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Biomedical subjects

E C Benzel

Publications and source records attributed to E C Benzel.

At least 37 records · Page 2Linked to original sources
PubMed2000

Cervical spine complications in rheumatoid arthritis patients. Awareness is the key to averting serious consequences.

Rheumatoid arthritis is associated with several pathologic changes in the cervical spine, including loss of articular cartilage, ligamentous destruction, and bone erosion. These changes may lead to one or a combination of complications, including atlantoaxial subluxation, cranial settling, subaxial cervical subluxation, and periodontoid pannus formation. Surgical management of these problems should focus on relieving pain, stabilizing the spine, and decompressing neural elements.

Arthritis, Rheumatoid↗
PubMed1999

MRI morphometry of mamillary bodies, caudate nuclei, and prefrontal cortices after chemotherapy for childhood leukemia: multivariate models of early and late developing memory subsystems.

Neurotoxic intrathecal chemotherapy for childhood acute lymphoblastic leukemia (ALL) affects developing structures and functions of memory and learning subsystems selectively. Results show significant reductions in magnetic resonance imaging morphometry of mamillary bodies, components of the corticolimbic-diencephalic subsystem subserving functionally later developing, single-trial memory, nonsignificant changes in bilateral heads of the caudate nuclei, components of the corticostriatal subsystem subserving functionally earlier developing, multitrial learning, significant reductions in prefrontal cortical volume, visual and verbal single-trial memory deficits, and visuospatial, but not verbal, multitrial learning deficits. Multiple regression models provide evidence for partial dissociation and connectivity between the subsystems, and suggest that greater involvement of caudate may compensate for inefficient corticolimbic-diencephalic components.

Adolescent↗
PubMed1999

Magnetic resonance imaging evaluation of the cervical spine in the comatose or obtunded trauma patient.

OBJECT: Confirmation of cervical spine stability is difficult to obtain in the comatose or obtunded trauma patient. Concurrent therapies such as endotracheal intubation and the application of rigid cervical collars diminish the utility of plain radiographs. Bony as well as supportive soft-tissue structures must be evaluated before the cervical spine can be determined to be uninjured. Although major injuries to extradural soft-tissue structures in the awake trauma patient are frequently excluded by physical examination, when the patient is obtunded the physical examination may be unreliable. Therefore, an enhanced diagnostic method for the evaluation of soft-tissue injury is desirable. The authors conducted a study in which magnetic resonance (MR) imaging was used as such a method to assess posttraumatic spinal stability in the comatose or obtunded patient. METHODS: Early, limited (sagittal T1- and T2-weighted) MR imaging was performed posttruama in 121 patients to assess soft-tissue injury. In all patients the mechanism of injury potentially could be associated with cervical spine instability, and each patient was endotracheally intubated because of head injury or severe multisystem injuries. All patients underwent imaging studies within 48 hours of injury and were either treated or cleared and spinal precautions were discontinued. Patients were excluded from this study if they had an obvious cervical spine injury identified on the initial radiographic studies or if they were determined to be too medically unstable to undergo MR imaging within the acute period (<48 hours postinjury). Thirty-one (25.6%) of the 121 patients were found to have sustained significant injury to the paravertebral ligamentous structures, the disc interspace, or the bony cervical spine. These injuries were undetected by plain radiography. The other 90 patients (74.4%) were determined within 48 hours not to have sustained a soft-tissue injury. Eight patients (6.6%) ultimately underwent surgery to treat the cervical spine injury, and MR imaging was the first test that identified the injury in each of these patients. There were no complications related to imaging procedures. CONCLUSIONS: Sagittal T1- and T2-weighted MR imaging appears to be a safe, reliable method for evaluating the cervical spine for nonapparent injury in comatose or obtunded trauma patients. In the early postinjury period, nursing and medical care are thereby facilitated for patients in whom occult injury to the spine is ruled out and for whom those attendant precautions are unnecessary.

Adolescent↗
PubMed1998

Whither neurosurgery?

Although trends in the marketplace demand for neurosurgeons should be of interest to neurosurgeons and prospective neurosurgeons, little data are available that accurately document these trends. A recent report published in the general medical journal Journal of the American Medical Association (JAMA) used the Conference Board help-wanted index to evaluate trends in physician marketplace demand. The authors of the JAMA study concluded that over the past 5 years there has been a significant fall in demand for specialist physicians. Because the discipline of neurosurgery was not included in the JAMA study, the authors of the present report attempt to evaluate the trend in the marketplace demand for neurosurgeons, using the same methodology of the JAMA study. The authors' data suggest that the conclusion of the JAMA study of steep declines in the demand for specialist physicians does not accurately reflect the job market for neurosurgeons, which in fact appears to be relatively stable. The present study attempts to document the stability of the neurosurgery market and outline the steps necessary to protect this market from existing threats.

Journal Article↗
PubMed1998

Evidence for cerebellar-frontal subsystem changes in children treated with intrathecal chemotherapy for leukemia: enhanced data analysis using an effect size model.

BACKGROUND: Following brain insult in early childhood, the later maturing neocerebellum and frontal lobes frequently show abnormalities. OBJECTIVE: To investigate the morphologic characteristics and function of a proposed cerebellar-frontal subsystem in children treated for acute lymphoblastic leukemia (ALL) with intrathecal methotrexate using quantitative magnetic resonance imaging, neuropsychological measures, nonlinear multiple regression analysis, and a statistical effect size model that augments interpretive validity of nonsignificant statistical findings, particularly from small sample size studies. DESIGN: Comparison and relationship of magnetic resonance imaging morphometry of cerebellar lobuli I-V and VI-VII and prefrontal cortices, and performance on 5 neuropsychological tests assessing visual-spatial attention, short-term memory, and visuomotor organization and coordination between childhood survivors of ALL and a matched control group. PARTICIPANTS: Ten childhood survivors of ALL treated between 1982 and 1989 with standard 3-year intrathecal chemotherapy, and matched control subjects. MAIN OUTCOME MEASURES: Morphometric results of cerebellar lobuli I-V and VI-VII and prefrontal cortices, and results of Trail-Making Tests, Rey-Osterreith Complex Figure Test, WISC-III Coding. RESULTS: Significant effect size model values for outcome measures in the ALL group support deficits in lobuli VI-VII and prefrontal cortices, and neuropsychological performance. Multiple regression analysis results were consistent with hypothesized involvement of a cerebellar-frontal brain subsystem. CONCLUSION: Treatment of children with ALL with intrathecal methotrexate before 5 years of age has structural and functional effects on the developing neocerebellar-frontal subsystem.

Adolescent↗
PubMed1998

Lateral extracavitary approach for thoracic and thoracolumbar spine trauma: operative complications.

BACKGROUND: The lateral extracavitary approach (LECA) to the thoracic and thoracolumbar spine allows ventral decompression and dorsal fixation of the spine through the same incision during a single procedure. The approach, however, is technically demanding and time-consuming. We sought to determine the incidence of complications associated with the LECA in patients with acute thoracolumbar spine injuries. PATIENTS AND METHODS: A retrospective chart review of all patients with acute fractures or dislocations of the thoracic or thoracolumbar spine who underwent surgery via the LECA was conducted to assess the incidence and type of perioperative complications associated with the LECA. RESULTS: Thirty-three patients with thoracic or thoracolumbar spine injuries treated using the LECA between June 1990 and June 1996 were identified and had available medical records. Complications occurred in 18 of these patients. Pulmonary complications predominated. Eleven patients required tube thoracostomy for hemothorax or persistent pleural effusions, and seven patients developed postoperative pneumonia. There were no cases of neurological worsening. There was no mortality. CONCLUSION: Decompression and stabilization of acute thoracolumbar fractures with the LECA in the acute setting is associated with a 55% incidence of morbidity. Whereas some of this morbidity may be attributed to the effects of the injury, there is a certain intrinsic morbidity associated with the LECA. Although this morbidity may compare favorably with that of sequential ventral/dorsal approaches, the biomechanical advantages obtained with a combined ventral and dorsal construct must be balanced against the inherent morbidity of such approaches.

Decompression, Surgical↗
PubMed1997

The management of unilateral lateral mass/facet fractures of the subaxial cervical spine: the use of magnetic resonance imaging to predict instability.

STUDY DESIGN: Retrospective review of the clinical course and cervical spine plain radiographs, computed tomography, and magnetic resonance imaging of 24 consecutive patients for a 2-year period with a unilateral lateral mass/facet fracture. OBJECTIVE: To propose a treatment algorithm for the management of unilateral lateral mass/facet fractures of the subaxial cervical spine based on ligamentous injury detected by magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: There have been no previous reports of the use of magnetic resonance imaging to predict clinical instability. METHODS: A retrospective review of the clinical course of all unilateral mass/facet fractures identified over a 2-year period was conducted. All cervical spine plain radiographs, computed tomography scans, and magnetic resonance images were reviewed by a neuroradiologist blinded to the clinical course of the patient. Magnetic resonance T1-weighted and inversion recovery images were used to evaluate the integrity of the facet region, interspinous ligament, anterior longitudinal ligament, and posterior longitudinal ligament. RESULTS: Twenty-four unilateral lateral mass/facet fractures were identified. Only six initial cervical spine series demonstrated a bony abnormality at the level of the fracture. The fractures were identified by computed tomography and were almost all nondisplaced or minimally displaced. Less than half of the fractures extended ventrally to involve the transverse process or foramen transversarium or dorsally to involve the lamina. Twelve fractures were nonoperatively treated and 12 were treated surgically for stabilization. Ten patients in the operative group presented with or developed a subluxation. Nine of these patients had injury to at least three of the four ligaments evaluated by magnetic resonance imaging. In the nonoperative group, only three patients had extensive ligamentous injury at the level of the fracture. All three of these patients were lost to follow-up. CONCLUSIONS: Plain radiographs of the cervical spine lack sensitivity to detect the presence of lateral mass/ facet fractures. The appearance of the fracture on computed tomography does not indicate instability. The degree of ligamentous injury at the level of the fracture demonstrated on magnetic resonance imaging correlates with instability in this series. Operative stabilization may be indicated for unilateral lateral mass fractures that present with a subluxation or that have injury to at least three of the following ligaments: the facet region, the interspinous ligament, the anterior longitudinal ligament, and the posterior longitudinal ligament. However, before a definitive management plan can be formulated, results from this small series require further validation.

Adult↗
PubMed1997

The metabolic response to spinal cord injury.

The metabolic response to trauma, including neurotrauma in general, has been studied extensively, but the acute metabolic response to spinal cord injury (SCI) has not. Therefore, 12 patients with SCI are presented in whom intensive nutrition assessment and management were instituted immediately after injury. Nitrogen balance (NB), predicted energy expenditure (PEE), and actual energy expenditure (MEE) were calculated or measured in each patient. A persistent negative NB was observed in all but one of the 12 patients. The single patient who did not exhibit persistent negative NB (no positive NB from week 2 to week 4 in the face of appropriate feeding) had an incomplete myelopathy, thus implying that the degree of motor dysfunction correlates with the obligatory nature of the negative NB. The negative NB observed in several of the patients did not occur until the second or third post-injury week. In addition, calculations of PEE by successively multiplying the Harris-Benedict equation by an activity factor of 1.2 and then by a stress factor of 1.6, resulted in excessive feeding (as assessed by metabolic cart measurements; ie indirect calorimetry) in the majority of the patients. In all of the 11 patients with persistent negative NBs, protein administration in the amount of 2 g/k of ideal body weight and aggressive caloric delivery did not alter the negative pattern of the NBs. Therefore, it is concluded that the negative NB following SCI is obligatory. Furthermore, the extent of SCI (extent of myelopathy or of neurological injury) correlates with the obligatory nature of the negative NB. In addition, the results from using the above method for estimating caloric requirements and the delayed manifestation of the negative NB may cause an additional tendency to acutely overfeed SCI patients. Therefore, eliminating the activity factor of 1.2 (due to the diminished activity arising from paralysis) and a diminution of the stress factor is recommended for initial PEE calculations. Serial metabolic cart (indirect calorimetry) measurements are recommended to accurately assess the patient's subsequent metabolic requirements.

Adult↗
PubMed1997

Biomechanics of the thoracolumbar spine.

The thoracolumbar spine is the principal load-bearing structure of the body. As such, it is subject to a wide variety of forces that can be described by biomechanical principles. Forces act through vectors, depending on the direction of force and the relative location of the instantaneous axis of rotation. Patterns of failure due to supraphysiologic loading or through the loss of structural integrity may be predicted based on the applied force vectors and the stabilization components lost. An understanding of these forces and their effects on the spine is crucial for the safe and efficacious treatment of spinal deformities.

Biomechanical Phenomena↗
PubMed1996

Cervical spondylotic myelopathy: surgical decision making.

Cervical spondylotic myelopathy can produce a variety of clinical signs and symptoms secondary to neural compromise and biomechanical involvement of the spine. The surgical treatment of cervical spondylotic myelopathy remains a controversial issue after many years of study, evolution, and refinement. Several ventral, dorsal, or combined approaches have been defined. The complications associated with ventral approaches and the concerns about kyphosis following dorsal approaches led to the development of a variety of laminoplasty procedures. This paper reviews the biomechanical basis of cervical spondylotic myelopathy and its effect on choosing the appropriate surgical approach.

Journal Article↗
PubMed1996

Cervical spondylotic myelopathy treated with corpectomy: technique and results in 44 patients.

Forty-four patients with cervical spondylotic myelopathy who underwent a ventral surgical approach were evaluated with respect to the results of surgery. The neurological status of the patients was categorized according to the modified Japanese Orthopedic Association scale (0-18). Three patients had a functional score of 8, one patient 9, five patients 10, five patients 11, seven patients 12, seven patients 13, seven patients 14, and nine patients had a functional score of 15, preoperatively. Twenty-three patients underwent a one-level corpectomy, 15 patients a two-level corpectomy, and six patients underwent a three-level corpectomy. Forty-one (93.1%) of the 44 patients underwent ventral cervical plate fixation. Complications among the 44 patients included graft- and instrumentation-related complications in seven cases, iliac crest donor-site infection in three cases, and respiratory complications in three cases. The follow-up periods ranged between 7 and 60 months (mean 42.3 months). Overall, the fusion rate was 97.72%. Three patients showed no functional change (6.8%), two patients were worse (4.5%), and 39 patients (88.6%) showed functional improvement in their score between +1 and +6 points (mean 2.16 points). There was no statistically significant difference in the functional improvement score in patients younger or older than 60 years old. The mean improvement in the functional score was found to be +2.857 +/- 1.352, +2.400 +/- 1.454, and +0.5000 +/- 1.871 following one-level corpectomy, two-level, and three-level corpectomies, respectively. There were statistically significant differences in the neurological improvement observed between patients with one-level corpectomy and three-level corpectomy (p < 0.01), as well as between those with two-level and three-level corpectomy (p < 0.05). There was no statistically significant difference in the neurological outcome between patients with one-level and two-level corpectomy (p > 0.05). The results of this study demonstrate a high rate of solid bone fusion and a high rate of functional (neurological) improvement. Five patients underwent reoperation, predominantly for instrumentation failure. The use of instrumentation dictates careful consideration of the risk/benefit ratio associated with its use in each case.

Journal Article↗
PubMed1996

Surgical needle design: torsion resistance.

OBJECTIVE: The interface between a surgical needle and forceps affects needle-forceps stability. Stability has become more important with the introduction of blunt-point surgical needles. The stability at the needle-forceps interface can be assessed by quantitating resistance to both rotation and twisting. Two commonly used surgical needles are the MO and CT needles, which are particularly useful for soft tissue closure for which significant strength of closure is required. Their comparison is thus of importance to surgeons. The design of the MO needle (greater flat section width than the CT needle) should allow for a greater resistance to rotation at the needle-forceps junction. This theoretically makes the MO needle a better choice when blunt-point needles (which require a greater force to penetrate tissue) are used. The objective of this study is to document and quantitate the differences, if any, between the CT and MO needles with regard to rotation and twisting at the needle-forceps junction. METHODS: To compare the efficacy of the CT and MO needles with regard to needle-forceps stability, the resistance of the needles to rotation and twisting was assessed using a Hios HP-10 digital torque meter. RESULTS: The resistance to twisting of the CT and MO needles was not significantly different. However, the MO needle is 25% more resistant to rotation than the CT needle. This differed by 10% from the expected difference. CONCLUSION: The resistance to twisting is not significantly affected by needle geometry, whereas the resistance to rotation is significantly affected. The difference between expected and observed differences in rotation is explained by study design.

Equipment Design↗