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Biomedical subjects

C B Shields

Publications and source records attributed to C B Shields.

At least 55 records · Page 3Linked to original sources
PubMed1989

Transcranial magnetic motor evoked potentials (tcMMEP) for functional monitoring of motor pathways during scoliosis surgery.

Transcranial magnetic motor evoked potentials (tcMMEP) were used to assess the functional integrity of the descending motor pathways. The tcMMEP, recorded bilaterally from anterior tibialis muscles, were evoked by an electric current induced in the motor cortex by a high-intensity transient magnetic field applied to the scalp surface. Potentials were recorded from ten of 12 volunteer subjects and preoperatively in 11 of 11 scoliotic patients. Group mean latency in the volunteers (32.0 +/- 2.1 msec) did not differ from that of the scoliotics (28.6 +/- 5.0 msec), but values in the latter group were more variable. During nitrous oxide-narcotic anesthesia, tcMMEP with reproducible latencies were obtained in 9 of 11 (82%) cases. A small, but statistically significant, increase in latency occurred during anesthesia. Compared with preoperative values (523 +/- 490 microV), individual tcMMEP amplitudes were significantly decreased intraoperatively (163 +/- 153 microV). Although the absolute amplitudes varied widely, the minimum recorded value was over 20 microV. Thus, intraoperative tcMMEP waveforms were readily discriminable from background electrical noise. These results demonstrate the technical feasibility of intraoperative tcMMEP monitoring. Combined somatosensory evoked potential and tcMMEP monitoring may provide a more complete picture of spinal cord function, intraoperatively.

Electromagnetic Fields↗
PubMed1989

Magnetically evoked facial nerve potential.

Facial nerve stimulation by electrical current is painful and tends to discourage serial studies. Transcutaneous magnetic stimulation of the facial nerve is painless, easily reproducible, and elicits facial muscle responses identical to electrical stimulation.

Electromyography↗
PubMed1988

Safety and efficacy of chymopapain (Discase) in the treatment of sciatica due to a herniated nucleus pulposus. Results of a randomized, double-blind study.

A prospective, multiinstitutional, double-blind trial comparing the effect of chymopapain (Discase) vs. placebo (cysteine-edetate-iothalamate: CEI) for lumbar intervertebral disc rupture with sciatica was carried out on 173 patients, the largest such study reported to date. Patients were matched with respect to age, sex, physical habitus, and level of injection. The procedure was carried out under local anaesthesia. The success rate was superior in the chymopapain group regardless of the method used to assess outcome or the time over the first 6 months at which the two groups were compared: 71% vs. 45% if code breaks were analyzed at 6 months, and 67% vs. 44% if code breaks were defined as lost to follow-up. A single case of anaphylaxis and one case of septic discitis were the only serious complications noted. This study supports the role of chymopapain in the treatment of lumbar disc rupture with sciatica.

Adolescent↗
PubMed1988

The rat hippocampal slice preparation as an in vitro model of ischemia.

In vivo models of cerebral ischemia do not fully control for the interacting effects of many variables (e.g., anesthesia, temperature, cerebrovascular changes) and often do not clearly define the region affected. Numerous in vivo studies have indicated that hyperglycemia augments ischemic brain damage; this effect is often attributed to lactic acidosis. To separate the effects on neuronal tissue of ischemia from those due to actions on the cerebrovascular system, we used an in vitro blood-free system as an ischemic model. In our study we evaluated the effects of various combinations of oxygen and glucose levels on evoked synaptic activity in the CA1 region of the rat hippocampal slice preparation. A 50% inhibitory dose for both oxygen and glucose on neuronal synaptic function was determined. It is our intention to use this model for preliminary screening of antihypoxic/anti-ischemic drugs.

Animals↗
PubMed1987

Correlation of cerebral perfusion pressure and Glasgow Coma Scale to outcome.

Cerebral Perfusion Pressures (CPP) and Glasgow Coma Scale (GCS) scores were monitored to guide the management of severely head-injured patients. These measures were correlated to outcome (Glasgow Outcome Scale-GOS) in 136 consecutive patients at least 1 year after injury. The GOS showed highly significant positive correlations to either CPP or GCS assessments (p less than 0.001). Two parameters that are correlated with subsequent death in most patients include 1) highest (h) GCS = 3 or 4 (Day 1: 31 of 32 patients died, and Day 2: 19 of 19 patients died), and 2) CPP less than or equal to 60 mm Hg more than 33% of the hourly measures during Day 2 (36% of all subsequent deaths; 11% overlap with the highest Glasgow Coma Scale). The Day 2 measures identifying two groups that have a greater than 75% incidence of "good outcome" or GOS = 4 or 5 include 1) hGCS greater than or equal to 6 (N = 45) and 2) the average (a) CPP greater than or equal to 90 mm Hg (N = 26). Of the 45 patients with a GOS = 4 or 5 who had both CPP and GCS recorded on the third day, 44 were identified by these "good outcome" parameters.

Blood Pressure↗
PubMed1987

Effect of the topical application of some newer antibiotics on the cerebral cortex.

Five currently used antibiotics--moxalactam, cefotaxime, cefoperazone, metronidazole, and piperacillin--and bacitracin were compared for epileptogenetic effect against penicillin G as a standard when applied directly to cat cerebral cortex. Piperacillin was half as epileptogenic as penicillin. Moxalactam, cefotaxime, and cefoperazone showed epileptogenicity one-fourth to one-eighth that of penicillin on a milligram per cubic centimetre basis. Neither metronidazole nor bacitracin produced any focal seizure activity at the highest concentrations tested. Some of the newer cephalosporin antibiotics may have a significant risk of inducing seizure activity if high concentrations come in direct contact with neocortical tissue.

Animals↗
PubMed1987

Chemonucleolysis with chymopapain: results in 150 patients.

Chemonucleolysis with chymopapain has been advocated for the treatment of lumbar disc disease. When polled by a mail questionnaire, 150 consecutive patients who had undergone chemonucleolysis reported an overall success rate of only 40% and a failure rate of 60%. However, 57% of the patients were active or had only mild restriction of daily activities. Of those patients employed prior to injection, only 63% had returned to work. Those with workmen's compensation benefits fared considerably worse than those covered by third-party insurance (17% vs. 51% success). These results cast doubt on the long-term benefits of chymopapain in the treatment of lumbar disc disease.

Adolescent↗
PubMed1986

Cervical spine fractures with major associated trauma.

A detailed review of 88 consecutive patients placed in skeletal tong traction for cervical fractures by the University of Louisville Neurosurgical Service during a 5-year period from July 1, 1979, through June 30, 1984, was carried out. Of this group, 60% of the patients had a major associated injury consisting of major facial and skull fractures, cerebral contusions or intracerebral blood clots, cardiac or pulmonary contusions, major thoracic injuries including rib fractures and hemo- or pneumothoraces, intra-abdominal injuries, and major extremity fractures. An additional 24% of the patients had minor associated injuries, including facial or scalp lacerations, general body lacerations, or abrasions and cerebral concussions. Only 16% of patients with cervical fractures had no evidence of any other associated injury. Acute cervical spine fractures require prompt assessment and resuscitation by personnel from multiple specialties, usually available only in major trauma centers where experienced personnel capable of handling diverse injuries are always present.

Adolescent↗
PubMed1986

Low back pain.

Low back pain is a frequent source of disability during the productive years of life. Repeated trauma is a major causative factor. Maintaining ideal body weight and good muscle tone, especially of the abdominal musculature, can minimize low back pain. Lumbar disc protrusion and extrusion may be treated by medical therapy, by neurosurgical intervention or possibly by chemonucleolysis. Other important causes of back pain are arthritis, facet disease and spinal stenosis. Evaluation of low back pain should include tests to uncover a psychogenic source.

Arthritis↗
PubMed1985

Dwight Parkinson.

Explore the source record for details and available documents.

History, 20th Century↗
PubMed1985

Update on chymopapain.

Chemonucleolysis with chymopapain is accepted by many surgeons as a reasonable alternative to lumbar diskectomy for the treatment of lumbar disk disease. Approximately 70 to 75 per cent of carefully selected patients are successfully treated following this therapy, but extreme care must be exercised for precise needle placement and prompt and vigorous management of major allergic reactions. Methods to avoid major complications and their management, should they occur, are discussed.

Adolescent↗
PubMed1984

Accurate intracranial pressure monitoring: technical note.

Intracranial pressure (ICP) monitoring may be misleading or inaccurate in patients who have sustained cerebral death or who have had cerebrospinal fluid drainage (e.g., due to skull fracture or craniotomy). ICP recording in these patients requires particular attention to the monitoring technique to avoid misleading values that may result in inappropriate therapy. We review methods for obtaining accurate ICP readings from fluid-interface systems using either a ventricular catheter or a subarachnoid screw. We suggest attention to the following: (a) elevation of the pressure in the external tubing and connections to ensure that there are no microleaks , (b) injection of a small volume of saline intracranially, and (c) awareness of what constitutes a true ICP reading.

Brain Death↗
PubMed1981

Spontaneous obliteration of carotid-cavernous fistulas.

We have described a patient with a carotid-cavernous fistula filling from both ends of a torn meningohypophyseal artery, with subsequent spontaneous resolution proven by angiography. No cause for the fistulas' obliteration could be identified, and the patient continues to do well four years later.

Angiography↗
PubMed1980

Isodense subdural hematoma presenting with paraparesis: case report.

Computerized tomography (CT) has replaced cerebral angiography in many institutions as the diagnostic test of choice in cranial trauma. However, isodense subdural hematomas can be a source of false-negative results on CT scans, resulting in omissions in therapy. The authors report a patient with bilateral isodense subdural hematomas who presented with paraparesis but was otherwise alert and fully oriented. The CT findings caused an initial diagnostic dilemma before being resolved.

Aged↗