Biochemical markers of cerebral injury in patients with minor head trauma and ethanol intoxication

A blood-based biomarker panel to risk-stratify mild traumatic brain injury

Mild traumatic brain injury (TBI) accounts for the vast majority of the nearly two million brain injuries suffered in the United States each year. Mild TBI is commonly classified as complicated (radiographic evidence of intracranial injury) or uncomplicated (radiographically negative). Such a distinction is important because it helps to determine the need for further neuroimaging, potential admission, or neurosurgical intervention. Unfortunately, imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) are costly and not without some risk. The purpose of this study was to screen 87 serum biomarkers to identify a select panel of biomarkers that would predict the presence of intracranial injury as determined by initial brain CT. Serum was collected from 110 patients who sustained a mild TBI within 24 hours of blood draw. Two models were created. In the broad inclusive model, 72kDa type IV collagenase (MMP-2), C-reactive protein (CRP), creatine kinase B type (CKBB), fatty acid binding protein-heart (hFABP), granulocyte-macrophage colony-stimulating factor (GM-CSF) and malondialdehyde modified low density lipoprotein (MDA-LDL) significantly predicted injury visualized on CT, yielding an overall c-statistic of 0.975 and a negative predictive value (NPV) of 98.6. In the parsimonious model, MMP-2, CRP, and CKBB type significantly predicted injury visualized on CT, yielding an overall c-statistic of 0.964 and a negative predictive value (NPV) of 97.2. These results suggest that a serum based biomarker panel can accurately differentiate patients with complicated mild TBI from those with uncomplicated mild TBI. Such a panel could be useful to guide early triage decisions, including the need for further evaluation or admission, especially in those environments in which resources are limited.

Clinical policy: neuroimaging and decisionmaking in adult mild traumatic brain injury in the acute setting

This clinical policy provides evidence-based recommendations on select issues in the management of adult patients with mild traumatic brain injury (TBI) in the acute setting. It is the result of joint efforts between the American College of Emergency Physicians and the Centers for Disease Control and Prevention and was developed by a multidisciplinary panel. The critical questions addressed in this clinical policy are: (1) Which patients with mild TBI should have a noncontrast head computed tomography (CT) scan in the emergency department (ED)? (2) Is there a role for head magnetic resonance imaging over noncontrast CT in the ED evaluation of a patient with acute mild TBI? (3) In patients with mild TBI, are brain specific serum biomarkers predictive of an acute traumatic intracranial injury? (4) Can a patient with an isolated mild TBI and a normal neurologic evaluation result be safely discharged from the ED if a noncontrast head CT scan shows no evidence of intracranial injury? Inclusion criteria for application of this clinical policy's recommendations are nonpenetrating trauma to the head, presentation to the ED within 24 hours of injury, a Glasgow Coma Scale score of 14 or 15 on initial evaluation in the ED, and aged 16 years or greater. The primary outcome measure for questions 1, 2, and 3 is the presence of an acute intracranial injury on noncontrast head CT scan; the primary outcome measure for question 4 is the occurrence of neurologic deterioration.

Mild traumatic brain injury

Mild traumatic brain injury accounts for 1% to 2% of emergency department visits in the United States. Up to 15% of these patients will have an acute intracranial lesion identified on head computed tomography; less than 1% of mild traumatic brain injuries will require neurosurgical intervention. Clinical research over the past decade has focused on identifying the subgroup of patients with mild traumatic brain injury with acute traumatic lesions on computed tomography and specifically those at risk for harboring a potentially catastrophic lesion. This research has been used to generate evidence-based guidelines to assist in clinical decision making. There is no evidence to support the use of plain film radiographs in the evaluation of patients with mild traumatic brain injury. The utility of brain-specific biomarkers is rapidly evolving, and a growing body of evidence supports their potential role in determining the need for neuroimaging. Clinical predictors for identifying patients with abnormal computed tomography have been established and, if used, may have a significant positive impact on traumatic brain injury-related morbidity and healthcare utilization in the United States. Patients with negative computed tomography are at almost no risk of deteriorating; however, they should be counseled regarding postconcussive symptoms and should be given appropriate written instructions and referrals at discharge.

Biomarkers in the clinical diagnosis and management of traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability among young adults. Numerous safety improvements in the workplace, the addition of airbags to vehicles, and the enforcement of speed limits have all helped to reduce the incidence and severity of head trauma. While improvements in emergency response times and acute care have increased TBI survivability, this has heightened the necessity for developing reliable methods to identify patients at risk of developing secondary pathologies. At present, the primary clinical indicators for the presence of brain injury are the Glasgow Coma Scale (GCS), pupil reactivity, and head computed tomography (CT). While these indices have proven useful for stratifying the magnitude and extent of brain damage, they have limited utility for predicting adverse secondary events or detecting subtle damage. Biomarkers, reflecting a biological response to injury or disease, have proven useful for the diagnosis of many pathological conditions including cancer, heart failure, infection, and genetic disorders. For TBI, several proteins synthesized in astroglial cells or neurons have been proposed as potential biomarkers. These proteins include the BB isozyme of creatine kinase (CK-BB, predominant in brain), glial fibrilary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE), and S100B.The presence of these biomarkers in the cerebrospinal fluid and serum of patients with moderate-to-severe TBI, and their correlation with outcome, suggest that they may have utility as surrogate markers in clinical trials. In addition, many of these markers have been found to be sensitive indicators of injury, and therefore may have the potential to diagnose persons with mild TBI. In addition to biomarkers that correlate with long-term outcome, a few studies have identified prognostic biomarkers for secondary injury that may be useful in individualizing patient management.

Blood genomic expression profile for neuronal injury

This study determined whether stroke and other types of insults produced a gene expression profile in blood that correlated with the presence of neuronal injury. Adult rats were subjected to ischemic stroke, intracerebral hemorrhage, status epilepticus, and insulin-induced hypoglycemia and compared with untouched, sham surgery, and hypoxia animals that had no brain injury. One day later, microarray analyses showed that 117 genes were upregulated and 80 genes were downregulated in mononuclear blood cells of the "injury" (n = 12) compared with the "no injury" (n = 9) animals. A second experiment examined the whole blood genomic response of adult rats after global ischemia and kainate seizures. Animals with no brain injury were compared with those with brain injury documented by TUNEL and PANT staining. One day later, microarray analyses showed that 37 genes were upregulated and 67 genes were downregulated in whole blood of the injury (n = 4) animals compared with the no-injury (n = 4) animals. Quantitative reverse transcription-polymerase chain reaction confirmed that the vesicular monoamine transporter-2 increased 2.3- and 1.6-fold in animals with severe and mild brain injury, respectively, compared with no-injury animals. Vascular tyrosine phosphatase-1 increased 2.0-fold after severe injury compared with no injury. The data support the hypothesis that there is a peripheral blood genomic response to neuronal injury, and that this blood response is associated with a specific blood mRNA gene expression profile that can be used as a marker of the neuronal damage.

Progression of skeletal muscle damage during treatment of severe falciparum malaria

To assess the relationship between severity of malaria and progression of skeletal muscle damage during initial treatment, we studied 28 Thai adults with slide-positive falciparum malaria. Six had uncomplicated malaria (Group 1), 12 had severe non-cerebral malaria (Group 2) and ten had cerebral malaria (Group 3). There were no significant differences between baseline serum creatine kinase (CK) levels in the three groups (P=0.071). There was no change in serum CK during the first 48 h of treatment in Group 1 cases. In Group 2 patients, the median peak serum CK was nine times that at baseline while in Group 3, serum CK peaked at a median concentration 20 times that at presentation. In Groups 2 and 3, the peak serum CK occurred at least 24 h after presentation in more than half the patients, and was independent of intramuscular injections and convulsions during initial therapy. These longitudinal data suggest that: (i) severe falciparum malaria is associated with skeletal muscle damage that increases during initial therapy especially in patients with coma; (ii) the effect of other major treatment or infection-specific factors that are associated with muscle damage does not diminish this relationship; and (iii) cerebral malaria in combination with a high baseline and rising serum CK should pre-empt monitoring and management strategies aimed at preserving renal function including renal dialysis.

The neglected prehospital phase of head injury: apnea and catecholamine surge

The prehospital phase of head injury, also called the critical phase, consists of trauma-induced apnea and stress catecholamine release. This immediate period after head injury remains poorly summarized in the literature and essentially ignored with respect to treatment. A MEDLINE search of the literature on apneustic response and catecholamine surge after head injury and a review of literature from my acquired references revealed 116 references (from more than 600) that were pertinent. Apnea induced by head injury produces hypoxia, hypercarbia, and subsequent cardiac failure and hypotension, which, along with substantially elevated catecholamine values, promote secondary mechanisms of organ injury. Treatment for this immediate period after head injury requires a rapid response to the scene of trauma and development of treatment options that can be instituted at the scene of injury.

Mild head trauma

Patients with mild traumatic brain injury constitute the overwhelming majority of head-injured patients seen in the emergency department. The indications for radiologic imaging in these patients are still undergoing study and revision. The Glasgow Coma Scale is a widely used triage score for head injury, but is less useful at identifying which patients with mild head injuries have intracranial pathology. There have been several retrospective studies and a few prospective studies examining the indications for imaging in mild to moderate head trauma. They all show that it is not easy to predict which patients will have CT abnormalities, and that some of these patients do go on to require neurosurgery. No set of clinical predictors have yet been put together that is capable of identifying all patients who are safe to be discharged without a CT scan. Pharmacologic therapy to help reduce axonal damage after head trauma and thus minimize the postconcussive sequelae of mild traumatic brain injury remains a challenge for physicians and neurobiologists into the next century.