Predicting outcome from closed head injury by early assessment of trauma severity

Diffuse Axonal Injury: Clinical Prognostic Factors, Molecular Experimental Models and the Impact of the Trauma Related Oxidative Stress. An Extensive Review Concerning Milestones and Advances

Traumatic brain injury (TBI) is a condition burdened by an extremely high rate of morbidity and mortality and can result in an overall disability rate as high as 50% in affected individuals. Therefore, the importance of identifying clinical prognostic factors for diffuse axonal injury (DAI) in (TBI) is commonly recognized as critical. The aim of the present review paper is to evaluate the most recent contributions from the relevant literature in order to understand how each single prognostic factor determinates the severity of the clinical syndrome associated with DAI. The main clinical factors with an important impact on prognosis in case of DAI are glycemia, early GCS, the peripheral oxygen saturation, blood pressure, and time to recover consciousness. In addition, the severity of the lesion, classified on the ground of the cerebral anatomical structures involved after the trauma, has a strong correlation with survival after DAI. In conclusion, modern findings concerning the role of reactive oxygen species (ROS) and oxidative stress in DAI suggest that biomarkers such as GFAP, pNF-H, NF-L, microtubule associated protein tau, Aβ42, S-100β, NSE, AQP4, Drp-1, and NCX represent a possible critical target for future pharmaceutical treatments to prevent the damages caused by DAI.

Prognosis in prolonged coma patients with diffuse axonal injury assessed by somatosensory evoked potentia

A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent (grades I–III) according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.

Time to recover consciousness in patients with diffuse axonal injury : assessment with reference to magnetic resonance grading

OBJECTIVE

This study was conducted to investigate the correlation between the degrees of injury on brain magnetic resonance imaging (MRI) and the time interval to recovery of consciousness in patients with diffuse axonal injury.

METHODS

From January 2004 to December 2008, 25 patients with diffuse axonal injury were treated at our hospital. We retrospectively investigated the patients' medical records and radiological findings. We divided the patients into three groups according to the grade of MRI finding : grade I, small scattered lesions on the white matter of the cerebral hemisphere; grade II, focal lesions on the corpus callosum; and grade III, additional focal lesions on the brain stem.

RESULT

Seven patients belonged to the grade I group; 10 to the grade II group; and 8 to the grade III group. The mean Glasgow Coma Scale (GCS) score of all patients at the time of admission was 7.28. Recovery of consciousness was observed in 23 of the 25 patients; the remaining two patients never regained consciousness. The time interval to recovery of consciousness (awake status) ranged from 1 day to 125 days (mean 22.1 days) : grade I group patients, within approximately 1 week (mean 3.7 days); grade II group patients, within approximately 2 weeks (mean 12.5 days); and grade III group patients, within approximately 2 months (mean 59.5 days).

CONCLUSION

Our study results suggest a correlation between the mean time interval to recovery of consciousness in patients with diffuse axonal injuries and the degrees of brain injuries seen on MRI. Patients with grade I and II diffuse axonal injuries recovered consciousness within 2 weeks, while patients with grade III injuries required approximately 2 months.

Brain trauma in head injuries presenting with and without concurrent skull fractures

Head injuries and skull fractures may be problematic in cause and manner of death. Over a 10-year period, 54 cases showing head injuries were studied. Of these, 34 had skull fractures and 20 had no skull fractures. Virtually all decedents with skull fractures had brain injuries. The most common injury in both groups was motor vehicle accidents (MVA), in which 50% had skull fractures. In cases of skull fracture, brain lacerations, hemorrhages, and cerebral edema were common. Of 20 decedents with head injury but no skull fracture, most were accidents, and all but 3 cases had brain injury, although often relatively minor, except for atlanto-occiptital dislocation. There were significant differences between the two groups. Decedents with skull fractures tended to by younger (mean 35 years) compared to those with head injury only (mean 52 years) (p=0.0021). The use of drugs or alcohol was more likely in decedents with skull fractures than in those with head trauma only (p=0.0431). Mean abbreviated injury scale scores were higher for the face and head/neck of decedents with skull fractures, while significantly lower for chest and extremities, compared to decedents without skull fractures. Brain injury of some kind occurred in 90% of cases of head trauma, so a high level of suspicion should be placed in seeking skull fractures or brain injury.

Traumatic brain injury in young children: postacute effects on cognitive and school readiness skills

Previous studies have documented weaknesses in cognitive ability and early academic readiness in young children with traumatic brain injury (TBI). However, few of these studies have rigorously controlled for demographic characteristics, examined the effects of TBI severity on a wide range of skills, or explored moderating influences of environmental factors on outcomes. To meet these objectives, each of three groups of children with TBI (20 with severe, 64 with moderate, and 15 with mild) were compared with a group of 117 children with orthopedic injuries (OI group). The children were hospitalized for their injuries between 3 and 6 years of age and were assessed an average of 1 1/2 months post injury. Analysis revealed generalized weaknesses in cognitive and school readiness skills in the severe TBI group and less pervasive effects of moderate TBI. Indices of TBI severity predicted outcomes within the TBI sample and environmental factors moderated the effects of TBI on some measures. The findings document adverse effects of TBI in early childhood on postacute cognitive and school readiness skills and indicate that these effects are related to both injury severity and the family environment.

Assessment of mitochondrial impairment in traumatic brain injury using high-resolution proton magnetic resonance spectroscopy

Object

The goal of this study was to demonstrate the posttraumatic neurochemical damage in normal-appearing brain and to assess mitochondrial dysfunction by measuring N-acetylaspartate (NAA) levels in patients with severe head injuries, using proton (1H) magnetic resonance (MR) spectroscopy.

Methods

Semiquantitative analysis of NAA relative to creatine-containing compounds (Cr) and choline (Cho) was carried out from proton spectra obtained by means of chemical shift (CS) imaging and single-voxel (SV) methods in 25 patients with severe traumatic brain injuries (TBIs) (Glasgow Coma Scale scores ≤ 8) using a 1.5-tesla MR unit. Proton MR spectroscopy was also performed in 5 healthy volunteers (controls).

Results

The SV studies in patients with diffuse TBI showed partial reduction of NAA/Cho and NAA/Cr ratios within the first 10 days after injury (means ± standard deviations 1.59 ± 0.46 and 1.44 ± 0.21, respectively, in the patients compared with 2.08 ± 0.26 and 2.04 ± 0.31, respectively, in the controls; nonsignificant difference). The ratios gradually declined in all patients as time from injury increased (mean minimum values NAA/Cho 1.05 ± 0.44 and NAA/Cr 1.05 ± 0.30, p < 0.03 and p < 0.02, respectively). This reduction was greater in patients with less favorable outcomes. In patients with focal injuries, the periphery of the lesions revealed identical trends of NAA/Cho and NAA/Cr decrease. These reductions correlated with outcome at 6 months (p < 0.01). Assessment with multivoxel methods (CS imaging) demonstrated that, in diffuse injury, NAA levels declined uniformly throughout the brain. At 40 days postinjury, initially low NAA/Cho levels had recovered to near baseline in patients who had good outcomes, whereas no recovery was evident in patients with poor outcomes (p < 0.01).

Conclusions

Using 1H-MR spectroscopy, it is possible to detect the posttraumatic neurochemical damage of the injured brain when conventional neuroimaging techniques reveal no abnormality. Reduction of NAA levels is a dynamic process, evolving over time, decreasing and remaining low throughout the involved tissue in patients with poor outcomes. Recovery of NAA levels in patients with favorable outcomes suggests marginal mitochondrial impairment and possible resynthesis from vital neurons.

[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.

Premorbid intellectual functioning, education, and brain size in traumatic brain injury: an investigation of the cognitive reserve hypothesis

Cognitive reserve theories have been postulated in an attempt to explain individual differences in functional outcome following cerebral insult or disease. These theories suggest that higher education and psychometric intelligence may preserve functional capacity regardless of injury or disease severity. This study investigated cognitive reserve in 25 participants with traumatic brain injury (TBI) using high-resolution magnetic resonance imaging (MRI) analyses. We examined the relationships between total intracranial volume (TICV), ventricle-tobrain ratio (VBR), education level, and standardized testing obtained prior to injury with post-injury cognitive outcome. Participants with lower post-injury IQ scores had significantly lower TICV values, irrespective of injury severity, and experienced significantly greater change in IQ from pre- to post-injury. TICV and education correctly predicted participants' post-injury IQ category ( Y 90 or < 90). However, premorbid standardized testing (PST) scores did not predict cognitive outcome. The results of this study suggest that larger premorbid brain volume and higher education level may decrease vulnerability to cognitive deficits following TBI, consistent with the notion of a cognitive reserve.

Long-term physical impairment and functional outcomes after complex facial fractures

To develop an understanding of the expected functional outcomes after facial trauma, a retrospective cohort study of patients with complex facial fractures was conducted. A cohort of adults aged 18 to 55 years who were admitted to the R. Adams Cowley Shock Trauma Center between July of 1986 and July of 1994 for treatment of a Le Fort midface fracture (resulting from blunt force) was retrospectively identified. Outcomes of interest included measures of general health status and psychosocial well being in addition to self-reported somatic symptoms. General health status was ascertained using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36). The Body Satisfaction Scale was used to define patient concerns about altered body image and shape. To determine whether complex maxillofacial trauma and facial fractures contributed to altered social interactions, the Social Avoidance and Distress scale was used. In addition, information about a patient, his or her injury, and its treatment were ascertained from the medical records. Using the methods described above, 265 patients with Le Fort fractures were identified. These individuals were matched to a similar group of 242 general injury patients. A total of 190 of the Le Fort patients (72 percent of those eligible for the study) and 144 (60 percent) general injury patients were successfully located, and long-term interview data were acquired.Le Fort fracture patients as a group had similar health status outcomes when compared with the group of general injury patients. However, when outcomes were examined by the complexity of the Le Fort fracture, the authors found that study subjects with severe, comminuted Le Fort injuries (group D) had significantly lower SF-36 scores (worse outcomes) for the two dimensions related to role limitations: role limitations due to physical problems and role limitations due to emotional problems (p < 0.05). SF-36 scores for all other dimensions except physical function were also lower for comminuted versus less complex Le Fort fractures, although differences were not statistically significant.Specifically, there was a direct relationship between severity of facial injury and patients reporting work disability. Of group C and D Le Fort patients (severely comminuted fractures) only 55 and 58 percent, respectively, had returned to work at the time of follow-up interview. These figures are significantly lower than the back-to-work percentage of patients with less severe facial injury (70 percent). When study participants were asked if they were experiencing specific somatic symptoms at the time of the interview that they had not experienced before the injury, a significantly larger percent of the Le Fort fracture patients (compared with the general injury patients) responded in the affirmative. Differences between the Le Fort fracture and general injury groups were statistically significant (p < 0.05) for all 11 symptoms. The percentage of patients reporting complaints increased with increasing complexity of facial fracture in the areas of visual problems, alterations in smell, difficulty with mastication, difficulty with breathing, and epiphora, and these differences reached statistical significance. Patients sustaining comminuted Le Fort facial fractures report poorer health outcomes than patients with less severe facial injury and substantially worse outcomes than population norms. It is also this severely injured population that reports the greatest percentage of injury-related disability, preventing employment at long-term follow-up. The long-term goal of centralized tertiary trauma treatment centers must be to return the patient to a productive, active lifestyle.

Do women fare worse: a metaanalysis of gender differences in traumatic brain injury outcome

OBJECT

The purpose of this metaanalysis was to investigate possible gender differences in traumatic brain injury (TBI) sequelae. The case fatality rates in patients after TBI have previously been shown to be significantly higher in women as compared with men.

METHODS

A quantitative review of published studies of TBI outcome revealed eight studies (20 outcome variables) of TBI, in which outcome was reported separately for men and women.

CONCLUSIONS

Outcome was worse in women than in men for 85% of the measured variables, with an average effect size of -0.15. Although clinical opinion is often that women tend to experience better outcomes than men after TBI, the opposite pattern was suggested in the results of this metaanalysis. However, this conclusion is limited by the fact that, in only a small percentage of the total published reports on TBI outcome, was outcome described separately for each sex. A careful, prospective study of sex differences in TBI outcome is clearly needed.

A study of the functional outcome and mortality in elderly patients with head injuries

The aim of this study was to determine the functional outcome and mortality in relation to the Glasgow coma score (GCS) on presentation in patients aged over 65 years with acute head injury. 2331 patients with head injury were identified by searching the neurosurgery database (1984-1996); 191 met the inclusion criteria and systematic review of medical records was undertaken. Functional outcome on discharge from hospital and mortality were tested statistically against GCS on presentation. Mortality overall was 33. 5%. All 59 patients with GCS <11 on presentation had poor outcomes on discharge from hospital. Comparison with outcome for the 132 patients with GCS >/=11, of whom 91 had satisfactory outcomes, was highly statistically significant (P<0.001). Elderly patients with presenting GCS <11 due to acute head injury have poor functional outcomes and high mortality rates. Conservative treatment of these patients should be considered.

Do women fare worse? A metaanalysis of gender differences in outcome after traumatic brain injury

The purpose of this metaanalysis was to investigate possible gender differences in TBI sequelae. The case fatality rates in patients after TBI have previously been shown to be significantly higher in women as compared with men. A quantitative review of published studies of TBI outcome revealed eight studies (20 outcome variables) of TBI in which outcome was reported separately for men and women. Outcome was worse in women than in men for 85% of the measured variables, with an average effect size of −0.15. Although clinical opinion is often that women tend to experience better outcomes than do men after TBI, the opposite pattern was suggested in the results of this metaanalysis. However, this conclusion is limited by the fact that in only a small percentage of the total published reports on TBI outcome was outcome described separately for each sex. A careful, prospective study of sex differences in TBI outcome is clearly needed.

Predicting survival using simple clinical variables: a case study in traumatic brain injury

OBJECTIVES

Prediction of patient outcome can be useful as an aid to clinical decision making, to explore possible biological mechanisms, and as part of the clinical audit process. Many studies have constructed predictive models for survival after traumatic brain injury, but these have often used expensive, time consuming, or highly specialised measurements. The aim of this study was to develop a simple easy to use model involving only variables which are rapidly and easily clinically achievable in routine practice.

METHODS

All consecutive patients admitted to a regional trauma centre with moderate or severe head injury were enrolled in the study. Basic demographic, injury, and CT characteristics were recorded. Patient survival at 1 year was used to construct a simple predictive model which was then validated on a very similar patient group.

RESULTS

372 patients were included in the study, of whom 365 (98%) were followed up for survival at 1 year. Multiple logistic regression resulted in a model containing age (p<0.001), Glasgow coma scale score (p<0.001), injury severity score (p<0.001), pupil reactivity (p=0.004), and presence of haematoma on CT (p=0.004) as independently significant predictors of survival. The model was validated on an independent set of 520 patients, showing good discrimination and adequate calibration, but with a tendency to be pessimistic about very severely injured patients. It is presented as an easy to use nomogram.

CONCLUSIONS

All five variables have previously been shown to be related to survival. All variables in the model are clinically simple and easy to measure rapidly in a centre with access to 24 hour CT, resulting in a model that is both well validated and clinically useful.

The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores

BACKGROUND

The Glasgow Coma Scale (GCS), which is the foundation of the Trauma Score, Trauma and Injury Severity Score, and the Acute Physiology and Chronic Health Evaluation scoring systems, requires a verbal response. In some series, up to 50% of injured patients must be excluded from analysis because of lack of a verbal component for the GCS. The present study extends previous work evaluating derivation of the verbal score from the eye and motor components of the GCS.

METHODS

Data were obtained from a state trauma registry for 24,565 unintubated patients. The eye and motor scores were used in a previously published regression model to predict the verbal score: Derived Verbal Score = -0.3756 + Motor Score * (0.5713) + Eye Score * (0.4233). The correlation of the actual and derived verbal and GCS scales were assessed. In addition the ability of the actual and derived GCS to predict patient survival in a logistic regression model were analyzed using the PC SAS system for statistical analysis. The predictive power of the actual and the predicted GCS were compared using the area under the receiver operator characteristic curve and Hosmer-Lemeshow goodness-of-fit testing.

RESULTS

A total of 24,085 patients were available for analysis. The mean actual verbal score was 4.4 +/- 1.3 versus a predicted verbal score of 4.3 +/- 1.2 (r = 0.90, p = 0.0001). The actual GCS was 13.6 + 3.5 versus a predicted GCS of 13.7 +/- 3.4 (r = 0.97, p = 0.0001). The results of the comparison of the prediction of survival in patients based on the actual GCS and the derived GCS show that the mean actual GCS was 13.5 + 3.5 versus 13.7 + 3.4 in the regression predicted model. The area under the receiver operator characteristic curve for predicting survival of the two values was similar at 0.868 for the actual GCS compared with 0.850 for the predicted GCS.

CONCLUSIONS

The previously derived method of calculating the verbal score from the eye and motor scores is an excellent predictor of the actual verbal score. Furthermore, the derived GCS performed better than the actual GCS by several measures. The present study confirms previous work that a very accurate GCS can be derived in the absence of the verbal component.

Measurement of post-traumatic amnesia: how reliable is it?

OBJECTIVE

To develop and test a clinical protocol for determining post-traumatic amnesia by retrospective questioning. To establish its limits and factors which influence reliability.

DESIGN

Two independent assessments using the Rivermead post-traumatic amnesia protocol were undertaken by separate observers on various groups of patients at various time intervals. Analysis investigated the correlations between assessments, the percentage difference between assessments, the number of patients changing category, and the differences between these analyses in the different patient subgroups. Assessments were undertaken both in hospital and in the patients' homes. Four different patient groups were studied. These were group A: 12 inpatients with very severe head injury late after injury; Group B: 40 patients interviewed at home six months after injury; group C: 22 patients interviewed within a few weeks of injury at home; group D: 116 patients interviewed initially within a few weeks and then at six months, on both occasions at home. The Rivermead post-traumatic amnesia protocol involved clinical questioning of the patient to establish how long after injury (in hours/days/weeks) the patient regained continuous day to day memory. All periods of coma were included. Severity was categorised with standard criteria.

RESULTS

Overall correlation was good (Spearman's r 0.79), but the correlation was lower for patients with post-traumatic amnesia < 24 hours and when there was a long delay between assessments. In all groups 19%-25% of patients changed categories between assessments, but only 2% changed by two categories.

CONCLUSIONS

The assessment of post-traumatic amnesia with the Rivermead post-traumatic amnesia protocol is reasonably reliable. The misclassification rate however, is significant enough that some caution should be taken in individual cases. Other evidence does show post-traumatic amnesia to be valid, and it probably remains the best simple prognostic item available. In clinical practice one should avoid placing too much weight on post-traumatic amnesia alone.

Appropriate use of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores

The Glasgow Coma Scale (GCS) has been shown to be a valuable tool in assessing the neurologic and physiologic status of critically ill patients. Unfortunately, the GCS requires assessment of the verbal response of the patient and this can be blocked by intubation. The purpose of this study was to assess the ability of a regression model based upon the eye and motor components of the GCS to accurately predict the verbal response of the GCS. The primary hypothesis was that the verbal response could be derived from the motor and eye responses of the GCS.

METHODS

Data were collected prospectively in an intensive care unit computer data base. Patients were divided into training and test data sets. Linear regression was used to derive a model of verbal score from the motor and eye scores of the GCS in the training data set. Correlation between the actual and the predicted verbal scores was calculated.

RESULTS

A total of 2,521 GCS assessments were available for analysis. The second order multiple regression model was an accurate predictor of the verbal score (Pearson's Correlation r = 0.9, R2 = 0.8, p = 0.0001) in 1,463 observations in the training data set. Second Order Multiple Regression Model: Estimated GCS Verbal = (2.3976) + [GCS Motor x (-0.9253)] + [GCS Eye x (-0.9214)] + [(GCS Motor)2 x (0.2208)] + [(GCS Eye)2 x (0.2318)] where r = 0.91, R2 = 0.83, and p = 0.0001. The accuracy of this model was confirmed by comparing the predicted verbal score to the actual verbal score in the test data set (n = 736, r = 0.92, R2 = 0.85, p = 0.0001)

CONCLUSIONS

The GCS is a useful tool in the intensive care unit and a critical part of the APACHE II assessment of patient acuity. GCS has been shown to be a useful tool in its own right as a predictor of outcome in the critically ill. Its use is limited with intubation. (See Segatore M, Way C: Heart Lung 21:548, 1992; and Lieh-Lai MW, Theodorou AA, Sarnaik AP, et al: J Pediatr 120:195, 1992.) The present study demonstrates that a relatively simple regression model can use the eye and motor components of the GCS to predict the expected verbal component of the GCS, thus allowing the calculation of the GCS sum score in intubated patients.

Predicting survival from head trauma 24 hours after injury: a practical method with therapeutic implications

OBJECTIVE

To develop a method to predict long-term outcome after head injury and determine if outcome can be accurately predicted 24 hours after injury.

DESIGN

A retrospective review was performed on a study cohort of 672 head-injured patients admitted in coma (Glascow Coma Scale score < or = 8) who remained comatose for at least 6 hours, survived more than 24 hours, and had 6-month outcome data available. Stepwise logistic regression analysis was used to determine which clinical variables predicted 6-month outcome. Statistically significant clinical predictors were combined into a single examination variable (MPX score), which reflected a rank-ordering of examinations from worst to best, which was then further weighted by patient age. The relation between 6-month outcome and MPX score at admission and 24 hours was plotted and analyzed.

MEASUREMENT AND MAIN RESULTS

Age, best motor score, and pupillary reactivity at admission and 24 hours were significant predictors of outcome; extraocular motility was predictive at 24 hours only. Age was the most important independent predictor, followed by best motor score, pupillary reactivity, and extraocular motility. Combining these predictors into MPX score resulted in a set of graphs that reliably predicted long-term outcome. The 24-hour MPX data were better predictors of 6-month outcome and were more specific in predicting negative outcomes than admission data.

CONCLUSIONS

The method is simple to use, relying on bedside neurologic examination and a single graph, but appears to predict long-term outcome accurately as early as 24 hours after head injury. If validated on other large series of patients, this method could provide an objective and practical basis for terminating care in patients unlikely to survive a head injury.

Post-traumatic apallic syndrome following head injury. Part 1: clinical characteristics

Epidemiological studies made within the western countries indicate an incidence of 200-300 traumatic head injuries per 100 000 residents each year. Severe head injuries account for 5-25% of all head injuries; 10-14% of all severe head-injured patients develop into a vegetative state, in which a sleep-wake rhythm is apparent, but however in which there is no evidence of awakeness or reactivity to the environment. The most commonly used labels, in the German and international literature, for these patients are 'vegetative state', 'apallic syndrome' and 'coma vigile'. This clinical characterization is not sufficient. It is necessary to employ additional criteria to distinguish subsets of vegetative patients e.g. computerized tomography, magnetic resonance imaging, single photon emission tomography, electroencephalography, brainstem reflexes, evoked potentials, assessment scales, age, premorbid brain disorders. Diagnostic and prognostic parameters must form the basis for various decisions relating to patients' care and intervention.

Prediction of recovery from traumatic brain injury

This paper encompasses the prediction of early and late recovery from traumatic brain injury (TBI). Predictors of the duration of coma and the utilization of posttraumatic amnesia duration to predict residual memory function are discussed. The issues surrounding prediction of long-term neurobehavioral recovery from TBI are considered, particularly the patient and clinical variables that are related to intellectual recovery. Findings from the NIH Traumatic Coma Data are reviewed pertaining to testability as a criterion for outcome. In addition to discussing the relationship of specific neurologic indices of TBI as predictors, the results obtained using a regression model are summarized. Finally, the relationship of neuroimaging findings to neurobehavioral outcome is discussed including directions for future research.

Withholding and withdrawing of life support from patients with severe head injury

OBJECTIVE

To characterize the withholding or withdrawing of life support from patients with severe head injury.

SETTING

San Francisco General Hospital, a city and county hospital with a Level I trauma center.

DESIGN

A standardized questionnaire was used to collect data on demographics and functional outcome of severely head-injured (Glasgow Coma Score of < or = 7) patients admitted to the medical-surgical intensive care unit, and to interview the patients' physician and family members.

PATIENTS

Forty-seven patients who were admitted to a medical-surgical intensive care unit over a 1-yr period.

INTERVENTIONS

Twenty-four patients had life support withheld or withdrawn, and 23 patients did not.

MEASUREMENTS AND MAIN RESULTS

Physician and family separately assessed patient's probable functional outcome, degree of communication between them, reasons important in recommending or deciding on discontinuation of life support, and the result of action taken. Six months later, the families reviewed the process of their decision, how well physician(s) had communicated, and what might have improved communication. Of 24 patients with life support discontinued, 22 died; two were discharged from the hospital. Twenty-three of the 24 patients had a poor prognosis on admission. Of the 23 patients who were continued on life support for the duration of their hospitalization, ten had a poor (p < .001) prognosis on admission. Prognosis improved for two patients from the first group and five from the latter. Family's assessment of prognosis agreed with physician's assessment in 22 of the 24 patients from whom life support was discontinued (p < .001). Physicians' ability to convey the prognosis appeared to influence families' assessments. Physicians' considerations in recommending limitation of care and families' considerations in making decisions were the same, primarily an inevitably poor prognosis. Neither physician nor families cited cost or availability of care as a deciding factor. Two families disagreed with the recommendation to limit care after initial agreement because the patients' prognosis improved from "likely death" to "vegetative." Care was therefore continued, and both patients remained vegetative 6 months after admission to the hospital and discharge to chronic care facilities.

CONCLUSIONS

Life support is commonly withheld or withdrawn from patients with severe head injury at San Francisco General Hospital, and usually it is accompanied by death. A reciprocal consideration exists in most cases between the physician and family making the difficult decision to limit care. Care is provided for patients whose families request it despite physician recommendations.

The Head Injury Severity Scale (HISS): a practical classification of closed-head injury

The authors introduce a two-dimensional scale for rating closed-head injury, the Head Injury Severity Scale (HISS). This system is based on a five-interval severity classification (minimal through critical), determined primarily by the initial post-resuscitation Glasgow Coma Scale score. The second dimension is predicated on the presence or absence of complications, appropriate for each severity interval. The outcomes of almost 25,000 patients with head injury encountered at our institution over a 7-year period were evaluated. We discovered that adding a complication dimension to each severity category resulted in significant outcome differences and effectively divided patients into groups with very different risks, prognosis and treatment requirements. The HISS is proposed as a framework on which further research can be done to guide care to predict outcome and to perform audits on head-injured patients.

Classification and regression trees (CART) for prediction of function at 1 year following head trauma

A cohort of 514 hospitalized head-injury survivors was identified based on their injury and 448 (87%) of them were followed for 1 year. Comprehensive neurobehavioral testing was performed 1 month and 1 year after injury. The authors developed predictions of six neuropsychological and two psychosocial outcomes 1 year after head injury. Prediction trees are presented for verbal IQ, Halstead's Impairment Index, and work status at 1 year. Early predictors of neurobehavioral outcome in survivors are similar to previously reported predictors of mortality. Extent (both depth and length) of coma and age are the medical and demographic variables most predictive of late outcome. Adding 1-month scores substantially improves prediction of neuropsychological variables. The classification and regression tree is a useful technique for predicting long-term outcome in patients with head injury. The trees are simple enough to be used in a clinical setting and, especially with 1-month scores, predictions are accurate enough for clinical utility.

Post-coma disturbance and post-traumatic amnesia as nonlinear predictors of cognitive outcome following severe closed head injury: findings from the Westmead Head Injury Project

This study sought to identify combinations of early neurological variables which best predict cognitive outcome 12 months after severe head injury. At the time of admission patients were assessed on seven neurological indices. Twelve months later a battery of neuropsychological tests examining recent memory functioning and speed of information processing was administered. Recent memory functioning was best predicted by a combination of post-coma disturbance (PCD; i.e. the duration of post-traumatic amnesia, PTA, minus the duration of coma) and presence of subarachnoid haemorrhage (multiple r = 0.54, p < 0.001). Speed of information processing was best predicted by the duration of PTA (r = 0.35, p < 0.01). However, these conclusions were based on square root transformation of PCD and PTA variables. The success of this transformation in assisting prediction confirms suggestions that the relationship between PTA and cognitive outcome is nonlinear.

Helicopter mountain rescue of patients with head injury and/or multiple injuries in southern Switzerland 1980-1990

The aim of prehospital treatment of head injuries and severe multiple injuries is to prevent additional cerebral damage. When accidents occur in remote mountain areas, time is lost covering the distance to the nearest cabin or village where the rescue team can be called by telephone. Rapid transport of a trained physician to the patient can save precious time and allows prompt control of respiration and circulation at the scene of the accident. In a series of 57 rescue operations between 1980 and 1990, we used a helicopter staffed by an emergency physician and equipped with a winch. The hospital mortality rate was 12 percent (7 out of 57 patients). At 6 months after the accident, a normal neurological state was registered in 44 of the 55 survivors (88 per cent), whereas mild neurological deficiencies were noted in six patients (12 per cent). No persistent coma or vegetative state was seen. This experience suggests that fast rescue by a helicopter equipped with a winch and with an experienced emergency physician on board in an effective way of preventing secondary cerebral damage after accidents in remote mountain areas.

The management of cerebral perfusion pressure and intracranial pressure after severe head injury

Neurosurgical intervention attempts to minimize secondary central nervous system injury after severe head injury through the evacuation of mass lesions with subsequent manipulation of cerebral perfusion pressure and intracranial pressure. The normal brain couples blood flow to metabolic demand through autoregulation of the cerebral vasculature. After severe head trauma and its attendant increase in intracranial pressure, marked alterations in cerebral blood flow and perfusion may occur. Currently, intervention is based on maintenance of coronary perfusion pressure and aggressive management of intracranial pressure. Both may be impacted by manipulation of ventilation, systemic blood pressure and volume status, administration of osmotic diuretics, and head elevation. Such therapy in the patient with severe head injury attempts to maintain coronary perfusion pressure and adequate oxygen delivery in a damaged central nervous system with altered hemodynamics and raised intracranial pressure.

Prediction of long-term cognitive outcome of brain injury with neuropsychological, severity of injury, and demographic data

A comparison was made of the relative power of a brief post-injury neuropsychological assessment and a brain-injury severity measure (PTA) to predict long-term cognitive outcome after severe brain injury. Subjects were 78 patients with severe brain injury. Regression analysis revealed that neuropsychological variables were as predictive of outcome as PTA. A combination of neuropsychological, brain-injury severity, and demographic variables predicted a substantial proportion of variance in both general cognitive ability and memory functioning at outcome. Removal of PTA from the set of predictors had only modest impact on predictive power, suggesting that, in the absence of accurate injury severity data, meaningful prediction about long-term cognitive outcome can still be made.

Comprehensive predictions of outcome in closed head-injured patients. The development of prognostic equations

A comprehensive diagnostic evaluation was administered to 162 closed head-injured patients within 1 to 21 days (mean, 7.5 days) after injury. Each evaluation consisted of (1) power spectral analyses of electroencephalogram (EEG) recorded from 19 scalp locations referenced to age-matched norms, (2) brainstem auditory evoked potentials, (3) computed tomography (CT)-scan, and (4) Glasgow Coma Score (GCS) at time of admission (GCS-A) and at time of EEG test (GCS-T). Functional outcome at one year following injury was assessed using the Rappaport Disability Rating Scale (DRS), which measures the level of disability in the six diagnostic categories of (1) eye opening, (2) best verbal response, (3) best motor response, (4) self-care ability for feeding, grooming, and toileting, (5) level of cognitive functioning, and (6) employability. The ability of the different diagnostic measures to predict outcome at one year following injury was assessed using stepwise discriminant analyses to identify patients in the extreme outcome categories of complete recovery versus death and multivariate regression analyses to predict patients with intermediate outcome scores. The best combination of predictor variables was EEG and GCS-T, which accounted for 74.6% of the variance in the multivariate regression analysis of intermediate outcome scores and 95.8% discriminant accuracy between good outcome and death. The best single predictors of outcome in both the discriminant analyses and the regression analyses were EEG coherence and phase. A gradient of prognostic strength of diagnostic measures was EEG phase greater than EEG coherence greater than GCS-T greater than CT-scan greater than EEG relative power. The value of EEG coherence and phase in the assessment of diffuse axonal injury was discussed.

Outcome in 134 patients with prolonged posttraumatic unawareness. Part 1: Parameters determining late recovery of consciousness

A retrospective study of 134 patients in a condition of prolonged unawareness state (that is, in coma for over 1 month) following brain trauma was conducted in order to identify prognostic factors. Eight easily evaluated parameters were found to be significant for predicting nonrecovery of consciousness. The following six features were present during the early posttraumatic phase (that is, during the 1st week after trauma): fever of central origin; diffuse body sweating; disturbances in antidiuretic hormone secretion; abnormal motor reactivity; respiratory disturbances; and diffuse nonneurological injuries. The first three features were manifestations of hypothalamic damage. Two factors, evident at a late phase following injury (after the 1st week posttrauma), namely late epilepsy and communicating hydrocephalus, were also significant in predicting nonrecovery.

Head injury, a multivariate study: predicting long-term productivity and independent living outcome

As the second of a two-part research project, this study attempted to build three clinically useful prediction equations; these equations would be used to predict three long-term functional outcomes: productivity status, living arrangement status, number of hours of assistance required per week. There were ten predictor variables used in each analysis. These ten variables belonged to four theoretical classes: pre-injury demographics, pre-injury social characteristics, severity of injury, and post-injury environmental variables. The analytical method used was the General Linear Model of multiple regression, rather than the most often used Stepwise regression procedure. The results indicate that in none of the three prediction equations was more than 28% of the criterion variance accounted for, and only a minority of the predictor variables were significant predictors. It is concluded that, while the equations are of only very limited utility, the theoretical model and the analytical technique will be useful for future investigators.

Relationships among pre- and post-injury intelligence, length of coma and age in individuals with severe closed-head injuries

Relationships among pre-injury ability, post-injury verbal intelligence, duration of coma and age were analysed in 34 closed-head injury patients, 7-28 years of age, whose coma lengths ranged from 5 to 180 days. The results obtained suggest that moderate to severe closed-head injury uniformly impairs verbal intellectual functioning without regard to premorbid status. Premorbid ability test scores had a markedly low correlation (0.04) with Wechsler Verbal IQs, obtained after patients had plateaued in intellectual recovery. Even when the effects of coma and age were controlled, the correlation was not significant. Mean post-injury IQs for patients grouped according to pre-injury intelligence (above average, average, below average) were all in the 80s. The findings do not support the prevailing assumption that the greater the premorbid ability, the greater the potential for intellectual recovery and the better the outcome. This study instead suggests that the higher the pre-injury IQ, the greater the IQ point loss. This has important implications for rehabilitation, counselling, discharge planning and follow-up. The greater the disparity between pre- and post-injury IQs, the more profound the loss and, hence, the greater the need for patient and family adjustments, coping and modifications of future personal, educational and vocational plans.

Late post-concussional symptoms in traumatic head injury. An analysis of frequency and risk factors

During follow-up of 485 adult patients with traumatic head injury, 51% of the patients reported new post-concussional symptoms after an observation period of 3-5 years (mean 4.0 years). Most data, including the level of consciousness on admission, length of post-traumatic amnesia and days of hospitalization were poor parameters for predicting which patients would suffer late complications. A few variables were statistically of predictive importance: Sex, repeated head injury and skull fracture. Age was a risk factor for multiple complaints.

Assessment of the accuracy of regression equations proposed for estimating premorbid intellectual functioning on the Wechsler Adult Intelligence Scale

This investigation examined the accuracy of regression equations proposed by Wilson et al. (1978) for estimating premorbid intellectual quotients (IQs) on the Wechsler Adult Intelligence Scale (WAIS). Actual Verbal, Performance, and Full Scale IQs in a sample of 69 neurologically normal adults were compared against their estimated premorbid levels. While the equations provided an adequate overall fit to the data, actual IQ values at the extremes of the WAIS Scales were found to be most susceptible to underestimation (high actual IQ values) or overestimation (low actual IQ values). The clinical importance of this finding and possible applications of the equations are discussed.