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R J Chabot

Publications and source records attributed to R J Chabot.

At least 19 recordsLinked to original sources
PubMed2004

The Patient State Index as an indicator of the level of hypnosis under general anaesthesia.

BACKGROUND: This retrospective study describes the performance of the Patient State Index (PSI), under standard clinical practice conditions. The PSI is comprised of quantitative features of the EEG (QEEG) that display clear differences between hypnotic states, but consistency across anaesthetic agents within the state. METHODS: The PSI was constructed from a systematic investigation of a database containing QEEG extracted from the analyses of continuous 19 channel EEG recordings obtained in 176 surgical patients. Induction was accomplished with etomidate, propofol, or thiopental. Anaesthesia was maintained by isoflurane, desflurane, or sevoflurane, total i.v. anaesthesia using propofol, or nitrous oxide/narcotics. It was hypothesized that a multivariate algorithm based on such measures of brain state, would vary significantly with changes in hypnotic state. RESULTS: Highly significant differences were found between mean PSI values obtained during the different anaesthetic states selected for study. The relationship between level of awareness and PSI value at different stages of anaesthetic delivery was also evaluated. Regression analysis for prediction of arousal level using PSI was found to be highly significant for the combination of all anaesthetics, and for the individual anaesthetics. CONCLUSIONS: The PSI, based upon derived features of brain electrical activity in the anterior/posterior dimension, significantly co-varies with changes in state under general anaesthesia and can significantly predict the level of arousal in varying stages of anaesthetic delivery.

Adolescent↗
PubMed2001

Quantitative EEG changes associated with loss and return of consciousness in healthy adult volunteers anaesthetized with propofol or sevoflurane.

Significant changes in topographic quantitative EEG (QEEG) features were documented during induction and emergence from anaesthesia induced by the systematic administration of sevoflurane and propofol in combination with remifentanil. The goal was to identify those changes that were sensitive to alterations in the state of consciousness but independent of anaesthetic protocol. Healthy paid volunteers were anaesthetized and reawakened using propofol/remifentanil and sevoflurane/remifentanil, administered in graded steps while the level of arousal was measured. Alterations in the level of arousal were accompanied by significant QEEG changes, many of which were consistent across anaesthetic protocols. Light sedation was accompanied by decreased posterior alpha and increased frontal/central beta power. Frontal power predominance increased with deeper sedation, involving alpha and, to a lesser extent, delta and theta power. With loss of consciousness, delta and theta power increased further in anterior regions and also spread to posterior regions. These changes reversed with return to consciousness.

Adult↗
PubMed2001

The clinical role of computerized EEG in the evaluation and treatment of learning and attention disorders in children and adolescents.

Quantitative EEG (QEEG) can play an important role in the evaluation and treatment of children and adolescents with attention deficit and learning disorders. Children with learning disorders are a heterogeneous population with QEEG abnormality in 25% to 45% of reported cases. EEG slowing is the most common abnormal finding, and the nature of the QEEG abnormality may be related to future academic performance. Children with attention disorders are a more homogeneous population, with QEEG abnormalities in up to 80%. In this population, frontal/polar regions are most likely to show deviations from normal development, with the thalamocortical and/or septal-hippocampal pathways most likely to be disturbed. QEEG shows high sensitivity and specificity for distinguishing normal children and children with learning disorders and attention disorders from each other and may provide useful information for determining the likelihood that children with attention problems will respond to treatment with stimulant medication.

Adolescent↗
PubMed1999

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.

Adolescent↗
PubMed1999

QEEG changes during cardiopulmonary bypass: relationship to postoperative neuropsychological function.

The relationship of changes in intraoperative QEEG and postoperative cognitive function was studied in 32 patients undergoing cardiac surgical procedures requiring cardiopulmonary bypass (CPB). All patients were anesthetized with a high dose narcotic technique in which CPB was carried out using moderate hypothermia. EEG recorded continuously throughout each procedure was analyzed using the neurometric technique. Neuropsychological (NP) evaluations were administered to all patients before, 1 week and 2-3 months postoperatively. A decrement in postoperative performance of 2 standard deviations in two or more tests from preoperative testing was defined as a new cognitive deficit. Of the patients studied, 40.6% demonstrated a new postoperative cognitive deficit at 1 week. At 2-3 months postoperatively, 28.1% continued to show a cognitive deficit. Discriminant analysis of the QEEG as a function of NP performance was calculated at select times during the surgical procedure. QEEG prediction of NP performance was just above chance at the 1 week comparison but excellent for the 2-3 month comparisons. This study suggests that with appropriate monitoring protocols, intraoperative QEEG may predict cognitive dysfunction experienced by patients 2-3 months postoperatively.

Anesthesia, General↗
PubMed1997

QEEG and neuropsychological profiles of patients prior to undergoing cardiopulmonary bypass surgical procedures.

Within our patient population undergoing cardiopulmonary bypass (CPB) surgery, evidence of pre-existing cortical dysfunction was highly prevalent, with 39.5% displaying QEEG and/or neuropsychological (NP) abnormality. These patients with pre-existing QEEG or NP abnormality were at increased risk for developing both short and long-term postoperative deficits in NP performance. Preoperative QEEG showed increased sensitivity and specificity over preoperative NP performance for predicting NP performance one week after surgery. One week after surgery NP deficits were quite common occurring in 40.6% of the patients. Two to three months after surgery evidence of continued NP performance deficits were still present in 28.1% of the patients. Preoperative NP performance predicted 3 month postoperative NP performance quite well, although preoperative QEEG proved equally effective.

Cardiac Surgical Procedures↗
PubMed1997

QEEG and neuropsychological profiles of patients after undergoing cardiopulmonary bypass surgical procedures.

One week after surgery neuropsychological (NP) deficits were quite common, occurring in 40.6% of the patients, with QEEG abnormality developing or increasing in the majority of patients. This change in the QEEG was an accurate predictor of NP performance 1 week after surgery. Two to three months after surgery evidence of continued NP performance deficits were still present in 28.1% of the patients. Preoperative versus one week postoperative QEEG change showed higher levels of sensitivity and specificity for predicting neuropsychological performance 3 months after CPB surgery than did preoperative versus one week postoperative NP performance. The mean values of specificity plus sensitivity were 74.5% for NP performance and 89.1% for the QEEG. These high levels of sensitivity and specificity for QEEG change for predicting postoperative cognitive function may justify the utility of performing these evaluations in the general CPB surgical population. In addition, this evidence supports the need to study the role of intraoperative QEEG monitoring to determine when QEEG change occurs so that possible remediational measures can be taken as soon as possible.

Cardiac Surgical Procedures↗
PubMed1996

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.

Adolescent↗
PubMed1996

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.

Adolescent↗
PubMed1995

The diagnostic utility of dermatomal evoked potentials.

A study was completed to evaluate the diagnostic utility of dermatomal evoked potentials (EPs) for identifying single and multiple sensory nerve root compromise. We examined the clinical records of 37 patients referred for neck and lower back pain with particular attention paid to presenting clinical symptoms, magnetic resonance (MR) imaging results, and cervical and/or lumbar dermatomal EP results. The primary object of this study was to determine whether or not dermatomal EPs provided useful diagnostic information about nerve root function that would supplement the structural information provided by the MR imaging. We evaluated an outpatient population presenting with neck and lower back pain. These patients had detailed clinical evaluations, MR images, and EP evaluations, each done by independent sources. EP studies included mixed nerve EPs (ulnar and median or tibial nerve), and either C6 and C8 or L4, L5, and S1 dermatomal EPs for cervical and lumbar disorders, respectively. Mixed nerve and dermatomal EPs provided reliable information about nerve root function that corresponded to clinical symptoms more closely than did the MR findings. Specifically, these EPs often provided additional information about lateralized nerve root dysfunction beyond that given by the MR imaging. In some cases, EPs identified disturbances in nerve root function in the absence of MR-imaging-identified structural abnormality.

Adult↗
PubMed1995

QEEG and evoked potentials in central nervous system Lyme disease.

Quantitative EEG, flash visual evoked potentials, auditory evoked potentials to common and rare tones, and median nerve somatosensory evoked potentials were obtained from 12 patients with active CNS Lyme disease and from 11 patients previously treated for active CNS Lyme disease. Abnormal QEEG and/or EPs were found in 75% of the active Lyme disease patients and in 54% of the post CNS Lyme disease patients. Three different types of neurophysiological abnormality were observed in these patients including QEEG slowing, possible signs of cortical hyperexcitability, and focal patterns indicating disturbed interhemispheric relationships. In patients tested before and after treatment QEEG and EP normalization was associated with clinical improvement.

Adolescent↗
PubMed1992

Quantitative electroencephalography. A new approach to the diagnosis of cerebral dysfunction in systemic lupus erythematosus.

OBJECTIVE: Neuropsychiatric manifestations are common in patients with systemic lupus erythematosus (SLE), but accurate diagnosis is often difficult. We conducted a prospective study to determine the utility of neurometric quantitative electroencephalography (QEEG) as an indicator of cerebral dysfunction in SLE patients. METHODS: Fifty-two SLE patients were divided into 4 groups based on the results of neuropsychiatric evaluations. These included patients with objective evidence of neuropsychiatric SLE (NPSLE), patients with neuropsychiatric symptoms, patients with no evidence of NPSLE, and patients with a prior history of NPSLE: All QEEG findings were compared with data in an age-regressed normative database and with findings in an independent sample of normal subjects. RESULTS: QEEG sensitivity was 87%, and specificity was 75%. QEEG results were abnormal in 74% of the SLE patients with neuropsychiatric symptoms and in 28% of the patients with no evidence of active NPSLE: QEEG profiles varied as a function of the severity and type of neuropsychiatric manifestation present. Within this patient population, QEEG was more sensitive than magnetic resonance imaging, computed tomography scanning, or conventional EEG. CONCLUSION: Neurometric QEEG may be a sensitive indicator of cerebral dysfunction in patients with NPSLE and can differentiate patients with diverse neuropsychiatric manifestations. When combined with a careful clinical history and evaluation, QEEG provides information that may be useful for the early detection of NPSLE and for serial evaluation of disease activity and treatment efficacy.

Adult↗
PubMed1990

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.

Adult↗
PubMed1989

Real-time intraoperative monitoring during neurosurgical and neuroradiological procedures.

A real-time intraoperative evoked potential (EP) monitoring system is described and evaluated. Unique features include (1) online artifact rejection to reduce noise contamination, (2) optimum digital filtering to improve the signal-to-noise ratio of the EP signal, (3) statistically defined confidence intervals to determine significant EP peak latency deviations, and (4) sliding windows of EP subaverages of various sizes to minimize feedback time to the surgeon. The reliability and validity of this system were determined by comparison with conventional intraoperative EP averaging and by examining the correlation of EP parameter changes with concurrent surgical and radiological manipulations. This system was clearly superior to conventional averaging systems. Reliable EPs could be obtained from neurologically compromised patients within the electrically hostile operating room environment, in cases in which conventional averaging failed to extract a stable EP signal. EP update times of 10-20 s were quite common and allowed direct moment-to-moment correlations with surgical and radiological events. Case histories are presented that show the utility of this system for aiding in the prevention of neurological complications. This utility is examined for neurosurgical and neuroradiological procedures involving spinal cord, brainstem, midbrain, and cortical structures, and affecting the somatosensory, motor, auditory, and visual system pathways.

Adult↗
PubMed1987

Response variability of somatosensory evoked potentials during scoliosis surgery.

Somatosensory evoked potentials (SSEP) were recorded from the scalp for intraoperative monitoring of patients undergoing surgical correction of spine deformities or spine fractures. Alterations in the SSEP with distraction, spine manipulation, anesthesia, hypotension, and other intraoperative variables are described. When loss of the SSEP occurred and a waiting period was undertaken until it returned, all patients with an SSEP present upon closing, which was within +/- 2 SD of their anesthetized control values, had no neurologic complications. Alterations in SSEP consisting of increases in latency of 15% and decreases in amplitude of 50% were not associated with any postoperative neurologic deficits.

Adolescent↗
PubMed1984

The late positive component of the evoked waveform II: Relationship to picture recognition processes.

Averaged evoked potentials were collected from Cz, C3', C4', and Pz while subjects made cognitive decisions about pairs of pictures using perceptual and semantic features. Decisions were made at three different levels within the picture recognition process. These levels correspond to feature detection and synthesis, and semantic memory activation at the basic category and superordinate category levels. The late positive component of the evoked waveform systematically varied as a function of the nature of the cognitive decision being made. The late positive component of the waveform was highly correlated with the response times associated with each experimental condition. It would appear that the late positive component of the waveform provides an internal index of the neural processes which accompany cognitive decisions. As such, the late positive component of the evoked waveform serves as a source of converging evidence, along with response latency measures, that the picture recognition process can be successfully tapped at several different levels within the information processing system. This work should be applicable for studying disruptions to the pattern recognition process which accompany stroke, head trauma, and neurological problems associated with learning disorders. It should also be sensitive to any disorder which influences central processing time more than early perceptual and peripheral processes.

Electroencephalography↗