Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society
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Status epilepticus (SE) is a condition wherein epileptic seizure discharges are sufficiently prolonged or repetitive so as to produce persistent alterations in neurologic function and in the underlying physiologic and neurochemical activities of the brain. Thus, the definition of SE now includes any disorder in which there is sustained and prolonged excitation of neurons. Electroencephalographic (EEG) patterns associated with specific types of SE are important components in their classification. ⋯ Progressive behavioral and electrical changes have not been reported in primarily generalized forms of SE. EEG is an important tool for verifying successful treatment of SE if the patient does not immediately recover neurologic function. EEG recordings also contribute substantially to understanding the mechanisms of, and development of better treatments for, human SE through their use in the study of experimental SE in the laboratory.
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J Clin Neurophysiol · May 1995
Assessment of intraspinal and intracranial conduction by P30 and P39 tibial nerve somatosensory evoked potentials in cervical cord, brainstem, and hemispheric lesions.
In routine recordings of tibial nerve somatosensory evoked potentials (SEPs), a global central conduction time is evaluated by measuring the interval between the segmental spinal N22 potential, recorded in the lumbar region, and the cortical P39 potential. In this study, we tested the reliability of the scalp far-field P30 potential, which originates in the vicinity of the cervico-medullary junction, in order to evaluate separately intraspinal and intracranial conduction in normal subjects and patients with cervical cord and intracranial lesions. P30 and cortical P39 potentials were studied in 23 healthy subjects and in 70 patients with cervical cord (n = 47), brainstem (n = 11) or hemispheric lesions (n = 12) selected on the basis of neuroimaging--computed tomography (CT) or magnetic resonance (MR)--findings. ⋯ Combined abnormalities of P30 and P39 potentials thus indicate that conduction is impaired at the spinal level and proved to be particularly informative for detecting spinal cord dysfunction in patients with neuroimaging evidence of a narrowed cervical canal. Recording of abnormal N13, P14, or P30 potentials provided evidence of a cervical cord dysfunction in 66% of patients who had a suspected spondylotic myelopathy. Recording of tibial nerve P30 potential has proven to give reliable and useful information when a separate assessment of intraspinal and intracranial somatosensory conduction is needed; it merits inclusion, as does the upper limb N13 potential, in the evaluation of patients whose MR image indicates cervical canal narrowing.
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J Clin Neurophysiol · Mar 1995
Arousal fluctuations in non-rapid eye movement parasomnias: the role of cyclic alternating pattern as a measure of sleep instability.
Some non-rapid eye movement (NREM) parasomnias, such as sleep-walking (SW), sleep terror (ST) and, in some aspects, sleep enuresis (SE), are considered "arousal disorders" without significant polysomnographic changes in classic sleep macrostructure. The aim of our study was to evaluate sleep microstructure and oscillations of arousal level by cyclic alternating pattern (CAP) scoring in some NREM parasomnias. ⋯ Compared with the controls, our patients' sleep microstructure, scored by CAP analysis, showed increases in CAP rate (a measure of NREM instability with high level of arousal oscillation), in number of the CAP cycles, and in arousals with EEG synchronization, the increases being more significant in Group A than in Group B. An increase in sleep instability and in arousal oscillation seems to be a typical microstructural feature of delta sleep-related parasomnias and probably plays a role in triggering abnormal motor episodes during sleep in these patients.
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J Clin Neurophysiol · Mar 1995
Auditory evoked responses in children during hypothermic cardiopulmonary bypass: report of cases.
Variations in core temperature and cerebral blood flow during open heart surgery may affect auditory brainstem responses (ABRs) and middle latency responses (MLRs) in both adults and children. We documented the changes in ABRs of two infants (ages 3 and 11 weeks, respectively) with variations in core temperature during hypothermic cardiopulmonary bypass and total circulatory arrest and compared them with those of a 19-year-old adult. Changes in MLRs that occurred in association with reductions in cerebral blood flow as monitored by transcranial Doppler are also reported in a 6-year-old child. ⋯ MLR amplitudes were transiently reduced during periods of normothermic hypoperfusion. Hypothermia partially prevented these changes, and normoperfusion after rewarming recovered MLRs. Monitoring ABRs and MLRs may be a useful technique for assessment of brain function during hypothermic cardiopulmonary bypass in children and infants.
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J Clin Neurophysiol · Nov 1994
ReviewQuantitative sensory testing: methodology, applications, and future directions.
Quantitative sensory testing (QST) is based on well-developed psychophysical methods that define not only the stimulus (type, characteristics, quantity, presentation, testing format, and environment) but also the response (form and analysis). With the availability of personal computers, transducers, electronic circuitry, and specially written software, it became possible to develop systems that delivered physical stimuli with waveforms that were precisely defined, quantitated, and graded over a broad range of magnitudes, and capable of eliciting unitary sensations. Specific algorithms of testing and finding threshold could now be programmed for exact and sequential error-free testing. ⋯ In detecting patterns of sensory abnormality, it can also suggest the presence of specific diseases and be used to follow the course of sensory loss. Finally, because it is the best approach to detect, characterize, and quantitate sensory abnormality, it is useful both in epidemiologic and controlled clinical trials. Although our review focuses especially on the approaches and system we have developed, other systems using standardized approaches are available allowing the evaluation of vibratory (VDT), cooling (CDT), and warming (WDT) detection thresholds and visual analog scaling of heat pain (HP VAS).