Progressive midbrain clefts after head trauma and decompressive surgery: a report of two patients.

This report describes two patients with acute-onset ptosis, oculomotor dysfunction, ataxia and drowsiness, referable to the midbrain tegmentum. Both patients had previously suffered severe closed head injuries requiring craniotomy for cerebral decompression. Serial brain scans in both cases revealed a newly developing cleft in the midbrain, with features suggestive of abnormal cerebrospinal fluid (CSF) flow across the aqueduct. A trial of acetazolamide was initiated to reduce CSF production, followed by a third ventriculostomy for CSF diversion in one patient, which resulted in arrested disease progression and partial recovery. There are only two previous reports in the literature of midbrain clefts that developed as remote sequelae of head trauma. We postulate that altered CSF flow dynamics in the aqueduct, possibly related to changes in brain compliance, may be contributory. Early recognition and treatment may prevent irreversible structural injury and possible death.

Multi-Scale White Matter Tract Embedded Brain Finite Element Model Predicts the Location of Traumatic Diffuse Axonal Injury.

Finite element models (FEMs) are used increasingly in the traumatic brain injury (TBI) field to provide an estimation of tissue responses and predict the probability of sustaining TBI after a biomechanical event. However, FEM studies have mainly focused on predicting the absence/presence of TBI rather than estimating the location of injury. In this study, we created a multi-scale FEM of the pig brain with embedded axonal tracts to estimate the sites of acute (≤6 h) traumatic axonal injury (TAI) after rapid head rotation. We examined three finite element (FE)-derived metrics related to the axonal bundle deformation and three FE-derived metrics based on brain tissue deformation for prediction of acute TAI location. Rapid head rotations were performed in pigs, and TAI neuropathological maps were generated and colocalized to the FEM. The distributions of the FEM-derived brain/axonal deformations spatially correlate with the locations of acute TAI. For each of the six metric candidates, we examined a matrix of different injury thresholds (thx) and distance to actual TAI sites (ds) to maximize the average of two optimization criteria. Three axonal deformation-related TAI candidates predicted the sites of acute TAI within 2.5 mm, but no brain tissue metric succeeded. The optimal range of thresholds for maximum axonal strain, maximum axonal strain rate, and maximum product of axonal strain and strain rate were 0.08-0.14, 40-90, and 2.0-7.5 s-1, respectively. The upper bounds of these thresholds resulted in higher true-positive prediction rate. In summary, this study confirmed the hypothesis that the large axonal-bundle deformations occur on/close to the areas that sustained TAI.

Clinical Usefulness of Transcranial Doppler as a Screening Tool for Early Cerebral Hypoxic Episodes in Patients with Moderate and Severe Traumatic Brain Injury.

BACKGROUND: Brain tissue oxygenation (PbtO2) in traumatic brain injury (TBI) is known to be dependent on cerebral blood flow (CBF) which remains difficult to assess during the very early phase of TBI management. This study evaluates if blood flow velocity measurement with 2D color-coded transcranial Doppler (TCD) can predict cerebral hypoxic episodes in moderate-to-severe TBI measured with a PbtO2 probe. METHODS: This is a prospective observational study of serial TCD measurements to assess blood flow velocity and its association with PbtO2. Measurements were done bilaterally on the middle cerebral artery (MCA) early after the insertion of PbtO2 monitoring, daily for 5 days and during dynamic challenge tests. Physiological parameters affecting PbtO2 and Doppler velocities were collected simultaneously (PaO2, PaCO2, hemoglobin [Hb] level, intracranial pressure, and cerebral perfusion pressure [CPP]). RESULTS: We enrolled 17 consecutive patients with a total of 85 TCD studies. Using 2D color-coded TCD, signal acquisition was successful in 96% of the cases. Twenty-nine (34%) TCD measures were performed during an episode of cerebral hypoxia (PbtO2 ≤ 20 mmHg). For early episodes of cerebral hypoxia (occurring ≤ 24 h from trauma), all Vmean < 40 cm/s were associated with an ipsilateral PbtO2 ≤ 20 mmHg (positive predictive value 100%). However, when considering all readings over the course of the study, however, we found no correlation between PbtO2 and MCA's mean blood flow velocity (Vmean). Vmean is also positively correlated with PaCO2, whereas PbtO2 is also correlated with PaO2, CPP, and Hb level. CONCLUSIONS: Early TCD measurements compatible with low CBF (mean velocity < 40 cm/s) detect brain tissue hypoxia early after TBI (≤ 24 h) and could potentially be used as a screening tool before invasive monitoring insertion to help minimize time-sensitive secondary injury. Various factors influence the relationship between Vmean and PbtO2, affecting interpretation of their interaction after 24 h.

Gray matter nuclei damage in acute carbon monoxide intoxication assessed in vivo using diffusion tensor MR imaging.

OBJECTIVE: To observe the structural changes of gray matter nuclei in patients with acute carbon monoxide intoxication by diffusion tensor imaging (DTI), quantify the degree of deep gray matter damage in the brain by adopting imaging technology and research the characteristics of the damage and its pertinence with memory and cognitive impairment. METHODS: Twenty-five patients with acute carbon monoxide intoxication and 25 healthy volunteers matched in sex and age were examined by routine head MRI and diffusion tensor imaging (DTI). Bilateral hippocampus, dater nucleus, thalamus, amygdala, globus pallidus and putamen were taken as regions of interest. The mean diffusion coefficient (MD), anisotropic fraction (FA) and appearance of deep gray matter nucleus in patients with acute carbon monoxide intoxication were analyzed. It found that the change of diffusion coefficient (ADC) and its clinical correlation with cognitive impairment were generated by carbon monoxide intoxication. RESULTS: Compared with the healthy control group, the FA values of bilateral globus pallidus, hippocampus, dater nucleus and putamen decreased, while the FA values of amygdala and thalamus had no statistical significance; the MD values and ADC values of hippocampus, globus pallidus and putamen increased, while the MD and ADC values of dater nucleus, thalamus and amygdala had no statistical significance, either. CONCLUSION: DTI is capable of sensitively reflecting the damage of gray matter nuclei caused by acute carbon monoxide intoxication and quantifying the degree of hypoxic brain damage in a certain extent, and may be related to cognitive impairment.

Patients with Mild Traumatic Brain Injury Recruited from Both Hospital and Primary Care Settings: A Controlled Longitudinal Magnetic Resonance Imaging Study.

With an emphasis on traumatic axonal injury (TAI), frequency and evolution of traumatic intracranial lesions on 3T clinical magnetic resonance imaging (MRI) were assessed in a combined hospital and community-based study of patients with mild traumatic brain injury (mTBI). The findings were related to post-concussion symptoms (PCS) at 3 and 12 months. Prospectively, 194 patients (16-60 years of age) were recruited from the emergency departments at a level 1 trauma center and a municipal outpatient clinic into the Trondheim mTBI follow-up study. MRI was acquired within 72 h (n = 194) and at 3 (n = 165) and 12 months (n = 152) in patients and community controls (n = 78). The protocol included T2, diffusion weighted imaging, fluid attenuated inversion recovery (FLAIR), and susceptibility weighted imaging (SWI). PCS was assessed with British Columbia Post Concussion Symptom Inventory in patients and controls. Traumatic lesions were present in 12% on very early MRI, and in 5% when computed tomography (CT) was negative. TAI was found in 6% and persisted for 12 months on SWI, whereas TAI lesions on FLAIR disappeared or became less conspicuous on follow-up. PCS occurred in 33% of patients with lesions on MRI and in 19% in patients without lesions at 3 months (p = 0.12) and in 21% with lesions and 14% without lesions at 12 months (p = 0.49). Very early MRI depicted cases of TAI in patients with mTBI with microbleeds persisting for 12 months. Patients with traumatic lesions may have a more protracted recovery, but the study was underpowered to detect significant differences for PCS because of the low frequency of trauma-related MRI lesions.

MRI-based measures of intracortical myelin are sensitive to a history of TBI and are associated with functional connectivity.

Traumatic brain injuries (TBIs) induce persistent behavioral and cognitive deficits via diffuse axonal injury. Axonal injuries are often examined in vivo using diffusion MRI, which identifies damaged and demyelinated regions in deep white matter. However, TBI patients can exhibit impairment in the absence of diffusion-measured abnormalities, suggesting that axonal injury and demyelination may occur outside the deep white matter. Importantly, myelinated axons are also present within the cortex. Cortical myelination cannot be measured using diffusion imaging, but can be mapped in-vivo using the T1-w/T2-w ratio method. Here, we conducted the first work examining effects of TBI on intracortical myelin in living humans by applying myelin mapping to 46 US Military Veterans with a history of TBI. We observed that myelin maps could be created in TBI patients that matched known distributions of cortical myelin. After controlling for age and presence of blast injury, the number of lifetime TBIs was associated with reductions in the T1-w/T2-w ratio across the cortex, most significantly in a highly-myelinated lateral occipital region corresponding with the human MT+ complex. Further, the T1-w/T2-w ratio in this MT+ region predicted resting-state functional connectivity of that region. By contrast, a history of blast TBI did not affect the T1-w/T2-w ratio in either a diffuse or focal pattern. These findings suggest that intracortical myelin, as measured using the T1-w/T2-w ratio, may be a TBI biomarker that is anatomically complementary to diffusion MRI. Thus, myelin mapping could potentially be combined with diffusion imaging to improve MRI-based diagnostic tools for TBI.

Asterixis como forma de presentación atípica de hipercalcemia / Asterixis as an atypical expression of hypercalcemia

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Hybrid Diffusion Imaging in Mild Traumatic Brain Injury.

Mild traumatic brain injury (mTBI) is an important public health problem. Although conventional medical imaging techniques can detect moderate-to-severe injuries, they are relatively insensitive to mTBI. In this study, we used hybrid diffusion imaging (HYDI) to detect white matter alterations in 19 patients with mTBI and 23 other trauma control patients. Within 15 days (standard deviation = 10) of brain injury, all subjects underwent magnetic resonance HYDI and were assessed with a battery of neuropsychological tests of sustained attention, memory, and executive function. Tract-based spatial statistics (TBSS) was used for voxel-wise statistical analyses within the white matter skeleton to study between-group differences in diffusion metrics, within-group correlations between diffusion metrics and clinical outcomes, and between-group interaction effects. The advanced diffusion imaging techniques, including neurite orientation dispersion and density imaging (NODDI) and q-space analyses, appeared to be more sensitive then classic diffusion tensor imaging. Only NODDI-derived intra-axonal volume fraction (Vic) demonstrated significant group differences (i.e., 5-9% lower in the injured brain). Within the mTBI group, Vic and a q-space measure, P0, correlated with 6 of 10 neuropsychological tests, including measures of attention, memory, and executive function. In addition, the direction of correlations differed significantly between groups (R2 > 0.71 and pinteration < 0.03). Specifically, in the control group, higher Vic and P0 were associated with better performances on clinical assessments, whereas in the mTBI group, higher Vic and P0 were associated with worse performances with correlation coefficients >0.83. In summary, the NODDI-derived axonal density index and q-space measure for tissue restriction demonstrated superior sensitivity to white matter changes shortly after mTBI. These techniques hold promise as a neuroimaging biomarker for mTBI.

Indications for CT-Angiography of the Vertebral Arteries After Trauma.

STUDY DESIGN: Retrospective. OBJECTIVE: The purpose of this project is to identify factors that predict vertebral artery injury (VAI) in an effort to assess risks and benefits of computed tomography angiography (CT-A) of the neck in the trauma setting. We seek to develop guidelines for practitioners to stratify patients at medium/high risk of VAI from those who are at low risk. SUMMARY OF BACKGROUND DATA: VAI and blunt carotid injury (BCI) together comprise blunt cerebrovascular injury (BCVI). More is known about risk factors for BCI than for VAI, but the neurovascular complications associated with VAI are similarly disastrous. With increasing frequency, trauma providers are using CT-A to screen for BCVI; this test carries risks that include radiation exposure and nephrotoxicity, in addition to higher cost of treatment and longer hospital stay. METHODS: Trauma patients seen over 4 months at an urban, level 1 trauma were analyzed. BCVI screening was conducted in 144/1854 (7.77%) patients. Presence of VAI and several clinical characteristics were recorded. Univariate analysis and binomial logistic regression analysis were conducted at a 95% significance level. RESULTS: VAI was diagnosed in 0.49% of the study population. Univariate analysis determined six factors associated with positive VAI screening. Regression analysis showed four factors that independently predicted VAI: female sex, decreased Glasgow Coma Scale, cervical spine (c-spine) fracture, and concurrent BCI. A positive c-spine physical examination trended toward predicting VAI without achieving significance. CONCLUSION: Several independent predictors of VAI were identified. This study highlights the importance of identifying patients at a higher risk for VAI and indicating CT-A of the neck versus those who are at low risk and can be evaluated without undergoing advanced imaging, as CT-A appears unnecessary for most trauma patients. LEVEL OF EVIDENCE: 3.

The Prognostic Value of MRI in Moderate and Severe Traumatic Brain Injury: A Systematic Review and Meta-Analysis.

OBJECTIVES: Traumatic brain injury is a major cause of death and disability, yet many predictors of outcome are not precise enough to guide initial clinical decision-making. Although increasingly used in the early phase following traumatic brain injury, the prognostic utility of MRI remains uncertain. We thus undertook a systematic review and meta-analysis of studies evaluating the predictive value of acute MRI lesion patterns for discriminating clinical outcome in traumatic brain injury. DATA SOURCES: MEDLINE, EMBASE, BIOSIS, and CENTRAL from inception to November 2015. STUDY SELECTION: Studies of adults who had MRI in the acute phase following moderate or severe traumatic brain injury. Our primary outcomes were all-cause mortality and the Glasgow Outcome Scale. DATA EXTRACTION: Two authors independently performed study selection and data extraction. We calculated pooled effect estimates with a random effects model, evaluated the risk of bias using a modified version of Quality in Prognostic Studies and determined the strength of evidence with the Grading of Recommendations, Assessment, Development, and Evaluation. DATA SYNTHESIS: We included 58 eligible studies, of which 27 (n = 1,652) contributed data to meta-analysis. Brainstem lesions were associated with all-cause mortality (risk ratio, 1.78; 95% CI, 1.01-3.15; I = 43%) and unfavorable Glasgow Outcome Scale (risk ratio, 2.49; 95% CI, 1.72-3.58; I = 81%) at greater than or equal to 6 months. Diffuse axonal injury patterns were associated with an increased risk of unfavorable Glasgow Outcome Scale (risk ratio, 2.46; 95% CI, 1.06-5.69; I = 74%). MRI scores based on lesion depth demonstrated increasing risk of unfavorable neurologic outcome as more caudal structures were affected. Most studies were at high risk of methodological bias. CONCLUSIONS: MRI following traumatic brain injury yields important prognostic information, with several lesion patterns significantly associated with long-term survival and neurologic outcome. Given the high risk of bias in the current body of literature, large well-controlled studies are necessary to better quantify the prognostic role of early MRI in moderate and severe traumatic brain injury.

Traumatic brain injury: Comparison between autopsy and ante-mortem CT.

PURPOSE: The aim of this study was to compare pathological findings after traumatic brain injury between autopsy and ante-mortem computed tomography (CT). A second aim was to identify changes in these findings between the primary posttraumatic CT and the last follow-up CT before death. METHODS: Through the collaboration between clinical radiology and forensic medicine, 45 patients with traumatic brain injury were investigated. These patients had undergone ante-mortem CT as well as autopsy. During autopsy, the brain was cut in fronto-parallel slices directly after removal without additional fixation or subsequent histology. Typical findings of traumatic brain injury were compared between autopsy and radiology. Additionally, these findings were compared between the primary CT and the last follow-up CT before death. RESULTS: The comparison between autopsy and radiology revealed a high specificity (≥80%) in most of the findings. Sensitivity and positive predictive value were high (≥80%) in almost half of the findings. Sixteen patients had undergone craniotomy with subsequent follow-up CT. Thirteen conservatively treated patients had undergone a follow-up CT. Comparison between the primary CT and the last ante-mortem CT revealed marked changes in the presence and absence of findings, especially in patients with severe traumatic brain injury requiring decompression craniotomy. CONCLUSION: The main pathological findings of traumatic brain injury were comparable between clinical ante-mortem CT examinations and autopsy. Comparison between the primary CT after trauma and the last ante-mortem CT revealed marked changes in the findings, especially in patients with severe traumatic brain injury. Hence, clinically routine ante-mortem CT should be included in the process of autopsy interpretation.

Diagnosis of delayed diffuse axonal Injury.

Diffuse axonal injury is usually caused by head trauma, and patients have significant clinical symptoms during admission to the emergency department. In our case, we present a five-year-old patient who was involved in a car accident. During admission to the emergency department, the patient had no symptoms of trauma. However, 6 h after admission to emergency service, neurological symptoms occurred, and mental status changed. Diffuse axonal injury (DAI) is characterized by diffuse nerve axon injury in the brain and brainstem. This is one of the worst results of a head trauma and occurs in one-third of the patients admitted to the hospital with head trauma. In some studies, it has been reported that diffuse axonal injury is permanent in accelerated and decelerated head traumas without accompanying loss of consciousness. Neurological sequels have occurred in the recovery phase of some patients with diffuse axonal damage. In this study, we present a delayed diffuse axonal injury case accompanying a head trauma.

Successful Revascularization of Aortic Arch in a 39-Year-Old Blunt Trauma Patient with Acute Diffuse Axonal Injury without the Use of Systemic Anticoagulation.

Blunt traumatic aortic injury is the second leading cause of death in trauma patients aged 4-34 years. Of the patients who are able to receive treatment, mortality rates as high as 40% have been reported. Endovascular repair options have allowed for more expeditious repairs with reduced iatrogenic trauma; however, when the injury involves the ascending aorta or arch, current endografts lack fenestrations needed for cerebral blood flow. Traditionally, on pump, cardiopulmonary bypass with systemic anticoagulation has been used to repair these injuries. In this paper, we describe a unique case of repairing a large traumatic aortic arch pseudoaneurysm in the setting of which systemic anticoagulation is contraindicated. The patient is a 39-year-old otherwise healthy Hispanic male who presented to Ryder Trauma Center in Miami, Florida, following a motor vehicle collision and found to have multiple intracranial hemorrhages and a large aortic pseudoaneurysm of the distal ascending aorta. In lieu of standard cardiopulmonary bypass, a hybrid approach was utilized. Cranial blood flow was maintained using a temporary extra-anatomical left femoral to bilateral carotid bypass during endovascular coverage of the aortic arch. Aortic arch revascularization was then achieved by means of in situ laser fenestration of the innominate artery followed by a right-to-left carotid-carotid-subclavian bypass. This case demonstrates the viability of a hybrid vascular repair of a complex aortic disruption without the use of systemic anticoagulation in the setting of contraindicated or unknown risk of systemic anticoagulation. Further research is warranted on whether emergent traumatic cases with contraindications to anticoagulation can be performed in a similar fashion to safely reduce the morbidity and mortality associated with aortic disruptions.

Brain Oxygen Relationship to Cerebral Perfusion Pressure Depends on Tip Location and Time Window: Can Brain O2 Be an Adjunctive Modality for Determining Optimal CPP?

Controversy exists regarding the brain tissue oxygen (PbtO2) monitor's optimal tip location and what it actually measures. Recent work [2] identified a "PbtO2 change point" (CPPbt), below which PbtO2 displays pressure-passive behavior, showing significant correlation with optimal cerebral perfusion pressure (CPPopt) as defined by the pressure reactivity index (PRx). This would further support the concept of CPPopt [1] as an individualized target. We endeavored to validate these findings and further explore the relationship between PbtO2 and suboptimal CPP. CPPopt can be determined 55 % of the time [1]. It is undetermined whether PbtO2 can be an adjunctive modality for determining CPPopt.

White Matter Injury Susceptibility via Fiber Strain Evaluation Using Whole-Brain Tractography.

Microscale brain injury studies suggest axonal elongation as a potential mechanism for diffuse axonal injury (DAI). Recent studies have begun to incorporate white matter (WM) structural anisotropy in injury analysis, with initial evidence suggesting improved injury prediction performance. In this study, we further develop a tractography-based approach to analyze fiber strains along the entire lengths of fibers from voxel- or anatomically constrained whole-brain tractography. This technique potentially extends previous element- or voxel-based methods that instead utilize WM fiber orientations averaged from typically coarse elements or voxels. Perhaps more importantly, incorporating tractography-based axonal structural information enables assessment of the overall injury risks to functionally important neural pathways and the anatomical regions they connect, which is not possible with previous methods. A DAI susceptibility index was also established to quantify voxel-wise WM local structural integrity and tract-wise damage of individual neural pathways. This "graded" injury susceptibility potentially extends the commonly employed treatment of injury as a simple binary condition. As an illustration, we evaluate the DAI susceptibilities of WM voxels and transcallosal fiber tracts in three idealized head impacts. Findings suggest the potential importance of the tractography-based approach for injury prediction. These efforts may enable future studies to correlate WM mechanical responses with neuroimaging, cognitive alteration, and concussion, and to reveal the relative vulnerabilities of neural pathways and identify the most vulnerable ones in real-world head impacts.