Can J Neurol Sci
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Disorders of both the central and peripheral nervous systems are important causes of respiratory insufficiency. However, simple clinical observations and pulmonary function measurements may fail to identify the location and type of disorder. ⋯ These studies have been preformed safely and with little discomfort on adults, children or infants, and in out-patient and general ward settings. We have found they are of particular value in the intensive care unit.
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Electroencephalography (EEG) and evoked potential studies are established monitoring tools in the neurological intensive care unit (ICU). These neurophysiologic techniques provide information on physiological state and response to therapy, and may aid diagnosis and prognosis. Serial studies or continuous monitoring may enable changes to be detected prior to irreversible deterioration in the patient's condition. ⋯ In addition, continuous EEG monitoring has revealed previously unsuspected non-convulsive seizures in one-third of patients. SEPs and BAEPs can provide useful prognostic information in coma-however, these tests are etiologically nonspecific and must be carefully integrated into the clinical situation. Motor evoked potentials offer a potentially useful tool for evaluating motor system abnormalities in the ICU.
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The rationale, basic considerations, and technique of intraoperative nerve action potential (NAP) recording have been reviewed. Experience using this technique in several thousand patients over a 25 year period has been summarized. The most frequent serious nerve injury is one that leaves it in continuity. ⋯ Where resection of the lesion was based on absence of an NAP, the injury was, without exception, neurotmetic and/or one with poor potential for useful recovery without repair. Some lesions had an NAP across their lesion but a portion of the cross-sectional area appeared more seriously injured. By use of NAP recordings, a split repair was done and usually with good results.
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Many biologically active tracers are available for positron emission tomography (PET) investigations, but most studies of epilepsy have utilized 18F-fluorodeoxyglucose (FDG) to measure local cerebral metabolic rate for glucose. Over 70% of patients with medically refractory partial seizures demonstrate an interictal zone of hypometabolism corresponding to the epileptogenic region. This metabolic defect commonly involves the temporal lobe in patients with complex partial seizures of mesial temporal origin, and is encountered less consistently with seizures of extratemporal neocortical origin. ⋯ When hemispherectomy or large multilobar resections are planned in small children, FDG-PET also provides useful supporting evidence that the contralateral hemisphere is functioning normally. It is difficult to obtain FDG-PET scans and to interpret results during spontaneous partial seizures. Ictal scans can be more easily obtained with single photon emission computed tomography (SPECT), which may provide information for planning surgical resections.
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We have briefly reviewed the experimental and clinical evidence for the importance of the amygdala and hippocampal formation in temporal lobe epilepsy. More specifically, we have analyzed our own experience in patients with temporal lobe epilepsy investigated with intracerebral stereotaxic electrodes and operated by various modalities of resection. ⋯ As a result, more and more selective procedures are being carried out involving the mesial structures. However, this shift has been slow and progressive because of the proven value of cortico-amygdalo-hippocampectomy which provides excellent results on seizure tendency with low morbidity.