Electroencephalography and clinical neurophysiology
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Multichannel recordings of visual evoked potentials (VEPs) have proved to be useful in the evaluation of visual field defects. We studied the topographic distribution of transient VEPs in 15 migraine patients (8 with visual aura and 7 without) and 15 age-matched controls during the migraine-free interval. All the subjects included in the study had normal visual fields. ⋯ According to the VEP cortical generator theory, these abnormalities suggest a functional anomaly consistent with the clinical syndrome and detectable also in the migraine-free interval. None of the migraine patients without aura or the controls showed VEP amplitude asymmetries. We conclude that multichannel VEP recordings may discriminate between different subtypes of migraine and contribute important physiopathological information to the study of this disease.
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Electroencephalogr Clin Neurophysiol · Oct 1994
Quantitative surface EMG of pericranial muscles in headache. A population study.
Quantitative EMG from the right frontal and both temporal muscles was studied in 547 adults randomly selected from the general population. The study was part of a multifaceted, epidemiological study of different headache disorders. Surface EMG was recorded by an observer blinded to the persons' history of headache, previous illness and mental state. ⋯ Moreover, amplitude values were decreased in both the temporal and the frontal muscles during maximal voluntary contraction indicating submaximal contraction during pain. The present study supports the importance of peripheral factors such as increased fatigability, morphological, and/or metabolic changes in the pathogenesis of tension-type headache. However, the diagnostic value of EMG in migraine and tension-type headache is limited.
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Electroencephalogr Clin Neurophysiol · Mar 1994
Randomized Controlled Trial Clinical TrialBispectral analysis of the electroencephalogram during induction of anesthesia may predict hemodynamic responses to laryngoscopy and intubation.
The use of electroencephalography as a measure of adequacy of anesthesia has achieved limited success. Our purpose was to determine whether the non-linear properties of the electroencephalogram (EEG) as defined by the bispectral index was a better predictor of autonomic responses to endotracheal intubation during opioid-based anesthesia than the linear statistical properties of the EEG formulated by power spectral analysis. Thirty-nine adults scheduled for elective non-cranial surgery had a continuous EEG recorded during induction of anesthesia and endotracheal intubation. ⋯ Heart rate changes did not differentiate between the two groups. There was a significant difference between response groups as measured by the bispectral index which distinguished responders from non-responders independently of the amount of drug given. None of the variables of power spectral analysis accurately distinguished responder from non-responder.(ABSTRACT TRUNCATED AT 250 WORDS)
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Electroencephalogr Clin Neurophysiol · Feb 1994
In vitro evaluation of a 4-leaf coil design for magnetic stimulation of peripheral nerve.
The performance of a 4-leaf magnetic coil was evaluated during magnetic stimulation of a peripheral nerve in vitro. The site of stimulation was below the coil center, and a 90 degrees rotation of the coil was equivalent to a change in current polarity. A hyperpolarizing magnetic stimulus failed to slow or block a propagating action potential.
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Electroencephalogr Clin Neurophysiol · Nov 1993
A physiological coma scale: grading of coma by combined use of brain-stem trigeminal and auditory evoked potentials and the Glasgow Coma Scale.
Forty-five comatose patients were prospectively studied by means of clinical examination and evoked potentials. In each patient, clinical data included Glasgow Coma Scale (GCS) score, age, pupillary response to light, corneal reflex, and eye movements. Neurophysiological evaluation was based on brain-stem trigeminal evoked potentials (BTEPs) and brain-stem auditory evoked potentials (BAEPs). ⋯ According to these findings, a clinical-physiological coma scale, the trigeminal-auditory Glasgow (Coma Scale) score (TAG score) was designed. The TAG score demonstrated the highest accuracy at each confidence level as compared to other single indicants. We concluded that the TAG score may improve the evaluation of deep comatose patients and assist the physician in the management of such patients.