Early and late magnetic resonance imaging and neuropsychological outcome after head injury

Diffuse axonal injury on magnetic resonance imaging and its relation to neurological outcomes in pediatric traumatic brain injury

OBJECTIVE

Diffuse axonal injury (DAI), a frequent consequence of pediatric traumatic brain injury (TBI), presents challenges in predicting long-term recovery. This study investigates the relationship between the severity of DAI and neurological outcomes in children.

METHODS

We conducted a retrospective analysis of 51 pediatric TBI patients diagnosed with DAI using Adam's classification. Neurological function was assessed at 2, 3, and 6 weeks, and 12 months post-injury using the Pediatric Glasgow Outcome Scale-Extended (PGOSE).

RESULTS

PGOSE scores significantly improved over time across all DAI grades, suggesting substantial recovery potential even in initially severe cases. Despite indicating extensive injury, patients with DAI grades II and III demonstrated significant improvement, achieving a good recovery by 12 months. Although the initial Glasgow Coma Scale (GCS) score did not show a statistically significant association with long-term outcomes in our limited sample, these findings suggest that the severity of DAI alone may not fully predict eventual recovery.

CONCLUSIONS

Our study highlights the potential for significant neurological recovery in pediatric patients with DAI, emphasizing the importance of long-term follow-up and individualized rehabilitation programs. Further research with larger cohorts and extended follow-up periods is crucial to refine our understanding of the complex relationships between DAI severity, injury mechanisms, and long-term neurological outcomes in children.

Examining the Subacute Effects of Mild Traumatic Brain Injury Using a Traditional and Computerized Neuropsychological Test Battery

This study investigates subacute cognitive effects of mild traumatic brain injury (MTBI) in the Trondheim Mild TBI Study, as measured, in part, by the neuropsychological test battery of the Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI) program, including computerized tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and traditional paper-and-pencil tests. We investigated whether cognitive function was associated with injury severity: intracranial traumatic lesions on neuroimaging, witnessed loss of consciousness (LOC), or post-traumatic amnesia (PTA) >1 h. Further, we explored which of the tests in the CENTER-TBI battery might be associated with the largest subacute effects of MTBI (i.e., at 2 weeks post-injury). We recruited 177 patients with MTBI (16-59 years of age) from a regional trauma center and an outpatient clinic,79 trauma control participants, and 81 community control participants. The MTBI group differed from community controls only on one traditional test of processing speed (coding; p = 0.009, Cliff's delta [Δ] = 0.20). Patients with intracranial abnormalities performed worse than those without on a traditional test (phonemic verbal fluency; p = 0.043, Δ = 0.27), and patients with LOC performed differently on the Attention Switching Task from the CANTAB (p = 0.020, Δ = -0.20). Patients with PTA >1 h performed worse than those with <1 h on 10 measures, from traditional tests and the CANTAB (Δ = 0.33-0.20), likely attributable, at least in part, to pre-existing differences in intellectual functioning between groups. In general, those with MTBI had good neuropsychological outcome 2 weeks after injury and no particular CENTER-TBI computerized or traditional tests seemed to be more sensitive to subtle cognitive deficits.

Measuring Change Over Time: A Systematic Review of Evaluative Measures of Cognitive Functioning in Traumatic Brain Injury

Objectives: The purpose of evaluative instruments is to measure the magnitude of change in a construct of interest over time. The measurement properties of these instruments, as they relate to the instrument's ability to fulfill its purpose, determine the degree of certainty with which the results yielded can be viewed. This work systematically reviews all instruments that have been used to evaluate cognitive functioning in persons with traumatic brain injury (TBI), and critically assesses their evaluative measurement properties: construct validity, test-retest reliability, and responsiveness. Data Sources: MEDLINE, Central, EMBASE, Scopus, PsycINFO were searched from inception to December 2016 to identify longitudinal studies focused on cognitive evaluation of persons with TBI, from which instruments used for measuring cognitive functioning were abstracted. MEDLINE, instrument manuals, and citations of articles identified in the primary search were then screened for studies on measurement properties of instruments utilized at least twice within the longitudinal studies. Study Selection: All English-language, peer-reviewed studies of longitudinal design that measured cognition in adults with a TBI diagnosis over any period of time, identified in the primary search, were used to identify instruments. A secondary search was carried out to identify all studies that assessed the evaluative measurement properties of the instruments abstracted in the primary search. Data Extraction: Data on psychometric properties, cognitive domains covered and clinical utility were extracted for all instruments. Results: In total, 38 longitudinal studies from the primary search, utilizing 15 instruments, met inclusion and quality criteria. Following review of studies identified in the secondary search, it was determined that none of the instruments utilized had been assessed for all the relevant measurement properties in the TBI population. The most frequently assessed property was construct validity. Conclusions: There is insufficient evidence for the validity and reliability of instruments measuring cognitive functioning, longitudinally, in persons with TBI. Several instruments with well-defined construct validity in TBI samples warrant further assessment for test-retest reliability and responsiveness. Registration Number: www.crd.york.ac.uk/PROSPERO/, identifier CRD42017055309.

Changes in Plasma von Willebrand Factor and Cellular Fibronectin in MRI-Defined Traumatic Microvascular Injury

The neuropathology of traumatic brain injury (TB) is diverse, including primary injury to neurons, axons, glial cells, vascular structures, and secondary processes, such as edema and inflammation that vary between individual patients. Traumatic microvascular injury is an important endophenotype of TBI-related injury. We studied patients who sustained a TBI requiring ER evaluation and had an MRI performed within 48 h of injury. We classified patients into 3 groups based on their MRI findings: (1) those that had evidence of traumatic microvascular injury on susceptibility or diffusion weighted MRI sequences without frank hemorrhage [Traumatic Vascular Injury (TVI) group; 20 subjects]. (2) those who had evidence of intraparenchymal, subdural, epidural, or subarachnoid hemorrhage [Traumatic Hemorrhage (TH) group; 26 subjects], and (3) those who had no traumatic injuries detected by MRI [MRI-negative group; 30 subjects]. We then measured plasma protein biomarkers of vascular injury [von Willebrand Factor (vWF) or cellular fibronectin (cFn)] and axonal injury (phosphorylated neurofilament heavy chain; pNF-H). We found that the TVI group was characterized by decreased expression of plasma vWF (p < 0.05 compared to MRI-negative group; p < 0.00001 compared to TH group) ≤48 h after injury. cFN was no different between groups ≤48 h after injury, but was increased in the TVI group compared to the MRI-negative (p < 0.00001) and TH (p < 0.00001) groups when measured >48 h from injury. pNF-H was increased in both the TH and TVI groups compared to the MRI-negative group ≤48 h from injury. When we used the MRI grouping and molecular biomarkers in a model to predict Glasgow Outcome Scale-Extended (GOS-E) score at 30–90 days, we found that inclusion of the imaging data and biomarkers substantially improved the ability to predict a good outcome over clinical information alone. These data indicate that there is a distinct, vascular-predominant endophenotype in a subset of patients who sustain a TBI and that these injuries are characterized by a specific biomarker profile. Further work to will be needed to determine whether these biomarkers can be useful as predictive and pharmacodynamic biomarkers for vascular-directed therapies after TBI.

Volumes of Chronic Traumatic Frontal Brain Lesions Measured by Mr Imaging and CBF Tomography

The volumes (ml) of chronic traumatic frontal brain lesions were compared measured “morphologically” with MR imaging (T1 and T2 weighted images) and “functionally” with a tomographic rCBF technique (SPECT with 133Xe i.v.). The T1 volumes varied between 11 and 220 ml. The correlation between T1 and T2 volumes was 0.95, the T2 volumes being 33% larger than T1 volumes (p < 0.001). The functional SPECT volumes were considerably larger (range 16–324 ml) than the MR volumes. The mean volume difference was 81% between T1 and SPECT images (p < 0.001), and 35% between T2 and SPECT images (p < 0.001). Correlations between the MR and SPECT volumes were also higher for T2 than T1 volumes. The volume difference is most likely explained by a functional decrease in regions around the lesion in which no morphologic change visible on MR images had taken place. MR and SPECT volume measurements were positively related to persistent lack of energy and personality changes, but only moderately related to duration of impaired consciousness and neuropsychologic outcome.

Brain Magnetic Resonance Imaging for Traumatic Brain Injury: Why, When, and How?

Conventional magnetic resonance imaging (MRI) and angiography (MRA) provide invaluable information in the evaluation of patients with all stages and grades of traumatic brain injury (TBI). The information obtained with MRI provides a more complete assessment of the patient's brain injury and possible long-term sequelae.

Interpretation of magnetic resonance imaging in the chronic phase of traumatic brain injury: what is missed in the original reports?

PRIMARY OBJECTIVE

To find eventual differences in detecting the late stage TBI findings in MRI between two neuroradiologists and to compare the results with the original reports.

METHODS AND PROCEDURE

Two neuroradiologists with different levels of experience (R1 and R2) reviewed 89 cranial 1.5 T MRI examinations of patients with clinically evident TBI. They recorded the nature, location and side of the finding and stated their view of traumatic axonal injury (TAI). The original reports were reviewed accordingly.

MAIN OUTCOMES AND RESULTS

TAI was reported as being evident or possible in 51 patients with TBI. However, only 30 (76%) of these concerned the same patients. R1 reported more contusion findings, but both found the same number of spot-like haemorrhages. The most striking difference was in the reporting of localized atrophy. R1 reported atrophy in 51/178 (29%) frontal lobes, whereas R2 in 14/178 (8%). Many of the findings were missed in the original reports.

CONCLUSIONS

The interpretation of TBI findings in late stage MRI yields significant variability between neuroradiologists. This may endanger diagnostics and lead to false treatment decisions and medico-legal problems. Standardized quantitative imaging analysis programs and advances in MRI technology should be utilized to improve radiological TBI diagnosis.

Frontal white matter damage impairs response inhibition in children following traumatic brain injury

Inhibition, the ability to suppress inappropriate cognitions or behaviors, can be measured using computer tasks and questionnaires. Inhibition depends on the frontal cortex, but the role of the underlying white matter (WM) is unclear. We assessed the specific impact of frontal WM damage on inhibition in 29 children with moderate-to-severe traumatic brain injury (15 with and 14 without frontal WM damage), 21 children with orthopedic injury, and 29 population controls. We used the Stop Signal Task to measure response inhibition, the Behavior Rating Inventory of Executive Function to assess everyday inhibition, and T2 fluid-attenuated inversion recovery magnetic resonance imaging to identify lesions. Children with frontal WM damage had impaired response inhibition compared with all other groups and poorer everyday inhibition than the orthopedic injury group. Frontal WM lesions most often affected the superior frontal gyrus. These results provide evidence for the critical role of frontal WM in inhibition.

The challenge of mild traumatic brain injury: role of biochemical markers in diagnosis of brain damage

During the past decade there has been an increasing recognition of the incidence of mild traumatic brain injury (mTBI) and a better understanding of the subtle neurological and cognitive deficits that may result from it. A substantial, albeit suboptimal, effort has been made to define diagnostic criteria for mTBI and improve diagnostic accuracy. Thus, biomarkers that can accurately and objectively detect brain injury after mTBI and, ideally, aid in clinical management are needed. In this review, we discuss the current research on serum biomarkers for mTBI including their rationale and diagnostic performances. Sensitive and specific biomarkers reflecting brain injury can provide important information regarding TBI pathophysiology and serve as candidate markers for predicting abnormal computed tomography findings and/or the development of residual deficits in patients who sustain an mTBI. We also outline the roles of biomarkers in settings of specific interest including pediatric TBI, sports concussions and military injuries, and provide perspectives on the validation of such markers for use in the clinic. Finally, emerging proteomics-based strategies for identifying novel markers will be discussed.

Traumatic brain injury and post-acute decline: what role does environmental enrichment play? A scoping review

Objectives: While a growing number of studies provide evidence of neural and cognitive decline in traumatic brain injury (TBI) survivors during the post-acute stages of injury, there is limited research as of yet on environmental factors that may influence this decline. The purposes of this paper, therefore, are to (1) examine evidence that environmental enrichment (EE) can influence long-term outcome following TBI, and (2) examine the nature of post-acute environments, whether they vary in degree of EE, and what impact these variations have on outcomes.

Methods: We conducted a scoping review to identify studies on EE in animals and humans, and post-discharge experiences that relate to barriers to recovery.

Results: One hundred and twenty-three articles that met inclusion criteria demonstrated the benefits of EE on brain and behavior in healthy and brain-injured animals and humans. Nineteen papers on post-discharge experiences revealed that variables such as insurance coverage, financial, and social support, home therapy, and transition from hospital to home, can have an impact on clinical outcomes.

Conclusion: There is evidence to suggest that lack of EE, whether from lack of resources or limited ability to engage in such environments, may play a role in post-acute cognitive and neural decline. Maximizing EE in the post-acute stages of TBI may improve long-term outcomes for the individual, their family and society.

Diffuse axonal injury in mild traumatic brain injury: a 3D multivoxel proton MR spectroscopy study

Since mild traumatic brain injury (mTBI) often leads to neurological symptoms even without clinical MRI findings, our goal was to test whether diffuse axonal injury is quantifiable with multivoxel proton MR spectroscopic imaging ((1)H-MRSI). T1- and T2-weighted MRI images and three-dimensional (1)H-MRSI (480 voxels over 360 cm(3), about 30 % of the brain) were acquired at 3 T from 26 mTBI patients (mean Glasgow Coma Scale score 14.7, 18-56 years old, 3-55 days after injury) and 13 healthy matched contemporaries as controls. The N-acetylaspartate (NAA), choline (Cho), creatine (Cr) and myo-inositol (mI) concentrations and gray-matter/white-matter (GM/WM) and cerebrospinal fluid fractions were obtained in each voxel. Global GM and WM absolute metabolic concentrations were estimated using linear regression, and patients were compared with controls using two-way analysis of variance. In patients, mean NAA, Cr, Cho and mI concentrations in GM (8.4 ± 0.7, 6.9 ± 0.6, 1.3 ± 0.2, 5.5 ± 0.6 mM) and Cr, Cho and mI in WM (4.8 ± 0.5, 1.4 ± 0.2, 4.6 ± 0.7 mM) were not different from the values in controls. The NAA concentrations in WM, however, were significantly lower in patients than in controls (7.2 ± 0.8 vs. 7.7 ± 0.6 mM, p = 0.0125). The Cho and Cr levels in WM of patients were positively correlated with time since mTBI. This (1)H-MRSI approach allowed us to ascertain that early mTBI sequelae are (1) diffuse (not merely local), (2) neuronal (not glial), and (3) in the global WM (not GM). These findings support the hypothesis that, similar to more severe head trauma, mTBI also results in diffuse axonal injury, but that dysfunction rather than cell death dominates shortly after injury.

Magnetic resonance imaging improves 3-month outcome prediction in mild traumatic brain injury

OBJECTIVE

To determine the clinical relevance, if any, of traumatic intracranial findings on early head computed tomography (CT) and brain magnetic resonance imaging (MRI) to 3-month outcome in mild traumatic brain injury (MTBI).

METHODS

One hundred thirty-five MTBI patients evaluated for acute head injury in emergency departments of 3 LEVEL I trauma centers were enrolled prospectively. In addition to admission head CT, early brain MRI was performed 12 ± 3.9 days after injury. Univariate and multivariate logistic regression were used to assess for demographic, clinical, socioeconomic, CT, and MRI features that were predictive of Extended Glasgow Outcome Scale (GOS-E) at 3 months postinjury.

RESULTS

Twenty-seven percent of MTBI patients with normal admission head CT had abnormal early brain MRI. CT evidence of subarachnoid hemorrhage was associated with a multivariate odds ratio of 3.5 (p = 0.01) for poorer 3-month outcome, after adjusting for demographic, clinical, and socioeconomic factors. One or more brain contusions on MRI, and ≥4 foci of hemorrhagic axonal injury on MRI, were each independently associated with poorer 3-month outcome, with multivariate odds ratios of 4.5 (p = 0.01) and 3.2 (p = 0.03), respectively, after adjusting for head CT findings and demographic, clinical, and socioeconomic factors.

INTERPRETATION

In this prospective multicenter observational study, the clinical relevance of abnormal findings on early brain imaging after MTBI is demonstrated. The addition of early CT and MRI markers to a prognostic model based on previously known demographic, clinical, and socioeconomic predictors resulted in a >2-fold increase in the explained variance in 3-month GOS-E.

Whole-brain proton MR spectroscopic imaging of mild-to-moderate traumatic brain injury and correlation with neuropsychological deficits

Changes in the distribution of the magnetic resonance (MR)-observable brain metabolites N-acetyl aspartate (NAA), total choline (Cho), and total creatine (Cre), following mild-to-moderate closed-head traumatic brain injury (mTBI) were evaluated using volumetric proton MR spectroscopic imaging (MRSI). Studies were carried out during the subacute time period following injury, and associations of metabolite indices with neuropsychological test (NPT) results were evaluated. Twenty-nine subjects with mTBI and Glasgow Coma Scale (GCS) scores of 10-15 were included. Differences in individual metabolite and metabolite ratio distributions relative to those of age-matched control subjects were evaluated, as well as analyses by hemispheric lobes and tissue types. Primary findings included a widespread decrease of NAA and NAA/Cre, and increases of Cho and Cho/NAA, within all lobes of the TBI subject group, and with the largest differences seen in white matter. Examination of the association between all of the metabolite measures and the NPT scores found the strongest negative correlations to occur in the frontal lobe and for Cho/NAA. No significant correlations were found between any of the MRSI or NPT measures and the GCS. These results demonstrate that significant and widespread alterations of brain metabolites occur as a result of mild-to-moderate TBI, and that these measures correlate with measures of cognitive performance.

The Relationship between age, injury severity, and MRI findings after traumatic brain injury

Age and injury severity are among the most significant predictors of outcome after traumatic brain injury (TBI). However, only a few studies have investigated the association between, age, injury severity, and the extent of brain damage in TBI. The purpose of this study was to investigate the association between age, measures of injury severity, and brain lesion volumes, as well as viable brain volumes, following TBI. Ninety-eight individuals with mild to very severe TBI (75.5% male, mean age at injury 34.5 years) underwent a structural MRI scan, performed with a 1.5-Tesla machine, on average 2.3 years post-injury. Lesion volumes were highly skewed in their distribution and were dichotomized for statistical purposes. Measures of injury severity were Glasgow Coma Scale score (GCS) and duration of post-traumatic amnesia (PTA). Logistic regression analyses predicting lesion volumes, controlling for participants' gender, cause of injury, time from injury to MRI scan, and total brain volume, revealed that both older age and longer PTA were associated with larger lesion volumes in both grey and white matter in almost all brain regions. Older age was also associated with smaller viable grey matter volumes in most neo-cortical brain regions, while longer PTA was associated with smaller viable white matter volumes in most brain regions. The results suggest that older age worsens the impact of TBI on the brain. They also indicate the validity of duration of PTA as a measure of injury severity that is not just related to one particular injury location.

Proton MR spectroscopy in mild traumatic brain injury

BACKGROUND

To assess the role of 1H MRS in the detection of changes in cerebral metabolite levels in pyramidal tracts after mild traumatic brain injury (MTBI) and to compare metabolite alterations to the clinical status (Glasgow Coma Scale).

MATERIAL/METHODS

Study group consisted of 25 patients after mild traumatic brain injury, with a score of 11 to 15 in GCS. The MR studies were performed with a 1.5 T scanner. The results of spectra approximation (presented as metabolite ratios: NAA/Cr, NAA/Cho, Cho/Cr, lac/Cr, lip/Cr, Glx/Cr) were subjected to statistical analysis. MR spectra were recorded from a normal-appearing brain region: internal capsules and cerebral peduncles. Spectra from traumatic patients were compared with a control group including 34 healthy volunteers recorded with the same techniques.

RESULTS

The statistical analysis revealed significant differences between the data obtained from various brain regions of the same patients after an MTBI and between the study and the control group. Proton MR spectroscopy detects changes in cerebral metabolite levels in apparently normal regions. In pyramidal tracts (internal capsules, cerebral peduncles), we noticed a significant reduction of NAA /Cho, lip/Cr, lac/Cr and Glx/Cr.

CONCLUSIONS

In patients with mild brain injury, we can detect some metabolite abnormalities in normal-appearing brain structures. Proton MRS is a very useful tool for evaluation of major changes in metabolite levels in pyramidal tracts after mild traumatic brain injury.

Magnetic resonance imaging of traumatic brain injury: relationship of T2 SE and T2*GE to clinical severity and outcome

PRIMARY OBJECTIVES

To evaluate (1) the sensitivity of magnetic resonance imaging (MRI) T2* weighted gradient echo (GE) vs T2 weighted spin echo (SE) technology for lesion detection in traumatic brain injury (TBI) and (2) the relationship of lesion patterns to acute clinical severity and 1 year post-injury outcome measures.

RESEARCH DESIGN

Comparative analysis.

METHODS AND PROCEDURES

Forty-three acute rehabilitation patients with TBI were imaged utilizing T2 SE and T2* GE techniques an average of 26 days post-injury. Acute clinical severity measures, including Glasgow Coma Scale (GCS), time to follow commands (TFC) and post-traumatic amnesia (PTA) were abstracted from medical records. One-year post-injury outcome measures including Glasgow Outcome Scale (GOS), Disability Rating Scale (DRS) and the Craig Handicap Assessment and Reporting Technique--Short Form (CHART-SF) were collected as part of a comprehensive annual follow-up.

MAIN OUTCOMES AND RESULTS

In comparison to T2 SE, T2* GE more frequently detected lesions in each of the cortical (p <0.0001), white matter (p <0.001), central grey (p <0.001) and brainstem (p <0.01) regions and in each of the frontal (p <0.0001), temporal (p <0.0001), parietal (p <0.001) and occipital (p <0.0001) lobes. With regards to acute clinical severity measures, T2* GE findings were the best predictors of GCS and the only significant predictors of PTA, while T2 SE findings were better predictors of TFC. For 1 year post-injury outcome measures, multivariate regression models utilizing T2 SE and T2* GE findings in combination were the best predictors of DRS and GOS and T2 SE findings alone were the best predictors of CHART-SF.

CONCLUSIONS

This study demonstrates the enhanced sensitivity of T2* GE for detecting haemorrhagic lesions associated with TBI and supports a complimentary role for both T2 SE and T2* GE weighted imaging in characterizing injury severity and predicting longer-term outcomes.

Magnetic resonance imaging evidence of progression of subacute brain atrophy in moderate to severe traumatic brain injury

OBJECTIVE

To demonstrate subacute progression of brain atrophy (from 4.5-29mo postinjury) in moderate to severe traumatic brain injury (TBI) using structural magnetic resonance imaging (MRI).

DESIGN

Within-subjects, repeated-measures design.

SETTING

Inpatient neurorehabilitation program and teaching hospital (MRI department).

PARTICIPANTS

Adults (N=14) with moderate to severe TBI.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Neuroradiologist readings and volumetric measurements (total brain cerebrospinal fluid and hippocampus) at 4.5 months and 2.5 years postinjury.

RESULTS

Ten of 14 patients showed visible atrophy progression. Significant increase in cerebrospinal fluid (CSF) volume (t(13)=-4.073, P<.001) and decrease in right and left hippocampal volumes (t(13)=4.221, P<.001 and t(13)=3.078, P<.005, respectively) were observed from 4.5 months to 2.5 years. Compared with published normative data, patients with TBI showed significantly more pathologic percent annual volume change for the hippocampi (t(26)=-3.864, P<.001, right; and t(26)=-2.737, P<.01, left), and a trend for CSF (t(26)=1.655, P=.059).

CONCLUSIONS

This study provides strong MRI evidence for subacute progression of atrophy, as distinct from early, acute neurologic changes observed.

Characterizing 'mild' in traumatic brain injury with proton MR spectroscopy in the thalamus: Initial findings

OBJECTIVE

Although most mild traumatic brain injury (mTBI) patients suffer any of several post-concussion symptoms suggestive of thalamic involvement, they rarely present with any MRI-visible pathology. The aim here, therefore, is to characterize their thalamic metabolite levels with proton MR spectroscopy (1H-MRS) compared with healthy controls.

METHODS

T1-weighted MRI and multi-voxel 1H-MRS were acquired at 3 Tesla from 20 mTBI (Glasgow Coma Scale score of 15-13) patients, 19-59 years old, 0-7 years post-injury; and from 17 age and gender matched healthy controls. Mixed model regression was used to compare patients and controls with respect to the mean absolute N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) levels within each thalamus.

RESULTS

The mTBI-induced thalamic metabolite concentration changes were under +/- 13.0% for NAA, +/- 13.5% for Cr and +/- 18.8% for Cho relative to their corresponding concentrations in the controls: NAA: 10.08 +/- 0.30 (mean +/- standard error), Cr: 5.62 +/- 0.18 and Cho: 2.08 +/- 0.09 mM. These limits represent the minimal detectable differences between the two cohorts.

CONCLUSION

The change in metabolic levels in the thalamus of patients who sustained clinically defined mTBI could be an instrumental characteristic of 'mildness'. 1H-MRS could, therefore, serve as an objective laboratory indicator for differentiating 'mild' from more severe categories of head-trauma, regardless of the presence or lack of current clinical symptoms.

Structural and functional neuroimaging in mild-to-moderate head injury

Head injury is a major cause of disability and death in adults. Significant developments in imaging techniques have contributed to the knowledge of the pathophysiology of head injury. Although extensive research is available on severe head injury, less is known about mild-to-moderate head injury despite the fact that most patients sustain this type of injury. In this review, we focus on structural and functional imaging techniques in patients with mild-to-moderate head injury. We discuss CT and MRI, including different MRI sequences, single photon emission computed tomography, perfusion-weighted MRI, perfusion CT, PET, magnetic resonance spectroscopy, functional MRI and magnetic encephalography. We outline the advantages and limitations of these various techniques in the contexts of the initial assessment and identification of brain abnormalities and the prediction of outcome.

Acute metabolic brain changes following traumatic brain injury and their relevance to clinical severity and outcome

BACKGROUND

Conventional MRI can provide critical information for care of patients with traumatic brain injury (TBI), but MRI abnormalities rarely correlate to clinical severity and outcome. Previous magnetic resonance spectroscopy studies have reported clinically relevant brain metabolic changes in patients with TBI. However, these changes were often assessed a few to several days after the trauma, with a consequent variation of the metabolic pattern due to temporal changes.

METHODS

Proton magnetic resonance spectroscopic imaging (1H-MRSI) examinations were performed in 10 patients with TBI 48-72 h after the trauma, to obtain early measurements of central brain levels of N-acetylaspartate (NAA), choline (Cho), creatine (Cr) and lactate (La). Metabolite values were expressed as ratios to (1) a metabolic pattern, given by the sum of the resonance intensities of all metabolites detected in the same voxel and (2) intravoxel Cr.

RESULTS

NAA ratios were found to be significantly lower in patients with TBI than in normal controls. In contrast, Cho ratios were significantly higher in patients with TBI than in normal controls. Increased La levels were found in 5 of 10 patients with TBI. Both NAA and La values correlated closely with those of the Glasgow Coma Scale at presentation (r = 0.73 and -0.62, respectively; p<0.01 for both) and the Glasgow Outcome Scale at 3 months (r = -0.79 and 0.79, respectively; p<0.01 for both).

CONCLUSION

Spectroscopic measures of neuro-axonal damage occurring soon after a brain trauma are clinically relevant. Significant increases in cerebral La level also may be detected when 1H-MRSI is performed early after the trauma and, at this stage, can represent a reliable index of injury severity and disease outcome in patients with TBI.

In vivo characterization of traumatic brain injury neuropathology with structural and functional neuroimaging

Quantitative neuroimaging is increasingly used to study the effects of traumatic brain injury (TBI) on brain structure and function. This paper reviews quantitative structural and functional neuroimaging studies of patients with TBI, with an emphasis on the effects of diffuse axonal injury (DAI), the primary neuropathology in TBI. Quantitative structural neuroimaging has evolved from simple planometric measurements through targeted region-of-interest analyses to whole-brain analysis of quantified tissue compartments. Recent studies converge to indicate widespread volume loss of both gray and white matter in patients with moderate-to-severe TBI. These changes can be documented even when patients with focal lesions are excluded. Broadly speaking, performance on standard neuropsychological tests of speeded information processing are related to these changes, but demonstration of specific brain-behavior relationships requires more refined experimental behavioral measures. The functional consequences of these structural changes can be imaged with activation functional neuroimaging. Although this line of research is at an early stage, results indicate that TBI causes a more widely dispersed activation in frontal and posterior cortices. Further progress in analysis of the consequences of TBI on neural structure and function will require control of variability in neuropathology and behavior.

MR imaging of head trauma: visibility of contusions and other intraparenchymal injuries in early and late stage

The aim of this study was to investigate the visibility of traumatic brain lesions on conventional magnetic resonance images (MRI) in early and late phase. Thirty-six patients were studied 1 week and 1 year after a traumatic brain injury. A similar MRI technique was used in both studies; T2-weighted fast or turbo spin echo images, fluid attenuated inversion recovery (FLAIR) images and T1-weighted images were used for analysis. The number and extent of contusions and semi-quantitative score of other traumatic intraparenchymal lesions were compared in the early and late phase. Contusions were seen in 18 patients both in acute and 1 year MRI; the number and extent of visible contusions was significantly decreased at 1 year. Other traumatic intraparenchymal lesions were detected in 12 patients in early MRI and in 10 patients in late MRI. The number of visible lesions and the semi-quantitative scores were significantly lower at 1 year. There is a significant decrease in the visibility of both cortical contusions and other intraparenchymal injuries in late MRI studies compared with studies in acute stage using conventional imaging techniques. Thus, early phase MRI is essential for the detection of brain injury at least using conventional imaging techniques.

Day-of-injury computerized tomography, rehabilitation status, and development of cerebral atrophy in persons with traumatic brain injury

OBJECTIVE

To compare day-of-injury (DOI) computerized tomography (CT) findings with acute injury severity markers, disability at acute hospital admission and discharge from inpatient rehabilitation, injury severity markers, and degree of postacute cerebral atrophy on magnetic resonance imaging (MRI).

DESIGN

Retrospective chart review of 240 consecutive traumatic brain injury (TBI) admissions (mean age 31.7 +/- 15.8 yrs) with moderate-to-severe initial brain injury. All DOI CT abnormalities were qualitatively rated. Disability was assessed using the Disability Rating Scale (DRS) and the FIM measure. In a representative subset, cerebral atrophy was determined by the ventricle-to-brain ratio (VBR) method and quantified from MRI scans 25 or more days postinjury.

RESULTS

CT classification resulted in nonsignificant differences in DRS and FIM ratings at the time of discharge from the rehabilitation unit, except in brainstem injury subjects who had significantly higher DRS and lower FIM scores at rehabilitation discharge. At 25 or more days postinjury, presence of any DOI CT abnormality was associated with larger VBR. Increased VBR, as an index of cerebral atrophy, was associated with worse rehabilitation discharge DRS and FIM ratings.

CONCLUSIONS

Other than brainstem injury, DOI CT findings relate poorly to rehabilitation outcome. Presence of DOI CT abnormalities were associated with the development of cerebral atrophy, which was associated with poorer rehabilitation discharge DRS and FIM scores.

Neuroimaging in traumatic brain imaging

Traumatic brain injury (TBI) is a common and potentially devastating clinical problem. Because prompt proper management of TBI sequelae can significantly alter the clinical course especially within 48 h of the injury, neuroimaging techniques have become an important part of the diagnostic work up of such patients. In the acute setting, these imaging studies can determine the presence and extent of injury and guide surgical planning and minimally invasive interventions. Neuroimaging also can be important in the chronic therapy of TBI, identifying chronic sequelae, determining prognosis, and guiding rehabilitation.

Diffusion-weighted MR imaging in closed head injury: high correlation with initial glasgow coma scale score and score on modified Rankin scale at discharge

PURPOSE

To determine whether diffusion-weighted magnetic resonance (MR) imaging findings and conventional MR imaging findings correlate with initial Glasgow Coma Scale score and score on modified Rankin scale at discharge.

MATERIALS AND METHODS

Twenty-six patients (18 male and eight female patients; mean age, 25.2 years; age range, 4-72 years) with diffuse axonal injury were examined with diffusion-weighted MR imaging and with fluid-attenuated inversion recovery, T2-weighted fast spin-echo, and T2*-weighted gradient-echo sequences. All images were evaluated by two neuroradiologists in consensus. Tissue volume with trauma-related signal-intensity abnormality on images from each sequence, number of lesions for each sequence, number of lesions for all sequences, and number of lesions with reduced apparent diffusion coefficient were correlated with scores on Glasgow Coma Scale and modified Rankin scale. Involvement of brainstem, deep gray matter, and corpus callosum were also correlated with clinical scores. Spearman rank correlation coefficients (r) were calculated.

RESULTS

The strongest correlation was between signal-intensity abnormality volume on diffusion-weighted images and modified Rankin score (r = 0.772, P <.001). The strength of this correlation did not improve when only volume of lesions with decreased apparent diffusion coefficient was considered. For lesion number, the strongest correlation was between lesion number on images acquired with all sequences and modified Rankin score (r = 0.662, P <.001). For lesion location, the strongest correlation was between lesion location in the corpus callosum and modified Rankin score (r = 0.513, P =.007).

CONCLUSION

Volume of lesions on diffusion-weighted MR images provides the strongest correlation with a score of subacute on modified Rankin scale at discharge. Total lesion number also correlates well with modified Rankin score. In future, diffusion-weighted images may be useful in determining treatment strategies for acute head injury.

Volumetric proton spectroscopic imaging of mild traumatic brain injury

BACKGROUND AND PURPOSE

Poor clinical outcomes without notable neuroimaging findings after mild traumatic brain injury (MTBI) suggest diffuse tissue damage and altered metabolism not observable with conventional MR imaging and CT. In this study, MTBI-associated metabolic changes were assessed over the entire brain by using volumetric proton MR spectroscopic imaging (MRSI) and the findings related to injury and outcome assessments.

METHODS

Fourteen subjects with mild closed head injury (Glasgow Coma Scale [GCS] scores of 13-15) underwent structural MR imaging and proton MRSI at 1.5 T within 1 month of injury. Distributions of N-acetylaspartate (NAA), total creatine (Cr), and total choline (Cho) were mapped over a wide region of the brain, and metabolite ratios were calculated for 25 regions without MR imaging abnormalities. Results were compared with data from 13 control subjects.

RESULTS

Significant changes (P <.05) were found for some, but not all, brain regions for the average values from all MTBI subjects, with reduced NAA/Cr, increased Cho/Cr, and reduced NAA/Cho. Global NAA/Cho obtained from the sum of all sampled regions in two subjects was significantly reduced. Metabolite ratios were not significantly correlated with GCS score at admission or Glasgow Outcome Scale (GOS) score at 6 months after injury, although they were weakly correlated with GOS score at discharge.

CONCLUSION

These results show evidence of widespread metabolic changes following MTBI in regions that appear normal on diagnostic MR images. Although the association with injury assessment and outcome is weak, this preliminary study demonstrates the applicability of volumetric proton MRSI for evaluating diffuse injury associated with MTBI.

The neurophysiology of brain injury

OBJECTIVE

This article reviews the mechanisms and pathophysiology of traumatic brain injury (TBI).

METHODS

Research on the pathophysiology of diffuse and focal TBI is reviewed with an emphasis on damage that occurs at the cellular level. The mechanisms of injury are discussed in detail including the factors and time course associated with mild to severe diffuse injury as well as the pathophysiology of focal injuries. Examples of electrophysiologic procedures consistent with recent theory and research evidence are presented.

RESULTS

Acceleration/deceleration (A/D) forces rarely cause shearing of nervous tissue, but instead, initiate a pathophysiologic process with a well defined temporal progression. The injury foci are considered to be diffuse trauma to white matter with damage occurring at the superficial layers of the brain, and extending inward as A/D forces increase. Focal injuries result in primary injuries to neurons and the surrounding cerebrovasculature, with secondary damage occurring due to ischemia and a cytotoxic cascade. A subset of electrophysiologic procedures consistent with current TBI research is briefly reviewed.

CONCLUSIONS

The pathophysiology of TBI occurs over time, in a pattern consistent with the physics of injury. The development of electrophysiologic procedures designed to detect specific patterns of change related to TBI may be of most use to the neurophysiologist.

SIGNIFICANCE

This article provides an up-to-date review of the mechanisms and pathophysiology of TBI and attempts to address misconceptions in the existing literature.

Brain Imaging as a Predictor of Early Functional Outcome Following Traumatic Brain Injury in Children, Adolescents, and Young Adults

OBJECTIVES

A depth of lesion (DOL) model using brain imaging has been proposed to aid in medical decision-making and planning for rehabilitation resource needs. The purpose of this study was to determine the early prognostic value of a DOL classification system for children and young adults following severe traumatic brain injury.

METHODS AND OUTCOME MEASURES

CT/MRI brain imaging studies on 92 patients, aged 3 to 21, admitted to the Kluge Children's Rehabilitation Center, University of Virginia, were evaluated to determine DOL. Images were classified according to 5 DOL levels (cortical to brainstem). Functional outcomes in mobility, self-care, and cognition, as rated on the WeeFIM instrument, were compared by DOL levels.

RESULTS

Admission WeeFIM scores were significantly different for the DOL levels with the highest score for frontal and/or temporal lesions and the lowest for lesions including the brainstem or cerebellum (P<.001). However, the deeper the lesion, the greater the functional gains (P=.05), resulting in discharge WeeFIM scores that were not significantly different across DOL levels. Patients with deeper lesions tended to have longer lengths of stay in rehabilitation but were able to "catch up" with patients who had more superficial lesions.

CONCLUSIONS

While relatively simple and convenient, the DOL classification system is limited in its usefulness as an early prognostic tool. It may not be possible to predict outcome in the early acute phase in the intensive care unit on the basis of standard brain imaging alone. Patients with deeper lesions may enter rehabilitation at a more impaired level but can make remarkable progress, though it may take longer than for less severely injured individuals.

[Assessing and predicting recovery from a coma following traumatic brain injury: contribution of neuroradiological data]

OBJECTIVE

Literature review concerning the contribution of neurological imaging to the assessment of traumatic lesions and the prognosis of traumatic coma.

MATERIAL AND METHODS

Interrogation of scientific databases Medline, Embase and Current Contents via key-words. One hundred and seventy-one articles were picked up out of which 67 were analysed according to the French ANAES' rules. Results and discussion are drawn from the literature data and the author's experience.

RESULTS AND DISCUSSION

In the acute stage the diagnosis approach prevails the prognostic dimension, is confused by secondary complications. Computerized-Tomography (CT) remains the best imaging modality, allowing a quick diagnosis of most of injuries, especially those which require an emergency treatment. But its predictive value in coma outcome is low. Although magnetic resonance imagery (MRI) is more sensitive, it does not at the acute stage lead to therapeutic modifications, increases the costs and is thus not necessary. MRI angiography may show cranial vessel injury which need specific therapeutic procedures. In the subacute or chronic stage after a severe head injury, CT is useful for the follow up and may provide some prognostic informations. But MRI with classical sequences has a higher sensitive and predictive power. Diffusion weighted imaging has not so far made the proof of it's predictive value. Proton MR spectroscopy seems to be able to provide data correlated with neurological outcome (NAA/Cr), but is not of routine use. Single-photon emission tomography is also useful to assess brain injury sequelae in the chronic stage; positron-emission tomography still remains a research technology. These 2 modalities have not yet a prognostic value.

CONCLUSION

In the acute stage CT remains the best imaging modality. In the subacute and chronic stage MRI has the highest predictive power. Special sequences raise new hopes. Single-photon emission tomography and positron-emission tomography have not yet a prognostic value.

Radiographic assessment of cranial gunshot wounds

Though advances in MRI will undoubtedly increase its use, particularly in the subacute period, CT will likely continue its primary role in the management of these injuries in the foreseeable future. The spectrum of imaging features of cranial gunshot injuries is vast, because they encompass all of the findings encountered in closed head injury in addition to the wide variety of problems associated with penetration. Thus, only a brief summary of the many varied aspects of this complex problem is presented here as a review of the more salient issues.

EFNS guideline on mild traumatic brain injury: report of an EFNS task force

In 1999, a Task Force on Mild Traumatic Brain Injury (MTBI) was set up under the auspices of the European Federation of Neurological Societies. Its aim was to propose an acceptable uniform nomenclature for MTBI and definition of MTBI, and to develop a set of rules to guide initial management with respect to ancillary investigations, hospital admission, observation and follow-up.

Current concepts: diffuse axonal injury-associated traumatic brain injury

OBJECTIVES

To review the probable physical, physiologic mechanisms that result in the medical and neuropsychologic complications of diffuse axonal injury (DAI)-associated traumatic brain injury (TBI).

DATA SOURCES

Various materials were accessed: MEDLINE, textbooks, scientific presentations, and current ongoing research that has been recently reported.

STUDY SELECTION

Included were scientific studies involving TBI, particularly direct injury to the axons and glia of the central nervous system (CNS) in both in vitro and in vivo models. These studies include pathologic findings in humans as well as the medical complications and behavioral outcomes of DAI. Studies that addressed animal models of DAI as well as cellular and/or tissue models of neuronal injury were emphasized. The review also covered work on the physical properties of materials involved in the transmission of energy associated with prolonged acceleration-deceleration injuries.

DATA EXTRACTION

Studies were selected with regard to those that addressed the mechanism of TBI associated with DAI and direct injury to the axon within the CNS. The material was generally the emphasis of the article and was extracted by multiple observers. Studies that correlate the above findings with the clinical picture of DAI were included.

DATA SYNTHESIS

Concepts were developed by the authors based on the current scientific findings and theories of DAI. The synthesis of these concepts involves expertise in physical science, basic science concepts of cellular injury to the CNS, acute medical indicators of DAI, neuropsychologic indicators of DAI, and rehabilitation outcomes from TBI.

CONCLUSIONS

The term DAI is a misnomer. It is not a diffuse injury to the whole brain, rather it is predominant in discrete regions of the brain following high-speed, long-duration deceleration injuries. DAI is a consistent feature of TBI from transportation-related injuries as well as some sports injuries. The pathology of DAI in humans is characterized histologically by widespread damage to the axons of the brainstem, parasagittal white matter of the cerebral cortex, corpus callosum, and the gray-white matter junctions of the cerebral cortex. Computed tomography and magnetic resonance imaging scans taken initially after injury are often normal. The deformation of the brain due to plastic flow of the neural structures associated with DAI explains the micropathologic findings, radiologic findings, and medical and neuropsychologic complications from this type of injury mechanism. There is evidence that the types of cellular injury in TBI (DAI, anoxic, contusion, hemorrhagic, perfusion-reperfusion) should be differentiated, as all may involve different receptors and biochemical pathways that impact recovery. These differing mechanisms of cellular injury involving specific biochemical pathways and locations of injury may, in part, explain the lack of success in drug trials to ameliorate TBI.

Neuropsychological outcome in relation to the traumatic coma data bank classification of computed tomography imaging

The Traumatic Coma Data Bank (TCDB) classification of CT (computed tomography) scan has been related to the general outcome and intracranial pressure evolution. Our aim was to analyse the relationship of this classification with neuropsychological outcome and late indices of ventricular dilatation. Fifty-seven patients with a moderate or severe head injury (mean admission Glasgow Coma Scale Score, 7.7) were studied from 122 consecutive cases. There were 49 males and 8 females (mean age, 27.7 years). Subjects were classified into TCDB categories on the basis of their most serious acute CT scan finding. From the last control CT scan image, performed at a mean of 6.12 months postinjury, several measures of ventricular dilatation were calculated. Neuropsychological assessment at 6-month included tests of verbal and visual memory, visuoconstructive functions, fine motor speed, and frontal lobe functions. Patients with diffuse injury type I showed better neuropsychological outcome than patients with more severe diffuse injuries and those with mass lesions. Within the diffuse injury groups, the degree of diffuse damage was related to measures of verbal memory and attention and cognitive flexibility. Ventricular enlargement was more evident in patients with mass lesions and it decreased in the remaining groups as the severity of diffuse injury diminished. These results show that there is a relationship between acute intracranial lesion diagnosis according to TCDB classification and neuropsychological results and ventricular dilatation indices at 6 months postinjury.

Abnormal cerebral blood volume in regions of contused and normal appearing brain following traumatic brain injury using perfusion magnetic resonance imaging

Following traumatic brain injury, there may be secondary alterations in cerebrovascular parameters leading to ischemia and further cellular damage. To assess possible subacute hemodynamic disturbances following traumatic brain injury, we used conventional and perfusion magnetic resonance imaging (MRI) in 18 patients, on average 10 days following injury. Six of the 18 patients had focal contusions or edema visible on conventional MRI. These six patients had a significantly reduced normalized regional cerebral blood volume (rCBV) in the regions of focal pathology compared to equivalent areas in control subjects (patients 0.47 +/- 0.20 [means +/- SD], controls 1.02 +/- 0.11, p < 0.001). In addition, four of these six patients had an increased rCBV (outside control range) in the region of normal appearing brain immediately surrounding the contusion. These six patients were more significantly injured and had a worse clinical outcome compared to the remaining patients (p = 0.004,p = 0.03, respectively). There were five patients who had a region of reduced rCBV (outside control range) in a quadrant of normal appearing white matter, away from any visible abnormality, who were not more significantly injured than the remaining patients but went on to have a significantly poorer clinical outcome (p = 0.27, p = 0.01, respectively). Traumatic brain injury is a heterogeneous insult causing a variety of pathology, not all of which is visible using conventional imaging methods. The current study has shown that regions of both normal appearing and contused brain may have an abnormal rCBV and that alterations in rCBV may play a role in determining the clinical outcome of patients.

Depth of lesion model in children and adolescents with moderate to severe traumatic brain injury: use of SPGR MRI to predict severity and outcome

OBJECTIVES

The utility of a depth of lesion classification using an SPGR MRI sequence in children with moderate to severe traumatic brain injury (TBI) was examined. Clinical and depth of lesion classification measures of TBI severity were used to predict neurological and functional outcome after TBI.

METHODS

One hundred and six children, aged 4 to 19, with moderate to severe TBI admitted to a rehabilitation unit had an SPGR MRI sequence obtained 3 months afterTBI. Acquired images were analyzed for location, number, and size of lesions. The Glasgow coma scale (GCS) was the clinical indicator of severity. The deepest lesion present was used for depth of lesion classification. Speed of injury was inferred from the type of injury. The disability rating scale at the time of discharge from the rehabilitation unit (DRS1) and at 1 year follow up (DRS2) were functional outcome measures.

RESULTS

The depth of lesion classification was significantly correlated with GCS severity, number of lesions, and both functional measures, DRS1 and DRS2. This result was more robust for time 1, probably due to the greater number of psychosocial factors impacting on functioning at time 2. Lesion volume was not correlated with the depth of lesion model. In multivariate models, depth of lesion was most predictive of DRS1, whereas GCS was most predictive of DRS2.

CONCLUSIONS

A depth of lesion classification of TBI severity may have clinical utility in predicting functional outcome in children and adolescents with moderate to severe TBI.

Magnetization transfer imaging and proton MR spectroscopy in the evaluation of axonal injury: correlation with clinical outcome after traumatic brain injury

BACKGROUND AND PURPOSE

Current imaging does not permit quantification of neural injury after traumatic brain injury (TBI) and therefore limits both the development of new treatments and the appropriate counseling of patients concerning prognosis. We evaluated the utility of magnetization transfer ratio (MTR) and proton MR spectroscopy in identifying patients with neuronal injury after TBI.

METHODS

Thirty patients with TBI (21-77 years old; mean age, 42 years; admission Glasgow Coma Scale (GOS) scores 3-15; mean score, 11) were studied on a 1.5-T system with magnetization transfer imaging and MR spectroscopy of the splenium. Magnetization transfer imaging was also performed in the brain stem in all patients, and other areas of the brain were sampled in one patient. The splenium of the corpus callosum and brain stem were studied because these are often affected by diffuse axonal injury. Scans were obtained 2 to 1129 days after injury (median, 41 days). MTR was considered abnormal if it was more than 2 SD below normal. Proton MR spectroscopy was used to calculate the N-acetylaspartate (NAA)/creatine (Cr) ratio. GOS was determined at least 3 months after injury.

RESULTS

In 10 patients with a GOS of 1 to 4, the mean NAA/Cr was 1.24 +/- 0.28; two of these patients had abnormal MTR in normal-appearing white matter (NAWM). In 20 patients with a GOS of 5, the mean NAA/Cr was 1.53 +/- 0.37 (P < .05); four of these patients had abnormal MTR in NAWM. MTR abnormalities in NAWM were identified in six patients, but these changes did not correlate with GOS or MR spectroscopy changes.

CONCLUSION

MTR and MR spectroscopy can quantify damage after TBI, and NAA levels may be a sensitive indicator of the neuronal damage that results in a worse clinical outcome.

Neuropsychological, MRI and EEG findings after very mild traumatic brain injury

Neuropsychological performance, magnetic resonance imaging (MRI) and electroencephalography (EEG) were investigated in 12 consecutive patients with very mild traumatic brain injury (MTBI) (Glasgow coma score 15) within 24 hours and 6 weeks after injury. The data were compared to 14 control subjects. There was a significant impairment in neuropsychological performance (verbal memory, arithmetic abilities and psychomotor reaction time) at onset and after 6 weeks, whereas verbal fluency and non-verbal memory test revealed no significant differences matching the control values. In MRI scans, three patients showed traumatic lesions (slight epidural haematoma, haemorrhagic contusions and white matter lesions indicating diffuse axonal injury). In the EEG recordings, no generalized slowing or focal changes were found. Structural and functional impairment can be identified using neuroimaging and neuropsychological examination, even in very MTBI patients.

Computed tomography and magnetic resonance imaging in mild to moderate head injury: early and late imaging related to outcome

Serial magnetic resonance imaging (MRI) and computed tomographic (CT) studies were performed in mild to moderate head injury to evaluate whether early and late imaging have additional value in predicting outcome in this category of patients. During 1-year follow-up of a series of 67 patients, a CT scan on admission was performed together with MRI studies within 1 to 3 months and 6 to 12 months after injury. With CT, intracranial lesions were seen in 62% of patients compared with 44% with early and 19% with late MRI, located predominantly in the frontal and temporal regions. More than half of the lesions revealed with CT resulted in focal atrophy on MRI. Outcome was found to be worse in patients with edema and lesions on CT. Likewise, abnormalities detected with MRI were associated with poor outcome scores. In multiple regression analysis, only lesions in the frontal regions detected with early MRI were found to be predictive of outcome. With late MRI, only focal atrophy in the frontotemporal regions was found to be predictive of outcome. The findings in this study suggests that MRI studies may be valuable for predicting long-term outcome in patients with mild to moderate HI.

Comparative use of magnetic resonance imaging and electrophysiologic investigation for the prognosis of head injury

BACKGROUND

To compare magnetic resonance imaging (MRI) and electrophysiologic investigation as prognostic methods in acute head injury.

METHODS

Fifty-seven patients suffering moderate to mild (Glasgow Coma Scale score > 8) or severe (Glasgow Coma Scale score < 8) head injury were included. Both groups were analyzed as a total and separately for outcome as assessed by Glasgow Outcome Score. Two outcome groups were separated (Glasgow Outcome Score 1-3: unfavorable vs. Glasgow Outcome Score 4-5: favorable). MRI scans (T1-, T2-, T2*-sequences; transverse, coronal, and sagittal slices) were obtained 1 to 39 days after trauma (mean, 14 days). Electrophysiologic investigations consisted of median nerve-evoked somatosensory responses to assess corticosubcortical function and brain stem auditory-evoked potentials and brain stem reflexes for brain stem function. Recordings were performed 24 to 72 hours after trauma and repeated every 3 to 5 days.

RESULTS

Evaluation of all patients revealed a prognostic significance of MRI lesions within the corpus callosum, the basal ganglia, the hippocampus, the midbrain, and the pons. In the severe head injury subgroup, significance was limited to lesions within the corpus callosum, the basal ganglia, and the midbrain. Among the electrophysiologic findings, dysfunction of the corticosubcortical region as well as of the midbrain were linked to an unfavorable outcome. In severe head injury, prognostic significance was restricted to bilateral corticosubcortical dysfunction. A statistical test for diagnostic convergence of both methods indicated a distinct convergence only for lesions of the midbrain and the pons.

CONCLUSION

MRI scans performed early after head injury provide several indicators for unfavorable outcome. Electrophysiologic investigations add to this prognostic evidence. Both methods have comparably high specificity. However, because of the higher density of prognostic information obtained, MRI seems superior to electrophysiologic testing.

Quantitative proton MRS predicts outcome after traumatic brain injury

OBJECTIVE

To determine whether proton MRS (1H-MRS) neurochemical measurements predict neuropsychological outcome of patients with traumatic brain injury (TBI).

BACKGROUND

Although clinical indices and conventional imaging techniques provide critical information for TBI patient triage and acute care, none accurately predicts individual patient outcome.

METHODS

The authors studied 14 patients with TBI soon after injury (45+/-21 days postinjury) and again at 6 months (172+/-43 days) and 14 age-, sex-, and education-matched control subjects. N-acetylaspartate (NAA), creatine, and choline were measured in normal-appearing occipitoparietal white and gray matter using quantitative 1H-MRS. Outcome was assessed with the Glasgow Outcome Scale (GOS) and a battery of neuropsychological tests. A composite measure of neuropsychological function was calculated from individual test z-scores probing the major functional domains commonly impaired after head trauma.

RESULTS

Early NAA concentrations in gray matter predicted overall neuropsychological performance (r = 0.74, p = 0.01) and GOS (F = 11.93, p = 0.007). Other metabolite measures were not related to behavioral function at outcome.

CONCLUSION

1H-MRS provides a rapid, noninvasive tool to assess the extent of diffuse injury after head trauma, a component of injury that may be the most critical factor in evaluating resultant neuropsychological dysfunction. 1H-MRS can be added to conventional MR examinations with minimal additional time, and may prove useful in assessing injury severity, guiding patient care, and predicting patient outcome.

Evaluation of brain injury related behavioral disturbances in community mental health centers

As a result of improved emergency trauma services, more individuals suffering a traumatic brain injury are surviving. Unfortunately, most of these survivors suffer chronic neuropsychiatric sequelae related to both the brain damage and the psychosocial impact of the injury on self-esteem, self-image, primary role, and vocational function. Current community supports are often inadequate to deal with the complex array of neurologic and psychiatric difficulties. This article outlines common features of brain injury, explores the link between these features and the common neuropsychiatric sequelae of brain injury, and suggests some principles helpful in the evaluation of the behaviorally challenged brain injured patient.

Magnetic resonance imaging in relation to functional outcome of pediatric closed head injury: a test of the Ommaya-Gennarelli model

OBJECTIVE

To characterize late neuropathological findings of pediatric closed head injury (CHI), to assess depth of brain lesion in relation to acute severity, and to assess long-term outcome to test the Ommaya-Gennarelli model.

METHODS

Magnetic resonance imaging (MRI) at least 3 months postinjury in a prospective sample (n 5 169) and at least 3 years after CHI in a retrospective sample (n 5 82) was studied. Lesion volume was measured by planimetry. Acute CHI severity was measured by the Glasgow Coma Scale. Patients were classified according to the depth of the deepest parenchymal lesion into no lesion, subcortical, and deep central gray/brain stem groups. The outcomes were assessed by the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale, which were performed at the time of the MRI in the retrospective sample and up to 3 years postinjury in the prospective sample.

RESULTS

Focal brain lesions were present in 55.4% of the total sample. Depth of brain lesion was directly related to severity of acute impairment of consciousness and inversely related to outcome, as measured by both the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale. A rostrocaudal gradient of hemispheric lesion frequency was observed, whereas the posterior lesions of the corpus callosum were particularly common. Total lesion volume could not explain the depth of lesion effect.

CONCLUSION

Our findings extend support for the Ommaya-Gennarelli model to pediatric CHI, indicating that depth of brain lesion is related to functional outcome. The relative frequency of focal brain lesions revealed by late MRI is higher than that of previous findings using acute computed tomography. Future investigations could explore whether depth of lesion observed using late MRI is sensitive to neuroprotective interventions.

Forgetting from long-term memory in severe closed-head injury patients: effect of retrieval conditions and semantic organization

This study was aimed at investigating long-term forgetting in chronic survivors of severe closed-head injury (CHI). For this purpose, performance decay passing from a 30-sec- to a 60-min-delay test in four memory procedures (Free Recall of unrelated stimuli, Free Recall of related stimuli. Cued Recall and y/n Recognition) of 20 CHI and 20 normal controls was analyzed. Comparable 30-sec-delay performance in CHI and control patients were obtained by manipulating exposure times to study material during the learning phase. Results demonstrated accelerated forgetting in CHI patients in the Free Recall of the related list only. This finding was particularly evident in CHI patients suffering from a focal temporal lobe lesion. These data are discussed in light of retrieval and encoding deficits characterizing memory disorders in CHI patients.