RESUMEN
Motor evoked potentials (MEPs) in cats, rats, and humans have been reported. They appear promising as a test of central nervous system function, and they are sensitive not only to mechanical injury but also to ischemia. In mechanical trauma, the peripheral nerve response is much more sensitive to damage than the cord response, with a lower threshold and an earlier disappearance. We are reporting that the MEP can also be produced in the dog and that, under conditions of cardiac arrest induced by fibrillation, the peripheral nerve response disappears first at about 30 seconds and then the spinal cord response disappears at about 10 to 13 minutes. The late disappearance of the spinal cord response raises serious questions about its role as an adequate injury monitor. The most useful warning feature of the spinal cord response is an increase in amplitude during the critical first 2 minutes of arrest. Latency changes in the cord and peripheral nerve response did not seem as useful as amplitude changes in terms of providing adequate detection of injury. We also evaluated the peripheral nerve signals to determine whether they are partially volume-conducted weak muscle responses, and evidence substantiates their nonmuscle origin.
Asunto(s)
Potenciales Evocados , Isquemia/fisiopatología , Corteza Motora/fisiopatología , Nervios Periféricos/fisiopatología , Médula Espinal/irrigación sanguínea , Animales , Perros , Estimulación Eléctrica , Nervio Radial/fisiopatología , Tiempo de Reacción , Nervio Ciático/fisiopatología , Médula Espinal/fisiopatologíaRESUMEN
Propranolol's potential as a protective agent against tissue injury has been noted in experimental myocardial, renal and early acute focal cerebral ischemia. The purpose of the present investigation was to study further the effects of racemic (d,l) propranolol on blood-brain barrier permeability, morphological changes, cortical electrical activity, and regional cerebral blood flow (rCBF) in experimental focal cerebral ischemia. Thirty adult cats, anesthetized with nitrous oxide, underwent 6 hours of right middle cerebral artery (MCA) occlusion. Fifteen cats were untreated. Fifteen cats were given a continuous infusion of racemic propranolol (1 mg/kg/hr) for 7 hours beginning 1 hour before MCA occlusion and a 4 mg/kg bolus immediately before occlusion, both directly into the right carotid artery. Right Sylvian rCBF did not significantly differ in the treated and untreated groups. Carbon filling defects and vital dye (i.e., Evans blue and fluorescein) extravasation were less severe in the propranolol treated animals. Light microscopic findings demonstrated no difference in infarct size between the two groups. The findings suggest that at doses given, racemic propranolol does not exert a protective effect upon cerebral tissue subjected to 6 hours of incomplete ischemia.
Asunto(s)
Ataque Isquémico Transitorio/tratamiento farmacológico , Propranolol/uso terapéutico , Animales , Presión Sanguínea/efectos de los fármacos , Barrera Hematoencefálica/efectos de los fármacos , Encéfalo/patología , Permeabilidad Capilar/efectos de los fármacos , Gatos , Circulación Cerebrovascular/efectos de los fármacos , Electroencefalografía , Frecuencia Cardíaca/efectos de los fármacos , Ataque Isquémico Transitorio/patología , Ataque Isquémico Transitorio/fisiopatología , Propranolol/farmacologíaRESUMEN
Fifty-seven cases of histologically confirmed cerebral oligodendroglioma treated at the Cleveland Clinic between 1950 and 1980 were reviewed. No difference in the 5-year survival rate was seen in patients treated with postoperative radiation therapy vs. operation alone. These data are compared to previously published series with special emphasis on the role of radiation therapy.