Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society
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J Clin Neurophysiol · Jan 2002
An approach to intraoperative neurophysiologic monitoring of thoracoabdominal aneurysm surgery.
Thoracoabdominal aneurysm surgery carries an approximate 10% risk of intraoperative paraplegia. Abrupt cord ischemia and the confounding effects of systemic alterations and limb or cerebral ischemia challenges neurophysiologic spinal cord monitoring. This investigation sought a rapid differential monitoring approach to predict or help prevent paraplegia. ⋯ Cord and subcortical SSEPs required excessive averaging time. In conclusion, bilateral arm and leg muscle MEPs with median and tibial peripheral nerve and cortical SSEPs provide sufficiently rapid detection and differentiation of cord ischemia from confounding factors. There were two predicted intraoperative spinal cord infarctions (6.5%) and nine circumstantial examples of possible contributions to deficit prevention.
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J Clin Neurophysiol · Nov 2001
Analogous corticocortical inhibition and facilitation in ipsilateral and contralateral human motor cortex representations of the tongue.
How the human brain controls activation of the ipsilateral part of midline muscles is unknown. We studied corticospinal and corticocortical network excitability of both ipsilateral and contralateral motor representations of the tongue to determine whether they are under analogous or disparate inhibitory and facilitatory corticocortical control. Motor evoked potentials (MEPs) to unilateral focal transcranial magnetic stimulation (TMS) of the tongue primary motor cortex were recorded simultaneously from the ipsilateral and contralateral lingual muscles. ⋯ ICI and ICF were identical in the ipsilateral and contralateral representations, with inhibition occurring at short ISIs (2 and 3 ms) and facilitation occurring at longer ISIs (10 and 15 ms). Moreover, changing one stimulus parameter regularly produced analogous changes in MEP size bilaterally, revealing strong linear correlations between ipsilateral and contralateral ICI and ICF (P < 0.0001). These findings indicate that the ipsilateral and contralateral representations of the tongue are under analogous inhibitory and facilitatory control, possibly by a common intracortical network.
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Vagus nerve stimulation (VNS) is an accepted therapy for the treatment of refractory epilepsy and now even depression. More than 10,000 people have had the device implanted over a period of 12 years. Initial side effects in the early years such as lower facial weakness and electrode lead breaks have now been resolved. ⋯ These side effects tend to diminish with time. Cognitive side effects often seen with antiepileptic drug use are not reported. The side effect profile of VNS is positive, and this treatment option offers patients with refractory epilepsy prospects of good efficacy with only minor and often resolvable side effects.
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J Clin Neurophysiol · Jul 2001
Comparative StudyEEG evidence for shunt requirement during carotid endarterectomy: optimal EEG derivations with respect to frequency bands and anesthetic regimen.
Currently there is no consensus on the derivations that should be used for EEG monitoring during carotid endarterectomy (CEA). The aim of this study was to determine which derivations distinguish the best between patients requiring a shunt and patients who do not need a shunt. Four predefined frequency bands and two regimens for general anesthesia (isoflurane versus propofol) were used. ⋯ The two different anesthetic regimens resulted in different patterns of EEG changes because of clamping. The optimal derivations to differentiate between the shunt and the nonshunt groups also differed for the two anesthetic regimens, although for both conditions, anterior head regions were especially preferred. The optimal derivations are given for each anesthetic regimen.
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J Clin Neurophysiol · Mar 2001
Case ReportsContinuous EEG monitoring in a patient with massive carbamazepine overdose.
The authors report a woman who took a massive overdose (OD) of carbamazepine (CBZ). On admission she was unconscious with absent brainstem reflexes and multifocal stimulus-sensitive myoclonus. Continuous EEG recordings showed a burst-suppression pattern with bursts containing only generalized spikes accompanying myoclonic activity. ⋯ Autopsy revealed that cortical and subcortical structures were normal without neuronal necrosis or eosinophilia. Massive CBZ OD may produce a reversible encephalopathy that includes cortical hyperexcitability, a profound burst-suppression EEG pattern, and cranial nerve areflexia. Continuous EEG monitoring is helpful in managing seizures that occur as a complication of CBZ OD, after the course of recovery or worsening, and in providing assistance with prognosis.