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EEG Patterns (eeg + pattern)

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Medical Sciences86%

Selected Abstracts

Visual Function in Infants with West Syndrome: Correlation with EEG Patterns

EPILEPSIA, Issue 7 2004
Teresa Randň
Summary:,Purpose: Several studies have reported behavioral and electrophysiological evidence of visual impairment during the active stage of West syndrome. The underlying mechanisms are, however, poorly understood, and little has been reported about the correlation between visual impairment, EEG patterns, and brain lesions. The aim of the study was to assess visual function at the onset of spasm and 2 months thereafter and relate visual findings to brain lesions and EEG features. Methods: Twenty-five infants with West syndrome were enrolled and studied with (a) a full clinical assessment including a battery of tests specifically designed to assess visual function, (b) a video-polygraphic study, and (c) brain magnetic resonance imaging (MRI). Besides brain neuroimaging and EEG comparison with visual function, an intra-EEG analysis was performed to investigate the possible relation of EEG patterns to fluctuating visual behavior (fixation and following). Results: Twenty-two children had at least one abnormal result on one or more of the tests assessing visual function at T0. Visual impairment at the spasm onset was related to the sleep disorganization rather than to the hypsarrhythmic pattern in awake EEG. After 2 months, both EEG features become significantly linked to visual function. Visual function improved in several cases after 2 months, in parallel with the seizure regression. No relation was found between EEG patterns and fluctuating visual behavior. Conclusions: The study supplies new evidence of the involvement of visual function in West syndrome. The presence of abnormal visual findings in infants without lesions on brain MRI suggests that visual abnormalities are due not only to brain injury but also to epileptic disorder per se. New insight is also provided into the possible mechanisms underlying clinical and EEG abnormalities. [source]

Ictal EEG Patterns in Band Heterotopia

EPILEPSIA, Issue 4 2002
Arthur C. Grant
Summary: Band heterotopia (BH) or "double cortex" syndrome is a neuronal migration disorder resulting in a diffuse band of subcortical grey matter and variable abnormality of the overlying cortex. Patients with BH have a spectrum of psychomotor delay and seizures. Associated epileptic syndromes and interictal EEG findings have been described, but ictal EEG patterns are lacking. Methods: We describe the clinical, interictal, and ictal EEG findings in two girls with BH and intractable seizures. Results: Ictal EEG patterns correlated well with clinical seizure types, and did not have features unique to BH. Similarly, seizure behaviors and interictal EEG findings were typical of those seen in symptomatic generalized epilepsies. Conclusions: Despite evidence implicating the ectopic grey matter in seizure discharges, we conclude that seizure semiology and associated ictal EEG patterns in BH are no different from those seen in other causes of symptomatic generalized epilepsies. [source]

Symptomatic Epilepsies Imitating Idiopathic Generalized Epilepsies

EPILEPSIA, Issue 2005
Hirokazu Oguni
Summary:, The diagnosis of idiopathic generalized epilepsies (IGEs) is not generally difficult if one follows the clinical and electroencephalogram (EEG) definitions of each subsyndrome that constitutes IGEs. In contrast, symptomatic epilepsies develop based on organic brain lesions and are easily diagnosed by the presence of developmental delay, neurologic abnormalities, and a characteristic seizure and EEG pattern. However, in clinical practice, it is sometimes difficult to differentiate IGEs from symptomatic epilepsies, especially when the clinical course from the onset of epilepsy is too short to exhibit typical clinical and EEG findings of either epilepsy type, or when patients with symptomatic epilepsies have atypical features that imitate the clinical characteristics of IGEs. The neurodegenerative or metabolic disorders at times start during the clinical course with epileptic seizures and later show typical neurologic abnormalities. The newly recognized metabolic disorder of glucose transporter type 1 deficiency syndrome (Glut-1 DS) may start with myoclonic seizures at an age of less than 1 year and imitate benign myoclonic epilepsy in infancy early in the clinical course. Progressive myoclonus epilepsies (PMEs) that develop at 1,4 years of age at times imitate epilepsy with myoclonic-astatic seizures with respect to the presence of astatic seizures and an epileptic encephalopathic EEG pattern. In addition, young children with focal cortical dysplasia may also have similar clinical and EEG patterns, although the latter may become localized after treatment. Approximately 15% of patients with juvenile myoclonic epilepsy (JME) are resistant to antiepileptic drugs (AEDs) and may require extensive study to make a differential diagnosis from symptomatic epilepsies. PMEs that develop during adolescence may imitate JME early in the clinical course; however, a detailed history and the differentiation between myoclonic seizures and myoclonus would help to distinguish both conditions. The diagnosis of IGEs is very demanding for patients with atypical features with regard to seizure type, EEG findings, and response to appropriate AEDs. [source]

fMRI of Generalized Absence Status Epilepticus in Conscious Marmoset Monkeys Reveals Corticothalamic Activation

EPILEPSIA, Issue 10 2004
Jeffrey R. Tenney
Summary:,Purpose: A nonhuman primate model of generalized absence status epilepticus was developed for use in functional magnetic resonance imaging (fMRI) experiments to elucidate the brain mechanisms underlying this disorder. Methods: Adult male marmoset monkeys (Callithrix jacchus) were treated with ,-butyrolactone (GBL) to induce prolonged absence seizures, and the resulting spike,wave discharges (SWDs) were analyzed to determine the similarity to the 3-Hz SWDs that characterize the disorder. In addition, blood-oxygenation-level,dependent (BOLD) fMRI was measured at 4.7 Tesla after absence seizure induction with GBL. Results: Electroencephalographic recordings during imaging showed 3-Hz SWDs typical of human absence seizures. This synchronized EEG pattern started within 15 to 20 min of drug administration and persisted for >60 min. In addition, pretreatment with the antiepileptic drug, ethosuximide (ESM), blocked the behavioral and EEG changes caused by GBL. Changes in BOLD signal intensity in the thalamus and sensorimotor cortex correlated with the onset of 3-Hz SWDs. The change in BOLD signal intensity was bilateral but heterogeneous, affecting some brain areas more than others. No significant negative BOLD changes were seen. Conclusions: The BOLD fMRI data obtained in this marmoset monkey model of absence status epilepticus shows activation within the thalamus and cortex. [source]

Clinical and Electrographic Features of Epileptic Spasms Persisting Beyond the Second Year of Life

EPILEPSIA, Issue 6 2002
Márcio A. Sotero De Menezes
Summary: ,Purpose: Few reports detailing the electroclinical features of epileptic spasms persisting beyond infancy have been published. We sought to characterize this unique population further. Methods: We retrospectively reviewed the clinical and video-EEG data on 26 patients (4,17 years; mean, 93 months) with a confirmed diagnosis of epileptic spasms and who were evaluated at our tertiary referral center between 1993 and 2000. Results: In half of our cases, epileptic spasms were associated with disorders of neuronal migration, severe perinatal asphyxia, and genetic anomalies. Interictal EEGs showed generalized slowing in the majority of patients, and a slow-wave transient followed by an attenuation of the background amplitude was the most common ictal EEG pattern associated with an epileptic spasm (19 cases). Other seizure types (number of cases in parentheses) included tonic seizures with or without a preceding spasm (13), partial seizures (11), myoclonic seizures (11), generalized tonic,clonic seizures (six), atypical absence seizures (two), and atonic seizures (one). Cases with a more organized EEG background (especially with frequencies ,7 Hz) were more likely to have better cognition. Continued disorganization of the EEG background and persistence of hypsarrhythmia were associated with poor developmental outcome. Conclusions: Patients with epileptic spasms persisting beyond age 2 years constitute a truly refractory population, one that should be better recognized by clinicians. Interestingly, although many therapies resulted in a >50% reduction in seizures, neither neurocognitive function nor quality of life was substantially improved with intervention. The interictal EEG background is the most helpful in predicting neurologic outcome. [source]

The Impact of Cerebral Source Area and Synchrony on Recording Scalp Electroencephalography Ictal Patterns

EPILEPSIA, Issue 11 2007
James X. Tao
Summary Purpose: To determine the cerebral electroencephalography (EEG) substrates of scalp EEG seizure patterns, such as source area and synchrony, and in so doing assess the limitations of scalp seizure recording in the localization of seizure onset zones in patients with temporal lobe epilepsy. Methods: We recorded simultaneously 26 channels of scalp EEG with subtemporal supplementary electrodes and 46,98 channels of intracranial EEG in presurgical candidates with temporal lobe epilepsy. We correlated intracranial EEG source area and synchrony at seizure onset with the corresponding scalp EEG. Eighty-six simultaneous intracranial- and scalp-recorded seizures from 23 patients were evaluated. Results: Thirty-four intracranial ictal discharges (40%) from 9 patients (39%) had sufficient cortical source area (namely > 10 cm2) and synchrony at seizure onset to produce a simultaneous or nearly simultaneous focal scalp EEG ictal pattern. Forty-one intracranial ictal discharges (48%) from 10 patients (43%) gradually achieved the necessary source area and synchrony over several seconds to generate a scalp EEG ictal pattern. These scalp rhythms were lateralized, but not localizable as to seizure origin. Eleven intracranial ictal discharges (13%) from 4 patients (17%) recruited the necessary source area, but lacked sufficient synchrony to result in a clearly localized or lateralized scalp ictal pattern. Conclusions: Sufficient source area and synchrony are mandatory cerebral EEG requirements for generating scalp-recordable ictal EEG patterns. The dynamic interaction of cortical source area and synchrony at the onset and during a seizure is a primary reason for heterogeneous scalp ictal EEG patterns. [source]

Symptomatic Epilepsies Imitating Idiopathic Generalized Epilepsies

EPILEPSIA, Issue 2005
Hirokazu Oguni
Summary:, The diagnosis of idiopathic generalized epilepsies (IGEs) is not generally difficult if one follows the clinical and electroencephalogram (EEG) definitions of each subsyndrome that constitutes IGEs. In contrast, symptomatic epilepsies develop based on organic brain lesions and are easily diagnosed by the presence of developmental delay, neurologic abnormalities, and a characteristic seizure and EEG pattern. However, in clinical practice, it is sometimes difficult to differentiate IGEs from symptomatic epilepsies, especially when the clinical course from the onset of epilepsy is too short to exhibit typical clinical and EEG findings of either epilepsy type, or when patients with symptomatic epilepsies have atypical features that imitate the clinical characteristics of IGEs. The neurodegenerative or metabolic disorders at times start during the clinical course with epileptic seizures and later show typical neurologic abnormalities. The newly recognized metabolic disorder of glucose transporter type 1 deficiency syndrome (Glut-1 DS) may start with myoclonic seizures at an age of less than 1 year and imitate benign myoclonic epilepsy in infancy early in the clinical course. Progressive myoclonus epilepsies (PMEs) that develop at 1,4 years of age at times imitate epilepsy with myoclonic-astatic seizures with respect to the presence of astatic seizures and an epileptic encephalopathic EEG pattern. In addition, young children with focal cortical dysplasia may also have similar clinical and EEG patterns, although the latter may become localized after treatment. Approximately 15% of patients with juvenile myoclonic epilepsy (JME) are resistant to antiepileptic drugs (AEDs) and may require extensive study to make a differential diagnosis from symptomatic epilepsies. PMEs that develop during adolescence may imitate JME early in the clinical course; however, a detailed history and the differentiation between myoclonic seizures and myoclonus would help to distinguish both conditions. The diagnosis of IGEs is very demanding for patients with atypical features with regard to seizure type, EEG findings, and response to appropriate AEDs. [source]

Visual Function in Infants with West Syndrome: Correlation with EEG Patterns

EPILEPSIA, Issue 7 2004
Teresa Randň
Summary:,Purpose: Several studies have reported behavioral and electrophysiological evidence of visual impairment during the active stage of West syndrome. The underlying mechanisms are, however, poorly understood, and little has been reported about the correlation between visual impairment, EEG patterns, and brain lesions. The aim of the study was to assess visual function at the onset of spasm and 2 months thereafter and relate visual findings to brain lesions and EEG features. Methods: Twenty-five infants with West syndrome were enrolled and studied with (a) a full clinical assessment including a battery of tests specifically designed to assess visual function, (b) a video-polygraphic study, and (c) brain magnetic resonance imaging (MRI). Besides brain neuroimaging and EEG comparison with visual function, an intra-EEG analysis was performed to investigate the possible relation of EEG patterns to fluctuating visual behavior (fixation and following). Results: Twenty-two children had at least one abnormal result on one or more of the tests assessing visual function at T0. Visual impairment at the spasm onset was related to the sleep disorganization rather than to the hypsarrhythmic pattern in awake EEG. After 2 months, both EEG features become significantly linked to visual function. Visual function improved in several cases after 2 months, in parallel with the seizure regression. No relation was found between EEG patterns and fluctuating visual behavior. Conclusions: The study supplies new evidence of the involvement of visual function in West syndrome. The presence of abnormal visual findings in infants without lesions on brain MRI suggests that visual abnormalities are due not only to brain injury but also to epileptic disorder per se. New insight is also provided into the possible mechanisms underlying clinical and EEG abnormalities. [source]

Angelman Syndrome: Difficulties in EEG Pattern Recognition and Possible Misinterpretations

EPILEPSIA, Issue 8 2003
Kette D. Valente
Summary: Purpose: This study aimed to evaluate the sensitivity of the EEG in Angelman syndrome (AS), to verify the age at onset of suggestive EEGs and to study EEG patterns, analyzing variations and comparing our findings with nomenclature previously used. Methods: Seventy EEG and 15 V-EEGs of 26 patients were analyzed. Suggestive EEG patterns of AS were classified in delta pattern (DP), theta pattern (TP), and posterior discharges (PDs). Generic terms were used to simplify the analysis. Results: Suggestive EEGs were observed in 25 (96.2%) patients. DP occurred in 22 patients with four variants,hypsarrhythmic-like: irregular, high-amplitude, generalized delta activity (DA) with multifocal epileptiform discharges (EDs); slow variant: regular, high-amplitude, generalized DA with rare EDs; ill-defined slow spike-and-wave: regular, high-amplitude, generalized DA with superimposed EDs characterizing a slow wave, with notched appearance; triphasic-like: rhythmic, moderate-amplitude DA over anterior regions with superimposed EDs. TP was observed in eight patients, as generalized or over the posterior regions. PDs were seen in 19 patients as runs of sharp waves or runs of high-amplitude slow waves with superimposed EDs. TP was the only age-related pattern (younger than 8 years) and observed only in patients with deletion. In 15 patients who had an EEG before the clinical diagnosis, 60% had a suggestive tracing. Conclusions: Although some EEG descriptions are not very detailed, and every author describes findings in a slightly different manner, obviously a common denominator must exist. In this context, EEG seems to be a very sensitive method for the diagnosis of AS, offering an opportunity to corroborate this etiologic diagnosis. Conversely, we do not believe that these patterns may be accounted as specific, except for the delta pattern, which seems to be extremely unusual in other syndromes. Other EEG patterns observed in AS, such as theta activity and PDs, occur in a wide variety of disorders. Nonetheless, their importance for the EEG diagnosis of AS is supported by the fact that they are associated with other features and may be helpful in a proper clinical setting. [source]

Ictal EEG Patterns in Band Heterotopia

EPILEPSIA, Issue 4 2002
Arthur C. Grant
Summary: Band heterotopia (BH) or "double cortex" syndrome is a neuronal migration disorder resulting in a diffuse band of subcortical grey matter and variable abnormality of the overlying cortex. Patients with BH have a spectrum of psychomotor delay and seizures. Associated epileptic syndromes and interictal EEG findings have been described, but ictal EEG patterns are lacking. Methods: We describe the clinical, interictal, and ictal EEG findings in two girls with BH and intractable seizures. Results: Ictal EEG patterns correlated well with clinical seizure types, and did not have features unique to BH. Similarly, seizure behaviors and interictal EEG findings were typical of those seen in symptomatic generalized epilepsies. Conclusions: Despite evidence implicating the ectopic grey matter in seizure discharges, we conclude that seizure semiology and associated ictal EEG patterns in BH are no different from those seen in other causes of symptomatic generalized epilepsies. [source]

Single neuron burst firing in the human hippocampus during sleep

HIPPOCAMPUS, Issue 6 2002
Richard J. Staba
Abstract Although there are numerous non-primate studies of the single neuron correlates of sleep-related hippocampal EEG patterns, very limited hippocampal neuronal data are available for correlation with human sleep. We recorded human hippocampal single neuron activity in subjects implanted with depth electrodes required for medical diagnosis and quantitatively evaluated discharge activity from each neuron during episodes of wakefulness (Aw), combined stage 3 and 4 slow-wave sleep (SWS), and rapid eye movement (REM) sleep. The mean firing rate of the population of single neurons was significantly higher during SWS and Aw compared with REM sleep (p = 0.002; p < 0.0001). In addition, burst firing was significantly greater during SWS compared with Aw (p = 0.001) and REM sleep (p < 0.0001). The synchronized state of SWS and associated high-frequency burst discharge found in human hippocampus may subserve functions similar to those reported in non-primate hippocampus that require burst firing to induce synaptic modifications in hippocampal circuitry and in hippocampal projections to neocortical targets that participate in memory consolidation. Hippocampus 2002;12:724,734. © 2002 Wiley-Liss, Inc. [source]

EEG correlates of emotions in dream narratives from typical young adults and individuals with autistic spectrum disorders

PSYCHOPHYSIOLOGY, Issue 2 2008
Anne-Marie Daoust
Abstract The relationship between emotional dream content and Alpha and Beta REM sleep EEG activity was investigated in typical individuals and in Autistic Spectrum Disorders (ASD). Dream narratives of persons with ASD contained fewer emotional elements. In both groups, emotions correlated positively with slow Alpha (8.0,10.0 Hz) spectral power over parieto-occipital and left central regions, as well as with a right occipital EEG asymmetry. Slow Alpha activity in ASD individuals was lower over midline and parasagittal areas and higher over lateral areas compared to controls. Both groups displayed a right-biased slow Alpha activity for midparietal and occipital (significantly higher in control) sites. Results indicate that Alpha EEG activity may represent a neurophysiological substrate associated with emotional dream content. Distinctive Alpha EEG patterns and asymmetries suggest that dream generation implies different brain connectivity in ASD. [source]

Epilepsy in fragile X syndrome

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 11 2002
Elizabeth Berry-Kravis MD PhD
Epilepsy is reported to occur in 10 to 20% of individuals with fragile X syndrome (FXS). A frequent seizure/EEG pattern in FXS appears to resemble that of benign focal epilepsy of childhood (BFEC, benign rolandic epilepsy). To evaluate seizure frequency and type in a Chicago FXS cohort, data regarding potential seizure history were reviewed for 136 individuals with FXS (age range 2 to 51 years: 113 males and 23 females). Seizures occurred in 15 males (13.3%) and one female (4.3%): of these, 12 had partial seizures. EEG findings were available for 35 individuals (13 of 16 with seizures and 22 of 120 without seizures) and showed an epileptiform abnormality in 10 (77%) individuals with seizures and five (23%) individuals without seizures - the most common epileptiform pattern being centrotemporal spikes. Seizures were easily controlled in 14 of the 16 individuals with seizures. Many individuals, including all with centrotemporal spikes, had remission of seizures in childhood. The most common seizure syndrome resembled BFEC and this pattern had the best prognosis for epilepsy remission. Deficiency of FMRP (fragile X mental retardation protein) appears to lead to increased neuronal excitability and susceptibility to epilepsy, but particularly seems to facilitate mechanisms leading to the BFEC pattern. [source]