Effects of epidural steroids on lumbar dura material properties.

Epidural steroid injections are commonly used in the treatment of low back pain and radiculopathy based on their antiinflammatory and analgesic benefits. However, steroids are known to affect collagen synthesis, material strength, and tissue healing. The purpose of this study was to assess the effects of serial epidural steroid injections on the material properties of the lumbar dura mater. Serial epidural steroid injections of saline or methylprednisolone at 2-week intervals were performed in three paired groups of canines; a separate noninjected group was used as controls. Postmortem, dural sample testing to failure and histologic analysis was performed. Mechanical failure testing revealed no clinically significant change in the transverse dorsal dura tensile strength between all saline-injected, steroid-injected, or noninjected controls. Histologic analysis demonstrated no overt disruption of collagen matrix organization; however, electron microscopy demonstrated a significant decrease in the number of intracytoplasmic mitochondria of dural fibroblasts in steroid-injected animals, suggesting a metabolic inhibitory effect within steroid-injected dura mater. In the clinical time frame of this study, serial epidural steroid injections appeared to produce no significant material or matrix changes in the lumbar dura.

Use of magnetic resonance imaging in spinal trauma: indications, techniques, and utility.

Magnetic resonance (MR) imaging of acute spinal injury provides excellent visualization of neurologic and soft-tissue structures in a noninvasive format. Advances in imaging-sequence techniques have made possible more rapid acquisition of images with greater spatial resolution. Appropriate selection of imaging sequences allows improved imaging and contrast of the pathologic processes involved in acute spinal trauma, including spinal cord, soft-tissue, and ligamentous injury. Three patterns of spinal cord injury have been identified. Type I is representative of acute cord hemorrhage. Type II represents spinal cord edema. Type III is a mixed hemorrhagic-edematous presentation. Correlation of MR findings with experimental and clinical spinal cord injury has given a relative predictive value to spinal cord injury patterns on MR images indicative of long-term neurologic outcome. Magnetic resonance imaging is useful in delineating soft-tissue injuries associated with spinal column trauma. Despite the improved spatial resolution of MR imaging, plain radiography and computed tomography remain the standard modalities for visualizing spinal fractures.

Carbon monoxide levels in cell saver salvaged blood exposed to electrocautery during lumbar spine surgery.

Carboxyhemoglobin levels were measured in patients undergoing posterior lumbar spine surgery with use of intraoperative cell saver blood salvage. Increased carboxyhemoglobin levels were demonstrated in cell saver salvaged blood. Systemic blood carboxyhemoglobin levels increased with cell saver blood transfusion. No patient demonstrated clinical effects of carbon monoxide toxicity.

A simple method for improving vertebral visualization on a scoliosis series lateral radiograph.

STUDY DESIGN: This technical note describe a method for improving vertebral body visualization on lateral scoliosis radiographs. OBJECTIVE: To improve vertebral column visualization on lateral radiographs. SUMMARY OF BACKGROUND DATA: The different density of the thoracic and abdominal cavities makes complete visualization of the vertebral column difficult on lateral radiographs. METHODS: An inexpensive, simple filter paper method was used to normalize the densities between adjacent body cavity and improve visualization of the vertebral column on a lateral scoliosis series radiograph. RESULTS: Use of a single-exposure, filter paper technique improved simultaneous visualization of the thoracic and lumbar vertebrae, compared with the standard single-exposure unfiltered technique. CONCLUSION: Accurate lateral vertebral visualization allows effective three-dimensional correlation of the sagittal plane deformity concurrent with the coronal plane deformity of scoliosis. Using a single-exposure, filter paper technique improves sagittal plane spinal visualization. Repeat radiographs and patients exposure are reduced by this technique.

Is postoperative intrathecal catheter use associated with central nervous system infection?

BACKGROUND: Continuation of intrathecal anesthesia into the postoperative period has been limited by important safety concerns. Principal among these has been the assumption that extended intrathecal therapy leads to spinal (epidural and intrathecal) space infections. To address the role of extended intrathecal catheter therapy as a cause of infections, we cultured all intrathecal catheters used to provide postoperative analgesia. METHODS: All intrathecal catheters were inserted in the operating room using sterile technique. The catheters were used either for the duration of the patients stay in the intensive care unit or until they were no longer judged to provide a therapeutic advantage. They were removed without skin preparation. The distal 2-3 cm of the catheters was cultured using semiquantitative culture methods. Results were divided into four groups: group 1, negative culture results; group 2, ten or fewer colonies of growth; group 3, more than 10 colonies on initial plates and/or growth from broth cultures; and group 4, any bacterial growth, along with evidence of local or central nervous system infections. RESULTS: Cultures were obtained from 139 patients with a mean indwelling catheter time of 66.1 h. Group 1 (102 patients) had a mean indwelling duration of 55 h. Group 2 (26 patients) and group 3 (11 patients) had significantly longer indwelling duration (83.2 h P = .0023, 129.6 h P = < .0001, respectively) than group 1. Cultures of cerebrospinal fluid obtained simultaneously with catheter cultures in 9 cases (5 in group 2 and 4 in group 3) showed no growth. No patient had evidence of local or central nervous system infection. Difficulty of catheter placement (number of attempts made and the number of levels explored), antibiotic administration, the composition of the postoperative infusions and the number of catheter breaks in the postoperative period were similar in each group. With the exception of two catheters in group 3, (cultured at 49 and 54 h), significant bacterial growth (more than ten colonies) was observed only after more than 96 h of indwelling duration. CONCLUSIONS: Application of semiquantitative culture methods assisted in explaining the results seen in group 2 as secondary to contamination of the catheter that occurred on removal. Higher numbers of bacteria (group 3) may define a population at increased risk for infectious complications. The results of this study do not absolutely resolve the issue of infectious risk associated with postoperative intrathecal catheter use, nor do they define a safe period beyond which the risk of continued catheter use would be unacceptable. However, it appears that limited periods of use (96 h or less) is not associated with either frequent local or spinal infections. Semiquantitative culture methods may help identify individuals (with catheter cultures yielding more than ten colonies) at increased risk for infectious complications and in need of closer observation.

Reduction of the cyclic adenosine 3',5'-monophosphate response to catecholamines in rat brain slices after repeated restraint stress.

Restraint stress reduces the cyclic AMP (cAMP) response to norepinephrine (NE) in slices of the rat cerebral cortex and hypothalamus. This effect is found after repeated but not single exposure to stress and persists for at least 24 hr poststress. The magnitude of the reduction is dose-dependent in that greater decreases are found after higher frequencies and longer durations of restraint as well as after more disturbance during the stress. Analysis of the NE-cAMP dose-response curve indicates that the stress reduces the maximum cAMP response to NE but does not increase the EC50 value of NE. The cAMP response to isoproterenol is only slightly affected by the stress. No effect is observed on specific [3H]dihydroalprenolol binding in either brain region at 24 hr poststress. These results suggest that repeated restraint stress produces a selective persistent reduction of the function of brain non-beta adrenergic receptors. This effect may be mediated by an increased release of adrenocorticotropic hormone as chronic infusion of the latter hormone mimics the action of stress on cAMP responses to catecholamines. An increased release of brain NE may also be involved as repeated administration of the NE-reuptake inhibiting antidepressant, desmethylimipamine, reduces the function of non-beta as well as beta adrenergic receptors as evidenced by reductions of both the NE- and isoproterenol-cAMP responses.

Reduction of the cAMP response to norepinephrine in rat cerebral cortex following repeated restraint stress.

The present studies examined the effect of restraint stress on the sensitivity of the catecholamine-cAMP generating system in the rat cerebral cortex. Restraint was found to cause a persistent reduction in the magnitude of the cAMP response to catecholamines. This effect occurred after repeated but not acute stress and was more marked with twice-daily as compared to once-daily treatment. The reduction in response was more marked with norepinephrine than with isoproterenol, indicating a selective action of stress on the non-beta component of the noradrenergic response. The findings suggest that subsensitivity of the cAMP response to norepinephrine is a general response to chronic stressful stimuli and may be related to the action of certain antidepressant agents.