Search PubMed⌕ Search

Biomedical subjects

J J Oro

Publications and source records attributed to J J Oro.

26 records · Page 2Linked to original sources
PubMed1990

Depressive effect of isoflurane anesthesia on motor evoked potentials.

The influence of the volatile anesthetic isoflurane (Forane) on motor evoked potentials was examined in rats. To record motor evoked potentials, single-shock electrical stimulation was delivered to the forelimb representation of the motor cortex. This resulted in elicitation of a compound muscle action potential from the contralateral extensor muscles. The effect of isoflurane was examined at various concentrations ranging from 0.2 to 1.5%. With increasing concentrations of isoflurane there was a progressive increase in onset latency of the compound muscle action potential and a decrease in peak-to-peak amplitude and duration. Latencies were significantly increased over baseline values for concentrations of isoflurane from 0.5 to 1.5% (P values were 0.001 to 0.007). For the amplitude and the duration, responses at 0.5 to 1.5% isoflurane were significantly lower than baseline (P values were 0.001 to 0.007). We conclude that isoflurane anesthesia significantly changes the muscle response evoked by motor cortex stimulation in experimental animals.

Anesthesia↗
PubMed1990

Suppression of motor evoked potentials by inhalation anesthetics.

The purpose of this study was to record evoked action potentials from forearm muscles in response to single-shock supramaximal electrical stimulation of motor cortex in room air and under different concentrations (0.5-1.5%) of isoflurane, enflurane, and halothane anesthesia in rats. Anesthesia was induced with a mixture of fentanyl and droperiodol, which was then followed by 10-min inhalation of each gas anesthetic under controlled ventilation. Increasing concentrations of isoflurane (n = 12) caused a progressive increase in onset latency and a decrease in peak-to-peak amplitude and duration. Similar increases in latency and decreases in amplitude and duration occurred under enflurane (n = 10) and halothane (n = 10) anesthesia. The three anesthetics caused a significant latency increase over baseline (room air) values for concentrations from 0.5 to 1.5% (p < 0.01). The amplitude and duration of muscle responses under all three volatile anesthetics at 0.5-1.5% concentrations were significantly lower than baseline (p < 0.01). Isoflurane, enflurane, and halothane anesthesia significantly altered the muscle response evoked by motor cortex stimulation in experimental animals.

Journal Article↗
PubMed1989

Effects of hypovolemic hypotensive shock on somatosensory and motor evoked potentials.

The utility of evoked potentials in monitoring spinal cord and cerebral function in various neurosurgical and orthopedic operations has now been established. To study the effects of graded hypotension upon spinal and cortical somatosensory evoked potentials (SMEPs), and spinal motor evoked potentials (SMEPs), 12 anesthetized cats were subjected to graded hypotension ranging from a mean arterial blood pressure of 100 mmHg to 30 mmHg or less. Hypotension causes a progressive increase in onset latency and a decrease in amplitude and conduction velocity of SEPs and SMEPs. Cortical SEPs and SMEPs were sensitive to profound hypotension (MAP less than 30 mmHg). Spinal SEPs showed more resistance and disappeared at lower levels of hypotension. Immediate blood transfusion caused resumption of cortical SEPs and SMEPs within 30 minutes after infusion; however, the latency and amplitude of responses did not reach the baseline values within 1 hour after transfusion. The sequential recovery of evoked responses was dependent upon the length of hypotension. When 15 minutes elapsed between loss of responses and transfusion, cortical SEPs and SMEPs did not resume within 1 hour after infusion. No return of signals occurred if 30 minutes elapsed between the loss of evoked responses and blood reperfusion. These findings suggest that ischemia associated with profound systemic hypotension can alter or obliterate evoked responses.

Animals↗
PubMed1989

Determination of death by neurological criteria.

Since 1981, Missouri law has defined death as occurring when cardiopulmonary function has ceased or when all brain and brain stem function is totally and irreversibly lost. The author reviews the current published guidelines for the determination of death by neurological criteria in order to assist physicians making the evaluation.

Brain↗
PubMed1984

Curved biopsy needle for stereotactic surgery: a technical note.

Needle brain biopsy and aspiration is an important technique for the diagnosis of tumors and for the evacuation of fluid collections. Current biopsy methods use a straight needle, which has the disadvantage of requiring multiple passes through the overlying brain to obtain multiple biopsies. Furthermore, a straight needle does not give optimal samples of tumor for diagnosis because the needle passes through the viable rim of the tumor instead of along it. We are reporting a curved plastic biopsy needle suitable for computed tomography-guided biopsy. It remains inside an outer guide catheter that holds it straight until it reaches the edge of the tissue to be biopsied. At this point, the needle is advanced beyond the guide catheter and obtains the biopsy sample by passing around the edge of a tumor. This can in principle produce an improvement in diagnostic yield. Furthermore, multiple biopsies of the tumor from a single guide catheter position are possible. The surgeon rotates the curved needle within its guide catheter to redirect it before the needle emerges, and a different biopsy is then obtained without reinsertion. This avoids multiple punctures of the overlying uninvolved tissue. We are reporting the technique and beginning an evaluation of it.

Biopsy, Needle↗
PubMed1983

Dumbbell ganglioneuroma of the lumbar spine associated with a herniated intervertebral disc: case report.

Paraspinal ganglioneuromas with extension into the spinal extradural space are rare tumors. Their management usually requires cooperation with surgeons of other specialties. The authors describe a case of a dumbbell ganglioneuroma arising from the lumbar sympathetic ganglia in a patient presenting with a herniated lumbar disc. The clinical features, radiographic analysis, and surgical approach to these tumors are briefly discussed.

Adult↗
PubMed1983

Septate bifrontal ependymal cyst. Case report.

The authors describe the case of a septate ependymal cyst involving both frontal lobes. The clinicopathological features, treatment, and results of previously reported cases are reviewed, and the etiology and pathogenesis of these cysts discussed.

Adult↗