Improved confidence of outcome prediction in severe head injury. A comparative analysis of the clinical examination, multimodality evoked potentials, CT scanning, and intracranial pressure

Prospective evaluation of a predictive model of mortality in patients with isolated head injury

BACKGROUND

In a previous retrospective study, we developed a predictive model of survival in isolated head injuries based on easily available parameters such as age, mechanism of injury, Glasgow Coma Scale, and head Abbreviated Injury Scale (AIS). The purpose of the present study is to prospectively evaluate this predictive model.

METHODS

Isolated head injuries admitted to a Level I urban trauma center were prospectively accrued from May 1, 2006 through April 30, 2007. Age, mechanism of injury, Glasgow Coma Scale, head AIS, and survival status were recorded for each patient. Patients with extracranial AIS >3, head AIS = 6, or hypotension were excluded. These data were entered into our previously developed predictive model and the percentage of correct classification was used to measure how well the predictive model predicted outcome. Sensitivity, specificity, positive and negative predictive values, and their 95% confidence intervals were calculated and compared with values obtained from our original, retrospective study.

RESULTS

Seven hundred eighty-six patients met the criteria for inclusion in the study with an overall mortality of 5.8% (46 patients). When entered into our predictive model, the percentage of correct classification rate was 92% compared with the 94% rate seen in the original study, which is better than other available predictive tools based on combined scoring systems such as the Trauma and Injury Severity Score methodology.

CONCLUSION

When evaluated prospectively, our predictive model has similar accuracy in predicting survival of all patients with head trauma as our original retrospective study and performs better than other predictive models such as the Trauma and Injury Severity Score methodology. This study demonstrates that a simple table based on easily obtained admission patient characteristics can rapidly provide information about the probability of survival in patients with head injuries.

Decompressive surgery for severe brain edema

Decompressive surgery has since long been a promising therapeutic approach for patients with acute severe brain injury at risk to develop severe brain edema. The underlying rationale of removing part of the cranium is to create space for the expanding brain to prevent secondary damage to vital brain tissue. However, until recently, randomized controlled trials that demonstrate the efficacy of decompressive surgery or benefit for outcome were missing. This has changed since the results of 3 randomized trials on hemicraniectomy in malignant infarction of the middle cerebral artery have been published in 2007. In this article, the current evidence for decompressive surgery in the treatment of cerebral ischemia, intracranial hemorrhage, traumatic brain injury, inflammatory diseases, or severe metabolic derangements is reviewed. Although there is increasing evidence for the efficacy of decompressive surgery in reducing intracranial pressure and even mortality, a critical point remains the definition of good or acceptable outcome.

Effect of 35 degrees C hypothermia on intracranial pressure and clinical outcome in patients with severe traumatic brain injury

BACKGROUND

From 1994, we have used therapeutic hypothermia in patients with severe traumatic brain injury (Glasgow Coma Scale scores of 5 or less). In 2000, we altered the target temperature to 35 degrees C from the former 33 degrees C, as our findings suggested that cooling to 35 degrees C is sufficient to control intracranial hypertension, and that hypothermia below 35 degrees C may predispose patients to persistent cumulative oxygen debt. We attempted to clarify whether 35 degrees C hypothermia has the same effect as 33 degrees C hypothermia in reducing intracranial hypertension and whether it is associated with fewer complications and improved outcomes.

METHODS

We compared intracranial pressure (ICP) and biochemical parameters in the 30 patients treated with 35 degrees C hypothermia (January 2000 to June 2005) with those in the 31 patients treated with 33 degrees C hypothermia (July 1994 to December 1999).

RESULTS

Patient characteristics were similar in the two groups. The mean temperature during hypothermia was 35.1 +/- 0.7 degrees C in the 35 degrees C hypothermia group and 33.4 +/- 0.8 degrees C in the 33 degrees C hypothermia group. Mean ICP was controlled under 20 mm Hg during hypothermia in both the 35 degrees C hypothermia and 33 degrees C hypothermia groups. The incidence of intracranial hypertension and low cerebral perfusion pressure did not differ between the two groups. The 35 degrees C hypothermic patients exhibited a significant improvement in the decline of serum potassium concentrations during hypothermia and in the increment of C-reactive protein after rewarming. The mortality rate and the incidence of systemic complications tended to be lower in the 35 degrees C group.

CONCLUSIONS

Cooling patients to 35 degrees C is safe and the ICP reduction effects of 35 degrees C hypothermia are similar to those of 33 degrees C hypothermia.

Classification of traumatic brain injury for targeted therapies

The heterogeneity of traumatic brain injury (TBI) is considered one of the most significant barriers to finding effective therapeutic interventions. In October, 2007, the National Institute of Neurological Disorders and Stroke, with support from the Brain Injury Association of America, the Defense and Veterans Brain Injury Center, and the National Institute of Disability and Rehabilitation Research, convened a workshop to outline the steps needed to develop a reliable, efficient and valid classification system for TBI that could be used to link specific patterns of brain and neurovascular injury with appropriate therapeutic interventions. Currently, the Glasgow Coma Scale (GCS) is the primary selection criterion for inclusion in most TBI clinical trials. While the GCS is extremely useful in the clinical management and prognosis of TBI, it does not provide specific information about the pathophysiologic mechanisms which are responsible for neurological deficits and targeted by interventions. On the premise that brain injuries with similar pathoanatomic features are likely to share common pathophysiologic mechanisms, participants proposed that a new, multidimensional classification system should be developed for TBI clinical trials. It was agreed that preclinical models were vital in establishing pathophysiologic mechanisms relevant to specific pathoanatomic types of TBI and verifying that a given therapeutic approach improves outcome in these targeted TBI types. In a clinical trial, patients with the targeted pathoanatomic injury type would be selected using an initial diagnostic entry criterion, including their severity of injury. Coexisting brain injury types would be identified and multivariate prognostic modeling used for refinement of inclusion/exclusion criteria and patient stratification. Outcome assessment would utilize endpoints relevant to the targeted injury type. Advantages and disadvantages of currently available diagnostic, monitoring, and assessment tools were discussed. Recommendations were made for enhancing the utility of available or emerging tools in order to facilitate implementation of a pathoanatomic classification approach for clinical trials.

Progression of traumatic intracerebral hemorrhage: a prospective observational study

ABSTRACT Preliminary evidence has shown that intracerebral hemorrhages, either spontaneous (sICH) or traumatic (tICH) often expand over time. An association between hemorrhage expansion and clinical outcomes has been described for sICH. The intent of this prospective, observational study was to characterize the temporal profile of hemorrhage progression, as measured by serial computed tomography (CT) scanning, with the aim of better understanding the natural course of hemorrhage progression in tICH. There was also a desire to document the baseline adverse event (AE) profile in this patient group. An important motive for performing this study was to set the stage for subsequent studies that will examine the role of a new systemic hemostatic agent in tICH. Subjects were enrolled if they had tICH lesions of at least 2 mL on a baseline CT scan obtained within 6 h of a head injury. CT scans were repeated at 24 and 72 h. Clinical outcomes and pre-defined AEs were documented. The data showed that 51% of the subjects demonstrated an increase in tICH volume, and that most of the increase occurred early. In addition, larger hematomas exhibited the greatest expansion. Thromboembolic complications were identified in 13% of subjects. This study demonstrates that tICH expansion between the baseline and 24-h CT scans occurred in approximately half of the subjects. The earlier after injury that the initial CT scan is obtained, the greater is the likelihood that the hematoma will expand on subsequent scans. The time frame during which hemorrhagic expansion occurs provides an opportunity for early intervention to limit a process with adverse prognostic implications.

A systematic review finds methodological improvements necessary for prognostic models in determining traumatic brain injury outcomes

OBJECTIVES

To describe the modeling techniques used for early prediction of outcome in traumatic brain injury (TBI) and to identify aspects for potential improvements.

STUDY DESIGN AND SETTING

We reviewed key methodological aspects of studies published between 1970 and 2005 that proposed a prognostic model for the Glasgow Outcome Scale of TBI based on admission data.

RESULTS

We included 31 papers. Twenty-four were single-center studies, and 22 reported on fewer than 500 patients. The median of the number of initially considered predictors was eight, and on average five of these were selected for the prognostic model, generally including age, Glasgow Coma Score (or only motor score), and pupillary reactivity. The most common statistical technique was logistic regression with stepwise selection of predictors. Model performance was often quantified by accuracy rate rather than by more appropriate measures such as the area under the receiver-operating characteristic curve. Model validity was addressed in 15 studies, but mostly used a simple split-sample approach, and external validation was performed in only four studies.

CONCLUSION

Although most models agree on the three most important predictors, many were developed on small sample sizes within single centers and hence lack generalizability. Modeling strategies have to be improved, and include external validation.

Intraventricular catheter placement by electromagnetic navigation safely applied in a paediatric major head injury patient

INTRODUCTION

In the management of severe head injuries, the use of intraventricular catheters for intracranial pressure (ICP) monitoring and the option of cerebrospinal fluid drainage is gold standard. In children and adolescents, the insertion of a cannula in a compressed ventricle in case of elevated intracranial pressure is difficult; therefore, a pressure sensor is placed more often intraparenchymal as an alternative option.

DISCUSSION

In cases of persistent elevated ICP despite maximal brain pressure management, the use of an intraventricular monitoring device with the possibility of cerebrospinal fluid drainage is favourable. We present the method of intracranial catheter placement by means of an electromagnetic navigation technique.

Traumatic brain injury in intoxicated patients

BACKGROUND

We sought to evaluate the effect alcohol intoxication may have had in nonsurgically treated patients with severe traumatic brain injury.

METHODS

The Montreal General Hospital Traumatic Brain Injury Registry was used to identify all adult patients with a Glasgow Coma Scale score < or =8 at admission, within a 15-month period. All charts were retrospectively reviewed.

RESULTS

Twenty-three patients had toxic blood alcohol levels (BAL > or =21.7 mmol/L), 24 were alcohol negative (BAL <3 mmol/L), and 10 were alcohol-influenced or had unknown BAL. Patients were more likely to have intracranial pressure monitoring if they had multiple intracranial hemorrhages, sustained multiple injuries, or had a post-resuscitative Glasgow Coma Scale score < or =8. Intoxicated patients had a mean delay of 151 minutes more in the insertion time of an intracranial pressure monitoring device, compared with alcohol-negative patients.

CONCLUSIONS

Alcohol was a confounding factor in the treatment of some of our patients.

[Management of patients with severe head injury in Hungary, in 2002]

In Hungary, epidemiological and clinical data regarding brain injury were rather scarce. The Hungarian Society for Neurotrauma aimed to make a nation-wide study about the number and the mortality of patients with severe head trauma, the organization of management, the diagnostics and monitoring in use, and finally about the clinical practice of management. A national survey was carried out with questionnaires asking about data of 2001, and a prospective, three-month-long data collection based on case studies was also executed in 2002. The Hungarian National Ambulance and Emergency Service centralized information gathering on rescue, and transportation. To collect data of hospital care, a network of regional coordinators and hospital communicators was developed. The responders covered 76% of the hospital neurotrauma care in the country. The number of brain trauma patients was close to 14,000 per year: 71.3% mild, 19.4% moderate, and 9.4% severe trauma. According to prospective study the mortality of those patients who were admitted as severe head injury patients was 55% and the mortality of those who got into severe condition later was 35% during the acute care. These data showed much worse outcome than those published in Western European countries and North America. In the background the authors found communication disorder between prehospital and hospital care, extreme long time spent until the patients got to the first CT-exam and to the definitive care. The implementation of Hungarian and international head trauma guidelines did not spread widely.

‘Talk and Die’ patients presenting to a major trauma centre over a 10 year period: A critical review

'Talk and die patients' describes a small number of patients who present with a mild head injury (Glasgow Coma Scale [GCS] 13-15) and then subsequently deteriorate and die from intracranial causes. We analysed the medical records of all those adult patients whose primary diagnosis as the cause of death was head injury, as determined by the coroner, who were admitted to a major Australian trauma centre between January 1994 and December 2003 (a 10-year period). The clinical profile of those patients who fulfilled the criteria of 'talk and die' were documented, including age, mode of injury, initial GCS, lucid interval, CT scan reports, operation performed, post mortem findings and intracranial cause of death. Factors considered potentially contributory to the patients' deterioration, such as delays in CT scanning or patient transfer, coagulopathy or hypoxic episodes were also noted. The incidence of 'talk and die' patients was 2.6% (15 out of 569) overall and the annual incidence did not significantly alter over the 10-year period of the study. The small number of patients precludes inferences regarding causal relationships, although potentially preventable factors, which could have been contributory to patient deterioration, were identified.

Clinical significance of alphaII-spectrin breakdown products in cerebrospinal fluid after severe traumatic brain injury

Following traumatic brain injury (TBI), the cytoskeletal protein alpha-II-spectrin is proteolyzed by calpain and caspase-3 to signature breakdown products. To determine whether alpha -II-spectrin proteolysis is a potentially reliable biomarker for TBI in humans, the present study (1) examined levels of spectrin breakdown products (SBDPs) in cerebrospinal fluid (CSF) from adults with severe TBI and (2) examined the relationship between these levels, severity of injury, and clinical outcome. This prospective case control study enrolled 41 patients with severe TBI, defined by a Glasgow Coma Scale (GCS) score of < or =8, who underwent intraventricular intracranial pressure monitoring. Patients without TBI requiring CSF drainage for other medical reasons served as controls. Ventricular CSF was sampled from each patient at 6, 12, 24, 48, 72, 96, and 120 h following TBI and analyzed for SBDPs. Outcome was assessed using the Glasgow Outcome Score (GOS) 6 months after injury. Calpain and caspase-3 mediated SBDP levels in CSF were significantly increased in TBI patients at several time points after injury, compared to control subjects. The time course of calpain mediated SBDP150 and SBDP145 differed from that of caspase-3 mediated SBDP120 during the post-injury period examined. Mean SBDP densitometry values measured early after injury correlated with severity of injury, computed tomography (CT) scan findings, and outcome at 6 months post-injury. Taken together, these results support that alpha -II-spectrin breakdown products are potentially useful biomarker of severe TBI in humans. Our data further suggests that both necrotic/oncotic and apoptotic cell death mechanisms are activated in humans following severe TBI, but with a different time course after injury.

Prognostic value of computerized tomography scan characteristics in traumatic brain injury: results from the IMPACT study

Computerized tomography (CT) scanning provides an objective assessment of the structural damage to the brain following traumatic brain injury (TBI). We aimed to describe and quantify the relationship between CT characteristics and 6-month outcome, assessed by the Glasgow Outcome Scale (GOS). Individual patient data from the IMPACT database were available on CT classification (N = 5209), status of basal cisterns ( N = 3861), shift ( N = 4698), traumatic subarachnoid hemorrhage (tSAH) ( N = 7407), and intracranial lesions ( N = 7613). We used binary logistic and proportional odds regression for prognostic analyses. The CT classification was strongly related to outcome, with worst outcome for patients with diffuse injuries in CT class III (swelling; OR 2.50; CI 2.09-3.0) or CT class IV (shift; OR 3.03; CI 2.12-4.35). The prognosis in patients with mass lesions was better for patients with an epidural hematoma (OR 0.64; CI 0.56-0.72) and poorer for an acute subdural hematoma (OR 2.14; CI 1.87-2.45). Partial obliteration of the basal cisterns (OR 2.45; CI 1.88-3.20), tSAH (OR 2.64; CI 2.42-2.89), or midline shift (1-5 mm-OR 1.36; CI 1.09-1.68); >5 mm-OR 2.20; CI 1.64-2.96) were strongly related to poorer outcome. Discrepancies were found between the scoring of basal cisterns/shift and the CT classification, indicating observer variation. These were less marked in studies that had used a central review process. Multivariable analysis indicated that individual CT characteristics added substantially to the prognostic value of the CT classification alone. We conclude that both the CT classification and individual CT characteristics are important predictors of outcome in TBI. For clinical trials, a central review process is advocated to minimize observer variability in CT assessment.

Prognostic value of demographic characteristics in traumatic brain injury: results from the IMPACT study

Outcome following traumatic brain injury (TBI) is not only dependent on the nature and severity of injury and subsequent treatment, but also on constituent characteristics of injured individuals. We aimed to describe and quantify the relationship between demographic characteristics and six month outcome assessed by the Glasgow Outcome Scale (GOS) after TBI. Individual patient data on age (n = 8719), gender (n = 8720), race (n = 5320), and education (n = 2201) were extracted from eight therapeutic Phase III randomized clinical trials and three surveys in moderate or severe TBI, contained in the IMPACT database. The strength of prognostic effects was analyzed with binary and proportional odds regression analysis and expressed as an odds ratio. Age was analyzed as a continuous variable with spline functions, and the odds ratio calculated over the difference between the 75 th and 25 th percentiles. Associations with other predictors were explored. Increasing age was strongly related to poorer outcome (OR 2.14; 95% CI 2.00-2.28) in a continuous fashion that could be approximated by a linear function. No gender differences in outcome were found (OR: 1.01; CI 0.92-1.11), and exploratory analysis failed to show any gender/age interaction. The studies included predominantly Caucasians (83%); outcome in black patients was poorer relative to this group (OR 1.30; CI 1.09-1.56). This relationship was sustained on adjusted analyses, and requires further study into mediating factors. Higher levels of education were weakly related to a better outcome (OR: 0.70; CI 0.52-0.94). On multivariable analysis adjusting for age, motor score, and pupils, the prognostic effect of race and education were sustained. We conclude that outcome following TBI is dependent on age, race, to a lesser extent on education, but not on gender.

Traumatic brain injury: intensive care management

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. The modern management of severe TBI has fallen into the domain of a multidisciplinary team led by neurointensivists, neuroanaesthetists, and neurosurgeons and is based on the avoidance of secondary injury, maintenance of cerebral perfusion pressure (CPP), and optimization of cerebral oxygenation. In this review, we will discuss the intensive care management of severe TBI with emphasis on the specific measures directed at the control of intracranial pressure and CPP.

Traumatic brain injury: assessment, resuscitation and early management

This review examines the evidence base for the early management of head-injured patients. Traumatic brain injury (TBI) is common, carries a high morbidity and mortality, and has no specific treatment. The pathology of head injury is increasingly well understood. Mechanical forces result in shearing and compression of neuronal and vascular tissue at the time of impact. A series of pathological events may then ensue leading to further brain injury. This secondary injury may be amenable to intervention and is worsened by secondary physiological insults. Various risk factors for poor outcome after TBI have been identified. Most of these are fixed at the time of injury such as age, gender, mechanism of injury, and presenting signs (Glasgow Coma Scale and pupillary signs), but some such as hypotension and hypoxia are potential areas for medical intervention. There is very little evidence positively in favour of any treatments or packages of early care; however, prompt, specialist neurocritical care is associated with improved outcome. Various drugs that target specific pathways in the pathophysiology of brain injury have been the subject of animal and human research, but, to date, none has been proved to be successful in improving outcome.

Outcomes of Blunt Head Trauma without Intracranial Pressure Monitoring

Although guidelines exist for intracranial pressure (ICP)-guided treatment after head trauma, no conclusive data exist that support routine ICP monitoring. A retrospective case series was reviewed of all patients admitted to the intensive care unit with a diagnosis of blunt head trauma between January 1, 1999 and December 31, 2004. None of the patients in the final analysis had ICP monitoring. Data collected included age, sex, mechanism of injury, Glasgow Coma Score (GCS) at admission, injury severity score, disposition, and length of stay. One hundred thirty-one patients with a median age of 41 years were included. There were 104 men (79%). The median GCS at admission was 12. There were 22 deaths (17% mortality). Stepwise logistic regression analysis identified older age, higher injury severity score, and lower GCS to be predictors of death. The mortality rate was higher in patients with GCS ≤8 compared with GCS >8 (33% vs 8%, respectively; P < 0.001). Ten of 23 patients with a GCS of 3 died (43% mortality). The median time to death for patients with a GCS of 3 was 2 days. Although the Brain Trauma Foundation has published guidelines advocating routine ICP monitoring, no large randomized prospective studies are available to determine its effect on outcome. None of the patients in this study had ICP monitoring. Our overall survival rate of 83 per cent is relatively high. Patients with a low GCS and, specifically, those with a GCS of 3 may not benefit from ICP monitoring because of early and irreversible trauma. Variability in the use of ICP monitoring will remain until ICP monitoring can be conclusively proven to improve outcome.

Hemodynamic manipulation in the neuro-intensive care unit: cerebral perfusion pressure therapy in head injury and hemodynamic augmentation for cerebral vasospasm

PURPOSE OF REVIEW

The intent of this manuscript is to summarize the pathophysiologic basis for hemodynamic manipulation in subarachnoid hemorrhage and traumatic brain injury, highlight the most recent literature and present expert opinion on indications and use.

RECENT FINDINGS

Hemodynamic augmentation with vasopressors and inotropes along with hypervolemia are the mainstay of treatment of vasospasm due to subarachnoid hemorrhage. Considerable variation continues to exist regarding fluid management and the use of vasopressors and inotropes. Blood pressure augmentation, volume expansion and cardiac contractility enhancement improve cerebral blood flow in ischemic areas, ameliorate vasospasm and improve clinical condition. In patients suffering from severe traumatic brain injury, while every attempt is made to control intracranial hypertension, cerebral perfusion-directed therapy with fluids and vasopressors is also used to keep cerebral perfusion pressure above 60-70 mmHg. Yet, recent observations suggest that posttraumatic mitochondrial dysfunction has been proposed as an alternative explanation for lower cerebral blood flow after acute trauma.

SUMMARY

Hemodynamic manipulation is routinely used in the management of patients with acute vasospasm following subarachnoid hemorrhage and severe head injury. The rationale is to improve blood flow to the injured brain and prevent secondary ischemia.

Role of intracranial pressure values and patterns in predicting outcome in traumatic brain injury: a systematic review

INTRODUCTION

Raised intracranial pressure (ICP) has been consistently associated with poor neurological outcome. Our purpose was to systematically review the literature to estimate the association between ICP values and patterns and short- and long-term vital and neurological outcome.

METHODS

Systematic review of studies identified from MEDLINE, EMBASE, and COCHRANE Registry search from 1966 to 2005, and reference lists of identified articles, with independent assessment of methodological quality, population, ICP values and patterns, management of raised ICP and neurological outcomes. Summary odds ratios (OR) were calculated for the main outcomes using proportional odds models and logistic regression.

RESULTS

Four prospective studies (409 patients) reported the effect of ICP values, and five studies (677 patients) reported the effect of ICP patterns on neurological outcome. No study reported neurological outcomes beyond 1 year. Relative to normal ICP (<20 mmHg), raised ICP was associated with elevated OR of death: 3.5 [95%CI: 1.7, 7.3] for ICP 20-40, and 6.9 [95%CI: 3.9, 12.4] for ICP>40. Raised but reducible ICP was associated with a 3-4-fold increase in the OR of death or poor neurological outcome. Refractory ICP pattern was associated with a dramatic increase in the relative risk of death (OR 114.3 [95%CI: 40.5, 322.3]).

CONCLUSIONS

Refractory ICP and response to treatment of raised ICP could be better predictors of neurological outcome than absolute ICP values. Limitations in the design of the studies analyzed precluded identification of the role of ICP monitoring in predicting short- and long-term outcomes.

A Review of the Predictive Ability of Glasgow Coma Scale Scores in Head-Injured Patients

According to 1999 data from the Centers for Disease Control and Prevention, traumatic brain injuries (TBI) caused by motor vehicle accidents, firearms, and falls are recorded as a leading cause of death and lifelong disability for young adults in the United States. Researchers have investigated if correlations exist between variables in the acute stage of injury and outcome measures in TBI patients. The Glasgow Coma Scale (GCS) score is one variable that was extensively studied for its ability to predict outcome in TBI patients. However, the use of different designs and methodologies in these studies makes the interpretation of the cumulative findings difficult. Therefore the purpose of this review was to provide a summary of the research findings on the ability of the GCS scores to predict outcome in TBI patients. A search was done on MEDLINE and CINAHL to identify studies that investigated the predictive ability of the GCS score. Studies that used the GCS as a variable in predicting outcome with adult patients who had sustained some type of head injury were included. GCS scores are most accurate at predicting outcome in head-injured patients when they are combined with patient age and pupillary response and when broad outcome categories are used. The motor component of the GCS yields similar prediction rates as the summed GCS score, and better prediction occurs with very high or very low GCS scores. Information about the cumulative research findings on the predictive ability of GCS scores aids nurses in providing support and education to family members during the acute stage of injury, and in coordinating the services of members of the healthcare team, which could result in improved outcomes for both patient and family.

Multivariable Prognostic Analysis in Traumatic Brain Injury: Results from The IMPACT Study

We studied the prognostic value of a wide range of conventional and novel prognostic factors on admission after traumatic brain injury (TBI) using both univariate and multivariable analysis. The outcome measure was Glasgow Outcome Scale at 6 months after injury. Individual patient data were available on a cohort of 8686 patients drawn from eight randomized controlled trials and three observational studies. The most powerful independent prognostic variables were age, Glasgow Coma Scale (GCS) motor score, pupil response, and computerized tomography (CT) characteristics, including the Marshall CT classification and traumatic subarachnoid hemorrhage. Prothrombin time was also identified as a powerful independent prognostic factor, but it was only available for a limited number of patients coming from three of the relevant studies. Other important prognostic factors included hypotension, hypoxia, the eye and verbal components of the GCS, glucose, platelets, and hemoglobin. These results on prognostic factors will underpin future work on the IMPACT project, which is focused on the development of novel approaches to the design and analysis of clinical trials in TBI. In addition, the results provide pointers to future research, including further analysis of the prognostic value of prothrombin time, and the evaluation of the clinical impact of intervening aggressively to correct abnormalities in hemoglobin, glucose, and coagulation.

Brief review: Practice variation in end of life care in the ICU: implications for patients with severe brain injury

PURPOSE

To review end of life care issues in the intensive care unit (ICU) and how practice variation might affect the ultimate outcome of acute brain injury.

SOURCES

Bibliographic literature search and personal files.

FINDINGS

In Canada, 10-20% of critically ill adults die in the ICU. Many of these deaths follow acute brain injury in the setting of clinical deterioration, life support limitation and brain death. This brief review addresses some key elements of end of life care for critically ill brain injured patients, including family interactions, making survival predictions, and factors influencing decision-making about cardiopulmonary resuscitation and withdrawal of mechanical ventilation.

CONCLUSIONS

Provision of compassionate high quality end of life care should be standard of practice for brain injured and all other critically ill patients who cannot survive. Inconsistencies in end of life care may affect where, when and how patients die, the quality of their death and whether or not they are considered for organ and tissue donation.

Early Prediction of Mortality in Isolated Head Injury Patients: A New Predictive Model

BACKGROUND

To construct a predictive model of survival in isolated head injury patients, on the basis of easily available parameters that are independent risk factors for survival outcome.

METHODS

Trauma registry-based study of head injury patients who had no other major extracranial injuries and were not hypotensive at admission. A predictive model of probability of death was constructed using discriminant analysis, on the basis of admission Glasgow Coma Scale (GCS) score, head Abbreviated Injury Score (AIS), age, and mechanism of injury.

RESULTS

The study included 7,191 patients with head trauma. The overall correct classification rate of the proposed predictive model was 94.2% as compared with 89.0% of the admission GCS score (p < 0.05) and 92.8% of the head AIS (p < 0.05). The correct classification rate of the predictive model developed for the severe head trauma (GCS score 4-8) patients was 79.9%, as compared with 72.6% using the admission GCS score alone or 75.1% (p < 0.05). A one-page, easy to use table summarizing the predicted mortality on the basis of GCS score, head AIS, mechanism of injury, and age was developed.

CONCLUSIONS

The proposed model has a significantly better predictive power, especially in severe head trauma, than the extensively used GCS and head AIS. A simple table on the probability of death of a particular patient based on admission GCS score, head AIS, mechanism of injury and age of patient can provide instant information.

Prognostic role of proton magnetic resonance spectroscopy in acute traumatic brain injury

Proton magnetic resonance spectroscopy (MRS) is being used to evaluate individuals after acute traumatic brain injury. These studies have shown that changes in certain brain metabolites are associated with poor neurologic outcomes. The majority of MRS studies have been obtained relatively late after injury, but there have been a few reports of use early after injury to assist with outcome prediction. Altered brain metabolites may be sensitive indicators of injury and thus provide additional prognostic information when spectroscopy is done early after injury. This technology may provide a noninvasive means to evaluate early excitotoxic injury, and show changes associated with both neuronal injury and membrane disruption secondary to diffuse axonal injury. This article will review the technology of MRS, discuss its role in patient assessment after traumatic brain injury, and present a summary of our published and ongoing research.

Apoptosis of neuronal cells induced by serum of patients with acute brain injury: a new in vitro prognostic model

OBJECTIVE

To investigate whether serum draining from the jugular bulb of patients with traumatic or haemorrhagic brain injury induced apoptosis of neuronal PC12 cells in vitro and whether the apoptotic rate correlated with patients' outcome at 6 months.

DESIGN AND SETTING

Prospective clinical investigation in a 21-bed intensive care unit (ICU) in a university hospital.

PATIENTS

Seventy patients who had suffered from acute brain injury requiring intensive care.

INTERVENTIONS

Jugular bulb vein and systemic samples were obtained on admission to the ICU and after 48 h. PC12 cells were incubated in the presence of 10% of heat-inactivated patient's sera and apoptotic rate was determined by flow cytometry using annexin V and 7-aminoactinomycin D.

RESULTS

Regional serum draining from the lesions induced higher early apoptosis of PC12 cells than systemic serum. Early apoptotic rate, Glasgow coma score, APACHE II score and the presence of pupil abnormalities were associated with mortality at 6 months in univariate statistical analyses. In logistic regression analysis only early apoptotic rate was an independent factor associated with mortality at 6 months (odds ratio: 1.502, 95% CI 1.2-1.9; p<0.001). The final model has a sensitivity of 82.4% and a specificity of 84.8% for predicting death within 6 months.

CONCLUSIONS

We developed a simple and reproducible in vitro model for predicting outcome in patients with traumatic or haemorrhagic brain injury that survived in the early phase. Our in vitro model combined with clinical and radiological measurements might improve the value of prognostic models to predict acute brain injury patients' outcome.

Over-Complete Discrete Wavelet Transformation of the Normal Auditory Brainstem Response Improves Prediction of Outcome following Severe Acute Closed Head Injury

Previous research has shown that complex statistical analysis (discriminant function analysis) of a 'normal' auditory brainstem response (ABR) result can improve this measure's ability to predict subject outcome following severe acute closed head injury (ACHI). We hypothesized that adding the ABR's time-frequency information to such an analysis would improve this predictive value even further. 'Normal' ABR results were sampled from 69 severe ACHI subjects (22 of whom died and 47 of whom lived) and their time-frequency information extracted using an over-complete discrete wavelet transformation (OCDWT). A series of logistic regression analyses then showed correct predictions of death and survival as follows: ABR measures only 72 and 89% (respectively), ABR OCDWT measures only 82 and 89% (respectively), and ABR and ABR OCDWT measures combined 86 and 93% (respectively). These results showed that the addition of time-frequency information can improve the ability of the 'normal' ABR result to predict outcome following severe ACHI.

Critical score of Glasgow Coma Scale for pediatric traumatic brain injury

The aim of this study is to determine the predictive critical value of the Glasgow Coma Scale for use as a determinant of outcome for children with traumatic brain injuries. A total of 309 children, aged 2-10 years, were enrolled in this study. Each subject underwent the following assessments: Glasgow Coma Scale; clinical data; brain computed tomography; and Glasgow Outcome Scale assessments. The receiver operating characteristic curve indicated that a critical point of the Glasgow Coma Scale set at 5 was most strongly correlated with outcome of pediatric traumatic brain injury. Subarachnoid hemorrhage with brain swelling and edema, subdural, intracerebral hemorrhage, and basal ganglion lesions were associated with severe injury and poor outcome (P < 0.05). However, cortical lesions did not affect injury severity and outcome. In injuries associated with traumatic brain injuries, only chest trauma had a tendency to be associated with poor outcome (P < 0.05). Of the factors analyzed, the score of the Glasgow Coma Scale was the most effective predictor for outcome in pediatric traumatic brain injury. Furthermore, the predictive critical score of the Glasgow Coma Scale should be set at 5 for pediatric traumatic brain injury. The computed tomographic findings also were important in determining injury severity and predicting outcome.

Do trauma patients with a Glasgow Coma Scale score of 3 and bilateral fixed and dilated pupils have any chance of survival?

BACKGROUND

Low Glasgow Coma Scale score (GCS) and pupillary status predict poor outcomes in head injury (HI) patients. We compared the mortality of GCS 3 patients having bilateral fixed and dilated pupils (BFDP) with GCS 3 patients having reactive pupils (RP). We then determined if trauma system or patient factors were responsible for the difference in mortality.

METHODS

We reviewed all adult, blunt HI patients with GCS=3, admitted to our institution from January 1, 2001 to December 31, 2003. Demographics, injury data, prehospital times, procedures, and outcomes were recorded.

RESULTS

During this period, 245 patients were admitted with GCS of 3, and met inclusion criteria. In all, 173 patients were analyzed, after excluding 23 patients who were dead-on-arrival, and 45 others, who were intoxicated with alcohol, or received paralytic agents in the trauma room. All BFDP patients died, whereas 42.0% of reactive pupil (RP) patients died (p < 0.0001). With regards to patient factors, BFDP patients were more likely to be unstable, have extra-axial bleeding, and evidence of midline shift and/or herniation. Trauma system factors, however, may also have had an impact on outcome. Despite having more extra-axial bleeding, BFDP patients were less likely to have a neurosurgical operation than RP patients.

CONCLUSION

Patients with GCS of 3 and BFDP have a dismal prognosis. These patients have suffered devastating brain injuries and tend to be hemodynamically unstable. Clinicians, however, are less likely to aggressively treat BFDP patients than RP patients. Further prospective studies are required to determine which patients with GCS of 3 and BFDP are likely to benefit from aggressive treatment.

Case mix, outcomes and comparison of risk prediction models for admissions to adult, general and specialist critical care units for head injury: a secondary analysis of the ICNARC Case Mix Programme Database

INTRODUCTION

This report describes the case mix and outcome (mortality, intensive care unit (ICU) and hospital length of stay) for admissions to ICU for head injury and evaluates the predictive ability of five risk adjustment models.

METHODS

A secondary analysis was conducted of data from the Intensive Care National Audit and Research Centre (ICNARC) Case Mix Programme, a high quality clinical database, of 374,594 admissions to 171 adult critical care units across England, Wales and Northern Ireland from 1995 to 2005. The discrimination and calibration of five risk prediction models, SAPS II, MPM II, APACHE II and III and the ICNARC model plus raw Glasgow Coma Score (GCS) were compared.

RESULTS

There were 11,021 admissions following traumatic brain injury identified (3% of all database admissions). Mortality in ICU was 23.5% and in-hospital was 33.5%. Median ICU and hospital lengths of stay were 3.2 and 24 days, respectively, for survivors and 1.6 and 3 days, respectively, for non-survivors. The ICNARC model, SAPS II and MPM II discriminated best between survivors and non-survivors and were better calibrated than raw GCS, APACHE II and III in 5,393 patients eligible for all models.

CONCLUSION

Traumatic brain injury requiring intensive care has a high mortality rate. Non-survivors have a short length of ICU and hospital stay. APACHE II and III have poorer calibration and discrimination than SAPS II, MPM II and the ICNARC model in traumatic brain injury; however, no model had perfect calibration.

Predicting Outcome after Traumatic Brain Injury: Development and Validation of a Prognostic Score Based on Admission Characteristics

The early prediction of outcome after traumatic brain injury (TBI) is important for several purposes, but no prognostic models have yet been developed with proven generalizability across different settings. The objective of this study was to develop and validate prognostic models that use information available at admission to estimate 6-month outcome after severe or moderate TBI. To this end, this study evaluated mortality and unfavorable outcome, that is, death, and vegetative or severe disability on the Glasgow Outcome Scale (GOS), at 6 months post-injury. Prospectively collected data on 2269 patients from two multi-center clinical trials were used to develop prognostic models for each outcome with logistic regression analysis. We included seven predictive characteristics-age, motor score, pupillary reactivity, hypoxia, hypotension, computed tomography classification, and traumatic subarachnoid hemorrhage. The models were validated internally with bootstrapping techniques. External validity was determined in prospectively collected data from two relatively unselected surveys in Europe (n = 796) and in North America (n = 746). We evaluated the discriminative ability, that is, the ability to distinguish patients with different outcomes, with the area under the receiver operating characteristic curve (AUC). Further, we determined calibration, that is, agreement between predicted and observed outcome, with the Hosmer-Lemeshow goodness-of-fit test. The models discriminated well in the development population (AUC 0.78-0.80). External validity was even better (AUC 0.83-0.89). Calibration was less satisfactory, with poor external validity in the North American survey (p < 0.001). Especially, observed risks were higher than predicted for poor prognosis patients. A score chart was derived from the regression models to facilitate clinical application. Relatively simple prognostic models using baseline characteristics can accurately predict 6-month outcome in patients with severe or moderate TBI. The high discriminative ability indicates the potential of this model for classifying patients according to prognostic risk.

Clinical Elements that Predict Outcome after Traumatic Brain Injury: A Prospective Multicenter Recursive Partitioning (Decision-Tree) Analysis

Traumatic brain injury (TBI) often presents clinicians with a complex combination of clinical elements that can confound treatment and make outcome prediction challenging. Predictive models have commonly used acute physiological variables and gross clinical measures to predict mortality and basic outcome endpoints. The primary goal of this study was to consider all clinical elements available concerning a survivor of TBI admitted for inpatient rehabilitation, and identify those factors that predict disability, need for supervision, and productive activity one year after injury. The Traumatic Brain Injury Model Systems (TBIMS) database was used for decision tree analysis using recursive partitioning (n = 3463). Outcome measures included the Functional Independence Measure(), the Disability Rating Scale, the Supervision Rating Scale, and a measure of productive activity. Predictor variables included all physical examination elements, measures of injury severity (initial Glasgow Coma Scale score, duration of post-traumatic amnesia [PTA], length of coma, CT scan pathology), gender, age, and years of education. The duration of PTA, age, and most elements of the physical examination were predictive of early disability. The duration of PTA alone was selected to predict late disability and independent living. The duration of PTA, age, sitting balance, and limb strength were selected to predict productive activity at 1 year. The duration of PTA was the best predictor of outcome selected in this model for all endpoints and elements of the physical examination provided additional predictive value. Valid and reliable measures of PTA and physical impairment after TBI are important for accurate outcome prediction.

The role of decompressive craniectomy in the management of traumatic brain injury: a critical review

Brain swelling and intracranial hypertension following severe head injury are known to contribute to secondary brain damage, and have been shown to adversely affect patient outcome. The use of unilateral craniectomy following the evacuation of a mass lesion, such as acute subdural haematoma or traumatic intracerebral haematoma, is accepted practice. The following review focuses on a bi-fronto-temporal decompressive craniectomy, used as an isolated operation for the control of intracranial hypertension, secondary to diffuse brain swelling refractory to medical management. Though the operation is being increasingly used, current opinion is still divided regarding its overall effects on outcome. This review examines the experimental and clinical evidence for and against the use of decompressive craniectomy, highlights the lack of class I evidence relevant to this topic and emphasises the necessity for well-designed prospective randomised controlled trials.

Predictive value of an early Glasgow Outcome Scale score: 15-month score changes

Object. Does an early Glasgow Outcome Scale (GOS) assessment provide a reliable indicator of later outcome in a patient with traumatic brain injury (TBI)? The authors examined the utility of the GOS during early treatment as a predictor of outcome score 15 months postinjury by analyzing outcome score change in a group of patients with closed head injuries.

Methods. Glasgow Outcome Scale scores assessed within 3 months of injury (baseline) were compared with scores obtained at 15 months postinjury in 121 patients, primarily young military personnel. Score changes between baseline and 8 months postinjury were also studied in a subgroup of 72 patients. The impact of initial injury severity (determined by the duration of unconsciousness) on score change was also explored. The GOS scores at three time points within the 15-month period—baseline (within 3 months of injury), 8, and 15 months postinjury—were examined to ascertain when the maximal GOS score had been reached.

Conclusions. Baseline GOS score was a reliable predictor of outcome in patients with an initial score of 5 (no disability) or 4 (mild disability), but not in patients with an initial score of 3 (severe disability). Patients who remained unconscious for more than 24 hours did not have significantly lower outcome scores than those who experienced loss of consciousness for less than 24 hours at 15 months postinjury. Interestingly, the duration of unconsciousness did not affect the likelihood of an improved score during the study period in patients with a GOS score of 3 or 4 at baseline. An updated evaluation conducted after the early phases of treatment is needed to provide a realistic prognosis of severe TBI.

Severe brain injuries in children

Authors present a seven years retrospective study on 85 cases of severe brain injuries (SBI) in children (GCS </= 8) treated in the Pediatric and ICU Departments of the Clinic Hospital "Bagdasar-Arseni" Bucharest, Romania. The relationship between ICP, GCS on admission, the CT-scan/MRI alteration and the outcome evaluated by the Glasgow Outcome Scale (GOS) were studied in order to highlight the most important factors to improve prognosis. An overall mortality of 25.9% was found in this series. Authors concluded that the ICP values at admission >/= 20 mmHg, the Diffuse Axonal Injury (DAI) on MRI and the GCS on admission are factors of prognosis in SBI in children. The politrauma context is an aggravating factor for SBI in this age group. Other factors which influence GCS on admission may have prognostic importance i.e.: prehospital care, transport time and adequate transport conditions.

Late Auditory and Event-Related Potentials Can Be Useful to Predict Good Functional Outcome After Coma

OBJECTIVE

To investigate whether late auditory and event-related potentials, and in particular N100 and mismatch negativity, together with clinical parameters, can help to predict good functional outcome in comatose patients.

DESIGN

Prospective cohort study.

SETTING

Hospital.

PARTICIPANTS

Consecutively sampled comatose patients (N=346) whose etiologies of coma were stroke (125 patients), brain injury (96 patients), anoxia (64 patients), complication of neurosurgery (54 patients), and encephalitis (7 patients).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Glasgow Outcome Scale score at 1 year postonset. Patients in a minimally conscious state and those who awoke and died during the follow-up period were classified separately.

RESULTS

Univariate analysis showed that all variables studied, except brainstem auditory evoked potentials, correlated significantly with functional outcome. Mismatch negativity showed the highest positive predictive value for good outcome. A validated model was obtained with multivariate logistic analysis, including pupillary light reflex, N100, mismatch negativity, etiology, and age.

CONCLUSIONS

Late auditory and event-related potentials, and particularly N100 and mismatch negativity, provide strong prognostic factors for good functional outcome. Furthermore, these components may enhance the accuracy of prognosis when associated with other clinical parameters available at the early stage of coma.

Are somatosensory evoked potentials the best predictor of outcome after severe brain injury? A systematic review

OBJECTIVE

Many tests have been used to predict outcome following severe brain injury. We compared predictive powers of clinical examination (pupillary responses, motor responses and Glasgow Coma Scale, GCS), electroencephalography (EEG) and computed tomography (CT) to that of somatosensory evoked potentials (SEPs) in a systematic review.

MATERIALS AND METHODS

Medline (1976-2002) and Embase (1980-2002) were searched, manual review of article reference lists was conducted, and authors were contacted. We selected 25 studies addressing the prediction of outcome after severe brain injury using SEPs and either GCS, EEG, CT, pupillary or motor responses. Outcomes were determined for patients with normal or bilaterally absent SEPs and graded measures of GCS, EEG, CT, pupillary responses or motor responses. For favourable outcome prediction SEPs were superior in sensitivity, specificity and positive and negative predictive values, except for pupillary responses which had superior sensitivity and GCS which had higher specificity. SEPs had superior summary receiver operating characteristic curves, with the exception of motor responses, and superior ratio of odds ratios. For unfavourable outcome prediction SEPs were superior to the other tests in sensitivity, specificity and positive and negative predictive values, except for motor and pupillary responses, GCS and CTs which had superior sensitivity. All SEP summary receiver operating characteristic curves and pooled ratio of odds ratios were superior.

CONCLUSIONS

Although imperfect, SEPs appear to be the best single overall predictor of outcome. There is sufficient evidence for clinicians to use SEPs in the prediction of outcome after brain injury.

Evoked potentials in severe brain injury

Three-modality evoked potentials (EPs) have been used for several years in association with the electroencephalogram (EEG) as a diagnostic and prognostic tool in acute traumatic or nontraumatic coma. In 1993 we proposed to combine these in two indices: the index of global cortical function (IGCF) and the index of brain-stem conduction (IBSC). Four EP patterns based on both indices emerge at the acute stage of severe head trauma. These are easily explainable by pathophysiology. Pattern 1 corresponds to alterations in the index of global cortical function without changes in the index of brain-stem conduction. Its prognosis is good (80 to 90% of these patients recover). Pattern 2 is characterized by alterations of somatosensory EPs that are suggestive of midbrain dysfunction. The prognosis depends both on the reversibility of the midbrain dysfunction and on the extent of associated diffuse axonal lesions, whose evaluation requires MRI. Patients who recovered from Pattern 2 sometimes did so after a long interval during which they remained vegetative. Pattern 3 is characterized by alterations of brain-stem auditory EPs that are suggestive of pontine involvement. It usually follows uncontrolled intracranial hypertension and corresponds to evolving transtentorial herniation. All patients with that transient pattern eventually died. Pattern 4 is categorized by the disappearance of all activities of intracranial origin, contrasting with the preservation of all activities of retinal, spinal-cord, and peripheral-nerve origin. This pattern corresponds to brain death. In our experience, three-modality EPs are currently the best bedside brain-death confirmatory tool.

Proton MRS in Acute Traumatic Brain Injury: Role for Glutamate/Glutamine and Choline for Outcome Prediction

Proton magnetic resonance spectroscopy (MRS) is being used to evaluate individuals with acute traumatic brain injury and several studies have shown that changes in certain brain metabolites (N-acetylaspartate, choline) are associated with poor neurologic outcomes. The majority of previous MRS studies have been obtained relatively late after injury and none have examined the role of glutamate/ glutamine (Glx). We conducted a prospective MRS study of 42 severely injured adults to measure quantitative metabolite changes early (7 days) after injury in normal appearing brain. We used these findings to predict long-term neurologic outcome and to determine if MRS data alone or in combination with clinical outcome variables provided better prediction of long-term outcomes. We found that glutamate/glutamine (Glx) and choline (Cho) were significantly elevated in occipital gray and parietal white matter early after injury in patients with poor long-term (6-12-month) outcomes. Glx and Cho ratios predicted long-term outcome with 94% accuracy and when combined with the motor Glasgow Coma Scale score provided the highest predictive accuracy (97%). Somatosensory evoked potentials were not as accurate as MRS data in predicting outcome. Elevated Glx and Cho are more sensitive indicators of injury and predictors of poor outcome when spectroscopy is done early after injury. This may be a reflection of early excitotoxic injury (i.e., elevated Glx) and of injury associated with membrane disruption (i.e., increased Cho) secondary to diffuse axonal injury.

[Prognostic factors in severe head injury]

The knowledge of the so called prognostic factors or indicators involved in severe head injury (SHI) is an issue of great interest to make predictions about the future of patients with this pathology. Those indicators constitute the basic elements of the different prognostic formulas or models carried out in order to make predictions in SHI. The mentioned models, therefore, will be constructed by a group of variables (prognostic indicators or factors) and several scales (prognostic scales) that are useful for measuring the final outcome of these patients. In this paper we resume, after an exhaustive review of the literature, the knowledge about the prognostic factors related to SHI. These indicators have been classified as follows: clinical, radiological, physiological, and biochemical. Moreover, we have briefly described the prognostic scales more commonly used in SHI.

Lessons from epidemiologic studies in clinical trials of traumatic brain injury

Lessions from epidemiological studies. The Clinical Trial Group for Neurosurgery of the University of California San Diego (UCSD) is involved in epidemiological studies and trials of new pharmacological agents in traumatic brain injury. A great number (> 10,000) of patients has been prospectively analyzed forming an integrated database for further purposes. The development of these databases is based on earlier work by the European Neurosurgeons Jennett and Braakmann and the US-Traumatic Coma Data Bank Study. These studies allowed for the development of sophisticated data collection instruments which were used in the international Tirilizad Trials which enrolled over 1,100 patients. A major observation from that trial was that pretreatment hypotension or hypoxia could be unbalanced even in a large two arm blinded study. Another issue of the tirilazad trial was the influence of gender affecting not only outcome but also drug metabolism. Similar experiences were gathered with the phase-III trial on the competitive NMDA-receptor antagonist selfotel, which interferes with the excitotoxic amino acid glutamate as mediator of secondary brain damage, as ischemia-induced neuronal degeneration. Unfortunately, the trial, already underway, had to be prematurely aborted, since concurrent stroke studies with enrollment of nonintubated patients on low-dose selfotel revealed an increased number of deaths and other adverse events. A retrospective analysis did not confirm that Selfotel was associated with an increased mortality in TBI, but there was also no evidence that the drug was efficacious. A problem here was that a major portion of patients did not have intracranial mass lesions (contusion, subdural haematoma) on CT, questioning whether these had a treatment responsive brain injury. Both studies on tirilazad or selfotel underscore the significance of well designed and conducted phase-I and -II trials to characterize the pharmacokinetics of the agent, to confirm availability of drug in the brain, and to identify a sufficient number of patients with lesions responding to the drug. A major issue is the blood-brain barrier permeability of the agent under study. Further, the phenomenon of secondary deterioration - neurological worsening - turned out as a powerful predictor of poor outcome. The findings and conclusions of both clinical trials (tirilazad, selfotel) were utilized for a subsequent patient study on CP101-606 in consultation with the Pfizer company, the US Brain Injury Consortium, and the San Diego Clinical Trial Group. The patient population was a priori selected towards responsiveness of the brain lesions to the treatment. The major conclusions are: I Development of therapeutic regimens targeted towards the mechanisms of brain injury. II Availability of adequate preclinical data. III Directing treatment towards an appropriate patient population. IV Central gathering and interpretation of the neuroradiological findings. V Monitoring of trial center performance. VI Stratification and pre-trial prognostic analysis for identification of subgroups.

Patient age and outcome following severe traumatic brain injury: an analysis of 5600 patients

OBJECT

Increasing age is associated with poorer outcome in patients with closed traumatic brain injury (TBI). It is uncertain whether critical age thresholds exist, however, and the strength of the association has yet to be investigated across large series. The authors studied the shape and strength of the relationship between age and outcome, that is, the 6-month mortality rate and unfavorable outcome based on the Glasgow Outcome Scale.

METHODS

The shape of the association was examined in four prospective series with individual patient data (2664 cases). All patients had a closed TBI and were of adult age (96% < 65 years of age). The strength of the association was investigated in a metaanalysis of the aforementioned individual patient data (2664 cases) and aggregate data (2948 cases) from TBI studies published between 1980 and 2001 (total 5612 cases). Analyses were performed with univariable and multivariable logistic regression. Proportions of mortality and unfavorable outcome increased with age: 21 and 39%, respectively, for patients younger than 35 years and 52 and 74%, respectively, for patients older than 55 years. The association between age and both mortality and unfavorable outcome was continuous and could be adequately described by a linear term and expressed even better statistically by a linear and a quadratic term. The use of age thresholds (best fitting threshold 39 years) in the analysis resulted in a considerable loss of information. The strength of the association, expressed as an odds ratio per 10 years of age, was 1.47 (95% confidence interval [CI] 1.34-1.63) for death and 1.49 (95% CI 1.43-1.56) for unfavorable outcome in univariable analyses, and 1.39 (95% CI 1.3-1.5) and 1.46 (95% CI 1.36-1.56), respectively, in multivariable analyses. Thus, the odds for a poor outcome increased by 40 to 50% per 10 years of age.

CONCLUSIONS

An older age is continuously associated with a worsening outcome after TBI; hence, it is disadvantageous to define the effect of age on outcome in a discrete manner when we aim to estimate prognosis or adjust for confounding variables.

The prognostic value of evoked responses from primary somatosensory and auditory cortex in comatose patients

OBJECTIVE

To evaluate somatosensory and auditory primary cortices using somatosensory evoked potentials (SEPs) and middle latency auditory evoked potentials (MLAEPs) in the prognosis of return to consciousness in comatose patients.

METHODS

SEPs and MLAEPs were recorded in 131 severe comatose patients. Latencies and amplitudes were measured. Coma had been caused by transient cardiac arrest (n=49), traumatic brain injury (n=22), stroke (n=45), complications of neurosurgery (n=12) and encephalitis (n=3). One month after the onset of coma patients were classified as awake, still comatose or dead. Three months after (M3), they were classified into one of the 5 categories of the Glasgow outcome scale (GOS).

RESULTS

At M3, 41.2% were dead, 47.3% were conscious (GOS 3-5) and 11.5% had not recovered consciousness. None of the patients in whom somatosensory N20 and auditory Pa were absent did return to consciousness and in the post-anoxic group, reduced cortical amplitude too was always associated with bad outcome. Conversely, N20 and Pa were present, respectively, in 33/69 and 34/69 patients who did not recover.

CONCLUSIONS

The prognostic value of SEPs and MLAEPs in comatose patients depends on the cause of coma. Measurement of response amplitudes is informative. Abolition of cortical SEPs and/or cortical MLAEPs precludes post-anoxic comatose patients from returning to consciousness (100% specificity). In any case, the presence of short latency cortical somatosensory or auditory components is not a guarantee for return to consciousness. Late components should then be recorded.

A different approach to missile induced head injuries

Missile induced head injuries can be influenced by the anatomical location of the injury, i.e. type of tissue and by the ballistic properties such as the design of the weapon and the mass, shape and construction of the projectile, as well as its velocity characteristics and trajectory angle. In the diagnostic work up of the patients with missile induced head injuries, every available modality can be used. It is important, however, to recognize that CT scan is the primary and most efficacious diagnostic tool in such patients. In this article we have identified risk factors for both morbidity and mortality in patients with missile induced head injury with excluding the patients who had also extracranial serious trauma and systemic disease.

Noninvasive intracranial compliance and pressure based on dynamic magnetic resonance imaging of blood flow and cerebrospinal fluid flow: review of principles, implementation, and other noninvasive approaches

Current techniques for intracranial pressure (ICP) measurement are invasive. All require a surgical procedure for placement of a pressure probe in the central nervous system and, as such, are associated with risk and morbidity. These considerations have driven investigators to develop noninvasive techniques for pressure estimation. A recently developed magnetic resonance (MR) imaging-based method to measure intracranial compliance and pressure is described. In this method the small changes in intracranial volume and ICP that occur naturally with each cardiac cycle are considered. The pressure change during the cardiac cycle is derived from the cerebrospinal fluid (CSF) pressure gradient waveform calculated from the CSF velocities. The intracranial volume change is determined by the instantaneous differences between arterial blood inflow, venous blood outflow, and CSF volumetric flow rates into and out of the cranial vault. Elastance (the inverse of compliance) is derived from the ratio of the measured pressure and volume changes. A mean ICP value is then derived based on a linear relationship that exists between intracranial elastance and ICP. The method has been validated in baboons, flow phantoms, and computer simulations. To date studies in humans demonstrate good measurement reproducibility and reliability. Several other noninvasive approaches for ICP measurement, mostly nonimaging based, are also reviewed. Magnetic resonance imaging-based ICP measurement may prove valuable in the diagnosis and serial evaluation of patients with a variety of disorders associated with alterations in ICP.

Predictive value of somatosensory evoked potentials for awakening from coma

OBJECTIVES

A systematic review of somatosensory evoked potentials performed early after onset of coma, to predict the likelihood of nonawakening. The pooled results were evaluated for rates of awakening, confidence intervals, and the possibility of rare exceptions.

DATA SOURCES

Forty-one articles reporting somatosensory evoked potentials in comatose patients and subsequent outcomes, from 1983 to 2000.

STUDY SELECTION

Studies were included if they reported coma etiology, age group, presence or absence of somatosensory evoked potentials, and coma outcomes.

DATA EXTRACTION

We separated patients into four groups: adults with hypoxic-ischemic encephalopathy, adults with intracranial hemorrhage, adults and adolescents with traumatic brain injury, and children and adolescents with any etiologies. Somatosensory evoked potentials were categorized as normal, abnormal, or bilaterally absent. Outcomes were categorized as persistent vegetative state or death vs. awakening.

DATA SYNTHESIS

For each somatosensory evoked potential result, rates of awakening (95% confidence interval) were calculated: adult hypoxic-ischemic encephalopathy: absent 0% (0%-1%), abnormal 22% (17%-26%), normal 52% (48%-56%); adult intracranial hemorrhage: absent 1% (0%-4%), present 38% (27%-48%); adult-teen traumatic brain injury: absent 5% (2%-7%), abnormal 70% (64%-75%), normal 89% (85%-92%); child-teen: absent 7% (4%-10%), abnormal 69% (61%-77%), normal 86% (80%-92%).

CONCLUSIONS

Somatosensory evoked potential results predict the likelihood of nonawakening from coma with a high level of certainty. Adults in coma from hypoxic-ischemic encephalopathy with absent somatosensory evoked potential responses have <1% chance of awakening.