Cerebral endothelial injury in elderly patients with severe head injury measured by serum thrombomodulin and von Willebrand factor

Plasma von Willebrand Factor Is Elevated Hyperacutely After Mild Traumatic Brain Injury

Each year in the United States, ∼2.7 million persons seek medical attention for traumatic brain injury (TBI), of which ∼85% are characterized as being mild brain injuries. Many different cell types in the brain are affected in these heterogeneous injuries, including neurons, glia, and the brain vasculature. Efforts to identify biomarkers that reflect the injury of these different cell types have been a focus of ongoing investigation. We hypothesized that von Willebrand factor (vWF) is a sensitive biomarker for acute traumatic vascular injury and correlates with symptom severity post-TBI. To address this, blood was collected from professional boxing athletes (n = 17) before and within 30 min after competition. Plasma levels of vWF and neuron-specific enolase were measured using the Meso Scale Discovery, LLC. (MSD) electrochemiluminescence array-based multi-plex format (MSD, Gaithersburg, MD). Additional symptom and outcome data from boxers and patients, such as the Rivermead symptom scores (Rivermead Post Concussion Symptoms Questionnaire [RPQ-3]), were collected. We found that, subsequent to boxing bouts, there was a 1.8-fold increase in vWF levels within 30 min of injury (p < 0.0009). Moreover, fold-change in vWF correlates moderately (r = 0.51; p = 0.03) with the number of head blows. We also found a positive correlation (r = 0.69; p = 0.002) between fold-change in vWF and self-reported post-concussive symptoms, measured by the RPQ-3. The receiver operating curve analysis of vWF plasma levels and RPQ-3 scoring yielded a sensitivity of 94.12% and a specificity of 76.5% with an area under the curve of 83% for boxers after a fight compared to the pre-bout baseline. This study suggests that vWF is a potential blood biomarker measurable in the hyperacute period after blunt mild TBI. This biomarker may prove to be useful in diagnosing and monitoring traumatic vascular injury.

Age-Related Differences in the Time Course of Coagulation and Fibrinolytic Parameters in Patients with Traumatic Brain Injury

Coagulopathy and older age are common and well-recognized risk factors for poorer outcomes in traumatic brain injury (TBI) patients; however, the relationships between coagulopathy and age remain unclear. We hypothesized that coagulation/fibrinolytic abnormalities are more pronounced in older patients and may be a factor in poorer outcomes. We retrospectively evaluated severe TBI cases in which fibrinogen and D-dimer were measured on arrival and 3–6 h after injury. Propensity score-matched analyses were performed to adjust baseline characteristics between older patients (the “elderly group,” aged ≥75 y) and younger patients (the “non-elderly group,” aged 16–74 y). A total of 1294 cases (elderly group: 395, non-elderly group: 899) were assessed, and propensity score matching created a matched cohort of 324 pairs. Fibrinogen on admission, the degree of reduction in fibrinogen between admission and 3–6 h post-injury, and D-dimer levels between admission and 3–6 h post-injury were significantly more abnormal in the elderly group than in the non-elderly group. On multivariate logistic regression analysis, independent risk factors for poor prognosis included low fibrinogen and high D-dimer levels on admission. Posttraumatic coagulation and fibrinolytic abnormalities are more severe in older patients, and fibrinogen and D-dimer abnormalities are negative predictive factors.

Protein biomarkers of epileptogenicity after traumatic brain injury

Traumatic brain injury (TBI) is a major risk factor for acquired epilepsy. Post-traumatic epilepsy (PTE) develops over time in up to 50% of patients with severe TBI. PTE is mostly unresponsive to traditional anti-seizure treatments suggesting distinct, injury-induced pathomechanisms in the development of this condition. Moderate and severe TBIs cause significant tissue damage, bleeding, neuron and glia death, as well as axonal, vascular, and metabolic abnormalities. These changes trigger a complex biological response aimed at curtailing the physical damage and restoring homeostasis and functionality. Although a positive correlation exists between the type and severity of TBI and PTE, there is only an incomplete understanding of the time-dependent sequelae of TBI pathobiologies and their role in epileptogenesis. Determining the temporal profile of protein biomarkers in the blood (serum or plasma) and cerebrospinal fluid (CSF) can help to identify pathobiologies underlying the development of PTE, high-risk individuals, and disease modifying therapies. Here we review the pathobiological sequelae of TBI in the context of blood- and CSF-based protein biomarkers, their potential role in epileptogenesis, and discuss future directions aimed at improving the diagnosis and treatment of PTE.

Age-related differences in fibrinolytic parameters in patients with acute traumatic brain injury

Background:

Coagulopathy and old age have been associated with poor outcomes in traumatic brain injury (TBI) patients; however, the relationships of coagulopathy and age with the acute phase of TBI remain unclear. We hypothesized that coagulation/fibrinolytic abnormalities are more severe in older patients in the acute phase of TBI and may explain, in part, their poor outcome.

Methods:

We analyzed the relationship between coagulation/fibrinolytic parameters and age in the acute phase of TBI by retrospectively evaluating 274 patients with initial blood samples obtained no more than 1 hour after injury. Measurement of platelet count, prothrombin time, activated partial thromboplastin time, plasma levels of fibrinogen, and D-dimer was done in the emergency department on arrival as well as 3, 6, and 12 hours following injury. Values were compared between patients aged 16–55 years (group 1) and those aged older than 55 years (group 2) with an Abbreviated Injury Score (AIS)-head of 3–5 to identify any relationship between these parameters and age.

Results:

When groups 1 and 2 were matched for AIS-head, plasma levels of D-dimer in group 2 were significantly higher than those in group 1 from hospital admission to 12 hours after injury. The Glasgow Outcome Scale scores at 3 months post-injury of group 2 with AIS 4 and 5 were significantly lower than those of group 1 (both P < 0.0001).

Conclusions:

Fibrinolytic abnormalities are more severe in older acute-phase TBI patients, which may be a factor associated with their poor prognosis.

Time course of recovery from cerebral vulnerability after severe traumatic brain injury: a microdialysis study

BACKGROUND

The aim of this study was to evaluate the time course of recovery from cerebral vulnerability, using microdialysis (MD) technique and cerebral vascular autoregulation measurement, to clarify the appropriate timing of subsequent major surgical procedures, and to minimize the possibility of secondary brain injury in patients with severe traumatic brain injury (STBI).

METHODS

In 3,470 MD samples of 25 patients with STBI, cerebral extracellular biomarkers (glucose, lactate, pyruvate, glycerol, and glutamate) were measured. In addition, to estimate cerebral vascular autoregulaton, the pressure reactivity index (PRx) was calculated with intracranial pressure (ICP) and mean arterial pressure. The data with ICP, cerebral perfusion pressure (CPP), and PRx were collected hourly for 7 days after injury and they were compared with MD biomarkers daily.

RESULTS

During the study period, the average ICP and CPP remained stable and were within the threshold of STBI treatment guidelines. After injury, the extracellular glucose concentration decreased, and the levels of glycerol, glutamate, and lactate/pyruvate ratio (LPR), which indicate cerebral ischemia and neural cell damage, increased. On the fourth day after injury, the extracellular glucose concentration improved, and the value of LPR decreased. The average PRx decreased daily and became negative on the fifth day after injury.

CONCLUSION

Our results indicated that cerebral vascular autoregulation would recover on the fourth day after STBI, and cerebral perfusion might be increased by recovery of autoregulation. Thus, subsequent nonemergent surgery should be performed at least 4 days after STBI to prevent secondary brain injury. In addition, we should keep in mind that the cerebral vulnerability might persist for 4 days after suffering STBI.

Lower extracellular glucose level prolonged in elderly patients with severe traumatic brain injury: a microdialysis study

Age may be an independent predictor of outcomes in traumatic brain injury (TBI), but the causes of the poor outcomes in elderly patients remain unclear. To clarify the differences between elderly and young patients with TBI, brain metabolism parameters were monitored with the microdialysis method in 30 patients with severe TBI (Glasgow Coma Scale scores 3-8). The microdialysis probe was inserted in the penumbra area of the brain and extracellular levels of glucose, glutamate, glycerol, lactate, and pyruvate were measured hourly for the initial 168 hours (7 days) after operation. The lactate/pyruvate ratio, which is considered to be a good indicator of neuronal ischemia, was also calculated. The patients were divided into the elderly group aged 65 years or older and the young group aged less than 65 years, and the biochemical markers were compared daily between these two groups. The value of extracellular glucose concentration was significantly lower in the elderly group than in the young group, and continued until the 7th day after injury. Moreover, the lactate/pyruvate ratio peaked on the 5th day after injury in the elderly group, later than in the young group. We concluded that neural vulnerability persisted longer in elderly patients than in young patients with TBI, and this should be considered to prevent the occurrence of additional secondary brain injury.