Abstracts of the Clinical EEG & Neuroscience Journal, Volume 31
January 2000, Volume 31
A Review of EEG Biofeedback Treatment of Anxiety Disorders
Norman C. Moore
Alpha, theta and alpha-theta enhancements are effective treatments of the anxiety disorders (Table 1). Alpha suppression is also effective, but less so (Table 2). Perceived success in carrying out the task plays an important role in clinical improvement. Research is needed to find out how much more effective they are than placebo, and which variables are important for efficacy. Variables needing study are: duration of treatment, type and severity of anxiety, number and type of EEG waveforms used, pretreatment with other kinds of feedback, position and number of electrodes, and presence of concomitant medication.
An EEG Biofeedback Protocol for Affective Disorders
J. Peter Rosenfeld
No abstract available.
The Treatment of Addictive Disorders by Brain Wave Biofeedback: a Review and Suggestions for Future Research
David L. Trudeau
No abstract available.
Self-Regulation of Electrocortical Activity in Schizophrenia and Schizotypy: A Review
Contrary to the belief that schizophrenic patients will be unable to learn self control of electrocortical activity due to attentional and motivational deficits, the two studies which have investigated this, both involving operant conditioning of slow cortical potentials, have demonstrated that self regulation can take place. This was particularly true of a study of interhemispheric control. Learning difficulties were found to be more to do with sustaining motivation towards the end of sessions or training programs, rather than in initial learning. Schizotypical features in the normal population have in the case of anhedonia been associated with slower learning, while withdrawn introversion has been associated with faster learning. In view of the affirmative evidence and advances in understanding the functional significance of electroencephalographic (EEG) rhythms, the undertaking of therepeutic regimens with electrocortical operant conditioning is warranted in the schizophrenia spectrum.
Treatment of Attention Deficit Hyperactivity Disorder with Neurotherapy
John K. Nash
Significant public health concerns exist regarding our current level of success in treating ADHD. Medication management is very helpful in 60-70% of patients. Side effects, lack of compliance and the fact that stimulant medications cannot be given late in the day limit the benefits largely to school hours. While stimulants improve behavior and attention, less of an effect has been noted on academic and social performance. Continuing concerns exist about long-term safety, and studies on long-term cardiovascular and neurophysiological effects have not been carried out. Neurotherapy for ADHD offers an effective alternate for patients whose treatment is limited by side effects, poor medication response and in cases in which the patients and/or their parents refuse to consider medications. Studies indicate clinical improvement is largely related to measurable improvements in the EEG signature, evidenced by declining theta/beta ratios over frontal/central cortex and/or reduced theta/alpha band amplitudes.
EEG Operant Conditioning (Biofeedback) and Traumatic Brain Injury
Robert W. Thatcher
A review is presented of the currently sparse literature about EEG operant conditioning or biofeedback as a treatment to reduce symptomology and patient complaints following a traumatic brain injury. The paper also evaluates the general use of quantitative EEG (QEEG) to assess traumatic brain injury and to facilitate EEG biofeedback treatment. The use of an age matched reference normative QEEG database and QEEG discriminant function are presented as a method to evaluate the nature or neurological basis of a patient’s complaints as well as to individualize an efficient and optimal feedback protocol and to help evaluate the efficacy of the biofeedback therapy. Univariate and multivariate statistical issues are discussed, different classes of experimental designs are described and then a "double blind" research study is proposed in an effort to encourage future research in the area of EEG biofeedback for the treatment and rehabilitation of traumatic brain injury.
Basic Concepts and Clinical Findings in the Treatment of Seizure Disorders with EEG Operant Conditioning
M. Barry Sterman
Two issues concerning sensorimotor EEG operant conditioning, or biofeedback, as a therapeutic modality for the treatment of seizure disorders are the focus of this review. The first relates to the question of whether relevant physiological changes are associated with this procedure. This question is addressed through review of an extensive neurophysiological literature that is likely unfamiliar to many clinicians but that documents both immediate and sustained functional changes that are consistent with elevation of seizure thresholds. The second focuses on the clinical efficacy of this method and whether it should carry the designation of "experimental". This designation is challenged through an assessment of over 25 years of peer-reviewed research demonstrating impressive EEG and clinical results achieved with the most difficult subset of seizure patients.
The History of the Electroencephalography and Clinical Neuroscience Society (ECNS)
Part I: A Brief History of The American Medical Electroencephalographic Association (AMEEGA)
No abstract available.
Part II: The American Psychiatric Electrophysiology Association (APEA): History and Mission
N. N. Boutros
No abstract available.
Somatosensory Evoked Spikes and Epileptic Seizures: A Study of 385 Cases
Lineu C. Fonseca and Gloria M. A. S. Tedrus
We examined 385 children whose EEG showed high voltage potentials evoked by taps applied to one or both feet or hands (SES). The relationship between characteristics of SES and the occurrence of epileptic seizures and the characterization of epileptic syndromes were studied. Ninety-one children (23.6%) had epilepsy, 42 (10.9%) had only febrile convulsions and 252 children had other complaints. Epilepsy occurred in a higher proportion of cases when: SES by foot tapping were multiphasic, with high amplitude or SES were obtained by hand stimulation and there was spontaneous epileptiform activity in the EEG. The following epileptic syndromes were diagnosed: benign childhood epilepsy with centrotemporal spikes in 21 cases, benign epilepsy of childhood with occipital paroxysms in 2, benign psychomotor epilepsy in 1, "partial idiopathic others" in 43, generalized idiopathic in 8, symptomatic epilepsies in 13 and undetermined in 3 cases.
In most cases SES were observed in children without evidence of cerebral organic lesion, suggesting the existence of an age-related, functional mechanism. Some characteristics of SES and the occurrence of spontaneous epileptiform activity showed a positive association with epileptic seizures. SES occurred in different types of partial and generalized epilepsies of childhood but in nearly 50% of the cases with epilepsy, there was a benign condition involving mainly the parietal lobe with versive, unilateral and sleep-generalized seizures.
Electroclinical Features in Children and Adolescents with Epilepsy and/or Migraine, and Occipital Epileptiform EEG Abnormalities
Mario Brinciotti, Maria Lucia Di Sabato, Maria Matricardi and Vincenzo Guidetti
This study attempted to better define clinical and EEG features for differential diagnosis between epilepsy and migraine in children with occipital epileptiform EEG abnormalities. We studied 126 children (57 males, 69 females; age 4-18 years) suffering from epilepsy (63), migraine (43) or both (20). Patients were selected because of the presence of epileptiform abnormalities in the occipital regions on their EEG at rest. Differences among groups were statistically analyzed (Pearson chi square; ANOVA) for sex, age at onset of seizures and migrainous attacks, family history, ictal signs and symptoms, EEG at rest (unilateral vs bilateral distribution of epileptiform abnormalities), and EEG during Hyperventilation (HV) and Intermittent Photic Stimulation (IPS).
Significant differences were found in family history, ictal signs and symptoms, EEG at rest and during activation tests. A family history of epilepsy, visual symptoms such as colored hallucinations and micro/macropsias, frequently associated with clinical signs in the visual system (eye deviation, nystagmus), unilateral EEG abnormalities, and abnormal response to IPS were closely related to diagnosis of epilepsy. On the other hand, a family history of migraine, visual symptoms such as amaurosis and scotomata, without evident clinical signs, bilateral EEG abnormalities, and no changes during IPS were significantly related to migraine.
In conclusion, these clinical and EEG differences should be considered in the differential diagnosis between epilepsy and migraine in children with occipital epileptiform EEG abnormalities.
Investigation of the Cerebral Response to Flicker Stimulation in Patients with Headache
P. Chorlton and N. Kane
Migraine affects 10% of the population, yet there is no proven diagnostic test. To date the most promising neurophysiological diagnostic technique has been the analysis of cerebral responses to photic stimulation or flicker (the "H" response). This test has proved to be sensitive in patients with "classic" migraine, but has not been re-evaluated since the introduction of the 1988 International Headache Society (IHS) classification system. In 33 migraineurs, we found that the "H" response was sensitive (86.4%) and specific (97.5%) in those with migraine defined according to IHS Committee as type 1.2.1 (typical aura) and type 1.1 (without aura), but not in basilar migraine (1.2.4).
Reduction of Auditory P50 Gating Response in Marihuana Users: Further Supporting Data
Gloria Patrick and Frederick A. Struve
This report attempts to replicate our recent finding 2 of a significantly reduced sensory gating response in medically and psychiatrically normal chronic marihuana users. After exclusions, 10 normal heavy marihuana users (= 3 times per week) and 10 normal non-user controls were tested with the paired auditory P50 sensory gating procedure. Sensory gating ratios were significantly higher (i.e., impaired suppression) for THC users as compared to controls. Using combined data from the current and previous report, 2 the degree of sensory gating impairment among THC users was significantly correlated with the frequency of marihuana use per week. Suggestions for further research are offered.
The Mozart Effect: Distinctive Aspects of the Music — A Clue to Brain Coding?
John R. Hughes and John J. Fino
The goal of this study was to determine distinctive aspects of Mozart music that may explain the "Mozart Effect," specifically, the decrease in seizure activity. As many as 81 musical selections of Mozart, but also 67 of J.C. Bach, 67 of J.S. Bach, 39 of Chopin and 148 from 55 other composers were computer analyzed to quantify the music in search of any distinctive aspect and later to determine the degree to which a dominant periodicity could be found. Long-term periodicity (especially 10-60 sec, mean and median of 30 sec), was found often in Mozart music but also that of the two Bachs, significantly more often than the other composers and was especially absent in the control music that had no effect on epileptic activity in previous studies. Short-term periodicities were not significantly different between Mozart and the Bachs vs. the other composers. The conclusion is that one distinctive aspect of Mozart music is long-term periodicity that may well resonate within the cerebral cortex and also may be related to coding within the brain.
Changes in Functional Coupling Between Neural Networks in the Brain During Maturation Revealed by Omega Complexity
C.J. Stam, E. M. Hessels-van der Leij, J. Meulstee and J. H. R. Vliegen
To study age-dependant changes in coupling between cortical neural networks we applied a new method (omega complexity) to determine overall coherence of EEGs of 34 subjects ranging in age from 3 months to 16 years. We found that the functional coupling between different brain regions is low at birth and increases significantly in the first two decades of life. We suggest that this coupling depends critically upon the system of associational and callosal fibers which is unmyelinated at birth, and which only finishes myelinization in the second or third decade. Thus age-dependant changes in omega complexity may reflect maturation of brain structures underlying higher cerebral functions. If these results can be replicated, preferably in prospective, cohort rather than transectional type studies, omega complexity might prove to be clinically useful as an objective, quantitative measure of brain maturation.
Effects of Scopolamine on Interhemispheric EEG Coherence in Healthy Subjects: Analysis During Rest and Photic Stimulation
Mitsuru Kikuchi, Yuji Wada,Yoshifumi Koshino, Yuko Nanbu and Takuma Hashimoto
The present study of coherence analysis, in 16 healthy male volunteers, aged 24-31 years, showed that the administration of 0.25 mg of scopolamine significantly reduced interhemispheric coherence in the delta and beta-1 bands in the resting state. Scopolamine also caused a significant increase both in EEG coherence during PS and in PS-related coherence reactivity in the beta band. In addition, this compound significantly reduced total WMS scores. These findings suggest that, in addition to causing cognitive impairments, central cholinergic dysfunction can alter interhemispheric functional connectivity under both nonstimulus and stimulus conditions.
Early Detection of Neurophysiological Abnormalities in Infection by Human Immunodeficiency Virus
Cristina Aznar-Bueno, Francisco Abad-Alegría and Juan Antonio Amiguet
The human immunodeficiency virus causes serious, progressive and irreversible deterioration of the immunocompetence system and of the nervous system, so neurological pathology in infected patients is frequent (30-40%), affecting both the central and the peripheral nervous systems. There are different clinical and laboratory indicators of bad prognosis, considering the important neurotropism of the virus. This study attempts to evaluate which neurophysiological parameters are altered during the initial phases of infection by HIV.
A total of 46 individuals were studied, 30 seronegative and 16 seropositive in stage A of the CDC-93 classification. Motor and sensory conduction studies were carried out on all of them on the upper and lower extremities, as well as visual, somatosensory and auditory evoked potentials and endogenous potentials, mainly P300. The analysis of the neurophysiological parameters evaluated in our series, showed alterations of the conduction velocity of the sural nerve, latency of N1 of the SSEP of median and posterior tibial nerves and P300 in the initial phases of the infection even in the absence of clinical symptomatology.
Real-time Detection of Epileptiform Activity in the EEG: A Blinded Clinical Trial
Michael A. Black, Richard D. Jones, Grant J. Carroll, Alison A. Dingle, Ivan M. Donaldson and Philip J. Parkin
The aim of this study was to determine the performance of a PC-based system for real-time detection and topographical mapping of epileptiform activity (EA) in the EEG during routine clinical recordings. The system incorporates a mimetic stage to locate candidate spikes (including sharp-waves) followed by two expert-system-based stages, which utilize spatial and wide-temporal contextual information in deciding whether candidate events are epileptiform or not. The data comprised 521 consecutive routine clinical EEG recordings (173 hours). Performance was evaluated by comparison with three independent electroencephalographers (EEGers-I). A second group of two EEGers (EEGers-II) separately interpreted the spike topographical maps and, for EEGs categorized as containing only questionable EA by the detection system, reviewed 6 sec segments of raw EEG centered on each questionable event. Thirty-eight of the EEGs were considered to contain definite EA by at least two of EEGers-I. The false detection rate of the system was 0.41 per hour. The system was found to have a sensitivity of 76% and a selectivity of 41% for EEGs containing definite EA. However, it only missed detection of EA in 5% of the recordings. EEGers-II agreed with EEGers-I on the distribution (generalized, lateralized, focal, multifocal) of EA in 79% of cases. This is by far the largest clinical evaluation of computerized spike detection reported in the literature and the only one to apply this in routine clinical recordings. The false detection rate is the lowest ever reported, suggesting that this multi-stage rule-based system is a powerful and practical tool in clinical electroencephalography and long-term EEG monitoring.
EEG in the Elderly: Seizures vs. Syncope
John R. Hughes and Miguel L. Zialcita
The EEGs of elderly patients with a definite seizure disorder (161 patients; 302 EEGs) were compared to patients with "syncope" (122 patients; 133 EEGs), especially to determine if the latter patients were sufficiently similar to the seizure patients that the syncope could be viewed as a seizure phenomenon. The two groups were similar only by the predominance of females in both groups (61-62%) and otherwise were very different. The seizure group had a higher incidence of (1) etiology (83 vs. 39%), (2) epileptiform discharges (93 vs. 49%), with a different location, more often parasagittal, and different number often with active or very active foci, (3) frontal slow waves, (4) more severe slow wave abnormalities, (5) slower background frequencies, that were less well organized and developed and (6) abnormal records. The conclusion is that the syncope patients as a group are usually not simply seizure patients. Regardless of etiology, the patients with "syncope" (33% with cerebrovascular and 21% cardiac etiologies) showed nearly a 50% incidence of epileptiform discharges, demonstrating a complex interrelationship between cardiac and cerebral mechanisms, which are discussed. The conclusion is that epileptiform activity in elderly patients with syncope is likely to be mildly epileptogenic, and may require additional cardiovascular mechanisms to generate an attack of unconsciousness.
Nonconvulsive Status Epilepticus Resulting from Jarisch-Herxheimer Reaction in a Patient with Neurosyphilis
Suleiman Kojan, Paul C. Van Ness and Ramon Diaz-Arrastia
We report a case of Jarisch-Herxheimer reaction in a patient with neurosyphilis, which was complicated by nonconvulsive status epilepticus. The EEG features suggested a focal seizure onset, although the patient’s MRI was normal. JHR is common in the treatment of neurosyphilis, but usually produces only transient systemic constitutional symptoms. Neurologic deterioration is rare, but can be dramatic, as in our patient. NCSE should be considered as an explanation for persistent obtundation and transient focal neurologic findings in this setting.
Topographic Quantitative Analysis of the Intrinsic Alpha Rhythm in Chronic Obstructive Pulmonary Disease
Roy R. Reeves, Frederick A. Struve, Gloria Patrick, D. Keith Payne and Larry L. Thirstrup
Twenty-two patients with documented COPD and no other significant illnesses were studied to assess the effect of varying degrees of COPD on the intrinsic alpha rhythm. The severity of COPD was determined by spirometry with assessment of FEV1, FVC, and FEV1/FVC. The alpha frequency for COPD patients was slower than that which characterizes age equated normals and averages 1.6 S.D. below normative data base mean values (range -0.43 S.D. to -1.85 S.D.). Impairment of pulmonary functioning significantly correlated with the degree of alpha frequency slowing over the posterior cortical regions, and the slowest alpha frequencies occurred in those COPD patients with the lowest FEV1/FVC ratios. Impairment of cognitive functioning is thus an important clinical consideration in treatment of patients with COPD but may go unrecognized until late in the course of the disease.
EEG Hemispheric Asymmetry as a Predictor and Correlate of Short-term Response to Clozapine Treatment in Schizophrenia
V. Knott, A. Labelle, B. Jones and C. Mahoney
In search of early neuroleptic response predictors in schizophrenia, functional interhemispheric and intrahemispheric asymmetry indices, derived from spectrally analyzed resting electroencephalographic (EEG) activity, were examined in 17 schizophrenic patients prior to open label treatment with the atypical neuroleptic clozapine. Compared to EEG asymmetry indices derived from a normative data bank, patients exhibited significant interhemispheric (left greater than right) and intrahemispheric (anterior greater than posterior) deviations in delta, theta, alpha and beta frequency bands. Intrahemispheric indices were positively correlated with clinical ratings of positive symptoms and global psychopathology. Clozapine-induced improvements in positive and negative symptoms and global psychopathology symptom ratings were related to pretreatment intrahemispheric asymmetry only, with relationships varying with symptom, recording region and frequency band. The results are discussed in relation to the neurobiology of schizophrenia and the utility of EEG as an informative predictor of treatment response.
Absence Seizures and the Frontal Lobe
Antonino Pavone and E. Niedermeyer
There is no doubt that the frontal lobe plays a major role in the 3/sec spike-wave absence seizure. It is pointed out initially that the controversies of cortical vs. thalamic origin of the spike-waves and the associated absence can be laid at rest as far as human absence seizures and human primary generalized epilepsy (PGE) are concerned: their origin is cortical with maximal frontal lobe involvement. Experimentally-induced spike-wave bursts or spontaneous spike-waves in animals pertain to other forms of epileptic seizure disorder.
The frontal maximum of the 3/sec spike-wave pattern indeed indicates maximal frontal lobe involvement including both prefrontal and frontomotor portions. The absence as such is presumed to be a suspension of the working memory — an eminently frontal lobe function. This explains the immediate restoration of ictally-impaired neurocognitive functions right at the termination of the seizures. This concept can be applied not only to the classical absence occurring in PGE but also to the rare cases of secondary bilateral synchrony with a primary frontal epileptogenic focus leading to true (though very slightly different) absences.
Nose Wiping: An Unrecognized Automatism in Absence Seizures
Betül Baykan, Candan Gürses and Ays¸en Gökyig?it
Nose wiping is a well-known postictal automatism in complex partial seizures, considered very important for lateralization. We report a 24-year-old woman selected from 32 patients with video-EEG investigations of absence seizures. The patient, with normal examination and imaging findings, had typical absence seizures from the age of 5 years, which were controlled with either ethosuximide or valproate and worsened by carbamazepine. In two of her recorded typical absence seizures associated with generalized 3 Hz symmetric spike-wave discharges, she wiped her nose as an automatism in the ictal and post-ictal period. Our case showed that nose wiping could be associated with generalized seizures, in contrast to other recent reports.
Early-latency Somatosensory Evoked Potentials Elicited by Electrical Acupuncture After Needling Acupoint LI-4
Haifeng Wei, Jian Kong, Ding Zhuang, Hongyan Shang and Xiuzhen Yang
The stimulating methods of prior studies on somatosensory evoked potentials (SEPs) elicited by acupoint stimulus had involved surface electrodes, while the clinical practice of acupuncture is mostly performed by inserting the acupuncture needle inside the body. Clinical observations show that there are often some special sensations when LI-4 is needled. To observe if the SEPs produced by acupoint acupuncture had a distinguishing property, we studied the SEPs elicited by electrical acupuncture after the acupuncture needle was inserted into LI-4 and its control point, and then mapped them with the 128-channel Electric Brain Signal Image system. We also compared this to SEPs by median nerve stimuli. Results showed that the most interesting finding was the marked differences of N1-P1 and N2-P2 amplitude between SEPs at LI-4 (SEP-LI) and its control point (SEP-CP), which were in the opposite direction. Marked differences were also found between latencies and amplitudes of the SEPs elicited by acupuncture and by median nerve stimulus (SEP-M). The differences between SEP-LI and SEP-CP might be due to the additional effects of the activation of nerve endings and muscle spindles in LI-4 to the SEPs formed by the activation of superficial and deep radial nerves during electrical acupuncture. The differences between SEPs to acupoint and median nerve stimuli might be mainly due to the different distances from the stimulated regions to the cerebral cortex, the diversity and the number of activated fibers.
Sources of Abnormal EEG Activity in Brain Infarctions
Antonio Fernández-Bouzas, Thalía Harmony, Thalía Fernández, Juan Silva-Pereyra, Pedro Valdés, Jorge Bosch, Eduardo Aubert, Gustavo Casián, Gloria Otero Ojeda, Josefina Ricardo, Adriana Hernández-Ballesteros and Efraín Santiago
EEGs from 16 patients with stroke in three different stages of evolution were recorded. EEG sources were calculated every 0.39 Hz by frequency domain VARETA. The main source was within the delta band in 2 out of 4 chronic patients, and in 67% of the patients in the acute or subacute stages when edema (cytotoxic or vasogenic) was present. Moreover, all patients showed abnormal activity in the theta band. Sources of abnormal activity in cortical or corticosubcortical infarcts were located in the cortex, surrounding the lesion. At the site of the infarct, a decrease of EEG power was observed. Sources of abnormal theta power coincided with edema and/or ischemic penumbra.
Effect of Normal Aging Upon Interhemispheric EEG Coherence : Analysis During Rest and Photic Stimulation
Mitsuru Kikuchi, Yuji Wada,Yoshifumi Koshino, Yuko Nanbu and Takuma Hashimoto
The present study was conducted to examine and compare interhemispheric EEG coherence at rest and during photic stimulation (PS; 5, 10 and 15 Hz) in 30 younger subjects aged 22.1 ± 2.2 (mean ± S.D.) and 25 elderly subjects aged 56.8 ± 4.9. The elderly subjects had significantly lower coherence in the resting EEG for the delta, theta, alpha-3, beta-1 and beta-2 frequency bands. In contrast, EEG analysis during PS showed that elderly subjects had significantly higher coherence in the frequency corresponding to PS at 15 Hz. In addition, when we examined the changes in coherence from the resting state to the stimulus condition (i.e., coherence reactivity), elderly subjects had significantly higher coherence reactivity to PS at 15 Hz. These findings suggest a low interhemispheric functional connectivity in elderly subjects under nonstimulus conditions and a high connectivity during photic stimulus.
Transitory Cognitive Impairment in Epileptic Children During a CPT Task
A. A. González-Garrido, J. L. Oropeza de Alba, F. R. Gómez-Velázquez,T. Fernández Harmony, J. L. Soto Mancilla, H. Ceja Moreno, D. Pérez Rulfo, S. González Cornejo, R. Riestra Castñeda, L. E. Aguirre Portillo, E. Gómez Limón and J. L. Ruiz Sandoval
EEGs and behavioral responses were studied in two sex matched groups of 58 epileptic and 20 healthy children between 8 and 12 years of age, during the execution of a go-no go CPT (X; A-X) task to determine transitory cognitive impairment (TCI) incidence. Paroxysmal discharges were found on 87.9% and 5% of the EEGs in the epileptic and control groups respectively, with no differences related to sex. The predominant EEG findings with respect to paroxysmal discharges were the association of two or more types of paroxysms with frequency higher than 5/minute, an average duration less than 0.5 second and topographical distribution over temporal-parietal-occipital areas without significant interhemispheric differences. TCI was detected in 36.2% of epileptic children. The epileptic group showed significantly higher numbers of behavioral errors and longer reaction times (RTs) in relation to the control group. Analyzing RTs on the two blocks of the task, linear discriminant analysis showed an acceptable classification of TCI incidence between groups.
Wavelet Analysis of Transient Biomedical Signals and Its Application to Detection of Epileptiform Activity in the EEG
Hansjerg Goelz, Richard D. Jones and Philip J. Bones
Wavelet based signal analysis provides a powerful new means for the analysis of nonstationary signals such as the human EEG. The properties of the discrete wavelet transform are reviewed in illustrated application examples. The continuous wavelet transform is shown to provide better detection and representation of isolated transients. An approach to extract features of edges and transients from the continuous wavelet transform is outlined. Matching pursuit is presented as a more general transform method that covers both transients and oscillation spindles. A statistical model for the continuous wavelet transform of background EEG is found. A spike detection system based on this background model is presented. The performance of this detection system has been assessed in a preliminary clinical study of 11 EEG recordings containing epileptiform activity and shown to have a sensitivity of 84% and a selectivity of 12%. The spatial context of epileptiform activity will be incorporated to improve system performance.
Considerations of Nonconvulsive Status Epilepticus
E. Niedermeyer and Marcia Ribeiro
The original concepts of absence status (AS) and complex partial status (CPS) are critically reviewed. This review has been prompted by a modern concept of nonconvulsive status epilepticus (NCSE), portrayed as a rather common condition occurring chiefly in the critically ill elderly with high morbidity and mortality. This new view is a striking departure from the original concepts of AS and CPS as rare protracted epileptic events occurring usually in temporarily confused but otherwise satisfactorily healthy and ambulatory patients.
This new trend appears to have been caused by a misinterpretation of EEG findings: prominent generalized spike activity is in reality the expression of a very severe encephalopathy rather than of NCSE, most often caused by an anoxic episode.
The role of EEG is emphasized but a valuable interpretation depends on an expert integration of EEG and clinical data. A brief discussion of epileptic twilight states further stresses the difficult differential diagnosis.
EEG Findings in Konzo: A Spastic Para/Tetraparesis of Acute Onset
D. Tshala Katumbay, V. Mutombo Lukusa and K. Edebol Eeg-Olofsson
EEGs were recorded on 21 konzo subjects (median age 17 years) and 13 of their close healthy relatives (median age 41 years). Konzo subjects were clinically selected and classified according to the WHO criteria. Standard waking EEG recordings were performed according to the International 10-20 System. Slowing of the background activity with theta activity was the most common abnormality (57%). The more clinically severely affected the konzo subject, the more often generalized EEG abnormalities were seen. None of these abnormalities were considered specific for konzo nor related to the duration of the disorder; however, the findings indicate involvement of the cerebral cortex.
Correlation Between Clinical Stages and EEG Findings of Subacute Sclerosing Panencephalitis
Candan Gürses, Aylin Öztürk, Betül Baykan, Ays¸en Gökyig?it,Mefkure Eraksoy, Meral Barlas, Ahmet Calis¸kan and Hifzi Özcan
In this retrospective study 67 patients with SSPE seen between the years 1980 and 1998 were reviewed. Using the criteria of SSPE diagnosis (clinical signs, characteristic EEG patterns, high titres of measles antibodies in the serum and CSF), the patients were divided into two groups. Group A fulfilled all criteria, however, due to the inability of measuring measles antibody before 1987, it was not possible to observe the third criterion in Group B. Among 67 patients, groups A and B consisted of 51 boys and 16 girls ranging in age between 1 to 23 years, mean age 13.1. The male/female ratio was 3.1.
The periodic EEG complexes (PCs) were usually bilateral, synchronous and symmetrical. PC amplitude asymmetry was seen in 12 patients and 2 patients had no PC synchronization between the hemispheres. Six patients had more than one form of PC. Delta activity in anterior hemispheres after PC was seen in 40 patients, mostly in stage 2A. Thirty-two patients had focal epileptiform abnormalities in multiple locations at every stage but most frequently in frontal, central and temporal regions. One patient had PC over both hemispheres and periodic lateralized epileptiform discharges (PLEDs) over the right hemisphere. The EEG findings described and observed in our study do not seem to be specific to SSPE but these findings were not atypical or unusual.
The Role of Tiagabine in the Treatment of Intractable Epilepsy of Childhood with Multifocal Independent Spikes: A Case Report
Cigdem Inan Akman and Romaine Schubert
Multifocal independent spike syndrome (MISS) is an identifiable electroclinical syndrome, which combines intractable motor seizures, mental retardation and multifocal independent spike discharges. Similarities to the Lennox Gastaut syndrome cause frequent misdiagnosis; however, MISS is a distinct electroclinical syndrome in children with a better prognosis and a different EEG pattern. We report an 8-year-old boy with MISS, whose intractable seizures were completely controlled for the first time with tiagabine as add-on therapy. Tiagabine should be studied further in the treatment of intractable multiple seizures of childhood.