Tight glycemic control increases metabolic distress in traumatic brain injury: a randomized controlled within-subjects trial.

OBJECTIVE: To determine the effects of tight glycemic control on brain metabolism after traumatic brain injury using brain positron emission tomography and microdialysis. DESIGN: Single-center, randomized controlled within-subject crossover observational trial. SETTING: Academic intensive care unit. METHODS: We performed a prospective, unblinded randomized controlled within-subject crossover trial of tight (80-110 mg/dL) vs. loose (120-150 mg/dL) glycemic control in patients with severe traumatic brain injury to determine the effects of glycemic control on brain glucose metabolism, as measured by [18F] deoxy-D-glucose brain positron emission tomography. Brain microdialysis was done simultaneously. MEASUREMENTS AND MAIN RESULTS: Thirteen severely injured traumatic brain injury patients underwent the study between 3 and 8 days (mean 4.8 days) after traumatic brain injury. In ten of these subjects, global brain and gray matter tissues demonstrated higher glucose metabolic rates while glucose was under tight control as compared with loose control (3.2 ± 0.6 vs. 2.4 + 0.4, p = .02 [whole brain] and 3.8 ± 1.4 vs. 2.9 ± 0.8, p = .05 [gray matter]). However, the responses were heterogeneous with pericontusional tissue demonstrating the least state-dependent change. Cerebral microdialysis demonstrated more frequent critical reductions in glucose (p = .02) and elevations of lactate/pyruvate ratio (p = .03) during tight glycemic control. CONCLUSION: Tight glycemic control results in increased global glucose uptake and an increased cerebral metabolic crisis after traumatic brain injury. The mechanisms leading to the enhancement of metabolic crisis are unclear, but delivery of more glucose through mild hyperglycemia may be necessary after traumatic brain injury.

Infections in patients with traumatic brain injury who undergo neurosurgery.

OBJECTIVE: Several factors place victims with traumatic brain injury (TBI) at increased risk for infection. The purpose of this study was to delineate the frequency, types and risk factors for infection in patients with TBI who undergo neurosurgery. MATERIALS AND METHODS: Retrospective surveillance of infections in patients with TBI, aged  ≥18 years who underwent neurosurgery in University of Crete between 1999 and 2005. RESULTS: Two hundred fifty-eight patients (76.7% men) who underwent 342 procedures were included. One hundred forty-two infections occurred, mainly lower respiratory tract infections (44.4% of the number of infections) and surgical site infections (SSIs) (25.4%). In multivariate analysis, SSIs were independently associated with the length of stay (p < 0.001), history of malignancy (p = 0.008), CSF leak (p = 0.012), any concomitant infection (p = 0.010), particularly urinary tract infections (p = 0.001) and the use of lumbar and/or ventricular drains (p = 0.005). Meningitis was independently associated with the total length of stay (p < 0.001), the need for intubation and mechanical ventilation beyond surgery (p = 0.028) and the presence of a lumbar and/or ventricular drain (p < 0.001). CONCLUSIONS: Respiratory tract infections were common in patients with TBI who underwent surgery with Acinetobacter spp. being the emerging offending pathogens. Device-related postoperative communication of the CSF and the environment was a significant risk factor for SSI development and meningitis in particular. Malignancy was an independent risk factor for SSIs. The prevalence of the offending pathogens must be determined institution by institution for the establishment of proper antibiotic treatment on suspicion.

Early metabolic crisis-related brain atrophy and cognition in traumatic brain injury.

Traumatic brain injury often results in acute metabolic crisis. We recently demonstrated that this is associated with chronic brain atrophy, which is most prominent in the frontal and temporal lobes. Interestingly, the neuropsychological profile of traumatic brain injury is often characterized as 'frontal-temporal' in nature, suggesting a possible link between acute metabolic crisis-related brain atrophy and neurocognitive impairment in this population. While focal lesions and diffuse axonal injury have a well-established role in the neuropsychological deficits observed following traumatic brain injury, no studies to date have examined the possible contribution of acute metabolic crisis-related atrophy in the neuropsychological sequelae of traumatic brain injury. In the current study we employed positron emission tomography, magnetic resonance imaging, and neuropsychological assessments to ascertain the relationship between acute metabolic crisis-related brain atrophy and neurocognitive outcome in a sample of 14 right-handed traumatic brain injury survivors. We found that acute metabolic crisis-related atrophy in the frontal and temporal lobes was associated with poorer attention, executive functioning, and psychomotor abilities at 12 months post-injury. Furthermore, participants with gross frontal and/or temporal lobe atrophy exhibited numerous clinically significant neuropsychological deficits in contrast to participants with other patterns of brain atrophy. Our findings suggest that interventions that reduce acute metabolic crisis may lead to improved functional outcomes for traumatic brain injury survivors.

Patient-tailored connectomics visualization for the assessment of white matter atrophy in traumatic brain injury.

Available approaches to the investigation of traumatic brain injury (TBI) are frequently hampered, to some extent, by the unsatisfactory abilities of existing methodologies to efficiently define and represent affected structural connectivity and functional mechanisms underlying TBI-related pathology. In this paper, we describe a patient-tailored framework which allows mapping and characterization of TBI-related structural damage to the brain via multimodal neuroimaging and personalized connectomics. Specifically, we introduce a graphically driven approach for the assessment of trauma-related atrophy of white matter connections between cortical structures, with relevance to the quantification of TBI chronic case evolution. This approach allows one to inform the formulation of graphical neurophysiological and neuropsychological TBI profiles based on the particular structural deficits of the affected patient. In addition, it allows one to relate the findings supplied by our workflow to the existing body of research that focuses on the functional roles of the cortical structures being targeted. A graphical means for representing patient TBI status is relevant to the emerging field of personalized medicine and to the investigation of neural atrophy.

Comparison of acute and chronic traumatic brain injury using semi-automatic multimodal segmentation of MR volumes.

Although neuroimaging is essential for prompt and proper management of traumatic brain injury (TBI), there is a regrettable and acute lack of robust methods for the visualization and assessment of TBI pathophysiology, especially for of the purpose of improving clinical outcome metrics. Until now, the application of automatic segmentation algorithms to TBI in a clinical setting has remained an elusive goal because existing methods have, for the most part, been insufficiently robust to faithfully capture TBI-related changes in brain anatomy. This article introduces and illustrates the combined use of multimodal TBI segmentation and time point comparison using 3D Slicer, a widely-used software environment whose TBI data processing solutions are openly available. For three representative TBI cases, semi-automatic tissue classification and 3D model generation are performed to perform intra-patient time point comparison of TBI using multimodal volumetrics and clinical atrophy measures. Identification and quantitative assessment of extra- and intra-cortical bleeding, lesions, edema, and diffuse axonal injury are demonstrated. The proposed tools allow cross-correlation of multimodal metrics from structural imaging (e.g., structural volume, atrophy measurements) with clinical outcome variables and other potential factors predictive of recovery. In addition, the workflows described are suitable for TBI clinical practice and patient monitoring, particularly for assessing damage extent and for the measurement of neuroanatomical change over time. With knowledge of general location, extent, and degree of change, such metrics can be associated with clinical measures and subsequently used to suggest viable treatment options.