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Biomedical subjects

Michael Gaetz

Publications and source records attributed to Michael Gaetz.

8 recordsLinked to original sources
PubMed2004

The neurophysiology of brain injury.

OBJECTIVE: This article reviews the mechanisms and pathophysiology of traumatic brain injury (TBI). METHODS: Research on the pathophysiology of diffuse and focal TBI is reviewed with an emphasis on damage that occurs at the cellular level. The mechanisms of injury are discussed in detail including the factors and time course associated with mild to severe diffuse injury as well as the pathophysiology of focal injuries. Examples of electrophysiologic procedures consistent with recent theory and research evidence are presented. RESULTS: Acceleration/deceleration (A/D) forces rarely cause shearing of nervous tissue, but instead, initiate a pathophysiologic process with a well defined temporal progression. The injury foci are considered to be diffuse trauma to white matter with damage occurring at the superficial layers of the brain, and extending inward as A/D forces increase. Focal injuries result in primary injuries to neurons and the surrounding cerebrovasculature, with secondary damage occurring due to ischemia and a cytotoxic cascade. A subset of electrophysiologic procedures consistent with current TBI research is briefly reviewed. CONCLUSIONS: The pathophysiology of TBI occurs over time, in a pattern consistent with the physics of injury. The development of electrophysiologic procedures designed to detect specific patterns of change related to TBI may be of most use to the neurophysiologist. SIGNIFICANCE: This article provides an up-to-date review of the mechanisms and pathophysiology of TBI and attempts to address misconceptions in the existing literature.

Animals↗
PubMed2004

Relation between subjective fogginess and neuropsychological testing following concussion.

The purpose of this study was to examine the relation between the subjective report of feeling foggy at one-week post concussion and acute neuropsychological outcome. The outcome variables were derived from a computerized neuropsychological screening battery, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). Participants were 110 high school students who sustained a sports-related concussion and were evaluated 5-10 days post injury (M = 6.8 days). Athletes were divided into two groups on the basis of self-reported fogginess. The first group reported no fogginess (n = 91), whereas the second group reported experiencing some degree of fogginess (n = 19) on a 6-point scale. The athletes with persistent fogginess experienced a large number of other post-concussion symptoms, compared to the athletes with no reported fogginess. In addition, the athletes with persistent fogginess had significantly slower reaction times, reduced memory performance, and slower processing speed. Thus, athletes with any degree of self-reported fogginess at one-week post injury are likely to have adverse effects from their concussions in multiple domains.

Adolescent↗
PubMed2004

Intraoperative electrode burns.

OBJECTIVES: The purpose of this paper is to increase awareness of electrode burns that occur in the operating room (OR), to discuss their causes, warning signs, and methods that may reduce their occurrence. Two general sources of electrical burns are described: 1) Excessive radio-frequency current density usually originating from a monopolar electrosurgical unit (ESU) and 2) Direct current (DC) originating from a battery or equipment malfunction. METHODS: Case examples associated with intraoperative neuromonitoring are provided and discussed in the context of the relevant literature. Seven cases are described, five associated with excessive radio-frequency current density and two associated with direct current originating from a battery or equipment malfunction. CONCLUSIONS: Recommendations on prevention and warning signs associated with these burns are presented in addition to procedures to follow if a burn is suspected.

Burns↗
PubMed2004

Cumulative effects of concussion in amateur athletes.

PRIMARY OBJECTIVE: To examine the possibility that athletes with multiple concussions show cumulative effects of injury. METHODS AND PROCEDURES: Amateur athletes with a history of three or more concussions were carefully matched (gender, age, education and sport) with athletes with no prior concussions. All completed a computerized neuropsychological test battery at preseason (ImPACT) and then within 5 days of sustaining a concussion (mean = 1.7 days). MAIN OUTCOMES AND RESULTS: There were differences between groups in symptom reporting and memory performance. At baseline (i.e. preseason), athletes with multiple concussions reported more symptoms than athletes with no history of concussion. At approximately 2 days post-injury, athletes with multiple concussions scored significantly lower on memory testing than athletes with a single concussion. Athletes with multiple concussions were 7.7 times more likely to demonstrate a major drop in memory perfomance than athletes with no previous concussions. CONCLUSIONS: This study provides preliminary evidence to suggest that athletes with multiple concussions might have cumulative effects.

Adolescent↗
PubMed2004

Self-organizing neural network analyses of cardiac data in depression.

OBJECTIVE: To determine if an unsupervised self-organizing neural network could create a clinically meaningful distinction of 'depression' versus 'no depression' based on cardiac time-series data. DESIGN: A self-organizing map (SOM) was used to separate the time-series of 84 subjects into groups based on characteristics of the data alone. MATERIALS AND METHODS: Analyses included natural log transformations and two types of filtering to enhance characteristics of the data as well as classifications of unprocessed data. A Pearson chi(2) analysis was performed to determine if the SOM groups bore any relation to the binary clinical groups. RESULTS: Overall correct SOM classifications ranged from 54 to 70.2% with two classifications being clinically meaningful. CONCLUSIONS: SOM classifications of cardiac time-series data with enhanced ultradian variations and cardiac data recorded around the interval when a person was in bed were useful in differentiating clinically meaningful subgroups with and without depression.

Adult↗
PubMed2002

Reliability of circadian heart pattern analysis in psychiatry.

The assessment of circadian heart patterns represents a new methodology for documenting physiological dysregulation associated with psychiatric illness. Previous research has demonstrated abnormal heart rate patterns, especially during the bedtime interval, that are associated with depression, generalized anxiety disorder, panic disorder, and schizophrenia. These patterns are derived from heart rate data obtained while wearing an unobtrusive, two-lead heart rate monitor over a 24-hour period. To establish basic reliability, the second author blindly rated heart-monitored data from 50 subjects on two occasions, separated by an average of 6.6 weeks (range = 2.9-15.7 weeks). Subjects were classified as "definitely psychiatric," "probably psychiatric," "borderline," "broadly normal," and "signature normal." The exact category agreement rate was 78%. If a one-category difference is permitted (e.g., "definitely psychiatric" and "probably psychiatric" counted as an agreement), the agreement rate was 92%. Circadian heart pattern analysis is a promising new technology in psychiatric research and warrants further investigation.

Adult↗