Cerebrospinal fluid biomarkers versus glasgow coma scale and glasgow outcome scale in pediatric traumatic brain injury: the role of young age and inflicted injury.

The Glasgow Coma Scale (GCS) and Glasgow Outcome Scale (GOS) are widely used clinical scoring systems to measure the severity of neurologic injury after traumatic brain injury (TBI), but have recognized limitations in infants and small children. Cerebrospinal fluid (CSF) concentrations of neuron-specific enolase (NSE) and S100B show promise as markers of brain injury. We hypothesized that the initial GCS and 6-month GOS scores would be inversely associated with CSF NSE and/or S100B concentrations after severe pediatric TBI. Using banked CSF obtained during ongoing studies of pediatric TBI, NSE and S100B were determined in CSF collected within 24 h of trauma from 88 infants and children with severe TBI (GCS < or = 8) versus 20 non-injured controls. Victims of inflicted (iTBI) and non-inflicted TBI (nTBI) showed similar (>10-fold) increases in both NSE and S100B versus control. Both markers showed overall significant, inverse correlation with GCS and GOS scores. In subgroup analysis, both markers correlated significantly with GCS and GOS scores only in older (>4 years) victims of nTBI; no correlation was found for patients < or =4 years old or victims of iTBI. While confirming the overall correlations between GCS/GOS score and CSF NSE and S100B seen in prior studies, we conclude that these clinical and CSF biomarkers of brain injury do not correlate in children < or =4 years of age and/or victims of iTBI. Although further, prospective study is warranted, these findings suggest important limitations in our current ability to assess injury severity in this important population.

Adenosine A1 receptor knockout mice develop lethal status epilepticus after experimental traumatic brain injury.

Adenosine, acting at A1 receptors, exhibits anticonvulsant effects in experimental epilepsy--and inhibits progression to status epilepticus (SE). Seizures after traumatic brain injury (TBI) may contribute to pathophysiology. Thus, we hypothesized that endogenous adenosine, acting via A1 receptors, mediates antiepileptic benefit after experimental TBI. We subjected A1-receptor knockout (ko) mice, heterozygotes, and wild-type (wt) littermates (n=115) to controlled cortical impact (CCI). We used four outcome protocols in male mice: (1) observation for seizures, SE, and mortality in the initial 2 h, (2) assessment of seizure score (electroencephalogram (EEG)) in the initial 2 h, (3) assessment of mortality at 24 h across injury levels, and (4) serial assessment of arterial blood pressure, heart rate, blood gases, and hematocrit. Lastly, to assess the influence of gender on this observation, we observed female mice for seizures, SE, and mortality in the initial 2 h. Seizure activity was noted in 83% of male ko mice in the initial 2 h, but was seen in no heterozygotes and only 33% of wt (P<0.05). Seizures in wt were brief (1 to 2 secs). In contrast, SE involving lethal sustained (>1 h) tonic clonic activity was uniquely seen in ko mice after CCI (50% incidence in males), (P<0.05). Seizure score was twofold higher in ko mice after CCI versus either heterozygote or wt (P<0.05). An injury-intensity dose-response for 24 h mortality was seen in ko mice (P<0.05). Physiologic parameters were similar between genotypes. Seizures were seen in 100% of female ko mice after CCI versus 14% of heterozygotes and 25% wt (P<0.05) and SE was restricted to the ko mice (83% incidence). Our data suggest a critical endogenous anticonvulsant action of adenosine at A1 receptors early after experimental TBI.

Characterization of the effects of adenosine receptor agonists on cerebral blood flow in uninjured and traumatically injured rat brain using continuous arterial spin-labeled magnetic resonance imaging.

Hypoperfusion after traumatic brain injury may exacerbate damage. Adenosine, a vasodilator, regulates cerebral blood flow (CBF). Treatment with adenosine receptor agonists has shown benefit in experimental CNS trauma; however, their effects on CBF after injury remain undefined. We used magnetic resonance imaging to assess CBF in uninjured rats both early and at 24 h after intrahippocampal administration of either the nonselective adenosine receptor agonist 2-chloroadenosine (2-CA, 12 nmol) or the A(2A)-receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarbox-amidoadenosine (CGS 21680, 6 nmol). We also assessed the effects of these agents on cerebral metabolic rate for glucose (CMRglu). We then assessed the effect of 2-CA on CBF at 3.5 to 5 h after controlled cortical impact (CCI). Injection of 2-CA into uninjured rat brain produced marked increases in CBF in ipsilateral hippocampus and cortex versus vehicle (P<0.05); CBF increases persisted even at 24 h. Measurement of hippocampal levels of 2-CA showed persistent increases to 24 h. CGS 21680 produced even more marked global increases in CBF than seen with 2-CA (2-6-fold versus vehicle, P<0.05 in 10/12 regions of interest (ROIs)). Neither agonist altered CMRglu versus vehicle. After CCI, 2-CA increased CBF in ipsilateral hippocampal and hemispheric ROIs (P<0.05 versus vehicle), but the response was attenuated at severe injury levels. We report marked increases in CBF after injection of adenosine receptor agonists into uninjured rat brain despite unaltered CMRglu. 2-Chloroadenosine produced enduring increases in CBF in uninjured brain and attenuated posttraumatic hypoperfusion. Future studies of adenosine-related therapies in CNS injury should address the role of CBF.

Enhanced oxidative stress in iNOS-deficient mice after traumatic brain injury: support for a neuroprotective role of iNOS.

Studies in experimental traumatic brain injury (TBI) suggest both deleterious and protective effects of inducible nitric oxide synthase (iNOS). Early after injury, iNOS may be detrimental via formation of peroxynitrite and iNOS inhibitors are protective. In contrast, we reported impaired long-term functional outcome after TBI in iNOS knockout (ko) versus wild-type (wt) mice. To elucidate potential neuroprotective and neurotoxic mechanisms for iNOS, we studied nitric oxide formation by electron paramagnetic resonance (EPR) spectroscopy using diethyldithiocarbamate-iron (DETC-Fe) as a spin trap and markers of nitrosative (S-nitrosothiol (RSNO, Fluorescent assay); nitrotyrosine (3NT, ELISA)) and oxidative stress (ascorbate, HPLC) at 72 h after controlled cortical impact (CCI) in iNOS ko and wt and in uninjured iNOS ko and wt mice. 3NT immunostaining with macrophage and myeloperoxidase (MPO) dual labeling was also assessed in brain sections. Brain DETC-Fe-NO low-temperature EPR signal intensity was approximately 2-fold greater in wt versus iNOS ko at 72 h after CCI. Ascorbate levels decreased in injured hemisphere in wt and iNOS ko versus uninjured -this decrease was more pronounced in iNOS ko. In wt mice, RSNO and 3NT levels were increased after CCI versus uninjured (50% and 400%, respectively, P < 0.05). RSNO levels were not increased in iNOS ko after CCI. Nitrotyrosine levels increased after CCI in wt and ko versus respective uninjured -this increase was more pronounced in wt (2.34 +/- 0.95 versus 1.27 +/- 0.49 pmol/mg protein, P < 0.05). Increased 3NT immunoreactivity was detected in wt versus iNOS ko at 72 h after CCI, and colocalized with macrophage marker and MPO. Our data support a role for iNOS-derived NO as an endogenous antioxidant after CCI. iNOS also contributes protein nitrosylation and nitration. Colocalization of 3NT with macrophages and MPO suggests generation of nitrating agents by macrophages and/or phagocytosis of nitrated proteins.

Continuous versus intermittent cerebrospinal fluid drainage after severe traumatic brain injury in children: effect on biochemical markers.

Drainage of cerebrospinal fluid (CSF) is routinely used in the treatment of severe traumatic brain injury (TBI), either continuously or intermittently in response to increases in intracranial pressure (ICP). There has been little study of the effect of CSF drainage method on the biochemistry, pathophysiology or outcome of TBI in adults or children. Having previously reported that a variety of markers of injury or repair increase in CSF after severe TBI, we chose to evaluate directly the effect of CSF drainage method on the biochemistry and volume of CSF drained as well as ICP. We hypothesized that concentrations of these markers would be similar in CSF drained continuously vs intermittently. We compared CSF levels of markers of neuronal injury (neuron specific enolase, [NSE]), glial injury (s100B), inflammation (interleukin-6 [IL-6]), and regeneration (vascular endothelial growth factor [VEGF]) (measured by ELISA) in 80 CSF samples from 19 severely injured children whose CSF was drained continuously (n = 13) versus intermittently (n = 6) as part of standard care in two institutions. Compared to continuous CSF drainage, intermittent drainage of CSF was associated with twofold greater CSF concentrations of NSE, s100B, IL-6 and VEGF (p < 0.05) and with about half the volume of CSF removal than continuous drainage (p = 0.002). The resulting elimination (concentration x volume) of these biochemicals, however, was not influenced by drainage method. Patients treated with continuous drainage had lower mean ICPs than those with intermittent drainage (13.6 +/- 0.69 vs. 21.8 +/- 0.95 mm Hg, p < 0.0001). We conclude that the method of CSF drainage greatly affects concentrations of CSF markers after TBI and may influence ICP. The influence of method on CSF marker concentration must be kept in mind when interpreting studies of CSF biomarkers. The striking difference in biomarker concentration, CSF volume drained, and ICP suggests the need for a randomized trial directly comparing these two approaches in infants and children with severe TBI.

Induction of the stress response after inflicted and non-inflicted traumatic brain injury in infants and children.

Rapid induction of 72-kD heat shock protein (Hsp70) is a key component of the stress response and is seen after a variety of insults to the brain including experimental hyperthermia, ischemia, seizures, and traumatic brain injury (TBI). Little is known about the endogenous stress response in pediatric patients after brain injury. Accordingly, the concentration of Hsp70 was determined in 61 cerebrospinal fluid (CSF) samples from 20 infants and children after TBI. Peak Hsp70 level were increased in TBI patients vs. controls (4.60 [1.49-78.99] vs. 2.18 [1.38-4.25] ng/mL, respectively, median (range), p = 0.01) and occurred most often on day 1 after injury. Strikingly, CSF levels of Hsp70 were positively and independently associated with inflicted vs. non-inflicted TBI (7.03 [2.30-27.22] vs. 2.06 [1.06-78.99] ng/mL, respectively, p = 0.05). Endogenous Hsp70 expression was confirmed by Western blot and immunocytochemistry using brain tissue samples removed from patients who underwent decompressive craniotomy for refractory intracranial hypertension or at autopsy. These data suggest that the endogenous stress response, as measured and quantified by the Hsp70 concentration in CSF, occurs in infants and children after TBI. The endogenous stress response is more robust in victims of child abuse, compared with patients with accidental TBI, supporting age-dependence or a difference in either injury frequency, duration, severity, or mechanism in this subgroup of TBI patients. Further studies are needed to determine the role of Hsp70 in both non-inflicted and inflicted TBI in infants and children.

Marked gender effect on lipid peroxidation after severe traumatic brain injury in adult patients.

Striking gender differences have been reported in the pathophysiology and outcome of acute neurological injury. Greater neuroprotection in females versus males may be due, in part, to direct and indirect sex hormone-mediated antioxidant mechanisms. Progesterone administration decreases brain levels of F(2)-isoprostane, a marker of lipid peroxidation, after experimental traumatic brain injury (TBI) in male rats, and estrogen is neuroprotective in experimental neurological injury. In this study, we evaluated the effect of gender on lipid peroxidation, as assessed by cerebrospinal fluid (CSF) levels of F(2)-isoprostane, after severe TBI in humans. Lipid peroxidation was assessed in CSF from 68 adults enrolled in two randomized controlled trials evaluating the effect of therapeutic hypothermia after severe TBI (Glasgow coma scale [GCS] score

Hyperglycolysis is exacerbated after traumatic brain injury with fentanyl vs. isoflurane anesthesia in rats.

Despite common use of narcotics in the clinical management of severe traumatic brain injury (TBI), in experimental models rats treated with fentanyl have exhibited worse functional outcome and more CA1 hippocampal death than rats treated with standard isoflurane anesthesia. We hypothesized that greater post-traumatic excitotoxicity, reflected by cerebral glucose utilization (CMRglu), may account for detrimental effects of fentanyl vs. isoflurane. Rats were anesthetized with either isoflurane (1% by inhalation) or fentanyl (10 mcg/kg iv bolus then 50 mcg/kg/h infusion). 14C-deoxyglucose autoradiography was performed 45 min after controlled cortical impact (CCI) to left parietal cortex (n=4 per anesthetic group) or in uninjured rats after 45 min of anesthesia (n=3 per anesthetic group). Uninjured rats treated with fentanyl vs. isoflurane showed 35-45% higher CMRglu in all brain structures (p<0.05) except CA3. After TBI in rats treated with isoflurane, CMRglu increased significantly only in ipsilateral CA1 and ipsilateral parietal cortex (p<0.05 vs. isoflurane uninjured). Conversely, after TBI in rats treated with fentanyl, CMRglu increased markedly and bilaterally in CA1 and CA3 (p<0.05 vs. fentanyl uninjured), but not ipsilateral parietal cortex. In contralateral CA1, CMRglu was nearly two times greater after TBI in fentanyl vs. isoflurane treated rats (p<0.05). Hyperglycolysis was exacerbated in CA1 and CA3 hippocampus after TBI in rats treated with fentanyl vs. isoflurane anesthesia. This post-traumatic hyperglycolysis suggests greater excitotoxicity and concurs with reports of worse functional outcome and more CA1 hippocampal death after TBI with fentanyl vs. isoflurane anesthesia.

F2-isoprostane and neuron-specific enolase in cerebrospinal fluid after severe traumatic brain injury in infants and children.

It has been hypothesized that oxidative stress plays an important role in mediating secondary damage after traumatic brain injury (TBI). To study the relationship between lipid peroxidation, clinical variables, and neuronal damage in pediatric TBI, we measured levels of F2-isoprostane, a marker of lipid peroxidation, and neuron-specific enolase (NSE), a marker of neuronal damage, in serial cerebrospinal fluid (CSF) samples from 23 infants and children with severe TBI (Glasgow Coma Scale score <8). These were compared to CSF samples from 10 uninjured pediatric controls. On d1 after injury, F2-isoprostane was increased 6-fold vs. control (36.59+/-8.96 pg/ml vs. 5.64+/-8.08 pg/ml, p=0.0035) and NSE was increased 10-fold (100.62+/-17.34 ng/ml vs. 8.63+/-2.76 ng/ml, p=0.0002). Multivariate analysis of F2-isoprostane levels and selected clinical variables showed a trend toward an inverse association with time after injury (p=0.0708). Multivariate analysis of NSE levels and selected variables showed a positive association between d1 NSE and F2-isoprostane (p=0.0426). CSF F2-isoprostane increases early after TBI in infants and children and is correlated with NSE, supporting a role for oxidative stress in the evolution of secondary damage early after severe TBI in infants and children.

Assessment of antioxidant reserves and oxidative stress in cerebrospinal fluid after severe traumatic brain injury in infants and children.

Studies in experimental traumatic brain injury (TBI) support a key role for oxidative stress. The degree of oxidative injury in clinical TBI, however, remains to be defined. We assessed antioxidant defenses and oxidative stress in pediatric TBI by applying a comprehensive battery of assays to cerebrospinal fluid samples. Using a protocol approved by our institutional review board, 87 cerebrospinal fluid samples from 11 infants and children with severe TBI (Glasgow Coma Scale score < or = 8) and 8 controls were studied. Cerebrospinal fluid was drained as standard care after TBI. CSF was assessed on d 1, 2, and 5-7 after ventricular drain placement. Biochemical markers of oxidative stress included F(2)-isoprostane and protein sulfhydryl (detected by ELISA and fluorescence assay, respectively). Antioxidant defenses were measured by determination of total antioxidant reserve (via chemiluminescence assay), and ascorbate (via HPLC) and glutathione (via fluorescence assay) concentrations. Free radical production (ascorbate radical) was assessed by electron paramagnetic resonance spectroscopy. F(2)-isoprostane was markedly increased versus control, maximal on d 1 (93.8 +/- 30.8 pg/mL versus 7.6 +/- 5.1 pg/mL, p < 0.05). Total antioxidant reserve was reduced versus control. Reduction was maximal on d 5-7 (81.8 +/- 3.7 microM versus 178.9 +/- 2.2 microM, p < 0.05). Ascorbate was remarkably reduced (53.8 +/- 8 microM versus 163.8 +/- 21 microM on d 1, p < 0.05). Ascorbate depletion was likely associated with its free radical oxidation, as evidenced by electron paramagnetic resonance spectroscopy. Glutathione levels increased on d 1, then decreased versus control (0.19 +/- 0.05 microM versus 1.2 +/- 0.16 microM, p < 0.05). This is the first comprehensive study of antioxidant reserve and oxidative injury in clinical TBI. Progressive compromise of antioxidant defenses and evidence of free radical-mediated lipid peroxidation are noted. These markers could be used to monitor antioxidant strategies in clinical trials.

Cerebrospinal fluid procalcitonin and severe traumatic brain injury in children.

OBJECTIVE: To determine the relationship between cerebrospinal fluid procalcitonin concentration and severe traumatic brain injury in children. DESIGN: Prospective, observational clinical study. SETTING: A multidisciplinary, tertiary-care pediatric intensive care unit. PATIENTS: Twenty-eight patients who required external ventricular drainage for management of severe traumatic brain injury (Glasgow Coma Scale score of <8) and 22 control patients for whom lumbar cerebrospinal fluid evaluation excluded possible meningitis. INTERVENTIONS: Standard intracranial pressure-directed neurointensive care, including intraventricular catheter placement and continuous cerebrospinal fluid drainage, was used to manage patients with severe traumatic brain injury. MEASUREMENTS AND MAIN RESULTS: Demographic data including age, mechanism of injury, time of injury, initial Glasgow Coma Scale score, and outcome were collected. Cerebrospinal fluid procalcitonin concentration was determined by immunoluminometric assay. Initial cerebrospinal fluid procalcitonin concentration (median [range]) in patients with severe traumatic brain injury was increased greater than three-fold vs. controls (0.41 ng/mL [0.15-2.14] vs. 0.12 ng/mL [0.00-0.24], p <.001). Initial cerebrospinal fluid procalcitonin concentration among patients with abusive head trauma (0.31 ng/mL [0.29-0.50]) also was increased vs. controls (p <.05), although this increase was less robust than patients with accidental trauma (0.41 ng/mL [0.15-2.14], p <.001 vs. controls). Additional examination of key demographic and outcome variables with a generalized linear regression model was performed for patients with severe traumatic brain injury. Univariate analysis revealed that both time after injury (p <.01) and abusive head trauma as a mechanism of injury (p <.001) were associated with attenuation of the increased cerebrospinal fluid procalcitonin response after traumatic brain injury. CONCLUSION: Cerebrospinal fluid procalcitonin concentration is increased in children after traumatic brain injury. The attenuated increase in cerebrospinal fluid procalcitonin among victims of abusive head trauma warrants further study because it may reflect impairment of endogenous neuroprotective mechanisms or delay in seeking medical attention. The significance of these observations remains to be determined as future studies elucidate the physiologic and mechanistic properties of procalcitonin.

The Th1 versus Th2 cytokine profile in cerebrospinal fluid after severe traumatic brain injury in infants and children.

OBJECTIVE: To further characterize the Th1 (proinflammatory) vs. the Th2 (antiinflammatory) cytokine profile after severe traumatic brain injury (TBI) by quantifying the ventricular cerebrospinal fluid concentrations of Th1 cytokines (interleukin [IL]-2 and IL-12) and Th2 cytokines (IL-6 and IL-12) in infants and children. DESIGN: Retrospective study. SETTING: University children's hospital. PATIENTS: Twenty-four children hospitalized with severe TBI (admission Glasgow Coma Scale score, <13) and 12 controls with negative diagnostic lumbar punctures. INTERVENTIONS: All TBI patients received standard neurointensive care, including the placement of an intraventricular catheter for continuous drainage of cerebrospinal fluid. MEASUREMENTS AND MAIN RESULTS: Ventricular cerebrospinal fluid samples (n = 105) were collected for as long as the catheters were in place (between 4 hrs and 222 hrs after TBI). Cerebrospinal fluid samples were analyzed for IL-2, IL-4, IL-6, and IL-12 concentrations by enzyme-linked immunoassay. Peak and mean IL-6 (335.7 +/- 41.4 pg/mL and 259.5 +/- 37.6 pg/mL, respectively) and IL-12 (11.4 +/- 2.2 pg/mL and 4.3 +/- 0.8 pg/mL, respectively) concentrations were increased (p <.05) in children after TBI vs. controls (2.3 +/- 0.7 pg/mL and 1.0 +/- 0.5 pg/mL) for IL-6 and IL-12, respectively. In contrast, peak and mean IL-2 and IL-4 concentrations were not increased in TBI children vs. controls. Increases in the cerebrospinal fluid concentration of IL-6 were significantly associated with admission Glasgow Coma Scale score of