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Ambulatory EEG monitoring

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... This limits the acquisition time, prevents the continuous monitoring of patients, and affects the diagnosis of the illness. Therefore, there is a growing demand for low-power, small-size, and ambulatory biopotential acquisition systems [1]–[3]. The ultimate goal is to implement a biopotential acquisition system that is comfortable and invisible to eye with long-term power autonomy, high signal quality, and configurability for different biopotential signals. ...
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There is a growing demand for low-power, small-size and ambulatory biopotential acquisition systems. A crucial and important block of this acquisition system is the analog readout front-end. We have implemented a low-power and low-noise readout front-end with configurable characteristics for Electroencephalogram (EEG), Electrocardiogram (ECG), and Electromyogram (EMG) signals. Key to its performance is the new AC-coupled chopped instrumentation amplifier (ACCIA), which uses a low power current feedback instrumentation amplifier (IA). Thus, while chopping filters the 1/f noise of CMOS transistors and increases the CMRR, AC coupling is capable of rejecting differential electrode offset (DEO) up to plusmn50 mV from conventional Ag/AgCl electrodes. The ACCIA achieves 120 dB CMRR and 57 nV/radicHz input-referred voltage noise density, while consuming 11.1 muA from a 3 V supply. The chopping spike filter (CSF) stage filters the chopping spikes generated by the input chopper of ACCIA and the digitally controllable variable gain stage is used to set the gain and the bandwidth of the front-end. The front-end is implemented in a 0.5 mum CMOS process. Total current consumption is 20 muA from 3V
... In recent years, the techniques of concomitant EEG and video visualization (video-EEG monitoring) have been developed and utilized extensively, especially in evaluating patients for surgical treatment of localized-origin epilepsies (Gotman et al., 1985). In addition, the method of EEG recording of the ambulatory patient, outside of the limited confines of the laboratory, has been a major advance (Stores, 1980; Ebersole, 1988). One can look forward to the combined utilization of EEG and magnetic resonance imaging (MRI), especially functional MRI, in three dimensions, in further studies of epilepsy and its diagnosis and treatment. ...
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This paper proposes a high gain, low power instrumentation amplifier (IA) for EEG signal processing. A three opamp instrumentation amplifier has been designed by using sub-threshold three-stage op-amps with PMOS input. NMOS transistors operating in the triode region have been used to replace the passive resistors of IA. This eliminates the problems of mismatch, temperature dependency and large area consumption, at the same time taking advantage of the high CMRR and DC offset cancellation properties of conventional IA. A BGR circuitry with temperature coefficient of 420 ppm/°C is used to bias the opamp. The instrumentation amplifier is simulated in Cadence Virtuoso 180nm CMOS technology by using a supply voltage of 1V. It achieves a Gain of 96.4dB, Bandwidth of 400 KHz, input-referred noise voltage of 610nV/√ Hz, CMRR in the range of 60dB and power consumption about 53.7 µW.
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Long-term electroencephalographic (EEG) monitoring, initially popular in the form of 24-hour video-EEG telemetries developed for the evaluation of patients who were candidates for epilepsy surgery, is now possible in diverse configurations. Studies can be designed to evaluate a variety of diagnostic problems and can be individualized to address specific clinical questions for each patient. A great variety of severe epilepsies present in infancy and childhood with daily seizures, often presenting difficult diagnostic problems. Extending the benefits of long-term EEG monitoring to these patients early in the course of the epileptic process can be expected to result in more accurate diagnoses, more effective treatment, and improved prognoses. Long-term EEG monitoring is needed to improve our understanding of the nosology of infant epilepsy, which is incomplete.
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Neuropsychological deficits following mild head injury have been reported recently in the literature. The purpose of this study was to investigate this issue with a strict methodological approach. The neuropsychological performance of 50 mildly head injured patients was compared with that of 50 normal controls chosen with the case-control approach. No conclusive evidence was found that mild head injury causes cognitive impairment one month after the trauma.
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A four-choice reaction time test was carried out on 45 minor head injury cases, 24 hours after the injury and 6 weeks later. Twenty-eight subjects were re-tested after a six month interval. Reaction time measures were also obtained in a matched, general practice control group. The concussion cases displayed significantly poorer performances than the matched controls in four measures, at day 0 and at 6 weeks. The patients also showed serial improvement in these measures up to six months after the injury, when their scores excelled those of the matched controls.
Delayed Recovery of Intellectual Function after Minor Head Injury Cumulative Effect of Concussion Duration of Post-Traumatic Amnesia after Mild Head Injury Disability caused by Minor Head Injury Measurement of reaction time following minor head injury
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  • P Wrightson
  • D Gronwall
  • P Wrightson
  • D Gronwall
  • P Wrightson
  • B Giordani
  • Jt Barth
  • Tj Boll
  • Jane
  • Jt Barth
  • Sn Macciochi
  • B Giordani
  • R Rimel
  • G Jane
  • Ea Montgomery
  • Gw Fenton
  • Rutherford
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