Robert J. Sclabassi

Computerized EEG spectral analysis in elderly normal, demented and depressed subjects

Computerized spectral analysis of the EEG was performed in 35 patients with Alzheimers disease and compared to patients with major depression (23) and healthy elderly controls (61). Compared to controls, demented patients had a significant increase in the theta and alpha 1 bandwidths as well as an increased theta-beta difference. The parasagittal mean frequency, beta 1 and beta 2 activity were significantly decreased. Depressed patients differed from demented patients, particularly at the lower end of the spectrum, having significantly less delta and theta activity. Like the demented group, depressed patients also had a decreased parasagittal mean frequency, beta 1 and beta 2 when compared to controls. In demented patients, there was a high correlation between several spectral parameters (parasagittal mean frequency, delta and theta activity, and the theta-beta difference) and the Folstein score, EEG measures used for discriminant analysis were more accurate in identifying demented patients who had lower Folstein scores.

Protective effects of combined superoxide dismutase and deferoxamine on recovery of cerebral blood flow and function after cardiac arrest in dogs.

Oxygen free radicals generated during reoxygenation after cardiac arrest may impair recovery of cerebral blood flow and function. In a randomized study in vivo, we tested the following anti-free radical combination therapy administered at the beginning of cardiopulmonary resuscitation after apnea-induced cardiac arrest of 7 minutes: 1) ventilation with 100% nitrogen for 30 seconds to allow the delivery of therapy before oxygen, 2) 10 mg/kg i.a. superoxide dismutase followed by 10 mg/kg i.v. over 1 hour to scavenge the superoxide anion radical, and 3) 20 mg/kg i.v. deferoxamine over 1 hour to prevent membrane lipid peroxidation. We evaluated the effects of this combined treatment on the recovery of cardiovascular variables, cerebral blood flow and oxygen consumption, and somatosensory evoked potentials in 20 dogs 6 hours after resuscitation. Compared with standard treatment (n = 10), the combined treatment (n = 10) did not affect cardiovascular variables, significantly mitigated cerebral blood flow changes after cardiac arrest, and enhanced recovery of somatosensory evoked potentials. We conclude that oxygen free radicals play a role in the pathogenesis of the arrest-related derangements of cerebral blood flow and function that are effectively reduced by this combined treatment; we recommend evaluation of its components in outcome studies.

A Wearable Electronic System for Objective Dietary Assessment

Dietary reporting by individuals is subject to error (1–3). Therefore, a research program has been initiated to develop a small electronic device to record food intake automatically. This device, which contains a miniature camera, a microphone, and several other sensors, can be worn on a lanyard around the neck. It collects visual data immediately in front of the participant and stores them on a memory card in the device. The data are transferred regularly to the dietitian’s computer for further processing and analysis. The device is designed to be almost completely passive to the participant, and thus hopefully will not intrude on or alter the participant’s eating activities. In addition to this function, in the future the device will have other functions, such as the measurement of physical activity, human behavior, and environmental exposure (e.g., pollutants).

Turning away from talking heads: the use of video-as-data in neurosurgery

Studies of video as a support for collaborative work have provided little hard evidence of its utility for either task performance or fostering telepresence, i.e. the conveyance of a face-to-face like social presence for remotely located participants. To date, most research on the value of video has concentrated on “talking heads” video in which the video images are of remote participants conferring or performing some task together. In contrast to talking heads video, we studied video-as-data in which video images of the workspace and work objects are the focus of interest, and convey critical information about the work. The use of video-as-data is intended to enhance task performance, rather than to provide telepresence. We studied the use of video during neurosurgery within the operating room and at remote locations away from the operating room. The workspace shown in the video is the surgical field (brain or spine) that the surgeon is operating on. We discuss our findings on the use of live and recorded video, and suggest extensions to video-as-data including its integration with computerized time-based information sources to educate and co-ordinate complex actions among distributed workgroups.

In vitro and in vivo studies on wireless powering of medical sensors and implantable devices

This paper investigates wireless electricity (witricity) and its application to medical sensors and implantable devices. Several coupling scenarios of resonators are analyzed theoretically. In vitro experiments are conducted in open air and through an agar phantom of the human head. An in vivo animal experiment is also carried out. Our studies indicate that witricity is a suitable tool for providing wireless power to a variety of medical sensors and implanted devices.

Lysis of intraventricular blood clot with urokinase in a canine model: Part 1. Canine intraventricular blood cast model.

To test the safety and feasibility of using direct instillation of urokinase to induce rapid lysis of intraventricular clots, an animal model of intraventricular blood cast is required. Injections of 11 ml of fresh, unclotted autologous blood into the ventricles of adult mongrel dogs did not produce a solid blood cast in the ventricular system, suggesting that the adult dogs have an unusual ability to clear uncoagulated whole blood from the ventricles and subarachnoid space. Injection of 9 ml of preclotted blood resulted in a subtotal cast of the ventricles, leaving only portions of the occipital horns free of solid clots. This volume of injected clots incurred no mortality and minimal morbidity, whereas injection of 10 to 12 ml resulted in a mortality of 42% and formidable morbidity. The technique of producing this intraventricular blood cast model, as well as that of implanting an indwelling ventricular catheter-reservoir system useful in chronic urokinase administration, is described.

Lysis of intraventricular blood clot with urokinase in a canine model: Part 2. In vivo safety study of intraventricular urokinase

It was determined from in vitro experiments that the minimal dose of urokinase required to lyse 10 ml of clotted canine blood within a closed space must exceed 10,000 IU. We empirically doubled this minimum effective dose and tested the in vivo safety of injecting 20,000 IU of urokinase every 12 hours for 4 days into the ventricles of six adult mongrel dogs through an implanted catheter-reservoir system. The animals were monitored carefully for local and systemic bleeding by neurological and clinical examination, hematological tests reflecting systemic fibrinolytic status, serial computed tomography, and postmortem histological examinations of the brain, meninges, and peripheral organs. It was found that this intraventricular dose regimen of urokinase did not cause intracranial hemorrhage even though the dogs had recent brain wounds related to transcerebral ventricular catheterization. Mild activation of systemic fibrinolysis, implying passage of the enzyme from ventricle to blood, occurred 4 to 6 hours after each intraventricular injection, but no systemic hemorrhages were seen. This dose regimen also did not cause acute or chronic inflammatory changes in the brain or meninges and did not disturb cerebrospinal fluid circulation.

Comparisons of EEG spectral and correlation measures between healthy term and preterm infants

Continuous 12-hour electroencephalography (EEG)-sleep studies were acquired by a computerized monitoring system under environmentally controlled conditions for 2 groups of neonates. Eighteen health preterm infants at a postconceptional term age were matched to 18 term infants. These 2 groups were also matched for gender, race, and socioeconomic class. For the entire 12-hour recording, relative spectral power values (i.e., ratio of specific EEG power in specific frequency band compared to total EEG power) were significantly reduced in the preterm group for theta (P < or = .007), alpha (P < or = .001), and beta (P < or = .018) frequency bands, while delta remained unchanged. Correlations between 91 pairs of EEG channels were also calculated and the preterm infants had significantly higher correlation values in 27 of the 91 pairs of channels (P < .05); 14 interhemispheric, 8 intrahemispheric, and 5 sagittal combinations, while 3 intrahemispheric combinations were higher in the term group. Fewer functional neuronal aggregates generate less oscillatory potential (i.e., lower spectral power) in the theta through beta frequency ranges in the preterm infant, while greater cortical connectivity (i.e., higher correlations) exists in many brain regions by postconceptional term ages in this group. These findings suggest a functional alteration in brain development of the preterm infant as a result of prolonged extrauterine experience and/or prematurity.

Maturational trends of EEG-sleep measures in the healthy preterm neonate

Five physiologic groupings of 45 EEG-sleep measures were acquired from serial 24-channel EEG-sleep recordings (i.e., sleep architecture, continuity, EEG spectral, phasic, and autonomic measures), utilizing 129 studies on 56 healthy preterm infants from 28 to 43 weeks postconceptional age (PCA) who were neurodevelopmentally normal on follow-up. Regression analyses chose the least number of measures that best reflected maturation. Four of 45 variables (i.e., spectral alpha energy during quiet sleep, total spectral EEG energy, arousal number during active sleep, and percentage of EEG discontinuity) most significantly explained brain maturation in neonates < 36 weeks PCA. Three of 45 variables (i.e., spectral theta and beta energies during active sleep and spectral alpha energy during quiet sleep) were most representative after 36 weeks PCA. Spectral EEG energies were the strongest indicators of maturation compared with other measures, particularly in near-term neonates.

Low power digital communication in implantable devices using volume conduction of biological tissues.

This work investigates the data communication problem of implantable devices using fundamental theories in communications. We utilize the volume conduction property of biological tissues to establish a digital communications link. Data obtained through animal experiments are used to analyze the time and frequency response of the volume conduction channel as well as to characterize the biological signals and noises present in the system. A low power bandwidth efficient channel-coded modulation scheme is proposed to conserve battery power and reduce the health risks associated