Robert J. Chabot

Quantitative electroencephalographic profiles of children with attention deficit disorder.

Quantitative electroencephalogram (QEEG) was obtained from 407 children with attention deficit disorder. These QEEGs were compared to those of 310 normal children. Discriminant analysis resulted in a specificity of 88% and a sensitivity of 93.7% for distinguishing normal children from those with attention deficit disorder. Two major neurophysiological subtypes were evident within the 92.6% abnormal QEEG profiles encountered. The first showed varying degrees of EEG slowing, especially in frontal regions, whereas the second showed an increase in EEG activity, especially in frontal regions. Deviations from normal development rather than maturational lag were present as the source of the neurophysiological abnormality in the majority of these children. In conjunction with recent magnetic resonance imaging, positron emission tomography, and regional cerebral blood flow studies, these results indicate neurophysiological dysfunction within the cortical and subcortical structures that serve the frontal/striatal system. Models suggesting both hypo- or hyperarousal of these structures are supported.

Sensitivity and Specificity of QEEG in Children with Attention Deficit or Specific Developmental Learning Disorders

The sensitivity and specificity of QEEG-based discriminant functions were evaluated in populations of children diagnosed with specific developmental learning disorders and those with attention deficit disorders. Both populations of children could be distinguished from each other, and from the normal population, with high levels of accuracy. Pretreatment QEEG could be utilized to distinguish ADD/ADHD children who responded to dextroamphetamine from those who responded to methylphenidate, again with high levels of accuracy. This paper provides a replication of all presented discriminant functions, and should provide the research basis for the generalized utilization of QEEG in the initial evaluation of children with learning and/or attention disorders.

Behavioral and Electrophysiologic Predictors of Treatment Response to Stimulants in Children with Attention Disorders

Behavioral and quantitative electroencephalography (EEG) techniques were used to evaluate treatment response to stimulant therapy in children with attention disorders. A sample of 130 children with attention disorders were evaluated with Conners and Diagnostic and Statistical Manual of Mental Disorders-III rating scales, and with neurometric quantitative EEG before and 6 to 14 months after treatment with stimulants. Significant quantitative EEG differences were found between the normal control population (N = 31) and the children with attention problems. Quantitative EEG abnormalities involved increased theta or alpha power, greatest in frontal regions, frontal theta/alpha hypercoherence, and posterior interhemispheric power asymmetry. Behavioral improvement after stimulant treatment was seen in 81.5% of the children with attention-deficit hyperactivity disorder and 44.7% of the children with attention-deficit disorder, with the degree of correspondence between behavioral and quantitative EEG changes at 78.5%. Pretreatment clinical and quantitative EEG features could predict treatment response with a sensitivity of 83.1% and a specificity of 88.2%. A combined behavioral and quantitative EEG approach can be useful for following and predicting treatment response to stimulants in children with attention disorders. (J Child Neurol 1999;14:343-351).

Acute effects and recovery after sport-related concussion: a neurocognitive and quantitative brain electrical activity study.

ObjectiveTo investigate the clinical utility and sensitivity of a portable, automatic, frontal quantitative electroencephalographic (QEEG) acquisition device currently in development in detecting abnormal brain electrical activity after sport-related concussion. DesignThis was a prospective, non-randomized study of 396 high school and college football players, including cohorts of 28 athletes with concussion and 28 matched controls. All subjects underwent preseason baseline testing on measures of postconcussive symptoms, postural stability, and cognitive functioning, as well as QEEG. Clinical testing and QEEG were repeated on day of injury and days 8 and 45 postinjury for the concussion and control groups. Main Outcomes and ResultsThe injured group reported more significant postconcussive symptoms during the first 3 days postinjury, which resolved by days 5 and 8. Injured subjects also performed poorer than controls on neurocognitive testing on the day of injury, but no differences were evident on day 8 or day 45. QEEG studies revealed significant abnormalities in electrical brain activity in the injured group on day of injury and day 8 postinjury, but not on day 45. ConclusionsResults from the current study on clinical recovery after sport-related concussion are consistent with early reports indicating a typical course of full recovery in symptoms and cognitive dysfunction within the first week of injury. QEEG results, however, suggest that the duration of physiological recovery after concussion may extend longer than observed clinical recovery. Further study is required to replicate and extend these findings in a larger clinical sample, and further demonstrate the utility of QEEG as a marker of recovery after sport-related concussion.

Patient state index : titration of delivery and recovery from propofol, alfentanil, and nitrous oxide anesthesia

Background The Patient State Index (PSI) uses derived quantitative electroencephalogram features in a multivariate algorithm that varies as a function of hypnotic state. Data are recorded from two anterior, one midline central, and one midline posterior scalp locations. PSI has been demonstrated to have a significant relation to level of hypnosis during intravenous propofol, inhalation, and nitrous oxide–narcotic anesthesia. This multisite study evaluated the utility of PSI monitoring as an adjunct to standard anesthetic practice for guiding the delivery of propofol and alfentanil to accelerate emergence from anesthesia. Methods Three hundred six patients were enrolled in this multicenter prospective randomized clinical study. Using continuous monitoring throughout the period of propofol–alfentanil–nitrous oxide anesthesia delivery, PSI guidance was compared with use of standard practice guidelines (both before [historic controls] and after exposure to the PSA 4000 monitor [Physiometrix, Inc., N. Billerica, MA; standard practice controls]). Anesthesia was always administered with the aim of providing hemodynamic stability, with rapid recovery. Results No significant differences were found for demographic variables or for site. The PSI group received significantly less propofol than the standard practice control group (11.9 &mgr;g · kg−1 · min−1;P < 0.01) and historic control group (18.2 &mgr;g · kg−1 · min−1;P < 0.001). Verbal response time, emergence time, extubation time, and eligibility for operating room discharge time were all significantly shorter for the PSI group compared with the historic control (3.3–3.8 min;P < 0.001) and standard practice control (1.4–1.5 min;P < 0.05 or P < 0.01) groups. No significant differences in the number of unwanted somatic events or hemodynamic instability and no incidences of reported awareness were found. Conclusions Patient State Index–directed titration of propofol delivery resulted in faster emergence and recovery from propofol–alfentanil–nitrous oxide anesthesia, with modest decrease in the amount of propofol delivered, without increasing the number of unwanted events.

Quantitative EEG correlates of crack cocaine dependence

Evidence for a distinctive syndrome of neuroadaptation in cocaine dependence has accumulated from behavioral, neurophysiological, and preclinical and clinical pharmacological studies. The authors report on the results of a preliminary investigation of the quantitative electroencephalographic (QEEG) correlates of severe DSM-III-R crack cocaine dependence in seven patients abstinent from cocaine for 1 to 68 days. The major QEEG finding was increased absolute and relative alpha power. Increased alpha power has also been reported in multiple previous studies of depressed patients. This series of crack-dependent patients showed significant depressive morbidity; four patients attempted suicide subsequent to initiating their use of crack and the group mean (+/- SD) Beck Depression Scale score was 18.9 (+/- 6.5). These results complement other studies that support the concept of neuroadaptation to chronic cocaine exposure. Prospective studies correlating QEEG measures with subsequent response to pharmacological interventions for cocaine dependence should be considered.

Measuring brain electrical activity to track recovery from sport-related concussion

Primary objective: To follow recovery from concussion in a sample of athletes using an electroencephalographic (EEG) index of quantitative brain activity developed previously on an independent Emergency Department (ED) sample of head-injured subjects with traumatic brain injury. Methods and procedures: EEG recordings from five frontal electrode sites were obtained on 59 injured athletes and 31 controls at the time of injury and at 8 and 45 days afterward. All subjects also completed standardized clinical assessment of post-concussion symptoms, postural stability and cognitive functioning at injury and 8 and 45 days post-injury. Results: Abnormalities in clinical assessment measures were observed in injured subjects only at time of injury. Statistical analysis of brain electrical activity measures with the ED-based algorithm revealed significant differences between injured athletes vs controls at the time of injury and at day 8. Measures from the two groups did not differ on day 45. Conclusions: This study demonstrated that an algorithm of brain electrical activity developed on an independent sample of ED subjects with head injury is sensitive to the effects of sport-related concussion. Using this algorithm, abnormal features of brain electrical activity were detected in athletes with concussion at the time of injury and persisted beyond the point of recovery on clinical measures.

Time Course of Clinical and Electrophysiological Recovery After Sport-Related Concussion

Background and Purpose:Recent neuroimaging studies suggest that abnormalities in brain function after concussion exist beyond the point of observed clinical recovery. This study investigated the relationship between an index of brain dysfunction (traumatic brain injury [TBI] Index), concussion severity, and outcome. Methods:EEG was collected from forehead locations in 65 male athletes with concussion within 24 hours of concussion, with follow-up at 8 and 45 days postinjury. Neurocognitive and symptom assessments were also performed and used to classify subjects in mild or moderate concussion categories. Time to return to play was recorded. Results:The TBI Index was higher in the moderate than mild concussion group at injury, day 8, and day 45. The moderate group had increased symptoms and decreased cognitive performance only at the time of injury. At the time of injury, only the TBI Index was significantly associated with the length of time to return to play. Conclusions:Recovery of brain function after sport-related concussion may extend well beyond the time course of clinical recovery and be related to clinical severity. An index of brain dysfunction may be an objective indicator of injury, recovery, and readiness to return to play. The relatively small sample indicates the need for further study on the time course of physiological recovery.

Use of brain electrical activity to quantify traumatic brain injury in the emergency department.

Primary objective: To validate a QEEG algorithm on traumatic brain injury in an Emergency Department (ED) setting. Methods and procedures: EEG data were collected from 105 patients with head injury (53 CT+ and 52 CT−) and 50 ED controls. Ten minutes of eyes closed resting EEG was collected from five frontal locations. A discriminant index of the probability of belonging to the TBI CT+ group was computed. Analysis of variance was computed comparing this index across the three patient groups. Using ROC curves, the p < 0.05 confidence level was determined to compute sensitivity and specificity for the TBI CT+ population. Results: CT+ patients had a mean TBI discriminant index of 80.4, CT− patients 38.9 and controls 24.5; F = 70.2, p < 0.0001. Sensitivity was 92.45% for the CT+ group and specificity was 90.00% for the control group. Conclusions: The TBI discriminant index appears to be a sensitive index of brain function. It may be used to suggest whether or not a patient presenting with altered mental status requires a CT scan. This index may aid in the triage of such patients in the ED. Such an easy to use, automated system may greatly enhance the clinical utility of EEG in the ED.

QEEG Studies in the Assessment and Treatment of Childhood Disorders

Quantifying EEG measures across age allows the ability to establish parameters of normalcy at any age which can be used as a reference when children exhibit developmental delays in their abilities and/or other atypical and maladaptive behaviors. A review of the current literature on the utilization of QEEG methods to serve as an aid for identifying these children as distinctively different from normal, and in some cases as distinctive from other clinical considerations has been shown to provide a sufficient sensitivity and specificity worthy of consideration as a diagnostic aid in evaluating clinical deviations in development. Furthermore, these same QEEG measures can provide a means of establishing treatment efficacy for the evident brain dysfunctions underlying these childhood disorders.