Trial of short-course antimicrobial therapy for intraabdominal infection.

BACKGROUND: The successful treatment of intraabdominal infection requires a combination of anatomical source control and antibiotics. The appropriate duration of antimicrobial therapy remains unclear. METHODS: We randomly assigned 518 patients with complicated intraabdominal infection and adequate source control to receive antibiotics until 2 days after the resolution of fever, leukocytosis, and ileus, with a maximum of 10 days of therapy (control group), or to receive a fixed course of antibiotics (experimental group) for 4±1 calendar days. The primary outcome was a composite of surgical-site infection, recurrent intraabdominal infection, or death within 30 days after the index source-control procedure, according to treatment group. Secondary outcomes included the duration of therapy and rates of subsequent infections. RESULTS: Surgical-site infection, recurrent intraabdominal infection, or death occurred in 56 of 257 patients in the experimental group (21.8%), as compared with 58 of 260 patients in the control group (22.3%) (absolute difference, -0.5 percentage point; 95% confidence interval [CI], -7.0 to 8.0; P=0.92). The median duration of antibiotic therapy was 4.0 days (interquartile range, 4.0 to 5.0) in the experimental group, as compared with 8.0 days (interquartile range, 5.0 to 10.0) in the control group (absolute difference, -4.0 days; 95% CI, -4.7 to -3.3; P<0.001). No significant between-group differences were found in the individual rates of the components of the primary outcome or in other secondary outcomes. CONCLUSIONS: In patients with intraabdominal infections who had undergone an adequate source-control procedure, the outcomes after fixed-duration antibiotic therapy (approximately 4 days) were similar to those after a longer course of antibiotics (approximately 8 days) that extended until after the resolution of physiological abnormalities. (Funded by the National Institutes of Health; STOP-IT ClinicalTrials.gov number, NCT00657566.).

Novel Method Suggests Global Superiority of Short-Duration Antibiotics for Intra-abdominal Infections.

Desirability of outcome ranking and response adjusted for duration of antibiotic risk (DOOR/RADAR) are novel and innovative methods of evaluating data in antibiotic trials. We analyzed data from a noninferiority trial of short-course antimicrobial therapy for intra-abdominal infection (STOP-IT), and results suggest global superiority of short-duration therapy for intra-abdominal infections.

Genotype-phenotype correlations in neurogenetics: Lesch-Nyhan disease as a model disorder.

Establishing meaningful relationships between genetic variations and clinical disease is a fundamental goal for all human genetic disorders. However, these genotype-phenotype correlations remain incompletely characterized and sometimes conflicting for many diseases. Lesch-Nyhan disease is an X-linked recessive disorder that is caused by a wide variety of mutations in the HPRT1 gene. The gene encodes hypoxanthine-guanine phosphoribosyl transferase, an enzyme involved in purine metabolism. The fine structure of enzyme has been established by crystallography studies, and its function can be measured with very precise biochemical assays. This rich knowledge of genetic alterations in the gene and their functional effect on its protein product provides a powerful model for exploring factors that influence genotype-phenotype correlations. The present study summarizes 615 known genetic mutations, their influence on the gene product, and their relationship to the clinical phenotype. In general, the results are compatible with the concept that the overall severity of the disease depends on how mutations ultimately influence enzyme activity. However, careful evaluation of exceptions to this concept point to several additional genetic and non-genetic factors that influence genotype-phenotype correlations. These factors are not unique to Lesch-Nyhan disease, and are relevant to most other genetic diseases. The disease therefore serves as a valuable model for understanding the challenges associated with establishing genotype-phenotype correlations for other disorders.

Predictive Value of Nutritional Markers for Wound Healing Complications in Bariatric Patients Undergoing Panniculectomy.

BACKGROUND: Hypoproteinemia and nutritional deficiencies are common after bariatric surgery, and although massive weight loss (MWL) patients experience increased wound complication rates, the association has not been causatively determined. OBJECTIVES: This study investigated preoperative nutritional parameters and wound complications in MWL patients (postbariatric and diet-controlled) undergoing panniculectomy at 2 academic institutions. METHODS: One hundred sixty-one consecutive patients undergoing elective panniculectomy after bariatric surgery or diet-controlled weight loss were identified. Patient demographics and nutritional indices (serum protein, albumin, and micronutrient levels) were analyzed. Complications including wound separation, infection, and operative debridements were compared. Post hoc comparisons tested for correlation between complications and nutritional markers. RESULTS: Postbariatric patients lost an average of 151 lb and presented at an average of 32 months after gastric bypass. Diet-controlled weight loss patients lost an average of 124 lb. Despite MWL, albumin levels were higher in the bariatric group (3.8 vs 3.4 g/dL, P < 0.05). Conversely, bariatric patients experienced increased wound complications (27% vs 14%; P < 0.05). Factors which were found to correlate to increased risk of wound dehiscence and infection were elevated body mass index at time of panniculectomy and amount of tissue removed. Multivariate analysis did not show serum albumin or percent weight loss to independently predict complications. CONCLUSIONS: Bariatric patients presenting for elective operations are at risk for protein and micronutrient deficiency. Despite aggressive replacement and normalization of nutritional markers, bariatric patients experience increased wound complications when compared to nonbariatric patients and traditional measures of nutritional evaluation for surgery may be insufficient in bariatric patients.

Chronic spinal cord injury impairs primary antibody responses but spares existing humoral immunity in mice.

Spinal cord injury (SCI) results in immune depression. To better understand how injury inhibits humoral immunity, the effects of chronic thoracic SCI on B cell development and immune responses to thymus-independent type 2 and thymus-dependent Ags were determined. Mice received complete crush injury or control laminectomy at either thoracic level 3, which disrupts descending autonomic control of the spleen, or at thoracic level 9, which conserves most splenic sympathetic activity. Although mature B cell numbers were only mildly reduced, bone marrow B cell production was transiently but profoundly depressed immediately after injury. Despite the return of normal B cell production 4 wk after SCI, mice receiving thoracic level 3 injury showed a significant reduction in their ability to mount primary thymus-independent type 2 or thymus-dependent immune responses. The latter were marked by decreases in germinal center B cells as well as class-switched high-affinity Ab-secreting cells. Importantly, injury did not affect affinity maturation per se, pre-existing B cell memory, or secondary humoral immune responses. Taken together, these findings show that chronic high thoracic SCI impairs the ability to mount optimal Ab responses to new antigenic challenges, but spares previously established humoral immunity.

Cutting edge: dendritic cell-restricted antigen presentation initiates the follicular helper T cell program but cannot complete ultimate effector differentiation.

Follicular helper T (T(FH)) cells are critical for germinal center (GC) formation. The processes that drive their generation and effector potential remain unclear. In this study, we define requirements for MHC class II APCs in murine T(FH) cell formation by either transiently ablating or restricting Ag presentation to dendritic cells (DCs). We find that cognate interactions with DCs are necessary and sufficient to prime CD4(+) T cells toward a CXCR5(+)ICOS(+)Bcl6(+) T(FH) cell intermediate. However, in the absence of additional APCs, these T(FH) cells fail to produce IL-21. Furthermore, in vitro priming of naive T cells by B cells engenders optimal production of IL-21, which induces a GC B cell transcriptional profile. These results support a multistep model for effector T(FH) cell priming and GC initiation, in which DCs are necessary and sufficient to induce a T(FH) cell intermediate that requires additional interactions with distinct APCs for full effector function.

Risk factors for blunt cerebrovascular injury in children: do they mimic those seen in adults?

BACKGROUND: Eastern Association for the Surgery of Trauma guideline for the evaluation of blunt cerebrovascular injury (BCVI) states that pediatric trauma patients should be evaluated using the same criteria as the adult population. The purpose of our study was to determine whether adult criteria translate to the pediatric population. METHODS: Retrospective evaluation was performed at a Level I trauma center of blunt pediatric trauma patients (age <15 years) presenting over a 5-year period. Data obtained included patient demographics, presence of adult risk factors for BCVI (Glasgow coma scale ≤8, skull base fracture, cervical spine fracture, complex facial fractures, and soft tissue injury to the neck), presence of signs/symptoms of BCVI, method of evaluation, treatment, and outcome. RESULTS: A total of 1,209 pediatric trauma patients were admitted during the study period. While 128 patients met criteria on retrospective review for evaluation based on Eastern Association for the Surgery of Trauma criteria, only 52 patients (42%) received subsequent radiographic evaluation. In all, 14 carotid artery or vertebral artery injuries were identified in 11 patients (all admissions, 0.9% incidence; all screened, 21% incidence). Adult risk factors were present in 91% of patients diagnosed with an injury. Major thoracic injury was found in 67% of patients with carotid artery injuries. Cervical spine fracture was found in 100% of patients with vertebral artery injuries. Stroke occurred in four patients (36%). Stroke rate after admission for untreated patients was 38% (3/8) versus 0.0% in those treated (0/2). Mortality was 27% because of concomitant severe traumatic brain injury. CONCLUSION: Risk factors for BCVI in the pediatric trauma patient appear to mimic those of the adult patient.

BLyS inhibition eliminates primary B cells but leaves natural and acquired humoral immunity intact.

We have used an inhibiting antibody to determine whether preimmune versus antigen-experienced B cells differ in their requisites for BLyS, a cytokine that controls differentiation and survival. Whereas in vivo BLyS inhibition profoundly reduced naïve B cell numbers and primary immune responses, it had a markedly smaller effect on memory B cells and long-lived plasma cells, as well as secondary immune responses. There was heterogeneity within the memory pools, because IgM-bearing memory cells were sensitive to BLyS depletion whereas IgG-bearing memory cells were not, although both were more resistant than naïve cells. There was also heterogeneity within B1 pools, as splenic but not peritoneal B1 cells were diminished by anti-BLyS treatment, yet the number of natural antibody-secreting cells remained constant. Together, these findings show that memory B cells and natural antibody-secreting cells are BLyS-independent and suggest that these pools can be separately manipulated.

Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America.

Evidence-based guidelines for managing patients with intra-abdominal infection were prepared by an Expert Panel of the Surgical Infection Society and the Infectious Diseases Society of America. These updated guidelines replace those previously published in 2002 and 2003. The guidelines are intended for treating patients who either have these infections or may be at risk for them. New information, based on publications from the period 2003-2008, is incorporated into this guideline document. The panel has also added recommendations for managing intra-abdominal infection in children, particularly where such management differs from that of adults; for appendicitis in patients of all ages; and for necrotizing enterocolitis in neonates.

Pentobarbital coma for refractory intra-cranial hypertension after severe traumatic brain injury: mortality predictions and one-year outcomes in 55 patients.

OBJECTIVE: To identify predictors of mortality and long-term outcomes in survivors after pentobarbital coma (PBC) in patients failing current treatment standards for severe traumatic brain injuries (TBI). This is a retrospective cohort study of severe TBI patients receiving PBC at Level I Trauma Center and tertiary university hospital. METHODS: Four thousand nine hundred thirty-four patients were admitted to the trauma intensive care unit with severe TBI (head Abbreviated Injury Scale >or= 3) between April 1998 and December 2004. Six hundred eleven received intracranial pressure (ICP) monitoring and 58 received PBC. Three patients underwent craniotomy for intracranial mass lesion and were excluded. The study group received standardized medical management for severe TBI including opiates, benzodiazepines, elevation of the head of bed, avoidance of hypotension and hypercapnia and hyperosmolar therapy (HOsmRx). In addition, 31 of 55 patients (56%) underwent placement of intraventricular catheters for cerebrospinal fluid drainage. If routine medical management and cerebrospinal fluid diversion failed to control ICP, then the patient was determined to have refractory intracranial hypertension (RICH) and PBC treatment was initiated. PBC was performed with pentobarbital infusion with continuous electroencephalogram monitoring to ensure adequate burst suppression. The measurements include serum sodium (Na) and osmolality (Osm) were assessed as indicators for initiation of PBC and to estimate the 50% mortality cut-points when controlling for ICP. Follow-up functional outcomes were assessed using the Glasgow Outcome Scale and stratified according to admission Glasgow Coma Scale score and Marshall computed tomography classification. Of the 55 PBC patients, 22 (40%) survived at discharge. 19 of 22 had long-term follow-up (1 year or more) available. Of these, 13 (68%) were normal or functionally independent (Glasgow Outcome Scale score 4 or 5). Serum Na and Osm were associated with death (p < 0.05) when controlling for ICP. The 50% mortality cut-points were Na of 160 mEq/L and Osm of 330 mOsm/kg H2O. Median minimum cerebral perfusion pressure after PBC was 42 mm Hg in survivors and 34 mm Hg in nonsurvivors (p = 0.013). CONCLUSIONS: In patients with severe TBI and RICH, survival at discharge of 40% with good functional outcomes in 68% of survivors at 1 year or more can be achieved with PBC after failure of HOsmRx. Based on 50% mortality cut-points, analysis suggests the limits of HOsmRx to be Na of 160 mEq/L and Osm of 330 mOsm/Kg H2O. Maintenance of higher cerebral perfusion pressure after PBC is associated with survival. PBC treatment of RIH may be even more important when other treatments of RIH, such as decompressive craniectomy, are not available.

Is MRI adequate to detect lesions in patients with ankle instability?

BACKGROUND: Chondral lesions, peroneal tendon tears, and other disorders in patients with chronic ankle instability may not be detected by preoperative MRI. Also, MRI often is obtained and interpreted at the referring institution, leading to variability in reading. QUESTIONS/PURPOSES: We assessed the accuracy of the radiologists' and orthopaedic surgeon's reading of preoperative MRI for diagnosing ankle lesions in patients with ankle instability warranting surgery. PATIENTS AND METHODS: We retrospectively reviewed 133 patients who underwent 135 surgeries for lateral ankle ligament reconstruction with concomitant ankle arthroscopy and who had preoperative MRI. RESULTS: We found 72 associated lesions in 66 of the 135 surgeries, including 38 chondral injuries, 18 peroneus brevis tears, seven loose bodies, and nine other miscellaneous abnormalities. Eliminating eight lesions for which the decision to operate was not based on operative findings, there were 127 surgeries with 64 associated lesions that required intraoperative confirmation or were detected intraoperatively. In the original reports, the radiologists identified 39% (15) of the chondral injuries, 56% (10) of the peroneal tears, and 57% (four) of the loose bodies. Radiologists' MRI sensitivity for detecting lesions was 45%. The attending surgeon identified 47% (18) of the chondral injuries, 89% (16) of the loose bodies, 71% (five) of the peroneus brevis tears, and the posterior talus process lesion, with a sensitivity of 63%. CONCLUSIONS: Our data suggest orthopaedic surgeons should review preoperative MRIs and also suggest the sensitivity of MRI may not be adequate to detect lesions in these patients before surgery. LEVEL OF EVIDENCE: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

An evaluation of multidetector computed tomography in detecting pancreatic injury: results of a multicenter AAST study.

BACKGROUND: Efforts to determine the suitability of low-grade pancreatic injuries for nonoperative management have been hindered by the inaccuracy of older computed tomography (CT) technology for detecting pancreatic injury (PI). This retrospective, multicenter American Association for the Surgery of Trauma-sponsored trial examined the sensitivity of newer 16- and 64-multidetector CT (MDCT) for detecting PI, and sensitivity/specificity for the identification of pancreatic ductal injury (PDI). METHODS: Patients who received a preoperative 16- or 64-MDCT followed by laparotomy with a documented PI were enrolled. Preoperative MDCT scans were classified as indicating the presence (+) or absence (-) of PI and PDI. Operative notes were reviewed and all patients were confirmed as PI (+), and then classified as PDI (+) or (-). As all patients had PI, an analysis of PI specificity was not possible. PI patients formed the pool for further PDI analysis. As sensitivity and specificity data were available for PDI, multivariate logistic regression was performed for PDI patients using the presence or absence of agreement between CT and operative note findings as an independent variable. Covariates were age, gender, Injury Severity Score, mechanism of injury, presence of oral contrast, presence of other abdominal injuries, performance of the scan as part of a dedicated pancreas protocol, and image thickness < or =3 mm or > or =5 mm. RESULTS: Twenty centers enrolled 206 PI patients, including 71 PDI (+) patients. Intravenous contrast was used in 203 studies; 69 studies used presence of oral contrast. Eight-nine percent were blunt mechanisms, and 96% were able to have their duct status operatively classified as PDI (+) or (-). The sensitivity of 16-MDCT for all PI was 60.1%, whereas 64-MDCT was 47.2%. For PDI, the sensitivities of 16- and 64-MDCT were 54.0% and 52.4%, respectively, with specificities of 94.8% for 16-MDCT scanners and 90.3% for 64-MDCT scanners. Logistic regression showed that no covariates were associated with an increased likelihood of detecting PDI for either 16- or 64-MDCT scanners. The area under the curve was 0.66 for the 16-MDCT PDI analysis and 0.77 for the 64-MDCT PDI analysis. CONCLUSION: Sixteen and 64-MDCT have low sensitivity for detecting PI and PDI, while exhibiting a high specificity for PDI. Their use as decision-making tools for the nonoperative management of PI are, therefore, limited.

Significant pediatric morbidity and mortality from intracranial ballistic injuries caused by nonpowder gunshot wounds. A case series.

Nonpowder (ball-bearing and pellet) weapons derive their source of energy from compressed air or carbon dioxide. Such weapons are dangerous toys that cause serious injuries and even death to children and adolescents. A retrospective chart review study was undertaken to describe nonpowder gun injuries at a southwestern US urban level I adult and pediatric trauma center. Specific emphasis was placed on intracranial injuries. Over the past 6 years, a total of 29 pediatric and 7 adult patients were identified as having nonpowder firearm injuries. The patient population was overwhelmingly male (89.7%; mean age, 11 years). Overall, 17 out of 29 pediatric patients (56.8%) sustained serious injury. Nine patients (30.0%) required operation, 6 (20.7%) sustained significant morbidity, and there were 2 deaths (6.9%). Injuries to the brain, eye, head, and neck were the most common sites of injury (65.6%). Specific intracranial injuries in 3 pediatric patients are described that resulted in the death of 2 children. We suggest that age warning should be adjusted to 18 years or older for unsupervised use to be considered safe of these potentially lethal weapons.

Homeostatic control of B lymphocyte subsets.

Lymphocyte homeostasis poses a multi-faceted biological puzzle, because steady pre-immune populations must be maintained at an acceptable steady state to yield effective protection, despite stringent selective events during their generation. In addition, activated, memory and both short- and long-term effectors must be governed by independent homeostatic mechanisms. Finally, advancing age is accompanied by substantial changes that impact the dynamics and behavior of these pools, leading to cumulative homeostatic perturbations and compensation. Our laboratory has focused on the over-arching role of BLyS family ligands and receptors in these processes. These studies have led to a conceptual framework within which distinct homeostatic niches are specified by BLyS receptor signatures, which define the BLyS family ligands that can afford survival. The cues for establishing these receptor signatures, as well as the downstream survival mechanisms involved, are integrated with cell extrinsic inputs via cross talk among downstream mediators. A refined understanding of these relationships should yield insight into the selection and maintenance of B cell subsets, as well as an appreciation of how homeostatic mechanisms may contribute to immunosenescence.

The relationship of plasma glucose and glycosylated hemoglobin A1C levels among nondiabetic trauma patients.

OBJECTIVE: : Hyperglycemia (blood glucose >/=110 mg/dL) in trauma patients without a known history of diabetes mellitus (DM) is often attributed to the metabolic stress response of injury. We studied whether this hyperglycemia may actually indicate the presence of occult DM (ODM) as demonstrated by elevated glycosylated hemoglobin A1C (gHbA1C). METHODS: : After obtaining approval from the Institutional Review Board, a prospective, sequential case series study of nondiabetic adult patients presenting to an urban Level I trauma center from September 2006 to February 2007 was performed. In addition to basic demographics, all hyperglycemic patients had a measured gHbA1C. ODM was diagnosed when gHbA1C was >/=6%. RESULTS: : A total of 1,039 trauma patients were screened with 192 (18%) noted to be hyperglycemic. Of these 192 patients, 22% (n = 42) were found to have an elevated gHbA1C. Using logistic regression, being older (Odds ratio [OR] = 1.04; p < 0.004), having a higher body mass index (BMI) (OR = 1.12; p < 0.003), and being Native American (OR = 5.08; p < 0.017) were each identified as significant risk factors for elevated gHbA1C levels and the diagnosis of ODM. In contrast, the magnitude of observed hyperglycemia, gender, or other races were not shown to be significant risk factors for the presence of ODM. CONCLUSION: : Almost a quarter of nondiabetic trauma patients presenting with hyperglycemia were found to have elevated gHbA1C levels and ODM. Risk factors for ODM included advancing age and body mass index as well as being Native American. The hyperglycemia seen in trauma patients should not solely be attributed to the hormonal and metabolic response to injury; wider ODM screening for both acute management strategies and long-term health benefits is warranted.

Rigidity comparison of locking plate and intramedullary fixation for tibiotalocalcaneal arthrodesis.

BACKGROUND: Obtaining adequate fixation during tibiotalocalcaneal (TTC) arthrodesis may be challenging. Various fixation constructs have been tested biomechanically, but the use of a locking plate has not been reported. We hypothesized that the locking plate with a TTC augmentation screw would provide structural rigidity comparable to that of the intramedullary (IM) nail with a TTC augmentation screw during dorsiflexion testing. MATERIALS AND METHODS: Six matched pairs of fresh frozen cadavers underwent TTC arthrodesis. Specimens in each pair were randomized to receive a locking plate or an intramedullary nail. Each specimen had an additional TTC augmentation screw through the calcaneus, talus, and medial tibia. All samples underwent dorsiflexion testing with determination of structural rigidity at the first cycle (initial rigidity) and last cycle (final rigidity) and the torque required to achieve a failure of 10 degrees of dorsiflexion. Statistical analysis was performed using a paired t-test to determine whether any differences were significant (p < 0.05). RESULTS: The locking plate construct showed higher final rigidity (mean +/- standard error of the mean) (27.7 +/- 2.6 N-m/degree versus 17.6 +/- 2.1 N-m/degree, p = 0.01) than the IM nail construct. There were no other differences measured. CONCLUSION: Rigidity with the the IM nail was inferior to that with locking plate fixation for TTC arthrodesis in one of the four parameters tested. CLINICAL RELEVANCE: Screw augmented IM nail fixation and augmented locking plate fixation may offer similar rigidity clinically for TTC arthrodesis.

Short-Course Antimicrobial Therapy Does Not Increase Treatment Failure Rate in Patients with Intra-Abdominal Infection Involving Fungal Organisms.

BACKGROUND: Fungi frequently are isolated in intra-abdominal infections (IAI). The Study to Optimize Peritoneal Infection Therapy (STOP-IT) recently suggested short-course treatment for patients with IAI. It remains unclear whether the presence of fungi in IAI affects the optimal duration of Antimicrobial therapy. We hypothesized that a shorter treatment course in IAI with fungal organisms would be associated with a higher rate of treatment failure. METHODS: Patients enrolled in the STOP-IT trial were stratified according to the presence or absence of a fungal isolate. They were analyzed as a subgroup based on original randomization to either the control group or an experimental group that received a four-day course of Antimicrobial therapy and by comparison with those without a fungal component to their infection. Descriptive comparisons were performed using a χ2, Fisher exact, or Kruskal-Wallis test as appropriate. The primary outcome was a composite of recurrent IAI, surgical site infection, and death. RESULTS: A total of 411 patients in the study (79%) had available culture data, of which 58 (14%) had positive fungal cultures. The most common organisms were Candida albicans and C. glabrata. The treatment failure rate was equivalent in the experimental and control arms (29.6% vs. 22.6%; p = 0.54). Patients with fungal isolates were more likely to have malignant disease (25.9% vs. 9.6%; p = 0.0004) and coronary artery disease (22% vs. 12%; p = 0.04), but were otherwise similar to those without fungal isolates. Patients with fungal isolates had more hospital days (median 10 vs. 7; p < 0.0001) and more days to resumption of enteral intake (median 5 vs. 3; p = 0.0006), but there was no difference in the composite outcome. CONCLUSIONS: Patients with IAI involving fungal organisms randomized to a shorter course of Antimicrobial therapy had no difference in the rate of treatment failure. These results suggest that the presence of fungi in IAI may not indicate independently the need for a longer course of Antimicrobial therapy.

Excursion and strain of the superficial peroneal nerve during inversion ankle sprain.

BACKGROUND: Traction is presumed to be the mechanism of injury to the superficial peroneal nerve in an inversion ankle sprain, but it is not known whether the amount of strain caused by nerve traction is sufficient to cause nerve injury. We hypothesized that the superficial peroneal nerve would experience significant excursion and strain during a simulated inversion sprain, that sectioning of the anterior talofibular ligament would increase excursion and strain, and that an impact force would produce strain in a range that can structurally alter the nerve. METHODS: Differential reluctance transducers were placed in the superficial peroneal nerve in sixteen lower-extremity cadaver specimens to measure excursion and strain in situ. Static weight was applied to the foot in increments starting at 0.454 kg and ending at 4.54 kg. The anterior talofibular ligament was sectioned, and the measurements were repeated. A final impact force of 4.54 kg was applied to each specimen. Two-way repeated-measures analysis of variance was used to evaluate differences in excursion and strain. RESULTS: The mean excursion and strain of the superficial peroneal nerve increased with increases in the applied weight in both the group with the intact anterior talofibular ligament and the group in which it had been sectioned. Nerve excursion was greater in the sectioned-ligament group than in the intact-ligament group with all applied weights (p < 0.05). The mean nerve strain was greater in the sectioned-ligament group (range, 5.5% to 12.9%) than in the intact-ligament group (range, 3.0% to 11.6%) with application of the 0.454, 0.908, 1.362, and 1.816-kg weights (p < 0.05). With the ligament sectioned, the 4.54-kg impact force produced significantly higher mean nerve excursion and strain than did the 4.54-kg static weight (p < 0.05). CONCLUSIONS: The magnitude of strain with the impact force was in the lower range of values that have been shown to structurally alter peripheral nerves. The superficial peroneal nerve is at risk for traction injury during an ankle inversion sprain and is at additional risk with more severe sprains or with an insufficient anterior talofibular ligament.

Practice management guidelines for the screening of thoracolumbar spine fracture.

BACKGROUND: Fractures to the thoracolumbar spine (TLS) commonly occur because of major trauma mechanisms. In one series, 4.4% of all patients arriving at a Level I trauma center were diagnosed as having TLS fracture. Approximately 19% to 50% of these fractures in the TLS region will be associated with neurologic damage to the spinal cord. To date there are no randomized studies and only a few prospective studies specifically addressing the subject. The Eastern Association for the Surgery of Trauma organization Practice Management Guidelines committee set out to develop an EBM guideline for the diagnosis of TLS fractures. METHODS: A computerized search of the National Library of Medicine and the National Institutes of Health MEDLINE database was undertaken using the PubMed Entrez (www.pubmed.gov) interface. The primary search strategy was developed to retrieve English language articles focusing on diagnostic examination of potential TLS injury published between 1995 and March 2005. Articles were screened based on the following questions. (1) Does a patient who is awake, nonintoxicated, without distracting injuries require radiographic workup or a clinical examination only? (2) Does a patient with a distracting injury, altered mental status, or pain require radiographic examination? (3) Does the obtunded patient require radiographic examination? RESULTS: Sixty-nine articles were identified after the initial screening process, all of which dealt with blunt injury to the TLS, along with clinical, radiographic, fluoroscopic, and magnetic resonance imaging evaluation. From this group, 32 articles were selected. The reviewers identified 27 articles that dealt with the initial evaluation of TLS injury after trauma. CONCLUSION: Computed tomography (CT) scan imaging of the bony spine has advanced with helical and currently multidetector images to allow reformatted axial collimation of images into two-dimensional and three-dimensional images. As a result, bony injuries to the TLS are commonly being identified. Most blunt trauma patients require CT to screen for other injuries. This has allowed the single admitting series of CT scans to also include screening for bony spine injuries. However, all of the publications fail to clearly define the criteria used to decide who gets radiographs or CT scans. No study has carefully conducted long-term follow-up on all of their trauma patients to identify all cases of TLS injury missed in the acute setting.