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Biomedical subjects

E C Benzel

Publications and source records attributed to E C Benzel.

At least 91 records · Page 5Linked to original sources
PubMed1991

Texas Scottish Rite Hospital rod instrumentation for thoracic and lumbar spine trauma.

The authors present their experience with 28 patients who had incurred unstable thoracic or lumbar spine fractures and who were intraoperatively stabilized with the Texas Scottish Rite Hospital (TSRH) universal instrumentation system. These patients were treated over a 1-year period and reflect an evolving insight into the treatment of thoracic and lumbar spine trauma with universal instrumentation. The TSRH instrumentation system appears equivalent to the more established Cotrel-Dubousset system in most respects. The construct design of the TSRH system facilitates the safe application of a rigid spinal implant. No cases of instability or pseudoarthrosis were observed during an average follow-up period of 9 months, (minimum 3 months). As the surgical treatment plan evolved, shorter and more compact constructs were increasingly utilized. There were no cases of instrumentation failure, regardless of the number of spinal levels fused or the number of levels instrumented. The value of using short rods when possible is emphasized: they may decrease the incidence of delayed instability and discomfort related to loosening at the hook/bone interface compared to that observed when long-rod systems are used in association with short spine fusions causing a fusion/instrumentation mismatch.

Adolescent↗
PubMed1990

The diagnosis of infections associated with acrylic cranioplasties.

Fifty-two methylmethacrylate cranioplasties were performed on forty-seven patients over a five year period. Two cranioplasties became infected and required removal. The overall infection rate for methylmethacrylate cranioplasty was thus 2/52 or 3.8%. Both of these patients had bifrontal cranioplasties involving both orbital rims and the frontal sinus. The infection rate for those cranioplasties involving the frontal sinus was 2 of 9 or 22%. None of the 43 cranioplasties not involving the frontal sinus became infected. Ten patients in this series had postoperative CT scans. Gas within the non-infected methylmethacrylate could simulate infection, making it difficult to diagnose cranioplasty infections by CT. Although certain CT changes, such as epidural air and soft tissue swelling, may be observed only with infected cranioplasties, the clinical picture is the only truly reliable indicator of infection.

Abscess↗
PubMed1990

Effect of dosage and timing of administration of naloxone on outcome in the rat ventral compression model of spinal cord injury.

The effect of the dosage and timing of administration of naloxone after spinal cord injury in rats via the ventral compression technique is presented. The rat ventral compression technique allows for a ventral compression of the spinal cord without the requirement of a previous laminectomy. It therefore facilitates the creation of an experimental lesion that is similar to that observed in the human clinicopathological situation. The first part of the two-part study presented herein involved the determination of the optimal dose of naloxone, administered intraperitoneally 45 minutes after the creation of the lesion. Of the groups studied (control group through 10.0 mg/kg group), 2.0 mg/kg of naloxone proved to be superior to both lesser and greater dosages. The second part of the study involved the administration of a 2.0 mg/kg dose of naloxone at varying intervals ranging from 10 minutes before lesioning to 24 hours after lesioning. A multiphasic response was again demonstrated, with an optimal time of administration occurring 45 minutes after the creation of the lesion. A significant effect was offered by a midrange dose of naloxone (2.0 mg/kg), administered at 45 minutes after injury (P less than 0.02 by analysis of variance and Duncan's multiple range test). These findings are discussed with respect to recent evidence regarding the effects of narcotic antagonists on both mu and kappa narcotic receptors. Past and future experiments must account for these responses to multiphasic dosage and timing of administration. Failure to do so may lead to erroneous conclusions.

Animals↗
PubMed1990

Fascia lata graft as a dural substitute in neurosurgery.

We present 37 cases in which fascia lata was used for dural patching when there was inadequate regional tissue, such as pericranium or temporalis fascia to repair the dural defect. Operative indications included tumor in 17 patients (46%), trauma in nine (25%), cerebrospinal fluid fistula in seven (19%), infection in two (5%), dural patching in two (5%). Follow-up ranged from one month to five years, with an average follow-up of two years. There were no cranial or spinal complications related to the fascia lata grafting (including cerebrospinal fluid leakage, meningitis, and wound infection). Fascia lata is relatively simple to obtain, but harvesting necessitates a second incision; this second incision resulted in no complications in our patients.

Adult↗
PubMed1990

A new rat spinal cord injury model: a ventral compression technique.

A new rat spinal cord injury model, which uses a modification of a DeBakey aortic aneurysm clamp to create the injury, is presented. The model produces a ventral persisting mass (bone and soft tissue) without the requirement of a prior decompressive operation (laminectomy). Modifications of the original technique have resulted in a nil surgical mortality rate. This technique has been applied to 138 animals. It has produced a consistent percentage of animals with complete myelopathies, as well as incomplete myelopathies and animals without apparent injury. The percent of baseline neurological function lost (change in degrees of the angle of tilt as measured by the inclined plane technique) in each group of surviving animals was 58, 36, and 9%, respectively. Sagittal postmortem sections confirmed mass lesions located ventral to the spinal cord. Histological sections confirmed neuronal loss consistent with the neurological findings.

Animals↗
PubMed1990

Dose-dependent effects of naloxone and methylprednisolone in the ventral compression model of spinal cord injury.

A study of the dose-response effects of naloxone and methylprednisolone after rat ventral spinal cord injury is presented. The spinal cord injury model used herein is unique in that it results in a ventral compression of the spinal cord without the need for a prior laminectomy. This allows for a close approximation of the human clinicopathological situation. There was a statistically significant positive effect on neurological outcome with a naloxone dose of 2.5 mg/kg, whereas higher and lower doses yielded little or no influence on outcome. Methylprednisolone was observed to offer similar results. These results, however, did not achieve statistical significance. The early administration of moderately high doses (45-60 mg/kg), however, offered the best results. The responses to the treatment regimens presented here offer hope for spinal cord injury victims. The observed dose-response relationships indicate that erroneous conclusions may arise from studies using inappropriate doses of narcotic antagonists, as well as other drugs.

Animals↗
PubMed1990

Communicating hydrocephalus in adults: prediction of outcome after ventricular shunting procedures.

A series of adult patients with idiopathic hydrocephalus in whom shunts were placed are presented. Preoperative diagnostic and prognostic criteria were evaluated. Findings on computed tomographic scans (significant ventricular enlargement, the absence of gyral atrophy, and the absence of sylvian fissure enlargement) and the clinical triad associated with hydrocephalus in adults (dementia, ataxia, and especially incontinence of urine) all contributed individually and in combination to the diagnosis of hydrocephalus that could be corrected by surgery. The use of radionucleotide cisternography did not add any additional information. Its use as a diagnostic or prognostic aid is, therefore, suspect. The use of high-pressure shunting systems for the initial shunting procedure is emphasized.

Adult↗
PubMed1989

Naloxone and mortality in the gerbil stroke model.

Endorphins and narcotics have been implicated in the exacerbation of neurologic deficits after stroke. To test the theory that narcotic antagonists might offer an improvement in neurologic sequelae following stroke, we administered various doses of naloxone intraperitoneally to 50 adult gerbils 45 minutes after carotid artery transsection. Low-dose naloxone therapy (1.0 to 2.5 mg/kg) was more effective in preventing death than either control (sterile saline) or high-dose naloxone (10 mg/kg). A naloxone dose of 1.0 or 2.5 mg/kg offered a significant improvement in mortality over both the control and the high-dose therapy (P = .026). It appears that an appropriate dose of naloxone (1.0 to 2.5 mg/kg), given early enough to alter outcome, offers an improved survival in the gerbil stroke model. This finding obviously has significant implications for the use of narcotic antagonists in human beings with stroke.

Animals↗
PubMed1989

Neurologic manifestations of child abuse.

During a four-year period, we saw 23 cases of child abuse with central nervous system involvement. Of these, five died and four were left with a substantial neurologic deficit as a result of injury. Of the 18 survivors, eight (44%) were removed from their home along with their siblings, one was placed in a sheltered environment with its mother, and nine (50%) were kept under surveillance. Six of the 12 patients with CT evidence of intracranial damage had no or minimal evidence of external cranial trauma. Although shaking as the major etiologic factor in neurologic impairment from child abuse has recently been questioned, our results implicate it as a common mechanism of injury. Every patient had a parent or guardian whose account of the mechanism of injury either changed from moment to moment or was inconsistent with the child's injury. Nine patients (39%) were known to have been seen previously by other physicians because of similar problems or other injuries consistent with child abuse. Early recognition of child abuse is paramount to saving not only the life of the affected child, but possibly the lives of siblings. Neurosurgeons should maintain a high index of suspicion for the diagnosis of child abuse.

Brain Diseases↗
PubMed1989

A comparison of the Minerva and halo jackets for stabilization of the cervical spine.

The motion at each intervertebral level permitted by the halo jacket and the thermoplastic Minerva body jacket was compared in 10 ambulatory patients with an unstable cervical spine. The thermoplastic Minerva body jacket is a new lightweight modification of a Minerva jacket which is fabricated from Polyform (a splinting material made of a polyester polycaprolactone) and Polycushion (a closed-cell foam for padding). Each patient served as his/her own control. The average movement from flexion to extension at each intervertebral level was significantly less in the thermoplastic Minerva body jacket (2.3 degrees +/- 1.7 degrees) than in the halo jacket (3.7 degrees +/- 3.1 degrees) (p less than 0.0025). This difference is attributable to the "snaking phenomenon" encountered with halo jacket immobilization and should be taken into account when considering an external splint for an unstable cervical spine. The thermoplastic Minerva body jacket also offered a substantial improvement in comfort for the patient over that experienced in the halo jacket. The apparent advantage with respect to stability and comfort of the thermoplastic Minerva body jacket over the halo jacket suggests that the former device is the orthosis of choice for ambulatory stabilization of most patients with an unstable posttraumatic cervical spine injury.

Adolescent↗
PubMed1989

Posterior cervical interspinous compression wiring and fusion for mid to low cervical spinal injuries.

A technique of posterior cervical interspinous compression wiring and fusion, which offers significant immediate stability, is presented. Its efficacy in 50 consecutive cases illustrates its utility. The technique involves the passage of an interspinous cerclage wire. Rather than placement of onlay laminar and facet grafts, a split-thickness tricortical iliac-crest graft is compressed against the involved medial laminae and spinous processes bilaterally. These grafts are held in place by a compression wire, which encircles the grafts and thus sandwiches the spinous processes between them. This virtually ensures subsequent bone fusion and offers substantial acute stability. The compression wire offers an added advantage of encircling the cerclage wire, thus pulling it dorsally. This significantly diminishes translational mobility at the unstable segment. It also minimizes hyperextension at the unstable segment via medial compression of the grafts into the interspinous space. The fusion of a minimal number of spinal segments is emphasized. This substantially diminishes the chance of flexible kyphosis and degenerative changes, both above and below the fusion site. A three- or four-level fusion was performed in only 11 patients. The remaining 39 patients underwent two-level fusion. A solid bone fusion was achieved in all cases, with a follow-up period of at least 6 months. In one patient, the spinous process fractured, necessitating an anterior fusion procedure. The technique presented here appears to acutely offer a very stable construct and, in addition, is a simple and straightforward procedure for the treatment of the unstable cervical spine.

Adolescent↗
PubMed1989

The apnea test for the determination of brain death.

By conventional criteria, an apneic patient's PaCO2 must be greater than 60 mm Hg before apnea can be attributed to brain death. The rate of a PaCO2 increase in the apneic patient traditionally has been thought to be in the range of 3 mm Hg/min. In order to assess the validity of these data and the validity of the "apnea test" for determination of brain death, the results of this test were reviewed in 20 patients. In all patients, arterial blood samples were drawn for blood gas measurements every 2 minutes following the cessation of volume ventilation (with an oxygen cannula at 6 liters O2/min passed into the tracheobronchial tree). The rate of PaCO2 increase was noted to be very erratic. The average rate of rise was 3.7 +/- 2.3 mm Hg/min (+/- standard deviation). This, however, varied from 0.5 to 10.5 mm Hg/min and was not predictable from the variables evaluated. The rate of PaCO2 increase was noted to decline throughout the duration of the test. This ranged from 3.9 +/- 1.2 mm Hg/min (for patients with baseline PaCO2 less than or equal to 30 mm Hg) and 4.5 +/- 1.9 mm Hg/min (for patients with baseline PaCO2 greater than or equal to 30 mm Hg) in the first 4 minutes of the test to an average of 0.92 mm Hg/min for patients with test lasted longer than 12 minutes. These unpredictable results might be related to CO2 washout, atelectasis, cardiac ventilations, or other yet-undefined parameters. The nonlinear relationship between rate of PaCO2 increase and time following onset of apnea resulted in the test being prolonged in several patients. In these patients, the PaCO2 approached 60 mm Hg in an asymptotic fashion. These lengthy tests could have been avoided by utilizing a standardized apnea test with a baseline PaCO2 of 40 mm Hg or greater. The observation that a high baseline PaCO2 greatly augments the efficiency and safety of the test allows criteria that have previously been based on conjecture to be documented and applied clinically. A standardized apnea test, utilizing these principles, may satisfy many of the criticisms regarding brain-death testing that have been raised by neurologists, neurosurgeons, and transplant surgeons.

Adult↗
PubMed1989

The lateral extracavitary approach to the spine using the three-quarter prone position.

A three-quarter prone position for the lateral extracavitary operative approach to the thoracic and lumbar spine is described. This approach has been used in 40 patients with anterior spinal cord compressive lesions in the thoracic and/or lumbar region. In this patient population, it has allowed a safe ventral decompression of the spinal cord. It also allows placement of spinal instrumentation through the same incision. Both the operating surgeon and the assistant have an excellent view of the operative site, including the dural sac. Patient positioning and the operative approach are described and illustrated.

Brachial Plexus↗