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.     

Four-year follow-up of children with low intelligence and ADHD

Twenty-six of 30 participants (87%) who took part in a medication study for treatment of ADHD were followed up 2.9 to 4.8 years (Mean = 3.9 years) later. Parent ratings on the Aberrant Behavior Checklist Community (ABC-C) indicated continued problems on the acting-out subscales, and parent assessments on the Stony Brook Checklist-3R showed a high rate of difficulty on domains called ADHD, Conduct Disorder, and Separation Anxiety Disorder. A high percentage of children (69%) were taking psychotropic drugs, substantial numbers of their families had sought nonmedical treatments, children's friendships were often rudimentary, and a significant minority of children had disciplinary problems in school or difficulty with the law. Using Pearson correlations, we identified a number of initial variables that predicted follow-up parent ratings on the ABC-C and Stony Brook. The ABC-C Irritability subscale was useful in predicting both internalizing and externalizing problems at follow-up, whereas parent and teacher hyperactivity subscales failed to predict later hyperactivity. Children identified with both low intelligence and ADHD appear to have significant behavioral and emotional problems in their early adolescence, and there may be some important qualitative differences in the outcome of these youngsters as compared with that of children identified with ADHD and normal IQ.     

Electroencephalographic studies myoclonus.

Electroencephalographic studies were carried out in 30 patients with various kinds of myoclonus. It was confirmed that the technique of jerk-locked averaging with a backward averaging program was useful for detecting cortical spikes in association with the spontaneously occurring myoclonus, which are not recognized on the convential polygraph, and for evaluating the temporal and topographical relationship between the spike and the myoclonus. By this technique, cortical spikes were shown to precede the myoclonus of a contralateral upper extremity muscle by 7 to 15 ms ith progressive myoclonic epilepsy showed a high amplitude somatosensory evoked potential (SEP) in response to electrical stimulation of the median nerve. The N33 component of this high amplitude SEP was found to be similar to the myoclonus-related cortical spike in their wave form, time relationship and topographical distribution, suggesting an involvement of similar physiological mechanisms in the genesis of both phenomena. Myoclonus in these patients is compatible with "pyramidal" or "cortical loop reflex" type.     

Electroencephalographic and clinicopathological studies on Creutzfeldt-Jakob syndrome

The correlation between the appearance of the characteristic electroencephalographic abnormality, cardinal clinical manifestations, and neuropathological features was studied in four cases of Creutzfeldt-Jakob syndrome consisting of subacute spongiform encephalopathy and classical Creutzfeldt-Jakob disease. Consideration is given to the differences in the electroencephalographic findings between these two subgroups of the syndrome and on the underlying pathological mechanism.     

Electroencephalographic studies in migraine]

The author reviews the pertinent literature and the results of own investigations in migraine. EEG changes in migraine are observed in nearly 50% of cases during attacks as well as in the periods free of pains. Most investigations were done in the periods between attacks. The H response characteristic of migraine was found by the author in 25% of cases only. Focal changes were present in 30% of cases. They were not related to the side of the pain, its duration and the form of migraine. Seizure activity was never observed. The author regards isolation of the so-called dysrhythmic form of migraine as not justified. EEG changes suggest--according to the author--that migraine is a primary cerebral and only secondarily a vascular disorder.     

Four-year follow-up of children with low intelligence and ADHD: a replication

Twenty children with attention deficit hyperactivity disorder (ADHD) and low IQs, who participated in a drug study, were followed up 4.5 years later, when their ages averaged 12.4 years (range: 8-20 years: SD = 2.78). Participants were assessed by their parents and teachers on the Aberrant Behavior Checklist-Community (ABC; Aman & Singh, 1994), on the Child Symptom Inventory (CSI; Gadow & Sprafkin, 1994), and on a structured interview. A majority of children continued to screen positive for ADHD at follow-up, as well as display high rates of comorbid anxiety disorders, tics, and elimination disorders. Educational placement became slightly more restrictive over the follow-up interval. Multiple medication trials (30 in all, among 14 participants) were attempted between initial contact and follow-up. Ratings on the ABC by parents and teachers showed significantly lower scores at follow-up on the Hyperactivity subscale. Relatively few associations were found between initial ratings and follow-up ratings on standardized scales.     

Electroencephalographic studies of skilled psychomotor performance.

Measurements based on the EEG have featured prominently in shaping present-day concepts of the neurocognitive aspects of skilled performance. The techniques include measurements of spectral power, interelectrode coherence, event-related potential components such as the P300, slow potentials, and the method of cognitive inference. The advantages offered by EEG-based approaches lies in their spatiotemporal resolution (potentially 1 mm and less than 1 millisecond, respectively) and the potential to preserve ecological validity, i.e., to obtain measurements of cortical function under the same conditions that the task is normally performed. These studies indicate that activity is reduced in specific regions of the cerebral cortex of experts relative to that observed in novices. These changes occur over time as a result of practice. The authors argue that such cortical change results in less attentional demand and less cognitive interference with motor planning and execution. The findings attest to the plasticity of the central nervous system when one is engaged in goal-directed learning, and hold implications for understanding how the nervous system acquires voluntary skills, whether in the context of the training of an athlete or the rehabilitation of a patient who has lost motor skills due to a disease of the nervous system.