Midline shift after severe head injury: pathophysiologic implications

Modelling midline shift and ventricle collapse in cerebral oedema following acute ischaemic stroke

In ischaemic stroke, a large reduction in blood supply can lead to the breakdown of the blood-brain barrier and to cerebral oedema after reperfusion therapy. The resulting fluid accumulation in the brain may contribute to a significant rise in intracranial pressure (ICP) and tissue deformation. Changes in the level of ICP are essential for clinical decision-making and therapeutic strategies. However, the measurement of ICP is constrained by clinical techniques and obtaining the exact values of the ICP has proven challenging. In this study, we propose the first computational model for the simulation of cerebral oedema following acute ischaemic stroke for the investigation of ICP and midline shift (MLS) relationship. The model consists of three components for the simulation of healthy blood flow, occluded blood flow and oedema, respectively. The healthy and occluded blood flow components are utilized to obtain oedema core geometry and then imported into the oedema model for the simulation of oedema growth. The simulation results of the model are compared with clinical data from 97 traumatic brain injury patients for the validation of major model parameters. Midline shift has been widely used for the diagnosis, clinical decision-making, and prognosis of oedema patients. Therefore, we focus on quantifying the relationship between ICP and midline shift (MLS) and identify the factors that can affect the ICP-MLS relationship. Three major factors are investigated, including the brain geometry, blood-brain barrier damage severity and the types of oedema (including rare types of oedema). Meanwhile, the two major types (stress and tension/compression) of mechanical brain damage are also presented and the differences in the stress, tension, and compression between the intraparenchymal and periventricular regions are discussed. This work helps to predict ICP precisely and therefore provides improved clinical guidance for the treatment of brain oedema.

Imaging Findings in Acute Traumatic Brain Injury: a National Institute of Neurological Disorders and Stroke Common Data Element-Based Pictorial Review and Analysis of Over 4000 Admission Brain Computed Tomography Scans from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) Study

In 2010, the National Institute of Neurological Disorders and Stroke (NINDS) created a set of common data elements (CDEs) to help standardize the assessment and reporting of imaging findings in traumatic brain injury (TBI). However, as opposed to other standardized radiology reporting systems, a visual overview and data to support the proposed standardized lexicon are lacking. We used over 4000 admission computed tomography (CT) scans of patients with TBI from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study to develop an extensive pictorial overview of the NINDS TBI CDEs, with visual examples and background information on individual pathoanatomical lesion types, up to the level of supplemental and emerging information (e.g., location and estimated volumes). We documented the frequency of lesion occurrence, aiming to quantify the relative importance of different CDEs for characterizing TBI, and performed a critical appraisal of our experience with the intent to inform updating of the CDEs. In addition, we investigated the co-occurrence and clustering of lesion types and the distribution of six CT classification systems. The median age of the 4087 patients in our dataset was 50 years (interquartile range, 29-66; range, 0-96), including 238 patients under 18 years old (5.8%). Traumatic subarachnoid hemorrhage (45.3%), skull fractures (37.4%), contusions (31.3%), and acute subdural hematoma (28.9%) were the most frequently occurring CT findings in acute TBI. The ranking of these lesions was the same in patients with mild TBI (baseline Glasgow Coma Scale [GCS] score 13-15) compared with those with moderate-severe TBI (baseline GCS score 3-12), but the frequency of occurrence was up to three times higher in moderate-severe TBI. In most TBI patients with CT abnormalities, there was co-occurrence and clustering of different lesion types, with significant differences between mild and moderate-severe TBI patients. More specifically, lesion patterns were more complex in moderate-severe TBI patients, with more co-existing lesions and more frequent signs of mass effect. These patients also had higher and more heterogeneous CT score distributions, associated with worse predicted outcomes. The critical appraisal of the NINDS CDEs was highly positive, but revealed that full assessment can be time consuming, that some CDEs had very low frequencies, and identified a few redundancies and ambiguity in some definitions. Whilst primarily developed for research, implementation of CDE templates for use in clinical practice is advocated, but this will require development of an abbreviated version. In conclusion, with this study, we provide an educational resource for clinicians and researchers to help assess, characterize, and report the vast and complex spectrum of imaging findings in patients with TBI. Our data provides a comprehensive overview of the contemporary landscape of TBI imaging pathology in Europe, and the findings can serve as empirical evidence for updating the current NINDS radiologic CDEs to version 3.0.

A multicentre retrospective cohort study on health-related quality of life after traumatic acute subdural haematoma: does cranial laterality affect long-term recovery?

Background

Traumatic acute subdural haematoma is a debilitating condition. Laterality intuitively influences management and outcome. However, in contrast to stroke, this research area is rarely studied. The aim is to investigate whether the hemisphere location of the ASDH influences patient outcome.

Methods

For this multicentre observational retrospective cohort study, patients were considered eligible when they were treated by a neurosurgeon for traumatic brain injury between 2008 and 2012, were > 16 years of age, had sustained brain injury with direct presentation to the emergency room and showed a hyperdense, crescent shaped lesion on the computed tomography scan. Patients were followed for a duration of 3-9 months post-trauma for functional outcome and 2-6 years for health-related quality of life. Main outcomes and measures included mortality, Glasgow Outcome Scale and the Quality of Life after Brain Injury score. The hypothesis was formulated after data collection.

Results

Of the 187 patients included, 90 had a left-sided ASDH and 97 had a right-sided haematoma. Both groups were comparable at baseline and with respect to the executed treatment. Furthermore, both groups showed no significant difference in mortality and Glasgow Outcome Scale score. Health-related quality of life, assessed 59 months (IQR 43-66) post-injury, was higher for patients with a right-sided haematoma (Quality of Life after Brain Injury score: 80 vs 61, P = 0.07).

Conclusions

This study suggests patients with a right-sided acute subdural haematoma have a better long-term health-related quality of life compared to patients with a left-sided acute subdural haematoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02790-3.

Preoperative brain shift is a prognostic factor for survival in certain neurosurgical diseases other than severe head injury: a case series and literature review

Preoperative brain shift after severe brain injury is a prognostic factor for survival. The aim of this study was to determine whether preoperative brain shift in conditions other than severe head injury has significant prognostic value. We analyzed a radiological database of 800 consecutive patients, who underwent neurosurgical treatment. Brain shift was measured at two anatomical landmarks: Monro’s foramina (MF) and the corpus callosum (CC). Four hundred seventy-three patients were included. The disease exerting the highest mean brain shift was acute subdural hematoma (MF 11.6 mm, CC 12.4 mm), followed by intraparenchymal hematoma (MF 10.2 mm, CC 10.3 mm) and malignant ischemia (MF 10.4 mm, CC 10.5 mm). On univariate analysis, brain shift was a significant negative factor for survival in all diseases (p < 0.001). Analyzed individually by group, brain shift at both anatomical landmarks had a statistically significant effect on survival in malignant ischemia and at one anatomical landmark in chronic subdural and intraparenchymal hematomas. Multivariate analysis demonstrated that the only independent factor negatively impacting survival was brain shift at MF (OR = 0.89; 95% CI: 0.84–0.95) and CC (OR = 0.90; 95% CI: 0.85–0.96). Brain shift is a prognostic factor for survival in patients with expansive intracranial lesions in certain neurosurgical diseases. MF and CC are reliable anatomical landmarks and should be quoted routinely in radiological reports as well as in neurosurgical practice.

Functional Outcome Trajectories Following Inpatient Rehabilitation for TBI in the United States: A NIDILRR TBIMS and CDC Interagency Collaboration

OBJECTIVE

To describe trajectories of functioning up to 5 years after traumatic brain injury (TBI) that required inpatient rehabilitation in the United States using individual growth curve models conditioned on factors associated with variability in functioning and independence over time.

DESIGN

Secondary analysis of population-weighted data from a multicenter longitudinal cohort study.

SETTING

Acute inpatient rehabilitation facilities.

PARTICIPANTS

A total of 4624 individuals 16 years and older with a primary diagnosis of TBI.

MAIN OUTCOME MEASURES

Ratings of global disability and supervision needs as reported by participants or proxy during follow-up telephone interviews at 1, 2, and 5 years postinjury.

RESULTS

Many TBI survivors experience functional improvement through 1 and 2 years postinjury, followed by a decline in functioning and decreased independence by 5 years. However, there was considerable heterogeneity in outcomes across individuals. Factors such as older age, non-White race, lower preinjury productivity, public payer source, longer length of inpatient rehabilitation stay, and lower discharge functional status were found to negatively impact trajectories of change over time.

CONCLUSIONS

These findings can inform the content, timing, and target recipients of interventions designed to maximize functional independence after TBI.

Lateral Brain Displacement and Cerebral Autoregulation in Acutely Comatose Patients

OBJECTIVES

Lateral displacement and impaired cerebral autoregulation are associated with worse outcomes following acute brain injury, but their effect on long-term clinical outcomes remains unclear. We assessed the relationship between lateral displacement, disturbances to cerebral autoregulation, and clinical outcomes in acutely comatose patients.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Neurocritical care unit of the Johns Hopkins Hospital.

PATIENTS

Acutely comatose patients (Glasgow Coma Score ≤ 8).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cerebral oximetry index, derived from near-infrared spectroscopy multimodal monitoring, was used to evaluate cerebral autoregulation. Associations between lateral brain displacement, global cerebral autoregulation, and interhemispheric cerebral autoregulation asymmetry were assessed using mixed random effects models with random intercept. Patients were grouped by functional outcome, determined by the modified Rankin Scale. Associations between outcome group, lateral displacement, and cerebral oximetry index were assessed using multivariate linear regression. Increasing lateral brain displacement was associated with worsening global cerebral autoregulation (p = 0.01 septum; p = 0.05 pineal) and cerebral autoregulation asymmetry (both p < 0.001). Maximum lateral displacement during the first 3 days of coma was significantly different between functional outcome groups at hospital discharge (p = 0.019 pineal; p = 0.008 septum), 3 months (p = 0.026; p = 0.007), 6 months (p = 0.018; p = 0.010), and 12 months (p = 0.022; p = 0.012). Global cerebral oximetry index was associated with functional outcomes at 3 months (p = 0.019) and 6 months (p = 0.013).

CONCLUSIONS

During the first 3 days of acute coma, increasing lateral brain displacement is associated with worsening global cerebral autoregulation and cerebral autoregulation asymmetry, and poor long-term clinical outcomes in acutely comatose patients. The impact of acute interventions on outcome needs to be explored.

Long-term outcome in traumatic brain injury patients with midline shift: a secondary analysis of the Phase 3 COBRIT clinical trial

OBJECTIVE

Following traumatic brain injury (TBI), midline shift of the brain at the level of the septum pellucidum is often caused by unilateral space-occupying lesions and is associated with increased intracranial pressure and worsened morbidity and mortality. While outcome has been studied in this population, the recovery trajectory has not been reported in a large cohort of patients with TBI. The authors sought to utilize the Citicoline Brain Injury Treatment (COBRIT) trial to analyze patient recovery over time depending on degree of midline shift at presentation.

METHODS

Patient data from the COBRIT trial were stratified into 4 groups of midline shift, and outcome measures were analyzed at 30, 90, and 180 days postinjury. A recovery trajectory analysis was performed identifying patients with outcome measures at all 3 time points to analyze the degree of recovery based on midline shift at presentation.

RESULTS

There were 892, 1169, and 895 patients with adequate outcome data at 30, 90, and 180 days, respectively. Rates of favorable outcome (Glasgow Outcome Scale-Extended [GOS-E] scores 4-8) at 6 months postinjury were 87% for patients with no midline shift, 79% for patients with 1-5 mm of shift, 64% for patients with 6-10 mm of shift, and 47% for patients with > 10 mm of shift. The mean improvement from unfavorable outcome (GOS-E scores 2 and 3) to favorable outcome (GOS-E scores 4-8) from 1 month to 6 months in all groups was 20% (range 4%-29%). The mean GOS-E score for patients in the 6- to 10-mm group crossed from unfavorable outcome (GOS-E scores 2 and 3) into favorable outcome (GOS-E scores 4-8) at 90 days, and the mean GOS-E of patients in the > 10-mm group nearly reached the threshold of favorable outcome by 180 days postinjury.

CONCLUSIONS

In this secondary analysis of the Phase 3 COBRIT trial, TBI patients with less than 10 mm of midline shift on admission head CT had significantly improved functional outcomes through 180 days after injury compared with those with greater than 10 mm of midline shift. Of note, nearly 50% of patients with > 10 mm of midline shift achieved a favorable outcome (GOS-E score 4-8) by 6 months postinjury.

Midline shift in patients with closed traumatic brain injury may be driven by cerebral perfusion pressure not intracranial pressure

BACKGROUND

In traumatic brain injury (TBI), swelling may disturb the potentially uniform pressure distribution in the brain, producing sustained intercompartmental pressure gradients which may associate with midline shift. The presence of pressure gradients is often neglected since bilateral invasive intracranial pressure (ICP) monitoring is not usually considered because of risks and high costs. We evaluated the presence of interhemispheric pressure gradients using bilateral transcranial Doppler (TCD) as means for non-invasive ICP (nICP) monitoring in TBI patients presenting midline shift.

METHODS

From a retrospective cohort of 97 TBI patients with arterial blood pressure (ABP), ICP and bilateral TCD monitoring, 24 presented unilateral lesion and midline shift confirmed by computer tomography. nICP and non-invasive cerebral perfusion pressure (nCPP) on the left and right brain hemispheres were retrospectively calculated using a mathematical model associating TCD-derived cerebral blood flow velocity and ABP.

RESULTS

The nCPP difference was correlated with midline shift (R=-0.34, p<.01) showing a tendency to record higher CPP at the side of expansion. Accordingly, nICP at the side of expansion was significantly lower in comparison to the compressed side (18.86 [±5.71] mmHg (mean ± standard deviation) versus 20.30 [±6.78] mmHg for expansion and compressed sides, respectively). Subsequently, nCPP was greater on the side of brain expansion (79.48±7.84, 78.03±8.93 mmHg [p<.01], for expansion and compressed sides, respectively).

CONCLUSIONS

TCD-based interhemispheric nCPP difference showed significant correlation with midline shift. Cerebral perfusion pressure was greater on the side of brain expansion, acting as the driving force to shift brain structures.

Risk factors for nosocomial nontraumatic coma: sepsis and respiratory failure

Background

Coma’s are a major cause of clinical deterioration or death. Identification of risks that predispose to coma are important in managing patients; however, the risk factors for nosocomial nontraumatic coma (NNC) are not well known. Our aim was to investigate the risk factors in patients with NNC.

Methods

A retrospective case–control design was used to compare patients with NNC and a control group of patients without coma in a population-based cohort of 263 participants from the neurological intensive care unit in Shuyang County People’s Hospital of Northern China. Coma was diagnosed by a Glasgow Coma Scale score ≤8. Adjusted odds ratios for patients with NNC were derived from multivariate logistic regression analyses.

Results

A total of 96 subjects had NNC. The prevalence of NNC was 36.5% among the subjects. Among these, 82% had acute cerebrovascular etiology. Most of the NNC usually occurred at day 3 after admission to the neurological intensive care unit. Patients with NNC had higher hospital mortality rates (67.7% vs 3%, P<0.0001) and were more likely to have a central herniation (47.9% vs 0%, P<0.001) or uncal herniation (11.5% vs 0%, P<0.001) than those without NNC. Multiple logistic regression showed that systemic inflammatory response syndrome-positive sepsis (odds ratio =4, 95% confidence interval =1.875−8.567, P<0.001) and acute respiratory failure (odds ratio =3.275, 95% confidence interval =1.014−10.573, P<0.05) were the factors independently associated with a higher risk of NNC.

Conclusion

Systemic inflammatory response syndrome-positive sepsis and acute respiratory failure are independently associated with an increased risk of NNC. This information may be important for patients with NNC.

Neuroanatomical predictors of awakening in acutely comatose patients

OBJECTIVE

Lateral brain displacement has been associated with loss of consciousness and poor outcome in a range of acute neurologic disorders. We studied the association between lateral brain displacement and awakening from acute coma.

METHODS

This prospective observational study included all new onset coma patients admitted to the Neurosciences Critical Care Unit (NCCU) over 12 consecutive months. Head computed tomography (CT) scans were analyzed independently at coma onset, after awakening, and at follow-up. Primary outcome measure was awakening, defined as the ability to follow commands before hospital discharge. Secondary outcome measures were discharge Glasgow Coma Scale (GCS), modified Rankin Scale, Glasgow Outcome Scale, and hospital and NCCU lengths of stay.

RESULTS

Of the 85 patients studied, the mean age was 58 ± 16 years, 51% were female, and 78% had cerebrovascular etiology of coma. Fifty-one percent of patients had midline shift on head CT at coma onset and 43 (51%) patients awakened. In a multivariate analysis, independent predictors of awakening were younger age (odds ratio [OR] = 1.039, 95% confidence interval [CI] = 1.002-1.079, p = 0.040), higher GCS score at coma onset (OR = 1.455, 95% CI = 1.157-1.831, p = 0.001), nontraumatic coma etiology (OR = 4.464, 95% CI = 1.011-19.608, p = 0.048), lesser pineal shift on follow-up CT (OR = 1.316, 95% CI = 1.073-1.615, p = 0.009), and reduction or no increase in pineal shift on follow-up CT (OR = 11.628, 95% CI = 2.207-62.500, p = 0.004).

INTERPRETATION

Reversal and/or limitation of lateral brain displacement are associated with acute awakening in comatose patients. These findings suggest objective parameters to guide prognosis and treatment in patients with acute onset of coma.

Smaller but denser: postmortem changes alter the CT characteristics of subdural hematomas

PURPOSE

The aim of this study was to investigate if (1) the volume of subdural hematomas (SDH), midline shift, and CT density of subdural hematomas are altered by postmortem changes and (2) if these changes are dependent on the postmortem interval (PMI).

MATERIALS AND METHODS

Ante mortem computed tomography (AMCT) of the head was compared to corresponding postmortem CT (PMCT) in 19 adults with SDH. SDH volume, midline shift, and hematoma density were measured on both AMCT and PMCT and their differences assessed using Wilcoxon-Signed Rank Test. Spearman's Rho Test was used to assess significant correlations between the PMI and the alterations of SDH volume, midline shift, and hematoma density.

RESULTS

Mean time between last AMCT and PMCT was 109 h, mean PMI was 35 h. On PMCT mean midline displacement was decreased by 57% (p < 0.001); mean SDH volume was decreased by 38% (p < 0.001); and mean hematoma density was increased by 18% (p < 0.001) in comparison to AMCT. There was no correlation between the PMI and the normalization of the midline shift (p = 0.706), the reduction of SDH volume (p = 0.366), or the increase of hematoma density (p = 0.140).

CONCLUSIONS

This study reveals that normal postmortem changes significantly affect the extent and imaging characteristics of subdural hematoma and may therefore affect the interpretation of these findings on PMCT. Radiologists and forensic pathologists who use PMCT must be aware of these phenomena in order to correctly interpret PMCT findings in cases of subdural hemorrhages.

Does midline shift predict postoperative nausea in brain tumor patients undergoing awake craniotomy? A retrospective analysis

BACKGROUND

The presence of midline shift on neuroradiologic studies in brain tumor patients represents mass effect from the tumor and surrounding edema. We hypothesized that baseline cerebral edema as measured by midline shift would increase postoperative nausea (PON). We studied the incidence of PON in brain tumor patients, with and without midline shift on preoperative magnetic resonance (MRI) or computed tomographic (CT) imaging, undergoing awake craniotomy.

METHODS

After IRB approval, we retrospectively extracted data from perioperative records between January 2005 and December 2010. Post-craniotomy nausea and pain scores were collected. Intraoperative anti-emetic, anesthetic, and analgesic regimens were assessed. Both the rescue anti-emetic and cumulative postoperative analgesic requirements were collected up to 12 hours postoperatively. The amount of midline shift on preoperative neuroimaging was gathered from radiology reports. Univariate comparisons between groups (no midline shift vs. midline shift) were made with t-tests for continuous variables, and chi-square tests for categorical variables. A multivariable analysis was performed to identify predictors of postoperative nausea. Limitations of this study include the retrospective design and the inability to gather accurate data regarding vomiting from the medical record.

RESULTS

Data from 386 patients were available for analysis. Patients were divided into two groups: no midline shift (n = 283) and midline shift (n = 103). The mean midline shift distance was 5.96 mm (95% CI [5.32, 6.59]). There was no difference in the incidence of nausea or pain scores between the two groups. More malignant brain tumor patients were in the midline shift group, as determined by the postoperative histopathological diagnosis (P < 0.05). Patients in the midline shift group also had longer anesthesia and surgical times (P < 0.05).

CONCLUSION

In patients undergoing a standardized anesthetic for awake craniotomy for tumor resection, the presence of preoperative midline shift did not correlate with postoperative nausea.

Increased intracranial pressure is associated with the development of acute lung injury following severe traumatic brain injury

OBJECTIVE

This study investigated the relationship among intracranial pressure (ICP), the development of acute lung injury (ALI) and systemic inflammatory response syndrome (SIRS) following a severe traumatic brain injury (TBI).

METHODS

Post-traumatic ICP was continuously monitored for the first week following injury in a series of consecutive patients with isolated severe TBI. The initial ICP and the duration of intracranial hypertension (ICH) were calculated. The risk factors associated with the development of ALI and SIRS were evaluated.

RESULTS

Of the 86 patients enrolled, 22 patients developed ALI and 52 patients developed SIRS during the observation period. The patients with ALI presented with a significantly higher initial ICP (31.3±7.8 mmHg vs. 23.0±8.8 mmHg, p<0.001) and a longer duration of ICH (16.8±6.5 h vs. 11.9±6.0 h, p=0.002) than those without ALI. The incidence of both ALI and SIRS increased with increasing initial ICP, and the presence of SIRS was associated with a fourfold increase in the risk of developing ALI (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.2-13.0).

CONCLUSIONS

Increased ICP is associated with increased risks of developing ALI and SIRS following severe TBI. Future studies designed to verify the causative relationship between increased ICP and the systemic responses are warranted.

Traumatic brain injury: review of current management strategies

Head injury is a common condition with a high morbidity and mortality. Serious intracranial haematomas require early recognition and evacuation to maximise chances of independent outcomes. Recent organisational changes have promoted the development of trauma units and major trauma centres where patients can go through triage and be managed in an appropriate environment, and the development of management pathways in intensive treatment units has resulted in improvements in the outcome of traumatic brain injuries. Evidence for the treatment of cerebral perfusion pressure, and management of hyperventilation, osmotherapy, tracheostomy, and leakage of cerebrospinal fluid (CSF) has accumulated during the last decade and is important in the management of patients in all clinical settings. Since head injury is commonly associated with maxillofacial injuries, this review will be relevant to all who deal with this aspect of trauma.

150 years of treating severe traumatic brain injury: a systematic review of progress in mortality

Considerable effort and resources have been devoted to preserving life in patients with severe closed traumatic brain injury (TBI). We sought to identify temporal trends in mortality rates of these patients from the late 1800s to the present. We searched the literature for articles on severe TBI, abstracting numbers of patients studied, numbers of deaths, and years of patient entry. Mortality rates were calculated for each study, and meta-regression was used to pool data and to test for significant temporal trends. We reviewed 207 case series comprising more than 140,000 cases of severe closed TBI admitted to hospital over a span of almost 150 years. Since the late 1800s mortality has fallen by almost 50%. However, the rate has varied considerably among the four epochs chosen. Between 1885 and 1930, mortality decreased at a rate of 3% per decade. From 1970 to 1990, mortality declined at a rate of 9% per decade. Both changes are significant. There was no observed improvement in mortality between 1930 and 1970, nor is progress evident since 1990. The authors discuss possible reasons for the apparently intermittent progress in TBI survival over time.

Relationship of aggressive monitoring and treatment to improved outcomes in severe traumatic brain injury

OBJECT

Despite being common practice for decades and being recommended by national guidelines, aggressive monitoring and treatment of patients with severe traumatic brain injury (TBI) have not been supported by convincing evidence.

METHODS

The authors reviewed trials and case series reported after 1970 in which patients were treated for severe closed TBI, and mortality rates and favorable outcomes at 6 months after injury were analyzed. The patient groups were divided into those with and without intracranial pressure (ICP) monitoring and intensive therapy, and the authors performed a meta-analysis to assess the effects of treatment intensity on outcome.

RESULTS

Although the mortality rate fell during the years reviewed, it was consistently approximately 12% lower among patients in the intense treatment group (p < 0.001). Favorable outcomes did not change significantly over time, and were 6% higher among the aggressively treated patients (p = 0.0105).

CONCLUSIONS

Aggressive ICP monitoring and treatment of patients with severe TBI is associated with a statistically significant improvement in outcome. This improvement occurs independently of temporal effects.

Nonlinear pressure-flow relationship is able to detect asymmetry of brain blood circulation associated with midline shift

Reliable and noninvasive assessment of cerebral blood flow regulation is a major challenge in acute care monitoring. This study assessed dynamics of flow regulation and its relationship to asymmetry of initial computed tomography (CT) scan using multimodal pressure flow (MMPF) analysis. Data of 27 patients (38 +/- 15 years old) with traumatic brain injury (TBI) were analyzed. Patients were selected from bigger cohort according to criteria of having midline shift on initial CT scan and intact skull (no craniotomy or bone flap). The MMPF analysis was used to extract the oscillations in cerebral perfusion pressure (CPP) and blood flow velocity (BFV) signals at frequency of artificial ventilation, and to calculate the instantaneous phase difference between CPP and BFV oscillations. Mean CPP-BFV phase difference was used to quantify pressure and flow relationship. The TBI subjects had smaller mean BP-BFV phase shifts (left, 8.7 +/- 9.6; right 10.2 +/- 8.3 MCAs, mean +/- SD) than values previously obtained in healthy subjects (left, 37.3 +/- 7.6 degrees; right, 38.0 +/- 8.9 degrees; p < 0.0001), suggesting impaired blood flow regulation after TBI. The difference in phase shift between CPP and BFV in the left and right side was strongly correlated to the midline shift (R = 0.78; p < 0.0001). These findings indicate that the MMPF method allows reliable assessment of alterations in pressure and flow relationship after TBI. Moreover, mean pressure-flow phase shift is sensitive to the displacement of midline of the brain, and may potentially serve as a marker of asymmetry of cerebral autoregulation.

Hyperemia beneath evacuated acute subdural hematoma is frequent and prolonged in patients with an unfavorable outcome: a xe-computed tomographic study

OBJECTIVE

To verify the values and the time course of regional cerebral blood flow (rCBF) in the cortex located beneath an evacuated acute subdural hematoma (SDH) and their relationship with neurological outcome.

METHODS

rCBF levels were measured in multiple regions of interest, by means of a Xe-computed tomographic technique, in the cortex underlying an evacuated SDH and contralaterally in 20 patients with moderate or severe traumatic brain injury and an evacuated acute SDH. Twenty-three patients with moderate or severe traumatic brain injury and an evacuated extradural hematoma or diffuse injury served as the control group. Outcome was evaluated by means of the Glasgow Outcome Scale at 12 months.

RESULTS

Values for the maximum (rCBFmax) and the mean of all rCBF levels in the cortex beneath the evacuated SDH were more frequently consistent with hyperemia. The side-to-side differences in the mean of all rCBF and rCBFmax levels between lesioned and nonlesioned hemispheres were greater in patients with evacuated SDH than in controls (P = 0.0013 and P = 0.0018, respectively). The side-to-side difference in the maximum rCBF value was higher in SDH patients with unfavorable outcomes than in controls at 24 to 96 hours and at 4 to 7 days and higher than in patients with favorable outcomes at 4 to 7 days. The widest side-to-side difference in rCBFmax value was more elevated in patients with an evacuated SDH with unfavorable outcome than in patients with a favorable outcome (P = 0.047), whereas no differences were found in controls. The SDH thickness and the associated midline shift were greater in patients with unfavorable outcomes than in those with favorable outcomes.

CONCLUSION

On average, hyperemic long-lasting rCBF values frequently occur in the cortex located beneath an evacuated SDH and seem to be associated with unfavorable outcome.

The acute care of traumatic brain injury

During the past few decades, management of acute traumatic brain injury has advanced substantially on several fronts. Implementation of rapid transport systems and the advent of trauma centres, together with advances in emergency medicine, critical care medicine and trauma neurosurgery, have improved outcome following head injury. Technological advances made during the past years in the field of invasive neuromonitoring that provide real-time information on brain oxygenation may further improve outcome by enabling individualized therapies for intracranial hypertension. Furthermore, these recent technological advances will provide insights into the pathophysiological processes that are active in traumatic brain injury and a better understanding of the biochemical effects of specific therapeutic regimens.

Evolution of Brain Tissue Injury after Evacuation of Acute Traumatic Subdural Hematomas

OBJECTIVE:

Acute traumatic subdural hematoma complicated by brain parenchymal injury is associated with a 60 to 90% mortality rate. Early surgical evacuation of the mass lesion is essential for a favorable outcome, but the severity of the underlying brain injury determines the outcome, even when surgery has been prompt. The purpose of this study was to analyze tissue biochemical patterns in the brain underlying an evacuated acute subdural hematoma to identify a characteristic pattern of changes that might indicate evolving brain injury.

METHODS:

Prospectively collected data from 33 patients after surgical evacuation of acute subdural hematoma were analyzed. Both a brain tissue oxygen tension probe and an intracerebral microdialysis probe were placed in brain tissue exposed at surgery. On the basis of the postoperative clinical course, the patients were divided into three groups: patients with early intractable intracranial hypertension, patients with evolution of delayed traumatic injury (DTI), and patients with an uncomplicated course (the no-DTI group).

RESULTS:

The overall mortality rate was 46%, with 100% mortality in the intracranial hypertension group (five patients). Mortality in the DTI group was 53% compared with only 9% in the no-DTI group (P = 0.002). There were no significant differences in the initial computed tomographic scan characteristics, such as thickness of the subdural hematoma or amount of midline shift, among the three groups. Physiological variables, as well as the microdialysate measures of brain biochemistry, were markedly different in the intracranial hypertension group compared with the other groups. Differences between the other two groups were more subtle but were significant. Significantly lower values of brain tissue oxygen tension (14 ± 8 mm Hg versus 27 ± 14 mm Hg) and higher dialysate values of lactate and pyruvate were documented in patients who developed a delayed injury compared with patients with uncomplicated courses (4.1 ± 2.3 mmol/L versus 1.7 ± 0.7 mmol/L for lactate, and 104 ± 47 μmol/L versus 73 ± 54 μmol/L for pyruvate at 24 h after injury).

CONCLUSION:

Evolution of DTI in the area of brain underlying an evacuated subdural hematoma is associated with a significant increase in mortality. Postoperatively decreasing brain tissue oxygen tension and increasing dialysate concentrations of lactate and pyruvate in this area may warn of evolving brain injury and evoke further diagnostic and therapeutic activity.

Defining “therapeutically inconsequential” head computed tomographic findings in patients with blunt head trauma

STUDY OBJECTIVE

Many injuries detected by computed tomographic (CT) imaging of blunt head trauma patients are considered "therapeutically inconsequential." We estimate the prevalence of these findings and determine how frequently affected patients had "important neurosurgical outcomes," defined as either a directed intervention or a poor Glasgow Outcome Scale score.

METHODS

We prospectively enrolled all blunt head trauma patients undergoing emergency head CT imaging at 18 centers participating in the National Emergency X-radiography Utilization Study II (NEXUS). From these cases, we identified all patients whose official CT reading met predefined criteria for "therapeutically inconsequential" injuries. We obtained detailed follow-up information on all such patients at 6 sites, including the need for neurosurgical intervention and Glasgow Outcome Scale scores. Among patients having "important neurosurgical outcomes," we assessed the frequency of 2 potential clinical identifiers: altered mental status and coagulopathy.

RESULTS

"Therapeutically inconsequential" head CT findings were present in 155 of 8,374 subjects (1.85%; 95% confidence interval 1.57% to 2.16%). Sites participating in the follow-up study enrolled 81 of these patients, of whom 10 (12%) had "important neurosurgical outcomes." Follow-up information was available for 9 patients, all of whom had abnormal mental status at CT scanning. Coagulopathy was also present in 5 of 7 patients for whom coagulation status was known.

CONCLUSION

"Therapeutically inconsequential" findings are identified in less than 2% of blunt head trauma patients who undergo CT scanning. A small proportion of these patients have an "important neurosurgical outcome," but it appears that such patients may be identified clinically by the presence of abnormal mental status or coagulopathy.

Asymmetry of pressure autoregulation after traumatic brain injury

OBJECT

The aim of this study was to assess the asymmetry of autoregulation between the left and right sides of the brain by using bilateral transcranial Doppler ultrasonography in a cohort of patients with head injuries.

METHODS

Ninety-six patients with head injuries comprised the study population. All significant intracranial mass lesions were promptly removed. The patients were given medications to induce sedation and paralysis, and artificial ventilation. Arterial blood pressure (ABP) and intracranial pressure (ICP) were monitored in an invasive manner. A strategy based on the patient's cerebral perfusion pressure (CPP = ABP - ICP) was applied: CPP was maintained at a level higher than 70 mm Hg and ICP at a level lower than 25 mm Hg. The left and right middle cerebral arteries were insonated daily, and bilateral flow velocities (FVs) were recorded. The correlation coefficient between the CPP and FV, termed Mx, was calculated and time-averaged over each recording period on both sides. An Mx close to 1 signified that slow fluctuations in CPP produced synchronized slow changes in FV, indicating a defective autoregulation. An Mx close to 0 indicated preserved autoregulation. Computerized tomography scans in all patients were reviewed; the side on which the major brain lesion was located was noted and the extent of the midline shift was determined. Outcome was measured 6 months after discharge. The left-right difference in the Mx between the hemispheres was significantly higher in patients who died than in those who survived (0.16 +/- 0.04 compared with 0.08 +/- 0.01; p = 0.04). The left-right difference in the Mx was correlated with a midline shift (r = -0.42; p = 0.03). Autoregulation was worse on the side of the brain where the lesion was located (p < 0.035).

CONCLUSIONS

The left-right difference in autoregulation is significantly associated with a fatal outcome. Autoregulation in the brain is worse on the side ipsilateral to the lesion and on the side of expansion in cases in which there is a midline shift.

A new rat model of diffuse brain injury associated with acute subdural hematoma: assessment of varying hematoma volume, insult severity, and the presence of hypoxemia

The aim of this study was to develop a new rat model of diffuse brain injury (DBI) associated with acute subdural hemorrhage (SDH). In order to make this model more clinically relevant, we determined whether the varying hematoma volume, severity of DBI, or the presence of hypoxemia could influence the physiological consequence. SDH was made by an autologous blood injection, while DBI was induced using the impact acceleration model (mild, 450 g/1 m, severe, 450 g/2 m). Physiological parameters measured included intracranial pressure (ICP), mean arterial blood pressure (MABP), cerebral blood flow (CBF), and brain tissue water content. In the first series, 23 rats were randomized into the five following groups: Group 1, sham; Group 2, 400 (microL SDH; Group 3, SDH400 + mild DBI; Group 4, SDH400 + severe DBI; and Group 5, SDH300 + severe DBI. Results suggested that SDH300 + severe DBI (Group 5) may be the most suitable model, in which the MABP and CBF temporarily decreased during the SDH induction, but thereafter recovered to the baseline. Conversely, ICP was persistently elevated throughout the experiment. The water content was also significantly higher in both hemispheres compared to that of sham. In the second series, the animal was exposed to a hypoxemic insult (10 or 30 min) in addition to SDH300 + severe DBI (Group 6). The prolonged hypoxemia caused both a severe CBF reduction without recovery and a bilateral brain swelling, whereas the brief hypoxemia showed a gradual CBF recovery from the transient reduction and an increased water content only in the SDH side. These results suggest that these models may be potentially useful to study the combination of DBI and SDH with or without hypoxemia.

Hyperacute measurement of intracranial pressure, cerebral perfusion pressure, jugular venous oxygen saturation, and laser Doppler flowmetry, before and during removal of traumatic acute subdural hematoma

OBJECT

The poor prognosis for traumatic acute subdural hematoma (ASDH) might be due to underlying primary brain damage, ischemia, or both. Ischemia in ASDH is likely caused by increased intracranial pressure (ICP) leading to decreased cerebral perfusion pressure (CPP), but the degree to which these phenomena occur is unknown. The authors report data obtained before and during removal of ASDH in five cases.

METHODS

Five patients who underwent emergency evacuation of ASDH were monitored. In all patients, without delaying treatment, a separate surgical team (including the senior author) placed an ICP monitor and a jugular bulb catheter, and in two patients a laser Doppler probe was placed. The ICP prior to removing the bone flap in the five patients was 85, 85, 50, 59, and greater than 40 mm Hg, resulting in CPPs of 25, 3, 25, 56, and less than 50 mm Hg, respectively. Removing the bone flap as well as opening the dura and removing the blood clot produced a significant decrease in ICP and an increase in CPP. Jugular venous oxygen saturation (SjvO2) increased in four patients and decreased in the other during removal of the hematoma. Laser Doppler flow also increased, to 217% and 211% compared with preevacuation flow.

CONCLUSIONS

Intracranial pressure is higher than previously suspected and CPP is very low in patients with ASDH. Removal of the bone flap yielded a significant reduction in ICP, which was further decreased by opening the dura and evacuating the hematoma. The SjvO2 as well as laser Doppler flow increased in all patients but one immediately after removal of the hematoma.

N-Acetylaspartate reduction as a measure of injury severity and mitochondrial dysfunction following diffuse traumatic brain injury

N-Acetylaspartate (NAA) is considered a neuron-specific metabolite and its reduction a marker of neuronal loss. The objective of this study was to evaluate the time course of NAA changes in varying grades of traumatic brain injury (TBI), in concert with the disturbance of energy metabolites (ATP). Since NAA is synthesized by the mitochondria, it was hypothesized that changes in NAA would follow ATP. The impact acceleration model was used to produce three grades of TBI. Sprague-Dawley rats were divided into the following four groups: sham control (n = 12); moderate TBI (n = 36); severe TBI (n = 36); and severe TBI coupled with hypoxia-hypotension (n = 16). Animals were sacrificed at different time points ranging from 1 min to 120 h postinjury, and the brain was processed for high-performance liquid chromatography (HPLC) analysis of NAA and ATP. After moderate TBI, NAA reduced gradually by 35% at 6 h and 46% at 15 h, accompanied by a 57% and 45% reduction in ATP. A spontaneous recovery of NAA to 86% of baseline at 120 h was paralleled by a restoration in ATP. In severe TBI, NAA fell suddenly and did not recover, showing critical reduction (60%) at 48 h. ATP was reduced by 70% and also did not recover. Maximum NAA and ATP decrease occurred with secondary insult (80% and 90%, respectively, at 48 h). These data show that, at 48 h post diffuse TBI, reduction of NAA is graded according to the severity of insult. NAA recovers if the degree of injury is moderate and not accompanied by secondary insult. The highly similar time course and correlation between NAA and ATP supports the notion that NAA reduction is related to energetic impairment.

Intracranial pressure and surgical decompression for traumatic brain injury: biological rationale and protocol for a randomized clinical trial

Commonly, severe traumatic brain injury (TBI) patients undergo amputation of contused brain; the rationale being that edema in presumed unsalvageable cerebrum increases intracranial pressure (ICP). Neuro-critical care expends great effort to control ICP and prevent secondary injury. Non-randomized investigations have employed hemicraniectomy with duraplasty after developing refractory ICP. We undertook a randomized pilot of hemicraniectomy with duraplasty as the initial surgery for severe TBI patients. Goals included reduced ICP therapeutic intensity and return to the operating room, and improved neurological outcome. Upon hospital presentation, the study was to randomize 92 patients with midline shift greater than the size of a surgically removable hematoma. One group was to receive standardized hemicraniectomy and duraplasty; the other would undergo 'traditional' craniotomy (with brain amputation at the neurosurgeon's discretion). A standardized medical protocol followed. The six-month Glasgow Outcome Scale was the primary outcome, with secondary measures including quality of life one year after TBI, duration and frequency of elevated ICP, intensive care unit (ICU) therapeutic intensity, operating room return, and ICU and hospital lengths-of-stay. This article presents the biological rationale and the evidence-based standardized protocols of the study and its outcome measures. The study has stopped and a phase III outcome trial is being organized.