Journal of Clinical EEG & Neuroscience, January 2006
Table of Contents
Previous work has indicated that low temporal coherence of ultradian sleep EEG rhythms is characteristic of depressed patients and women in particular. It may also be evident in depressed children and adolescents, although most published studies are limited in sample size.
The present study evaluated temporal coherence of sleep EEG rhythms in 173 children and adolescents 8-17 years of age, including 97 who met criteria for major depressive disorder (MDD) and were symptomatic but unmedicated at the time of study and 76 healthy controls. Temporal coherence of all-night sleep EEG rhythms was evaluated on the second of two nights in the laboratory. Data were coded for diagnostic group, gender and age and subjected to MANOVAs.
Temporal coherence was significantly lower in adolescents with MDD, compared to healthy controls. Findings were most robust for coherence between left and right beta and between delta and beta in both hemispheres. Both gender and age strongly influenced between-group differences, with the lowest temporal coherence among MDD girls, even in those under 13 years of age.
In conclusion, early onset depression is associated with a reduction in synchronization of sleep EEG rhythms that shows a differential maturational course in boys and girls.
Functional Connectivity Between Hemispheres and Schizophrenic Symptoms: A Longitudinal Study of Interhemispheric EEG Coherence in Patients With Acute Exacerbations of Schizophrenia
To clarify whether interhemispheric electroencephalogram (EEG) coherence reflecting functional connectivity between the two cerebral hemispheres can change in a symptom-dependent manner in schizophrenia, we measured resting EEG and symptom severity twice at an average interval of 32.7 days during the course of treatment in 15 patients hospitalized for acute exacerbations of schizophrenia. Symptom severity was estimated quantitatively by means of the Brief Psychiatric Rating Scale (BPRS). Correlation analysis showed that increases in the beta-band coherence for frontal electrode pairs during the treatment were associated with improvement in the total score and the score on the positive subscale of BPRS. This result suggests that functional disconnection between the left and right frontal lobes may be related to the generation of psychotic symptoms and can normalize following antipsychotic treatment.
Frontal Alpha Power Asymmetry in Aggressive Children and Adolescents With Mood and Disruptive Behavior Disorders
Building on prior research, which has suggested a relationship between aggression and left frontal activity, our study tested the hypothesis that proneness to impulsive aggression would be related to relative left frontal overactivation. EEG one-hertz resting alpha power frontal asymmetry was examined in 65 pediatric male psychiatric patients with a history of impulsive aggression and comorbid mood and disruptive behavior disorders.
The strongest finding, which emerged from this analysis, was a finding of relative increases in left frontal activity compared with right frontal activity. The results also indicated that greater left frontal activity correlated positively with the severity of psychiatric disturbance. These findings suggest that relative increases in left frontal activity may be related to a locus of neurophysiological disruption associated with psychopathology characterized by behavioral and affective disinhibition. Results are discussed within a model of behavioral inhibition system-behavioral activation system theory.
Latency Differences of N20, P40/N60, P100/N140 SEP Components After Stimulation of Proximal and Distal Sites of the Median Nerve
The latencies of SEP N20, P40, N60, P100, and N140 components were measured after stimulation of two different sites, and the differences in relation to conduction velocity and their central functions are discussed.
Subjects were 8 healthy right-handed males (age 22-31 years, height 164-184 cm). An electrical pulse of 200µsec duration with an intensity of 2 times the motor threshold was delivered to the wrist and to the elbow alternately at a random rate of 0.1 to 0.3 Hz. Recording electrodes were Cz’, C3’, and C4’ referenced to linked ears. Analysis time was 50 msec before and 450 msec after the stimulus. The band pass was 0.5 Hz to 2 kHz. Subjects were asked to mentally count the number of stimuli. The averaging was interrupted after every 16 to 24 stimuli and checked to determine whether the subject was attentive to the stimuli by verifying the number of stimuli counted. A total of 100 responses each from elbow and wrist stimuli were averaged.
Differences in peak latency between elbow and wrist stimuli for N20, P40, N60, P100, and N140 were 3.7±0.7 msec, 5.0±1.8, 4.3±1.2, 8.1±6.3, and 7.4±2.6 msec, respectively. According to the latency differences, SEP components can be divided into 3 groups: the shortest difference for N20, medium difference for P40 and N60 and longest difference for P100 and N140.
Similar latency differences and similar potential distribution for P40 and N60, and for P100 and N140, and their differences from N20 confirmed that each of N20, P40/N60, and P100/N140 has a different function centrally. In addition, central processing time was longer with the more distal site stimulation.
The objective of this study was to determine if screening by a neurologist of all non-neurologist electroencephalogram (EEG) referrals prior to approval reduces the number of inappropriate requests. This retrospective survey included 600 consecutive EEG requisitions referred to the Anaheim Kaiser Permanente Neurodiagnostic Laboratory to rule out epilepsy. Patients with established epilepsy referred for a repeat EEG for management issues were excluded.
Three groups of EEG referrals were analyzed. Each group consisted of 200 EEGs (100 pediatric and 100 adult EEGs). The first group was referred directly by non-neurologists, the second group was referred by non-neurologists with scrutiny by a neurologist, and the third group was referred by a neurologist directly. In the pediatric group, the ratio of abnormal EEG vs normal EEG was 1:3.35 in the first group, 1:0.69 in the second group and 1:0.33 in the third group. In the adult group, the ratio of abnormal EEGs vs normal EEGs was 1:2.23 in the first group, 1:0.82 in the second group and 1:0.45 in the third group. In the combined pediatric and adult groups, the ratio of abnormal EEG vs normal EEG was 1:2.70 in the first group, 1:0.75 in the second group and 1:0.39 in the third group. There was a significant difference between the results of the EEGs ordered by non-neurologists directly versus non-neurologists with scrutiny (p=.334, chi-square test).
Scrutiny by a neurologist of EEG referrals from non-neurologists led to a reduction in the number of normal EEG results. This suggests that inappropriate EEG requests for non-epileptic patients that yield normal EEG results are significantly reduced with scrutiny. This can help reduce the indiscriminate overuse of EEGs by non-neurologists thereby leading to better utilization of healthcare resources.
Quantitative EEG has been shown to be effective for the assessment of hepatic encephalopathy. Initial quantitative EEG studies of patients who had undergone liver transplantation demonstrated improvement of frequency and the alpha-theta power ratio in the occipital area. This study involved the assessment of comprehensive quantitative EEG variables over the entire cortex following transplantation. Fourteen subjects underwent EEG recording prior to transplantation. Eight (6 without complications and 2 having problems with rejection) underwent the same recording between 3 and 6 months following transplantation.
For all subjects, EEG variables showing significant changes from pre- to post-transplantation included posterior alpha frequency (increase, p ≤ .03), central theta absolute power (decrease, p ≤ .03), theta relative power over anterior, central, and posterior regions (decrease, p ≤ .02, p ≤ .01, p ≤ .03, respectively), posterior beta absolute power (increase, p ≤ .01), and central and posterior beta relative power (increase, p ≤ .04, p ≤ .04, respectively). When the two subjects with complications were removed from the analyses, these variables and also anterior alpha absolute power (increase, p ≤ .02), alpha relative power over anterior, central, and posterior regions (increase, p ≤ .05, p ≤ .03, p ≤ .04, respectively), and anterior and central theta absolute power (decrease, p ≤ .05, p ≤ .04, respectively) showed significant pre- to post-transplant changes.
In conclusion, a combination of quantitative EEG parameters which are most affected by liver transplantation might provide an effective assessment tool for determining and quantitatively monitoring the cerebral status of post-transplant patients.
Ictal nystagmus (IN) is an uncommon phenomenon characterized by rhythmic saccadic eye movements occurring during epileptic seizures. We report a newborn baby with severe birth asphyxia, undergoing long-term video EEG monitoring with electro-oculogram (EOG), who showed irregular IN when eye movements crossed the midline from left to right and vice versa, resulting in large amplitude of the nystagmoid movements. The nystagmus was followed 15 to 29 seconds later by ictal discharges in the occipital regions. MRI of the brain showed features suggestive of periventricular leukomalacia. This interesting combination of findings suggests a complex mechanism for IN of cortical or subcortical ictal rhythms, which results in (a) the generation of subcortical electrical discharges in the pons and midbrain, causing nystagmoid eye movements, and (b) subsequent occipital spiking. We conclude that this clinical manifestation supports the existence of functioning cortical-subcortical connections between the brainstem ocular motor centers and the occipital cortex at birth.
Neuroacanthocytosis is a group of disorders, clinically characterized with movement disorders, self-mutilation and seizures. There is little information in the literature regarding the clinical and EEG findings of the accompanying seizures in this neurodegenerative disorder. A 46-year-old man who was diagnosed as chorea-acanthocytosis, a subgroup of neuroacanthocytosis, was investigated for severe drug resistant seizures. Continuous video-EEG monitoring revealed an active left temporal epileptogenic focus with left temporal rhythmic discharges detected during his complex partial seizures. T2-weighted cranial MRI indicated hyperintensity of the left amygdala as well as hyperintensity and atrophy of bilateral basal ganglia. We discuss the development of focal seizures in a patient who has a neurodegenerative disease, namely neuroacanthocytosis.
Necrotizing Leukoencephalopathy Associated With Nonconvulsive Status Epilepticus and Periodic Short-Interval Diffuse Discharges: A Clinicopathological Study
We describe the clinical, neuroimaging and neuropathological features of an immunocompromised patient diagnosed as having refractory nonconvulsive status epilepticus (NCSE), and whose consecutive electroencephalograms (EEGs) revealed persistent periodic short-interval diffuse discharges (PSIDDs). Prominent subcortical white matter lesions in keeping with the diagnosis of multifocal necrotizing leukoencephalopathy may be neuropathological substrate of NCSE with persistent PSIDDs.
Previous research has shown that quantitative electroencephalography (qEEG) can monitor treatment of Alzheimer’s Disease (AD). This study investigated the ability of a qEEG measure based on EEG variance, combined with a delayed recognition memory task, to measure treatment effects on patients with AD.
Three AD patients with very mild AD (CDR=0.5, FAST stage 3) were monitored with task specific EEG at multiple time points before and after medication treatment. Patients had their EEG recorded while performing a recognition memory task. A measure of (normalized) variance was applied to the EEG data. To the extent possible, the subjects received this treatment monitoring multiple times. These patients were monitored a total of 14 times, which yielded 11 measurements of qEEG change during the course of treatment.
The direction of change in patients’ qEEG values agreed with patients’ medication treatment on 10 out of 11 occasions, p < 0.006 (binomial test) and was more accurate than monitoring with the relative theta power, p < 0.05. The results of this monitoring also showed that the qEEG measure accurately reflected treatment in a dose dependent manner. These results were independent of the specific medication monitored; Galantamine, Memantine, Nicotine, and Rivastigmine. In conclusion, this qEEG method may be useful for measuring AD treatment responses.