The Effect of Elevated Mean Arterial Blood Pressure in Cervical Traumatic Spinal Cord Injury with Hemorrhagic Contusion

OBJECTIVE

Hemorrhagic contusion in cervical spinal cord injury (CSCI) is poorly understood. We investigated hemorrhagic expansion in patients with CSCI with an assigned elevated mean arterial pressure (MAP) goal of >85 mm Hg. The change in hemorrhagic area and long-term follow-up data ≥6 months after injury was studied.

METHODS

A retrospective review was performed from 2005 to 2016 to identify patients with motor complete CSCI with 2 cervical magnetic resonance imaging (MRI) scans within 7 days of injury showing evidence of hemorrhagic contusion and assigned a MAP goal of >85 mm Hg for 7 days. T2-weighted MRI was used to calculate the hemorrhagic surface area in the sagittal plane. A calculated MAP was recorded for each blood pressure measure between the initial and follow-up MRI scans. The American Spinal Injury Association impairment scale (AIS) and American Spinal Injury Association motor scores were recorded at the final follow-up examination at ≥6 months.

RESULTS

A total of 193 patients were identified. The mean change in the hemorrhagic area was 24.0 mm². Of the 193 patients, the AIS grade was A for 114 and B for 79 patients. Multiple logistic regression analysis demonstrated that the MAP and systolic blood pressure were nonsignificant predictors of hemorrhagic contusion expansion. An increased hemorrhagic contusion area on the follow-up MRI scan was associated with a reduced odds of AIS improvement of ≥1 and ≥2 points (odds ratio, 0.97; 95% confidence interval, 0.87-0.97; P = 0.028; and odds ratio, 0.92; 95% confidence interval, 0.99-1.13; P = 0.008, respectively) at the final ≥6-month follow-up examination.

CONCLUSION

The present study investigated the clinical safety of elevated MAP goals for patients with CSCI and hemorrhagic contusion. Elevated MAPs did not significantly increase the risk of hemorrhagic expansion in those with CSCI. We have also reported the use of hemorrhagic contusion size as a potential radiographic biomarker for neurological outcomes.

Investigational growth factors utilized in animal models of spinal fusion: Systematic review

BACKGROUND

Over 400000 Americans annually undergo spinal fusion surgeries, yet up to 40% of these procedures result in pseudoarthrosis even with iliac crest autograft, the current “gold standard” treatment. Tissue engineering has the potential to solve this problem via the creation of bone grafts involving bone-promoting growth factors (e.g., bone morphogenetic protein 2). A broad assessment of experimental growth factors is important to inform future work and clinical potential in this area. To date, however, no study has systematically reviewed the investigational growth factors utilized in preclinical animal models of spinal fusion.

AIM

To review all published studies assessing investigational growth factors for spinal fusion in animal models and identify promising agents for translation.

METHODS

We conducted a systematic review of the literature using PubMed, Embase, Cochrane Library, and Web of Science databases with searches run on May 29^th, 2018. The search query was designed to include all non-human, preclinical animal models of spinal fusion reported in the literature without a timespan limit. Extracted data for each model included surgical approach, level of fusion, animal species and breed, animal age and sex, and any other relevant characteristics. The dosages/sizes of all implant materials, spinal fusion rates, and follow-up time points were recorded. The data were analyzed and the results reported in tables and text. PRISMA guidelines were followed for this systematic review.

RESULTS

Twenty-six articles were included in this study, comprising 14 experimental growth factors: AB204 (n = 1); angiopoietin 1 (n = 1); calcitonin (n = 3); erythropoietin (n = 1); basic fibroblast growth factor (n = 1); growth differentiation factor 5 (n = 4), combined insulin-like growth factor 1 + transforming growth factor beta (n = 4); insulin (n = 1); NELL-1 (n = 5); noggin (n = 1); P-15 (n = 1); peptide B2A (n = 2); and secreted phosphoprotein 24 (n = 1). The fusion rates of the current gold standard treatment (autologous iliac crest bone graft, ICBG) and the leading clinically used growth factor (BMP-2) ranged widely in the included studies, from 0-100% for ICBG and from 13%-100% for BMP-2. Among the identified growth factors, calcitonin, GDF-5, NELL-1, and P-15 resulted in fusion rates of 100% in some cases. In addition, six growth factors - AB204, angiopoietin 1, GDF-5, insulin, NELL-1, and peptide B2A - resulted in significantly enhanced fusion rates compared to ICBG, BMP-2, or other internal control in some studies. Large heterogeneity in animal species, fusion method, and experimental groups and time points was observed across the included studies, limiting the direct comparison of the growth factors identified herein.

CONCLUSION

Several promising investigational growth factors for spinal fusion have been identified herein; directly comparing the fusion efficacy and safety of these agents may inform clinical translation.