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There is an urgent need for both the scientific development and clinical validation of novel therapies for acute spinal cord injury (SCI). The scientific development of novel therapies would be facilitated by a better understanding of the acute pathophysiology of human SCI. Clinical validation of such therapies would be facilitated by the availability of biomarkers with which to stratify injury severity and predict neurological recovery. Cerebrospinal fluid (CSF) samples were obtained over a period of 72 h in 27 patients with complete SCI (ASIA A) or incomplete SCI (ASIA B or C). Cytokines were measured in CSF and serum samples using a multiplex cytokine array system and standard enzyme-linked immunosorbent assay (ELISA) techniques. Neurological recovery was monitored, and patient-reported neuropathic pain was documented. IL-6, IL-8, MCP-1, tau, S100beta, and glial fibrillary acidic protein (GFAP) were elevated in a severity-dependent fashion. A biochemical model was established using S100beta, GFAP, and IL-8 to predict injury severity (ASIA A, B, or C). Using these protein concentrations at 24-h post injury, the model accurately predicted the observed ASIA grade in 89% of patients. Furthermore, segmental motor recovery at 6 months post injury was better predicted by these CSF proteins than with the patients' baseline ASIA grade. The pattern of expression over the first 3 to 4 days post injury of a number of inflammatory cytokines such as IL-6, IL-8, and MCP-1 provides invaluable information about the pathophysiology of human SCI. A prediction model that could use such biological data to stratify injury severity and predict neurological outcome may be extremely useful for facilitating the clinical validation of novel treatments in acute human SCI.

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Object Ischemia is an important factor in the pathophysiology of secondary damage after traumatic spinal cord injury (SCI) and, in the setting of thoracoabdominal aortic aneurysm repair, can be the primary cause of paralysis. Lowering the intrathecal pressure (ITP) by draining CSF is routinely done in thoracoabdominal aortic aneurysm surgery but has not been evaluated in the setting of acute traumatic SCI. Additionally, while much attention is directed toward maintaining an adequate mean arterial blood pressure (MABP) in the acute postinjury phase, little is known about what is happening to the ITP during this period when spinal cord perfusion pressure (MABP − ITP) is important. The objectives of this study were to: 1) evaluate the safety and feasibility of draining CSF to lower ITP after acute traumatic SCI; 2) evaluate changes in ITP before and after surgical decompression; and 3) measure neurological recovery in relation to the drainage of CSF. Methods Twenty-two patients seen within 48 hours of injury were prospectively randomized to a drainage or no-drainage treatment group. In all cases a lumbar intrathecal catheter was inserted for 72 hours. Acute complications of headache/nausea/vomiting, meningitis, or neurological deterioration were carefully monitored. Acute Spinal Cord Injury motor scores were documented at baseline and at 6 months postinjury. Results On insertion of the catheter, mean ITP was 13.8 ± 1.3 mm Hg (± SD), and it increased to a mean peak of 21.7 ± 1.5 mm Hg intraoperatively. The difference between the starting ITP on catheter insertion and the observed peak intrathecal pressure after decompression was, on average, an increase of 7.9 ± 1.6 mm Hg (p < 0.0001, paired t-test). During the postoperative period, the peak recorded ITP in the patients randomized to the no-drainage group was 30.6 ± 2.3 mm Hg, which was significantly higher than the peak intraoperative ITP (p = 0.0098). During the same period, the peak recorded ITP in patients randomized to receive drainage was 28.1 ± 2.8 mm Hg, which was not statistically higher than the peak intraoperative ITP (p = 0.15). Conclusions The insertion of lumbar intrathecal catheters and the drainage of CSF were not associated with significant adverse events, although the cohort was small and only a limited amount of CSF was drained. Intraoperative decompression of the spinal cord results in an increase in the ITP measured caudal to the injury site. Increases in intrathecal pressure are additionally observed in the postoperative period. These increases in intrathecal pressure result in reduced spinal cord perfusion that will otherwise go undetected when measuring only the MABP. Characteristic changes in the observed intrathecal pressure waveform occur after surgical decompression, reflecting the restoration of CSF flow across the SCI site. As such, the waveform pattern may be used intraoperatively to determine if adequate decompression of the thecal sac has been accomplished.

Neurologic impairment after spinal cord injury (SCI) is currently measured and classified by functional examination. Biological markers that objectively classify injury severity and predict outcome would greatly facilitate efforts to evaluate acute SCI therapies. The purpose of this study was to determine how well inflammatory and structural proteins within the cerebrospinal fluid (CSF) of acute traumatic SCI patients predicted American Spinal Injury Association Impairment Scale (AIS) grade conversion and motor score improvement over 6 months. Fifty acute SCI patients (29 AIS A, 9 AIS B, 12 AIS C; 32 cervical, 18 thoracic) were enrolled and CSF obtained through lumbar intrathecal catheters to analyze interleukin (IL)-6, IL-8, monocyte chemotactic protein (MCP)-1, tau, S100β, and glial fibrillary acidic protein (GFAP) at 24 h post-injury. The levels of IL-6, tau, S100β, and GFAP were significantly different between patients with baseline AIS grades of A, B, or C. The levels of all proteins (IL-6, IL-8, MCP-1, tau, S100β, and GFAP) were significantly different between those who improved an AIS grade over 6 months and those who did not improve. Linear discriminant analysis modeling was 83% accurate in predicting AIS conversion. For AIS A patients, the concentrations of proteins such as IL-6 and S100β correlated with conversion to AIS B or C. Motor score improvement also was strongly correlated with the 24-h post-injury CSF levels of all six biomarkers. The analysis of CSF can provide valuable biological information about injury severity and recovery potential after acute SCI. Such biological markers may be valuable tools for stratifying individuals in acute clinical trials where variability in spontaneous recovery requires large recruitment cohorts for sufficient power.

We demonstrate that maintaining SCPP above 50 mm Hg is a strong predictor of improved neurologic recovery following spinal cord injury. This suggests that SCPP (the difference between MAP and CSFP) can provide useful information to guide the hemodynamic management of patients with acute spinal cord injury.

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