Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society
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J Clin Neurophysiol · Mar 2001
Clinical TrialThe development of spectral EEG changes during short periods of circulatory arrest.
The EEG was monitored in 56 patients during implantation of an internal cardioverter defibrillator. The purpose of this study was to determine the main EEG frequency ranges that represent ischemic changes during short periods of circulatory arrest. The EEG was recorded with a 16-channel common reference montage (Cz). ⋯ In general, the spectral changes in the alpha and beta frequency ranges were most pronounced and consistent. In conclusion, to detect intraoperative cerebral ischemia, monitoring of changes in the four frequency ranges found is preferable to monitoring changes in the classically defined frequency bands. Furthermore, these results stress the importance of the alpha and beta ranges in detecting cerebral ischemia.
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J Clin Neurophysiol · Nov 2000
Pain-related somatosensory evoked magnetic fields induced by controlled ballistic mechanical impacts.
The purpose of this study was to investigate cortical processing of painful compared with tactile mechanical stimulation by means of magnetoencephalography (MEG) using the novel technique of mechanical impact loading. A light, hard projectile is accelerated pneumatically in a guiding barrel and elicits a brief sensation of pain when hitting the skin in free flight. Controllable noxious and innocuous impact velocities facilitate the generation of different, predetermined stimulus intensities. ⋯ Additional long-latency responses occurred in these cortical areas as long as 280 msec after painful stimulation in three subjects. In contrast to tactile stimulation, painful mechanical impacts elicited SSEF responses in cortical areas demonstrated to be involved in central pain processing by previous MEG and neuroimaging studies. Because of its similarity to natural noxious stimuli and the possibility of adjustable painful and tactile impact velocities, the technique of mechanical impact loading provides a useful method for the neurophysiologic evaluation of cortical pain perception.
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J Clin Neurophysiol · Sep 2000
ReviewThe role of evoked potentials in anoxic-ischemic coma and severe brain trauma.
The early recognition of comatose patients with a hopeless prognosis-regardless of how aggressively they are managed-is of utmost importance. Median somatosensory evoked potentials supplement and enhance neurologic examination findings in anoxic-ischemic coma and severe brain trauma, and are useful as an early guide to outcome. The key finding is that bilateral absence of cortical evoked potentials, generated by thalamocortical tracts, reliably predicts unfavorable outcome in comatose patients after cardiac arrest, and correlates strongly with death or persistent vegetative state in severe brain trauma. ⋯ The majority of patients with normal central conduction times had a good outcome, whereas a delay in central conduction times increased the likelihood of neurologic deficit or death. This report includes a systematic review of the literature concerning adults in anoxic-ischemic coma and severe brain trauma, in which somatosensory evoked potentials were used as an early guide to predict clinical outcome. Greater use of somatosensory evoked potentials in anoxic-ischemic coma and severe brain trauma would identify those patients unlikely to recover and would avoid costly medical care that is to no avail.
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J Clin Neurophysiol · Sep 2000
Ethics in the intensive care unit with emphasis on medical futility in comatose survivors of cardiac arrest.
Medical futility refers to situations or cases in which treatment offers no meaningful benefit to the patient. Brain death does not pose a management problem because patients are considered to be dead. Management of other cases requires sequential considerations. ⋯ Then, if it is determined that there is no possibility of the patient regaining conscious awareness, a level of care should be decided through discussions involving the physician and significant others. Usually there is a consensus that high-level intensive care is not justified to maintain such a low quality of life. When the patient's advance directives or the substitute decision maker's request differs from the physician's recommendations, there are methods of resolving the issues that respect ethical and legal principles.