Vineland scale. Cognitive functions were normal in only one patient, whereas severe cognitive delay was observed in 12 of 15. Conclusion: Epileptic spasms may appear after the age of one. They are more frequently observed in patients with epileptic encephalopathy. In few patients this type of seizure was observed before the patients fulfill Lennox‐Gastaut syndrome criteria. In one patient, we diagnosed a focal epilepsy with seizures occurring in cluster. When LOS are related to an epileptic encephalopathy, this epileptic syndrome seems to be linked to refractory epilepsy and severe cognitive outcome unrelated to the etiology.     

Evolution of seizures and electroencephalographical findings in 23 cases of deletion type Angelman syndrome

Angelman syndrome (AS) is a genetic disorder with characteristic clinical and EEG findings. We report here the results of long-term follow-up studies on the epileptic seizures and EEG findings of 23 cases of deletion type AS confirmed by FISH analysis, including seven cases previously reported by Matsumoto et al. in 1992. The age at last follow-up in 23 patients was from 1 to 37 years of age (average: 18.0 years), with 10 patients (43.5%) in their 20s, and five over 30. Epileptic seizures were seen in all patients, and the age at seizure onset ranged from 3 to 50 months (average: 21.7 months). Status epilepticus was seen in 11 patients (47.8%). The percentages of cases seizure-free for more than 3 years were 25% (4/16) at 10 years of age, 70% (7/10) at 20, and 80% (4/5) at 30. The EEG findings were classified into six patterns according to the previous report: N (no spike, including focal slow waves), HVS (diffuse high-voltage slow bursts with or without spikes), F (focal spikes or multifocal spikes), S (diffuse spike and waves), C (continuous diffuse spike and waves), Hy (hypsarrythmia or hypsarrhythmia like waves). Hy was noted at ages 0-2 years in two cases. C was observed from the ages 2 to 15 years, being most frequently noted at 3-6 years of age, and it was never seen after 16 years of age. S was observed from ages 1 to 21 years. F was seen from 2 to 21 years of age, and most frequently during the ages of 2-7 years. HVS was seen from 0 years, and still remained after the age of 20. After 22 years of age, all patients showed N pattern including focal slow waves. One of the two patients who had bilateral frontal dominant delta slow waves in their 30s, had a recent seizure. Even if the spikes disappear with age, when bi-frontal focal slow waves remain, seizures may occur even in patients over 30.     

伴强直性发作癫痫患儿的临床表现和脑电图特征

目的通过对67例伴强直性发作癫痫患儿的临床表现及视频脑电图(VEEG)特点分析,提高对该发作类型的诊断水平。结果收集河北省儿童医院神经内科67例伴强直性发作的癫痫患儿的病例资料,分析其临床表现和VEEG特征。结果 67例患儿均监测到明确的临床发作,其中清醒期发作19例(28%),睡眠期发作30例(45%),且容易出现在睡眠I期、II期。发作间期脑电图表现:①背景活动正常37例,慢化者15例;②广泛性棘波节律阵发,易出现在非快速眼动期(NREM期);③广泛性及多灶性慢波、棘慢波或多棘慢波阵发;④一侧或双侧前头部棘波、棘慢波或θ活动发放;⑤单侧或双侧Rolandic区棘慢波发放;⑥高度失律。发作期脑电图表现:①局灶起始的棘波节律发放;②广泛性棘波节律发放;③广泛性慢波阵发,其上复合或其后跟随棘波节律;④广泛性4~6Hz棘慢波发放→广泛性棘波节律阵发;⑤广泛性低波幅棘波节律发放→广泛性高波幅棘慢波阵发。以上表现形式有时会组合出现于同一例患者中。发作持续时间与背景活动的关系:发作持续约1~8s者39例(39/67,58.2%),背景活动慢化者4例(4/39,10.3%);发作持续8~15s,甚者更长者(15s)28例(28/67,41.7%),背景活动慢化者11例(11/28,39.3%)。67例患者随访研究1年,最终诊断为:8例(11.9%)诊断为婴儿痉挛征,7例(10.4%)诊断为Lennox-Gastaut综合征(LGS),3例(4.4%)诊断为额叶癫痫,15例(22.3%)诊断为伴有中央颞区棘波的儿童良性癫痫(BECT),34例(50.7%)仅停留在发作类型的诊断层面。结论强直性发作可单独出现,也可出现在多种癫痫综合征中;VEEG可监测患儿发作期临床表现及脑电图异常波形,为临床诊断及鉴别诊断提供理论依据。     

Characteristic EEG findings in ring 20 syndrome as a diagnostic clue

Objective: To review the EEG features of ring 20 syndrome in two patients to disclose the characteristic pattern of this syndrome. The features of our cases and 24 patients reported in the literature will be discussed.Subjects and methods: Report of two patients and review of literature.Results: The two patients had intractable epilepsy since childhood. Their clinical seizures were mostly complex partial seizures. Often the patients seizures were of prolonged duration. Ictal EEG revealed characteristic slow waves, and sharp waves. The slow waves were (1) usually synchronous high-voltage slow waves with or without a spike component predominantly in the frontal and frontopolar areas, (2) sometimes showed a change in frequency every several seconds, (3) continued for a long period, and (4) easily spread diffusely. The sharp waves were 5–6 Hz irregular and diffuse discontinuous sharp waves, and sometimes appeared predominantly in the centroparietal area. The clinical seizure pattern and EEG findings were similar in the 24 published cases.Conclusions: These EEG findings may be a characteristic feature of ring 20 syndrome and thus may be useful as a diagnostic clue.     

Electroclinical and cytogenetic features of epilepsy in cri‐du‐chat syndrome

Cri‐du‐chat syndrome (CdCs) is caused by deletion in the short arm of chromosome 5, occurring in 1:15,000 to 1:50,000 live births. Recent genotype‐phenotype correlation studies show the importance of 5p15.2 for facial dysmorphism and intellectual disability, and 5p15.3 for cat‐like cry. Numerous reports have shown the relative rarity of epilepsy in this syndrome. We identified two cases with epilepsy in CdCs, and described their electroclinical and cytogenetic features. The first case was a 25‐year‐old female who had axial tonic seizures with flexion of the neck and shoulders. Interictal EEG was characterized by generalized spike‐and‐slow‐wave complexes. Her ictal EEG started with diffuse electrodecremental pattern, followed by alpha‐range activities. High‐resolution banding analysis of chromosomes revealed a terminal deletion of 5p14.1. The second case was a 30‐year‐old female who had startle epilepsy with falling. Interictal EEG demonstrated generalized spike and slow waves. High‐resolution banding analysis revealed a terminal deletion of 5p13.3 with additional chromosomal material of unknown origin. Based on the cases presented here, as well as those previously reported, the relationship between epilepsy and CdCs is discussed. The data suggests that although CdCs patients rarely suffer from epileptic seizures, the seizures may vary in type.     

Ring chromosome 20: a distinctive syndrome identifiable by electroclinical diagnosis

The ring chromosome 20 syndrome is characterized by treatment resistant non-convulsive status epilepticus, and slow waves intercalated by spikes/spike waves predominantly in the front-temporal regions. Here, we describe the case of an 18 year old patient, whose seizures began at the age of 10, these being resistant to treatment. Neurologic examination and cranial MRI were normal. Interictal EEG showed normal background activity with burst of 2-20 seconds with bilateral spike wave. Ictal EEG showed continuous paroxysmal activity with generalized spike waves discharges and slow delta waves, coinciding with nonconvulsive status epilepticus. After 1 mg of intravenous clonazepam, both clinical semiology and EEG abnormalities disappeared. A cytogenetic study showed ring chromosome 20 in 35 % of metaphases. The epilepsy associated with ring chromosome 20 constitutes a syndrome with its distinctive electroclinical characteristics.     

Guidelines for EEG in encephalopathy related to ESES/CSWS in children

Electrical status epilepticus during slow sleep (ESES) or continuous spikes and waves during slow sleep (CSWS) is a phenomenon characterized by strong activation of epileptiform activity in the electroencephalogram (EEG) during sleep. The literature contains several small series of patients and many case reports. Large prospective studies are lacking. Definitions of the syndromes and EEG criteria and methods vary, as does their classification. The fluctuating clinical course and EEG findings complicate the diagnostic process and evaluation of effect of therapy. Studies describing quantitative aspects of the epileptiform abnormalities in EEG are overrepresented in literature, whereas qualitative aspects are relatively undervalued. Guidelines for evaluation of the EEG in these syndromes, which focus on both aspects, are presented.     

Lateralized and focal clinical, EEG, and FLAIR MRI abnormalities in Creutzfeldt-Jakob disease.

OBJECTIVE: Creutzfeldt-Jakob disease (CJD) is a rapidly progressive fatal prion disorder with typical clinical findings of dementia, motor dysfunction, and myoclonus and characteristic electroencephalographic (EEG) findings of bilateral synchronous periodic sharp waves. Advances in neuroimaging capabilities with diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) techniques have shown promise in the non-invasive diagnosis of CJD. This series illustrates the correlation between the lateralized and focal clinical, EEG, and MRI FLAIR sequence abnormalities in 8 patients (7 men and one woman 55-73 years old) with CJD. METHODS: A case series of 8 patients, evaluated at Mayo Clinic, who had a history of rapidly progressive lateralized or focal neurologic dysfunction and laboratory findings consistent with CJD between 1996 and 1999 were identified. EEG, MRI of the head with FLAIR sequence, and cerebrospinal fluid studies were performed in all patients. RESULTS: Mean time to death from symptom onset was 4 months. Symptoms were lateralized to the left hemisphere in 5 patients and to the right hemisphere in two. One patient showed bilateral occipital lobe involvement. In all patients, the EEG showed lateralized or focal periodic sharp waves that colocalized with clinical cerebral dysfunction. FLAIR MRI images revealed increased signal in the cortical ribbon and deep gray matter corresponding to the lateralized clinical and EEG findings in 7 patients. The other patient had bilateral occipital increased signal on FLAIR MRI. CONCLUSIONS: CJD may present with lateralized or focal cortical syndromes with colocalizing EEG and MRI findings. With the appropriate clinical history and laboratory evaluation, the corresponding areas of increased signal on FLAIR MRI provide supportive evidence of the disease. SIGNIFICANCE: CJD can sometimes present with more focal or lateralized clinical findings, and the colocalizing EEG and MRI findings can help make or confirm the diagnosis of CJD.     

EEG examination during delirium tremens.

In 30 male patients several EEG examinations could be carried out during delirium tremens (d.t.) or shortly thereafter. Most of the patients showed a normal EEG or changes which can be explained with regard to sedation through medication. 1 patient showed generalized paroxysmal spike wave bursts. On account of experimental results, we may assume that a transitory cerebral excitibality change occures in d.t. This pathophysiological basis explains the normal EEGs and paroxysmal bursts during d.t. 4 cases showed passages of pronounced diffuse slow activity during d.t. partly accompanied by thythmic bilateral slow waves. These changes point to a complication of d.t. that occurs because of another disease which results in cerebral functional disturbances as in other organic psychoses.     

Benign epileptiform discharges in Rolandic region with mesial temporal lobe epilepsy: MEG, scalp and intracranial EEG features

AIM OF THE STUDY: To report benign epileptiform discharges (BEDs) in the Rolandic region, coexisting in a pediatric patient with intractable localization-related epilepsy, secondary to hippocampal sclerosis. METHODS: We describe the clinical features, MRI, scalp video EEG, magnetoencephalography (MEG) and intracranial video EEG findings, and surgical outcome in a 9-year-old boy with BEDs and intractable complex partial seizures. RESULTS: MRI showed left hippocampal sclerosis. Scalp video EEG interictally demonstrated left temporal spike and sharply contoured slow waves, and right fronto-centro-temporal spike and waves. Ictal scalp video EEG showed left temporal rhythmic sharp waves after the clinical onset of epigastric aura, followed by staring. MEG showed interictal dipoles in the bilateral Rolandic regions with a uniform orientation and right hemispheric predominance. Intracranial video EEG, with bilateral mesial temporal depth and fronto-temporo-parietal strip electrodes, interictally showed polyspikes and slow waves with superimposed low-amplitude fast waves in the left mesial and posterior lateral temporal regions, and spike and waves in the bilateral fronto-parietal regions. Ictal onset was marked by low-amplitude fast waves in the left mesial and posterior lateral temporal regions. He underwent left anterior temporal lobectomy with hippocampectomy. Pathology was hippocampal sclerosis. Predominant right fronto-centro-temporal spike and waves and MEG right Rolandic dipoles persisted after surgery. He was seizure-free 14 months after surgery. CONCLUSION: This is the first report on MEG and intracranial video EEG features of BEDs in the Rolandic region, coexisting with hippocampal sclerosis. Persistence of contralateral benign MEG Rolandic dipoles after surgery indicates that BEDs are coincidental in mesial temporal lobe epilepsy. MEG identified Rolandic dipoles, although was unable to localize the deep and focal epileptogenic dipoles from the hippocampal sclerosis.     

The Lennox-Gastaut Syndrome

Summary: One of the most challenging areas in nosology is in the field of severe generalized epilepsy of early childhood. This is certainly true in the case of Lennox-Gastaut syndrome (LGS), an age-related epileptogenic encephalopathy which comprises several types of generalized seizures including tonic seizures, atypical absence seizures and frequent status epilepticus. EEG shows generalized slow spike waves, and as the disease progresses, cognitive functions deteriorate. LGS is listed in the 1989 classification of the International League Against Epilepsy alongside epilepsy with myoclonic astatic seizures and West's syndrome. A number of variants or atypical forms have been proposed. As a result, differential diagnosis presents a major challenge and includes specific generalized epilepsies, i.e., metabolic or inflammatory; secondarily generalized epilepsies, i.e., those arising from the frontal lobe; and severe forms of idiopathic generalized epilepsy, i.e., Doose syndrome. Antiepileptic drug (AED) treatment of LGS has been disappointing. Results obtained from anterior callosotomy have been promising, but only a small number of patients have been evaluated. Although the syndrome is rare, the severe nature and intractability of LGS emphasizes the need for the development of specific AEDs which would completely modify the quality of life for these patients.     

A case of Panayiotopoulos syndrome showing an atypical course

We describe herein a patient with Panayiotopoulos syndrome (PS) showing an atypical course. The patient initially had seizures typical of this syndrome from 3 to 5 years of age. EEG showed right occipital high-amplitude sharp and slow-wave complexes followed by brief generalized discharges of slow waves. Sequential EEGs obtained from 5 to 11 years of age showed both multifocal discharges and generalized spike and wave complexes. With these changes in EEG findings, the patient experienced various types of seizures. The seizures were frequent and showed oculocephalic deviation followed by absence, atonic seizures, generalized tonic clonic convulsions and clonic seizures of the eyelids, which were observed between 7 and 10 years of age. Antiepileptic drugs were only partially effective for these seizures. Ictal EEG recorded at 8 years of age revealed high-voltage slow waves from the bilateral frontal and occipital regions prior to diffuse high-amplitude spike-wave bursts. At 9 years of age, magnetoencephalography (MEG) revealed the calculated dipoles of the preceding bifrontal spike-wave discharges to be in the frontal areas, while those of the following generalized spike-wave bursts were in the bilateral mid-temporal areas. In PS, reportedly, dipoles of multifocal epileptic discharges are usually located in the occipital and Rolandic areas. The unique clinical evolution in our case may be associated with the unusual frontal localization of dipoles detected by MEG.     

Benign familial infantile convulsions: phenotypic variability in a family

Benign familial infantile convulsion is an autosomal dominant epilepsy syndrome characterized by seizures starting from 3 to 12 months and a favorable outcome. We present a Turkish family with benign familial infantile convulsions and report the clinical variability associated with this syndrome in three generations. All 11 affected members had benign infantile seizures, which were primarily generalized in all but one patient, who had partial seizures with secondary generalization. The seizures started within the first year and were accompanied by normal neurologic development and a good response to treatment with phenobarbital. In this family, the phenotype extended beyond infancy. The index patient had unilateral occipital spike and waves on electroencephalography (EEG), although he had no clinical seizures at 4 years of age. Follow-up EEG of this patient 1 year later showed that the discharges shifted to the occipital lobe of the other hemisphere. The grandmother of this patient had temporal lobe seizures as an adult, years after the remission of infantile convulsions. One of the patients experienced paroxysmal choreoathetosis during adolesence. Our findings highlight the intrafamilial phenotypic variability of benign familial infantile convulsions in a large pedigree with long-term follow-up.     

Focal features in patients with idiopathic generalized epilepsy

Purpose: The stringent dichotomy between focal and generalized epilepsies has become a contentious issue, since neuropathological studies as well as structural and functional imaging data hypothesized the existence of focal brain abnormalities in patients with well-documented idiopathic generalized epilepsy. The aim of our study was to investigate whether clinical and EEG features generally considered typical for a focal seizure disorder also occur in patients with generalized epilepsies to further support the hypothesis of a more continuous transition between focal and generalized epilepsies in contrast to the present concept of a stringent pathophysiologic dichotomy. Methods: We retrospectively studied 20 consecutive patients with idiopathic generalized epilepsy who underwent video EEG monitoring either because of uncertainty of their epilepsy syndrome or because of a difficult to treat epilepsy. We determined the incidence of (a) focal interictal epileptiform discharges (IEDs), (b) intermittent temporal slow waves, and (c) clinical signs that are widely accepted as typical for a focal seizure onset, i.e. version, tonic/dystonic unilateral posturing, postictal hemiparesis, postictal nose wiping and figure of 4. Results: Focal IEDs occurred in seven patients (35.0%), intermittent temporal slow waves in six (30%), and clinical signs pointing towards a focal seizure onset were found in seven patients (35%). Conclusion: Our study of EEG and clinical data supports the more sophisticated previous investigations in which structural and functional imaging as well as histopathological data suggested the presence of focal brain abnormalities in patients with ‘generalized’ epilepsies. Furthermore we emphasize the cautious use of isolated focal EEG abnormalities and certain clinical signs to prevent a premature diagnosis of focal epilepsy in patients who may indeed suffer from a generalized seizure disorder.     

Acquired auditory agnosia in childhood and normal sleep electroencephalography subsequently diagnosed as Landau–Kleffner syndrome: a report of three cases

Aim We report three cases of Landau–Kleffner syndrome (LKS) in children (two females, one male) in whom diagnosis was delayed because the sleep electroencephalography (EEG) was initially normal. Method Case histories including EEG, positron emission tomography findings, and long‐term outcome were reviewed. Results Auditory agnosia occurred between the age of 2 years and 3 years 6 months, after a period of normal language development. Initial awake and sleep EEG, recorded weeks to months after the onset of language regression, during a nap period in two cases and during a full night of sleep in the third case, was normal. Repeat EEG between 2 months and 2 years later showed epileptiform discharges during wakefulness and strongly activated by sleep, with a pattern of continuous spike‐waves during slow‐wave sleep in two patients. Patients were diagnosed with LKS and treated with various antiepileptic regimens, including corticosteroids. One patient in whom EEG became normal on hydrocortisone is making significant recovery. The other two patients did not exhibit a sustained response to treatment and remained severely impaired. Interpretation Sleep EEG may be normal in the early phase of acquired auditory agnosia. EEG should be repeated frequently in individuals in whom a firm clinical diagnosis is made to facilitate early treatment.