Host tolerance and resistance to parasitic nest flies differs between two wild bird species.

Hosts have developed and evolved defense strategies to limit parasite damage. Hosts can reduce the damage that parasites cause by decreasing parasite fitness (resistance) or without affecting parasite fitness (tolerance). Because a parasite species can infect multiple host species, determining the effect of the parasite on these hosts and identifying host defense strategies can have important implications for multi-host-parasite dynamics.Over 2 years, we experimentally manipulated parasitic flies (Protocalliphora sialia) in the nests of tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis). We then determined the effects of the parasites on the survival of nestlings and compared defense strategies between host species. We compared resistance between host species by quantifying parasite densities (number of parasites per gram of host) and measured nestling antibody levels as a mechanism of resistance. We quantified tolerance by determining the relationship between parasite density and nestling survival and blood loss by measuring hemoglobin levels (as a proxy of blood recovery) and nestling provisioning rates (as a proxy of parental compensation for resources lost to the parasite) as potential mechanisms of tolerance.For bluebirds, parasite density was twice as high as for swallows. Both host species were tolerant to the effects of P. sialia on nestling survival at their respective parasite loads but neither species were tolerant to the blood loss to the parasite. However, swallows were more resistant to P. sialia compared to bluebirds, which was likely related to the higher antibody-mediated immune response in swallow nestlings. Neither blood recovery nor parental compensation were mechanisms of tolerance.Overall, these results suggest that bluebirds and swallows are both tolerant of their respective parasite loads but swallows are more resistant to the parasites. These results demonstrate that different host species have evolved similar and different defenses against the same species of parasite.

The importance of a neck exam in sport-related concussion: Cervical schwannoma in post concussion syndrome.

OBJECTIVE: Few cases of cervical schwannoma have been reported following head trauma. The present case, involves a schwannoma of the C2 spinal nerve mimicking post-concussion symptoms following a sport-related concussion (SRC). DESIGN: Case study. SETTING: University of Calgary, Sport Medicine Clinic, Calgary, Alberta, Canada. RESULTS: We report a 28 year old, athlete who developed headache, dizziness, photophobia, and neck pain following a cycling accident. She presented nine months later to our sports clinic with persistent symptoms. She had a normal neurological examination but complained of painful neck range of motion, and exacerbation of symptoms with neck extension. On palpation, a lump was found in the right suboccipital muscles and MRI showed a T2 hyperintense mass at the C1-2 level. The patient underwent resection and histology revealed a schwannoma of the C2 nerve root. Following resection her symptoms improved, with no recurrence at 2 months follow up. CONCLUSION: Our patient's slow recovery following SRC is consistent with a schwannoma formation, which may have been precipitated by the injury itself or merely unmasked from trauma. This case illustrates the importance of a thorough physical examination and broad differential in patients presenting with worsening of symptoms after initial improvement in SRC.

Development of a Competence-Based Spine Surgery Fellowship Curriculum Set of Learning Objectives in Canada.

STUDY DESIGN: Modified-Delphi expert consensus method. OBJECTIVE: The aim of this study was to develop competence-based spine fellowship curricula as a set of learning goals through expert consensus methodology in order to provide an educational tool for surgical educators and trainees. Secondarily, we aimed to determine potential differences among specialties in their rating of learning objectives to defined curriculum documents. SUMMARY OF BACKGROUND DATA: There has been recent interest in competence-based education in the training of future surgeons. Current spine fellowships often work on a preceptor-based model, and recent studies have demonstrated that graduating spine fellows may not necessarily be exposed to key cognitive and procedural competencies throughout their training that are expected of a practicing spine surgeon. METHODS: A consensus group of 32 spine surgeons from across Canada was assembled. A modified-Delphi approach refined an initial fellowship-level curriculum set of learning objectives (108 cognitive and 84 procedural competencies obtained from open sources). A consensus threshold of 70% was chosen with up to 5 rounds of blinded voting performed. Members were asked to ratify objectives into either a general comprehensive or focused/advanced curriculum. RESULTS: Twenty-eight of 32 consultants (88%) responded and participated in voting rounds. Seventy-eight (72%) cognitive and 63 (75%) procedural competency objectives reached 70% consensus in the first round. This increased to 82 cognitive and 73 procedural objectives by round 4. The final curriculum document evolved to include a general comprehensive curriculum (91 cognitive and 53 procedural objectives), a focused/advanced curriculum (22 procedural objectives), and a pediatrics curriculum (22 cognitive and 9 procedural objectives). CONCLUSION: Through a consensus-building approach, the study authors have developed a competence-based curriculum set of learning objectives anticipated to be of educational value to spine surgery fellowship educators and trainees. To our knowledge, this is one of the first nationally based efforts of its kind that is also anticipated to be of interest by international colleagues.

Predictive value of 3-month lumbar discectomy outcomes in the NeuroPoint-SD Registry.

OBJECT: The authors have established a multicenter registry to assess the efficacy and costs of common lumbar spinal procedures using prospectively collected outcomes. Collection of these data requires an extensive commitment of resources from each site. The aim of this study was to determine whether outcomes data from shorter-interval follow-up could be used to accurately estimate long-term outcome following lumbar discectomy. METHODS: An observational prospective cohort study was completed at 13 academic and community sites. Patients undergoing single-level lumbar discectomy for treatment of disc herniation were included. SF-36 and Oswestry Disability Index (ODI) data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. Quality-adjusted life year (QALY) data were calculated using SF-6D utility scores. Correlations among outcomes at each follow-up time point were tested using the Spearman rank correlation test. RESULTS: One hundred forty-eight patients were enrolled over 1 year. Their mean age was 46 years (49% female). Eleven patients (7.4%) required a reoperation by 1 year postoperatively. The overall 1-year follow-up rate was 80.4%. Lumbar discectomy was associated with significant improvements in ODI and SF-36 scores (p < 0.0001) and with a gain of 0.246 QALYs over the 1-year study period. The greatest gain occurred between baseline and 3-month follow-up and was significantly greater than improvements obtained between 3 and 6 months or 6 months and 1 year(p < 0.001). Correlations between 3-month, 6-month, and 1-year outcomes were similar, suggesting that 3-month data may be used to accurately estimate 1-year outcomes for patients who do not require a reoperation. Patients who underwent reoperation had worse outcomes scores and nonsignificant correlations at all time points. CONCLUSIONS: This national spine registry demonstrated successful collection of high-quality outcomes data for spinal procedures in actual practice. Three-month outcome data may be used to accurately estimate outcome at future time points and may lower costs associated with registry data collection. This registry effort provides a practical foundation for the acquisition of outcome data following lumbar discectomy.

Validation of the Calgary Spine Severity Score.

BACKGROUND CONTEXT: The Calgary Spine Severity Score (CSSS) is a published triage score reported in the Spine Journal in 2010. It separates spine referrals into four time categories of urgency. It stratifies patients according to clinical, radiologic, and pathologic findings. The CSSS however still requires external validation at another institution and in an unselected sample of patients. PURPOSE: The aim was to validate the CSSS. STUDY DESIGN/SETTING: This was a validation study. PATIENT SAMPLE: The sample included a total of 316 consecutive patients undergoing spinal surgery between April 2014 and September 2014 at a tertiary care hospital in Canada. OUTCOME MEASURES: The outcome was validity of the CSSS via its predicted time to operating room (OR) to predict actual time to OR. METHODS: We applied the CSSS to an unselected sample of consecutive patients from a tertiary care hospital between April 2014 and September 2014. Demographic and clinical data were collected. The CSSS was determined. We compared the time with OR predicted by the CSSS in one of four categories (routine>6 months=CSSS 3-5, priority<6 months=CSSS 6-8, urgent<1 month=CSSS 9-11, and emergent<1 week=CSSS 12-15) with the actual time to OR. We used Kaplan-Meier survival analysis to assess the CSSS predictive ability. Cox proportional hazard models were built and compared via analysis of variance to determine whether the models differed in their ability to fit the data. RESULTS: Three hundred sixteen patients were eligible. Two hundred eighty-nine had sufficient data. One hundred eighteen were a mismatch with the actual time to OR yielding an accuracy of 63%. The CSSS overestimated the urgency in 68 cases and underestimated it in 50 cases. Notably, seven cauda equina syndrome cases were classified as priority (<6 months) instead of emergent. The concordance was 0.70 and the R-square 0.33. We proposed several adjustments to the CSSS to increase its accuracy. The modified CSSS had an accuracy of 96%, overestimating nine cases and underestimating one case. The concordance was 0.77, and the R-square 0.70. CONCLUSIONS: The modified CSSS is an easy-to-use triage score, which represents a substantial improvement as compared with the original CSSS. It now requires further external validation.

Serum neurofilament light chain is a biomarker of human spinal cord injury severity and outcome.

BACKGROUND: Neurofilaments (Nf) are major structural proteins that occur exclusively in neurons. In spinal cord injury (SCI), the severity of disease is quantified by clinical measures that have limited sensitivity and reliability, and no blood-based biomarker has been established to further stratify the degree of injury. We aimed to examine a serum-based NfL immunoassay as predictor of the clinical outcome in SCI. METHODS: Longitudinal measurement of serum NfL was performed in patients with central cord syndrome (CCS, n=4), motor-incomplete SCI (iSCI, n=10), motor-complete SCI (cSCI, n=13) and healthy controls (HC, n=67), and correlated with clinical severity, neurological outcome, and neuroprotective effect of the drug minocycline. RESULTS: Baseline NfL levels were higher in iSCI (21 pg/mL) and cSCI (70 pg/mL) than in HC (5 pg/mL, p=0.006 and p<0.001) and CCS (6 pg/mL, p=0.025 and p=0.010). Levels increased over time (p<0.001) and remained higher in cSCI versus iSCI (p=0.011) and than in CCS (p<0.001). NfL levels correlated with American Spinal Injury Association (ASIA) motor score at baseline (r=-0.53, p=0.004) and after 24 h (r=-0.69, p<0.001) and 3-12-month motor outcome (baseline NfL: r=-0.43, p=0.026 and 24 h NfL: r=-0.72, p<0.001). Minocycline treatment showed decreased NfL levels in the subgroup of cSCI patients. CONCLUSIONS: Serum NfL concentrations in SCI patients show a close correlation with acute severity and neurological outcome. Our data provide evidence that serum NfL is of prognostic value in SCI patients for the first time. Further, blood NfL levels may qualify as drug response markers in SCI.

Surgical management of primary bone tumors of the spine: validation of an approach to enhance cure and reduce local recurrence.

STUDY DESIGN: Multicenter ambispective cohort analysis. OBJECTIVE: The purpose of this study is to determine whether applying Enneking's principles to surgical management of primary bone tumors of the spine significant decreases local recurrence and/or mortality. SUMMARY OF BACKGROUND DATA: Oncologic management of primary tumors of spine has historically been inconsistent, controversial, and open to individual interpretation. METHODS: A multicenter ambispective cohort analysis from 4 tertiary care spine referral centers was done. Patients were analyzed in 2 cohorts, "Enneking Appropriate" (EA), surgical margin as recommended by Enneking, and "Enneking Inappropriate" (EI), surgical margin not recommended by Enneking. Benign tumors were not included in mortality analysis. RESULTS: Two cohorts represented an analytic dataset with 147 patients, 86 male, average age 46 years (range: 10-83). Median follow-up was 4 (2-7) years in the EA and 6 (5.5-15.5) years in the EI. Seventy-one patients suffered at least 1 local recurrence during the study, 57 of 77 in the EI group and 14 of 70 in the EA group. EI surgical approach caused higher risk of first local recurrence (P < 0.0001). There were 48 deaths in total; 29 in the EI group and 19 in the EA. There was a strong correlation between the first local recurrence and mortality with an odds ratio of 4.69, (P < 0.0001). EI surgical approach resulted in a higher risk of mortality with a hazard ratio of 3.10, (P = 0.0485) compared to EA approach. CONCLUSION: Surgery results in a significant reduction in local recurrence when primary bone tumors of the spine are resected with EA margins. Local recurrence has a high concordance with mortality in resection of these tumors. A significant decrease in mortality occurs when EA surgery is used.

Interrater reliability of identifying indicators of posterior ligamentous complex disruption when plain films are indeterminate in thoracolumbar injuries.

BACKGROUND: The Spine Trauma Study Group (STSG) has proposed a novel thoracolumbar injury classification system and score (TLICS) in an attempt to define traumatic spinal injuries and direct appropriate management schemes objectively. The TLICS assigns specific point values based on three variables to generate a final severity score that guides potential treatment options. Within this algorithm, significant emphasis has been placed on posterior ligamentous complex (PLC) integrity. The purpose of this study was to determine the interrater reliability of indicators surgeons use when assessing PLC disruption on imaging studies, including computed tomography (CT) and magnetic resonance imaging (MRI). METHODS: Orthopedic surgeons and neurosurgeons retrospectively reviewed a series of thoracolumbar injury case studies. Thirteen case studies, including images, were distributed to STSG members for individual, independent evaluation of the following three criteria: (1) diastasis of the facet joints on CT; (2) posterior edema-like signal in the region of PLC components on sagittal T2-weighted fat saturation (FAT SAT) MRI; and (3) disrupted PLC components on sagittal T1-weighted MRI. Interrater agreement on the presence or absence of each of the three criteria in each of the 13 cases was assessed. RESULTS: Absolute interrater percent agreement on diastasis of the facet joints on CT and posterior edema-like signal in the region of PLC components on sagittal T2-weighted FAT SAT MRI was similar (agreement 70.5%). Interrater agreement on disrupted PLC components on sagittal T1-weighted MRI was 48.9%. Facet joint diastasis on CT was the most reliable indicator of PLC disruption as assessed by both Cohen's kappa (kappa = 0.395) and intraclass correlation coefficient (ICC 0.430). CONCLUSIONS: The interrater reliability of assessing diastasis of the facet joints on CT had fair to moderate agreement. The reliability of assessing the posterior edema-like signal in the region of PLC components was lower but also fair, whereas the reliability of identifying disrupted PLC components was poor.

Similarities and differences in the treatment of spine trauma between surgical specialties and location of practice.

STUDY DESIGN: Questionnaires administered to practicing orthopedic and neurosurgical spine surgeons from various regions of the United States and abroad. OBJECTIVES: To determine similarities and differences in the treatment of spinal trauma. SUMMARY OF BACKGROUND DATA: Spinal trauma is generally referred to subspecialists of orthopedic or neurosurgical training. Prior studies have suggested that there is significant variability in the management of such injuries. METHODS: Questionnaires based on eight clinical scenarios of commonly encountered cervical, thoracic, and lumbar injuries were administered to 35 experienced spinal surgeons. Surgeons completed profile information and answered approximately one dozen questions for each case. Data were analyzed with SPSS software to determine the levels of agreement and characteristics of respondents that might account for a lack of agreement on particular aspects of management. RESULTS: Of the 35 surgeons completing the questionnaire, 63% were orthopedists, 37% were neurosurgeons, and 80% had been in practice for more than 5 years. Considerable agreement was found in the majority of clinical decisions, including whether or not to operate and the timing of surgery. Of the differences noted, neurosurgeons were more likely to obtain a MRI, and orthopedists were more likely to use autograft as a sole graft material. Physicians from abroad were, in general, more likely to operate and to use an anterior approach during surgery than physicians from the northeastern United States. CONCLUSIONS: More commonalities were identified in the management of spinal trauma than previously reported. When found, variability in opinion was related to professional and regional differences.