Epidural electrical stimulation of the cervical spinal cord opposes opioid-induced respiratory depression

Opioid overdose suppresses brainstem respiratory circuits, causes apnoea and may result in death. Epidural electrical stimulation (EES) at the cervical spinal cord facilitated motor activity in rodents and humans, and we hypothesized that EES of the cervical spinal cord could antagonize opioid-induced respiratory depression in humans. Eighteen patients requiring surgical access to the dorsal surface of the spinal cord between C2 and C7 received EES or sham stimulation for up to 90 s at 5 or 30 Hz during complete (OFF-State) or partial suppression (ON-State) of respiration induced by remifentanil. During the ON-State, 30 Hz EES at C4 and 5 Hz EES at C3/4 increased tidal volume and decreased the end-tidal carbon dioxide level compared to pre-stimulation control levels. EES of 5 Hz at C5 and C7 increased respiratory frequency compared to pre-stimulation control levels. In the OFF-State, 30 Hz cervical EES at C3/4 terminated apnoea and induced rhythmic breathing. In cadaveric tissue obtained from a brain bank, more neurons expressed both the neurokinin 1 receptor (NK1R) and somatostatin (SST) in the cervical spinal levels responsive to EES (C3/4, C6 and C7) compared to a region non-responsive to EES (C2). Thus, the capacity of cervical EES to oppose opioid depression of respiration may be mediated by NK1R+/SST+ neurons in the dorsal cervical spinal cord. This study provides proof of principle that cervical EES may provide a novel therapeutic approach to augment respiratory activity when the neural function of the central respiratory circuits is compromised by opioids or other pathological conditions. KEY POINTS: Epidural electrical stimulation (EES) using an implanted spinal cord stimulator (SCS) is an FDA-approved method to manage chronic pain. We tested the hypothesis that cervical EES facilitates respiration during administration of opioids in 18 human subjects who were treated with low-dose remifentanil that suppressed respiration (ON-State) or high-dose remifentanil that completely inhibited breathing (OFF-State) during the course of cervical surgery. Dorsal cervical EES of the spinal cord augmented the respiratory tidal volume or increased the respiratory frequency, and the response to EES varied as a function of the stimulation frequency (5 or 30 Hz) and the cervical level stimulated (C2-C7). Short, continuous cervical EES restored a cyclic breathing pattern (eupnoea) in the OFF-State, suggesting that cervical EES reversed the opioid-induced respiratory depression. These findings add to our understanding of respiratory pattern modulation and suggest a novel mechanism to oppose the respiratory depression caused by opioids.

Sedation-Induced Burst Suppression Predicts Positive Outcome Following Traumatic Brain Injury

While electroencephalogram (EEG) burst-suppression is often induced therapeutically using sedatives in the intensive care unit (ICU), there is hitherto no evidence with respect to its association to outcome in moderate-to-severe neurological patients. We examined the relationship between sedation-induced burst-suppression (SIBS) and outcome at hospital discharge and at 6-month follow up in patients surviving moderate-to-severe traumatic brain injury (TBI). For each of 32 patients recovering from coma after moderate-to-severe TBI, we measured the EEG burst suppression ratio (BSR) during periods of low responsiveness as assessed with the Glasgow Coma Scale (GCS). The maximum BSR was then used to predict the Glasgow Outcome Scale extended (GOSe) at discharge and at 6 months post-injury. A multi-model inference approach was used to assess the combination of predictors that best fit the outcome data. We found that BSR was positively associated with outcomes at 6 months (P = 0.022) but did not predict outcomes at discharge. A mediation analysis found no evidence that BSR mediates the effects of barbiturates or propofol on outcomes. Our results provide initial observational evidence that burst suppression may be neuroprotective in acute patients with TBI etiologies. SIBS may thus be useful in the ICU as a prognostic biomarker.

Distribution and volume analysis of early hemorrhagic contusions by MRI after traumatic brain injury: a preliminary report of the Epilepsy Bioinformatics Study for Antiepileptogenic Therapy (EpiBioS4Rx)

Traumatic brain injury (TBI) can produce heterogeneous injury patterns including a variety of hemorrhagic and non-hemorrhagic lesions. The impact of lesion size, location, and interaction between total number and location of contusions may influence the occurrence of seizures after TBI. We report our methodologic approach to this question in this preliminary report of the Epilepsy Bioinformatics Study for Antiepileptogenic Therapy (EpiBioS4Rx). We describe lesion identification and segmentation of hemorrhagic contusions by early posttraumatic magnetic resonance imaging (MRI). We describe the preliminary methods of manual lesion segmentation in an initial cohort of 32 TBI patients from the EpiBioS4Rx cohort and the preliminary association of hemorrhagic contusion and edema location and volume to seizure incidence.

A-121 Functional Outcomes in Bilingual Persons with Traumatic Brain: The Role of Mood

Introduction

We examined the relationship between depression and anxiety, language, and functional outcomes in persons with traumatic brain injury (TBI).

Methods

The sample consisted of 48 acute TBI (ATBI: 23 Spanish-English Bilinguals; 25 English monolinguals), 30 chronic TBI (CTBI: 17 Spanish English Bilinguals; 12 English monolinguals), and 47 healthy comparison (HC: 29 Spanish-English Bilinguals; 18 English monolinguals) participants. The Hospital Anxiety and Depression Scale was used to measure depression (HADS-D) and anxiety (HADS-A). The Mayo Portland Adaptability Inventory-4 (MPAI-4) was used to measure functional outcomes (ability, adjustment, participation).

Results

An ANCOVA, controlling for age, revealed the ATBI group reported lower anxiety levels compared to the CTBI group, p = 0.034 np2 = 0.06. HC participants demonstrated significantly higher functional ability compared to both TBI groups, p < 0.05, np2 = 0.08–0.19. The ATBI group demonstrated worse participation scores compared to the CTBI and HC groups, p = 0.001, np2 = 0.11. Pearson correlations revealed mood was related to functional status in ATBI monolinguals (HADS-A: r = 0.29–0.64; HADS-D, r = 0.49–0.62). Monolingual participants with ATBI demonstrated correlations between depressive symptoms and functional adjustment (r = 0.57, p = 0.005) and ability (r = 0.44, p = 0.034). For monolinguals with CTBI, HADS-A correlated with functional outcomes, r = 0.60–0.66, p < 0.05. For bilinguals with CTBI, functional outcomes correlated with HADS-A, r = 0.53–0.66, p < 0.05, and HADS-D, r = 0.54–0.66, p < 0.05. For HC monolinguals, functional outcomes correlated with HADS-A, r = 0.53–0.70, p < 0.05, and HADS-D, r = 0.50–0.72, p < 0.05. Finally, for HC bilinguals, functional outcomes correlated with HADS-A, r = 0.59–0.68, p < 0.05.

Conclusion

Our results suggest that a relationship between anxiety and depressive symptoms is related more to functional outcomes in monolingual TBI survivors compared to bilingual TBI survivors.

A-92 Assessing Perceived Workload on the Brief Visual Memory Test in Traumatic Brain Injury Survivors

Objective

We examined perceived workload as it is related to Brief Visual Memory Test-Revised (BVMT-R) short-delay and long-delay performance in traumatic brain injury (TBI) and healthy comparison (HC) participants.

Method

The sample consisted of 39 TBI participants and 54 HC participants. Demographically corrected BVMT-R scores were used to evaluate short-delay and long-delay performances. The perceived workload was measured using the NASA-TLX.

Results

ANOVA revealed that the HC group outperformed the TBI group on the BVMT-R short-delay and long-delay score, p < 05, η p 2 = 0.05. ANCOVAs controlling for age were used to evaluate NASA-TLX group differences. In regards to the NASA-TLX, TBI participants reported higher levels of physical demand, effort, frustration and overall subjective workload on the BVMT-R short-delay compared to HC participants, p < 05, η p 2 = 0.01–0.09. Furthermore, on the long-delay of the BVMT-R, the NASA-TLX revealed that the TBI group reported higher levels of temporal demand, effort, frustration and overall subjective workload compared to the HC group, p < 0.05, η p 2 = 0.05–0.14.

Conclusions

Results revealed that TBI participants demonstrated worse BVMT-R performances than HC participants. However, TBI survivors reported higher perceived workload demands compared to the HC group in both short-delay and long-delay of the BVMT-R. Our findings suggest that TBI impacts non-verbal memory performance in both BVMT-R short-delay and long-delay. Also, brain injury may be impacting TBI survivors’ awareness of their non-verbal memory performance. Further work is required to determine what drives the impaired perception of non-verbal memory performance among TBI survivors.

Flying After Concussion and Symptom Recovery in College Athletes and Military Cadets

IMPORTANCE

Concussions are a common occurrence in young athletes. Hypobaric hypoxemia, such as that experienced during airplane travel, can potentially cause alterations to cerebral blood flow and increased neuroinflammatory response. It remains unknown whether flying early after a concussion may influence the clinical course of injury.

OBJECTIVE

To determine whether there is an association between concussion recovery and airplane travel in collegiate athletes and military cadets.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted by the National Collegiate Athletic Association and US Department of Defense Concussion Assessment, Research, and Education Consortium from August 3, 2014, to September 13, 2018. Participant groups were categorized by those who flew within 72 hours of injury and those who did not fly. All participants included in the final analyses had complete data of interest and only 1 injury during the study. Data analysis was performed from September 2018 to March 2020.

MAIN OUTCOMES AND MEASURES

Recovery outcome measures were defined as time (in days) from injury to return to activity, school, and baseline symptoms. Symptom and headache severity scores were derived from the Sports Concussion Assessment Tool-Third Edition. Scores for both groups were taken at baseline and a median of 2 days after injury.

RESULTS

A total of 92 participants who flew (mean [SD] age, 19.1 [1.2] years; 55 male [59.8%]) and 1383 participants who did not fly (mean [SD] age, 18.9 [1.3] years; 809 male [58.5%]) were included in the analysis of symptom recovery outcomes (analysis 1). Similarly, 100 participants who flew (mean [SD] age, 19.2 [1.2] years; 63 male [63.0%]) and 1577 participants who did not fly (mean [SD] age, 18.9 [1.3] years; 916 male [58.1%]) were included in the analysis of symptom severity outcomes (analysis 2). No significant group differences were found regarding recovery outcome measures. Likewise, there were no group differences in symptom (estimated mean difference, 0.029; 95% CI, -0.083 to 0.144; P = .67) or headache (estimated mean difference, -0.007; 95% CI, -0.094 to 0.081; P = .91) severity scores.

CONCLUSIONS AND RELEVANCE

Airplane travel early after concussion was not associated with recovery or severity of concussion symptoms. These findings may help guide future recommendations on flight travel after concussion in athletes.

Early brain biomarkers of post-traumatic seizures: initial report of the multicentre epilepsy bioinformatics study for antiepileptogenic therapy (EpiBioS4Rx) prospective study

BACKGROUND

Traumatic brain injury (TBI) causes early seizures and is the leading cause of post-traumatic epilepsy. We prospectively assessed structural imaging biomarkers differentiating patients who develop seizures secondary to TBI from patients who do not.

DESIGN

Multicentre prospective cohort study starting in 2018. Imaging data are acquired around day 14 post-injury, detection of seizure events occurred early (within 1 week) and late (up to 90 days post-TBI).

RESULTS

From a sample of 96 patients surviving moderate-to-severe TBI, we performed shape analysis of local volume deficits in subcortical areas (analysable sample: 57 patients; 35 no seizure, 14 early, 8 late) and cortical ribbon thinning (analysable sample: 46 patients; 29 no seizure, 10 early, 7 late). Right hippocampal volume deficit and inferior temporal cortex thinning demonstrated a significant effect across groups. Additionally, the degree of left frontal and temporal pole thinning, and clinical score at the time of the MRI, could differentiate patients experiencing early seizures from patients not experiencing them with 89% accuracy.

CONCLUSIONS AND RELEVANCE

Although this is an initial report, these data show that specific areas of localised volume deficit, as visible on routine imaging data, are associated with the emergence of seizures after TBI.

The subcortical basis of outcome and cognitive impairment in TBI: A longitudinal cohort study

OBJECTIVE

To understand how, biologically, the acute event of traumatic brain injury gives rise to a long-term disease, we address the relationship between evolving cortical and subcortical brain damage and measures of functional outcome and cognitive functioning at 6 months after injury.

METHODS

For this longitudinal analysis, clinical and MRI data were collected in a tertiary neurointensive care setting in a continuous sample of 157 patients surviving moderate to severe traumatic brain injury between 2000 and 2018. For each patient, we collected T1- and T2-weighted MRI data acutely and at the 6-month follow-up, as well as acute measures of injury severity (Glasgow Coma Scale), follow-up measures of functional impairment (Glasgow Outcome Scale-extended), and, in a subset of patients, neuropsychological measures of attention, executive functions, and episodic memory.

RESULTS

In the final cohort of 113 subcortical and 92 cortical datasets that survived (blind) quality control, extensive atrophy was observed over the first 6 months after injury across the brain. However, only atrophy within subcortical regions, particularly in the left thalamus, was associated with functional outcome and neuropsychological measures of attention, executive functions, and episodic memory. Furthermore, when brought together in an analytical model, longitudinal brain measurements could distinguish good from bad outcome with 90% accuracy, whereas acute brain and clinical measurements alone could achieve only 20% accuracy.

CONCLUSION

Despite great injury heterogeneity, secondary thalamic pathology is a measurable minimum common denominator mechanism directly relating biology to clinical measures of outcome and cognitive functioning, potentially linking the acute event and the longer-term disease of traumatic brain injury.

pH-weighted molecular MRI in human traumatic brain injury (TBI) using amine proton chemical exchange saturation transfer echoplanar imaging (CEST EPI)

Cerebral acidosis is a consequence of secondary injury mechanisms following traumatic brain injury (TBI), including excitotoxicity and ischemia, with potentially significant clinical implications. However, there remains an unmet clinical need for technology for non-invasive, high resolution pH imaging of human TBI for studying metabolic changes following injury. The current study examined 17 patients with TBI and 20 healthy controls using amine chemical exchange saturation transfer echoplanar imaging (CEST EPI), a novel pH-weighted molecular MR imaging technique, on a clinical 3T MR scanner. Results showed significantly elevated pH-weighted image contrast (MTRasym at 3 ppm) in areas of T2 hyperintensity or edema (P < 0.0001), and a strong negative correlation with Glasgow Coma Scale (GCS) at the time of the MRI exam (R2 = 0.4777, P = 0.0021), Glasgow Outcome Scale - Extended (GOSE) at 6 months from injury (R2 = 0.5334, P = 0.0107), and a non-linear correlation with the time from injury to MRI exam (R2 = 0.6317, P = 0.0004). This evidence suggests clinical feasibility and potential value of pH-weighted amine CEST EPI as a high-resolution imaging tool for identifying tissue most at risk for long-term damage due to cerebral acidosis.

Improving transparency and scientific rigor in academic publishing

Progress in basic and clinical research is slowed when researchers fail to provide a complete and accurate report of how a study was designed, executed, and the results analyzed. Publishing rigorous scientific research involves a full description of the methods, materials, procedures, and outcomes. Investigators may fail to provide a complete description of how their study was designed and executed because they may not know how to accurately report the information or the mechanisms are not in place to facilitate transparent reporting. Here, we provide an overview of how authors can write manuscripts in a transparent and thorough manner. We introduce a set of reporting criteria that can be used for publishing, including recommendations on reporting the experimental design and statistical approaches. We also discuss how to accurately visualize the results and provide recommendations for peer reviewers to enhance rigor and transparency. Incorporating transparency practices into research manuscripts will significantly improve the reproducibility of the results by independent laboratories. SIGNIFICANCE: Failure to replicate research findings often arises from errors in the experimental design and statistical approaches. By providing a full account of the experimental design, procedures, and statistical approaches, researchers can address the reproducibility crisis and improve the sustainability of research outcomes. In this piece, we discuss the key issues leading to irreproducibility and provide general approaches to improving transparency and rigor in reporting, which could assist in making research more reproducible.

Improving transparency and scientific rigor in academic publishing

Progress in basic and clinical research is slowed when researchers fail to provide a complete and accurate report of how a study was designed, executed, and the results analyzed. Publishing rigorous scientific research involves a full description of the methods, materials, procedures, and outcomes. Investigators may fail to provide a complete description of how their study was designed and executed because they may not know how to accurately report the information or the mechanisms are not in place to facilitate transparent reporting. Here, we provide an overview of how authors can write manuscripts in a transparent and thorough manner. We introduce a set of reporting criteria that can be used for publishing, including recommendations on reporting the experimental design and statistical approaches. We also discuss how to accurately visualize the results and provide recommendations for peer reviewers to enhance rigor and transparency. Incorporating transparency practices into research manuscripts will significantly improve the reproducibility of the results by independent laboratories.

Improving transparency and scientific rigor in academic publishing

Progress in basic and clinical research is slowed when researchers fail to provide a complete and accurate report of how a study was designed, executed, and the results analyzed. Publishing rigorous scientific research involves a full description of the methods, materials, procedures, and outcomes. Investigators may fail to provide a complete description of how their study was designed and executed because they may not know how to accurately report the information or the mechanisms are not in place to facilitate transparent reporting. Here, we provide an overview of how authors can write manuscripts in a transparent and thorough manner. We introduce a set of reporting criteria that can be used for publishing, including recommendations on reporting the experimental design and statistical approaches. We also discuss how to accurately visualize the results and provide recommendations for peer reviewers to enhance rigor and transparency. Incorporating transparency practices into research manuscripts will significantly improve the reproducibility of the results by independent laboratories.

Acute glucose and lactate metabolism are associated with cognitive recovery following traumatic brain injury

Traumatic brain injury (TBI) is associated with acute cerebral metabolic crisis (ACMC). ACMC-related atrophy appears to be prominent in frontal and temporal lobes following moderate-to-severe TBI. This atrophy is correlated with poorer cognitive outcomes in TBI. The current study investigated ability of acute glucose and lactate metabolism to predict long-term recovery of frontal-temporal cognitive function in participants with moderate-to-severe TBI. Cerebral metabolic rate of glucose and lactate were measured by the Kety-Schmidt method on days 0-7 post-injury. Indices of frontal-temporal cognitive processing were calculated for six months post-injury; 12 months post-injury; and recovery (the difference between the six- and 12-month scores). Glucose and lactate metabolism were included in separate regression models, as they were highly intercorrelated. Also, glucose and lactate values were centered and averaged and included in a final regression model. Models for the prediction frontal-temporal cognition at six and 12 months post-injury were not significant. However, average glucose and lactate metabolism predicted recovery of frontal-temporal cognition, accounting for 23% and 22% of the variance, respectively. Also, maximum glucose metabolism, but not maximum lactate metabolism, was an inverse predictor in the recovery of frontal-temporal cognition, accounting for 23% of the variance. Finally, the average of glucose and lactate metabolism predicted frontal-temporal cognitive recovery, accounting for 22% of the variance. These data indicate that acute glucose and lactate metabolism both support cognitive recovery from TBI. Also, our data suggest that control of endogenous fuels and/or supplementation with exogenous fuels may have therapeutic potential for cognitive recovery from TBI.

Influence of Glycemic Control on Endogenous Circulating Ketone Concentrations in Adults Following Traumatic Brain Injury

BACKGROUND

The objective was to investigate the impact of targeting tight glycemic control (4.4-6.1 mM) on endogenous ketogenesis in severely head-injured adults.

METHODS

The data were prospectively collected during a randomized, within-patient crossover study comparing tight to loose glycemic control, defined as 6.7-8.3 mM. Blood was collected periodically during both tight and loose glycemic control epochs. Post hoc analysis of insulin dose and total nutritional provision was performed.

RESULTS

Fifteen patients completed the crossover study. Total ketones were increased 81 μM ([38 135], p < 0.001) when blood glucose was targeted to tight (4.4-6.1 mM) compared with loose glycemic control (6.7-8.3 mM), corresponding to a 60 % increase. There was a significant decrease in total nutritional provisions (p = 0.006) and a significant increase in insulin dose (p = 0.008).

CONCLUSIONS

Permissive underfeeding was tolerated when targeting tight glycemic control, but total nutritional support is an important factor when treating hyperglycemia.

Traumatic hemorrhagic brain injury: impact of location and resorption on cognitive outcome

OBJECTIVE

Hemorrhagic contusions are often the most visible lesions following traumatic brain injury. However, the incidence, location, and natural history of traumatic parenchymal hemorrhage and its impact on neurological outcome have been understudied. The authors sought to examine the location and longitudinal evolution of traumatic parenchymal hemorrhage and its association with cognitive outcome.

METHODS

Sixteen patients with hemorrhagic contusions due to acceleration-deceleration injuries underwent MRI in the acute (mean 6.3 days postinjury) and chronic (mean 192.9 days postinjury) phases. ImageJ was used to generate GRE and FLAIR volumes. To account for the effect of head-size variability across individuals, the authors calculated each patient's total brain tissue volume using SIENAX. GRE and FLAIR volumes were normalized to the total brain tissue volume, and values for absolute and percent lesion volume and total brain volume change were generated. Spearman's rank correlations were computed to determine associations between neuroimaging and 6-month postinjury neuropsychological testing of attention (Symbol Digit Modalities Test [SDMT], oral [O] and written [W] versions), memory (Selective Reminding Test, total learning and delayed recall), and executive function (Trail Making Test Part B [TMT-B]).

RESULTS

The patients' mean age was 31.4 ± 14.0 years and their mean Glasgow Coma Scale score at admission was 7.9 ± 2.8. Lesions were predominantly localized to the frontal (11 lesions) and temporal (9 lesions) lobes. The average percent reductions in GRE and FLAIR volumes were 44.2% ± 46.1% and 80.5% ± 26.3%, respectively. While total brain and frontal lesion volumes did not correlate with brain atrophy, larger temporal lobe GRE and FLAIR volumes were associated with larger volumes of atrophy (GRE: acute, −0.87, p < 0.01, chronic, −0.78, p < 0.01; FLAIR: acute, −0.81, p < 0.01, chronic, −0.88, p < 0.01). Total percent volume change of GRE lesions correlated with TMT-B (0.53, p < 0.05) and SDMT-O (0.62, p < 0.05) scores. Frontal lobe lesion volume did not correlate with neuropsychological outcome. However, robust relationships were seen in the temporal lobe, with larger acute temporal lobe GRE volumes were associated with worse scores on both oral and written versions of the SDMT (SDMT-W, −0.85, p < 0.01; SDMT-O, −0.73, p < 0.05). Larger absolute change in temporal GRE volume was strongly associated with worse SDMT scores (SDMT-W, 0.88, p < 0.01; SDMT-O, 0.75, p < 0.05). The same relationships were also seen between temporal FLAIR lesion volumes and neuropsychological outcome.

CONCLUSIONS

Traumatic parenchymal hemorrhages are largely clustered in the frontal and temporal lobes, and significant residual blood products are present at 6 months postinjury, a potential source of ongoing secondary brain injury. Neuropsychological outcome is closely tied to lesion volume size, particularly in the temporal lobe, where larger GRE and FLAIR volumes are associated with more brain atrophy and worse SDMT scores. Interestingly, larger volumes of hemorrhage resorption were associated with worse SDMT and TMT-B scores, suggesting that the initial tissue damage had a lasting impact on attention and executive function.

Adjuvant Radiosurgery Versus Serial Surveillance Following Subtotal Resection of Atypical Meningioma: A Systematic Analysis

BACKGROUND

Atypical meningioma (AM) is an aggressive subtype of meningioma associated with a high recurrence rates (RR) following surgical resection. Recent studies have compared outcomes of various treatment strategies, but advantages of adjuvant radiosurgery (ARS) over serial surveillance (SS) following subtotal resection (STR) remain unclear. To further elucidate this issue, we systematically analyzed the current literature on AM and compared outcomes of ARS versus SS after STR.

METHODS

Embase, PubMed, and Cochrane databases were queried using relevant search terms. Retrospective case series that described patients with AM treated with ARS and SS after STR were included. Tests of proportions were performed to detect significant variations in RR, 5-year progression-free survival (PFS), and 5-year overall survival (OS) between the treatment strategies (ARS vs. SS) and among individual studies.

RESULTS

A total of 619 patients (263 in the ARS group and 356 in the SS group) were identified. Mean RR, 5-year PFS, and 5-year OS were 53.5%, 50.3%, and 74.9%, respectively, for ARS versus 89.8%, 19.1%, and 89.8% for SS. RR differed between treatment strategies and ARS studies (P < 0.001), and 5-year PFS differed among treatment strategies, ARS, and SS studies (P < 0.001, P = 0.007, and P < 0.001, respectively).

CONCLUSIONS

The data presented here show significant differences in RR and 5-year PFS between ARS and SS, suggesting a potential benefit of ARS. As our understanding of the clinical outcomes of various treatment strategies for AM increases, we also move closer to integrating modalities, such as radiosurgery, into management guidelines.

Compliance With Evidence-Based Guidelines and Interhospital Variation in Mortality for Patients With Severe Traumatic Brain Injury

IMPORTANCE

Compliance with evidence-based guidelines in traumatic brain injury (TBI) has been proposed as a marker of hospital quality. However, the association between hospital-level compliance rates and risk-adjusted clinical outcomes for patients with TBI remains poorly understood.

OBJECTIVE

To examine whether hospital-level compliance with the Brain Trauma Foundation guidelines for intracranial pressure monitoring and craniotomy is associated with risk-adjusted mortality rates for patients with severe TBI.

DESIGN, SETTING, AND PARTICIPANTS

All adult patients (N = 734) who presented to a regional consortium of 14 hospitals from January 1, 2009, through December 31, 2010, with severe TBI (ie, blunt head trauma, Glasgow Coma Scale score of <9, and abnormal intracranial findings from computed tomography of the head). Data analysis took place from December 2013 through January 2015. We used hierarchical mixed-effects models to assess the association between hospital-level compliance with Brain Trauma Foundation guidelines and mortality rates after adjusting for patient-level demographics, severity of trauma (eg, mechanism of injury and Injury Severity Score), and TBI-specific variables (eg, cranial nerve reflexes and findings from computed tomography of the head).

MAIN OUTCOMES AND MEASURES

Hospital-level risk-adjusted inpatient mortality rate and hospital-level compliance with Brain Trauma Foundation guidelines for intracranial pressure monitoring and craniotomy.

RESULTS

Unadjusted mortality rates varied by site from 20.0% to 50.0% (median, 42.6; interquartile range, 35.5-46.2); risk-adjusted rates varied from 24.3% to 56.7% (median, 41.1; interquartile range, 36.4-47.8). Overall, only 338 of 734 patients (46.1%) with an appropriate indication underwent placement of an intracranial pressure monitor and only 134 of 335 (45.6%) underwent craniotomy. Hospital-level compliance ranged from 9.6% to 65.2% for intracranial pressure monitoring and 6.7% to 76.2% for craniotomy. Despite widespread variation in compliance across hospitals, we found no association between hospital-level compliance rates and risk-adjusted patient outcomes (Spearman ρ = 0.030 [P = .92] for ICP monitoring and Spearman ρ = -0.066 [P = .83] for craniotomy).

CONCLUSIONS AND RELEVANCE

Hospital-level compliance with evidence-based guidelines has minimal association with risk-adjusted outcomes in patients with severe TBI. Our results suggest that caution should be taken before using compliance with these measures as independent quality metrics. Given the complexity of TBI care, outcomes-based metrics, including functional recovery, may be more accurate than current process measures at determining hospital quality.

Targeting the Epidemic: Interventions and Follow-up Are Necessary in the Pediatric Traumatic Brain Injury Clinic

Traumatic brain injury is a major public health problem in the pediatric population. Previously, management was acute emergency department/primary care evaluation with follow-up by primary care. However, persistent symptoms after traumatic brain injury are common, and many do not have access to a specialized traumatic brain injury clinic to manage chronic issues. The goal of this study was to determine the factors related to outcomes, and identify the interventions provided in this subspecialty clinic. Data were extracted from medical records of 151 retrospective and 403 prospective patients. Relationships between sequelae, injury characteristics, and clinical interventions were analyzed. Most patients returning to clinic were not fully recovered from their injury. Headaches were more common after milder injuries, and seizures were more common after severe. The majority of patients received clinical intervention. The presence of persistent sequelae for traumatic brain injury patients can be evaluated and managed by a specialty concussion/traumatic brain injury clinic ensuring that medical needs are met.

The UCLA Study of Children with Moderate-to-Severe Traumatic Brain Injury: Event-Related Potential Measure of Interhemispheric Transfer Time

Traumatic brain injury (TBI) frequently results in diffuse axonal injury and other white matter damage. The corpus callosum (CC) is particularly vulnerable to injury following TBI. Damage to this white matter tract has been associated with impaired neurocognitive functioning in children with TBI. Event-related potentials can identify stimulus-locked neural activity with high temporal resolution. They were used in this study to measure interhemispheric transfer time (IHTT) as an indicator of CC integrity in 44 children with moderate/severe TBI at 3-5 months post-injury, compared with 39 healthy control children. Neurocognitive performance also was examined in these groups. Nearly half of the children with TBI had IHTTs that were outside the range of the healthy control group children. This subgroup of TBI children with slow IHTT also had significantly poorer neurocognitive functioning than healthy controls-even after correction for premorbid intellectual functioning. We discuss alternative models for the relationship between IHTT and neurocognitive functioning following TBI. Slow IHTT may be a biomarker that identifies children at risk for poor cognitive functioning following moderate/severe TBI.

Endogenous Nutritive Support after Traumatic Brain Injury: Peripheral Lactate Production for Glucose Supply via Gluconeogenesis

We evaluated the hypothesis that nutritive needs of injured brains are supported by large and coordinated increases in lactate shuttling throughout the body. To that end, we used dual isotope tracer ([6,6-(2)H2]glucose, i.e., D2-glucose, and [3-(13)C]lactate) techniques involving central venous tracer infusion along with cerebral (arterial [art] and jugular bulb [JB]) blood sampling. Patients with traumatic brain injury (TBI) who had nonpenetrating head injuries (n=12, all male) were entered into the study after consent of patients' legal representatives. Written and informed consent was obtained from healthy controls (n=6, including one female). As in previous investigations, the cerebral metabolic rate (CMR) for glucose was suppressed after TBI. Near normal arterial glucose and lactate levels in patients studied 5.7±2.2 days (range of days 2-10) post-injury, however, belied a 71% increase in systemic lactate production, compared with control, that was largely cleared by greater (hepatic+renal) glucose production. After TBI, gluconeogenesis from lactate clearance accounted for 67.1% of glucose rate of appearance (Ra), which was compared with 15.2% in healthy controls. We conclude that elevations in blood glucose concentration after TBI result from a massive mobilization of lactate from corporeal glycogen reserves. This previously unrecognized mobilization of lactate subserves hepatic and renal gluconeogenesis. As such, a lactate shuttle mechanism indirectly makes substrate available for the body and its essential organs, including the brain, after trauma. In addition, when elevations in arterial lactate concentration occur after TBI, lactate shuttling may provide substrate directly to vital organs of the body, including the injured brain.

Lactate: brain fuel in human traumatic brain injury: a comparison with normal healthy control subjects

We evaluated the hypothesis that lactate shuttling helps support the nutritive needs of injured brains. To that end, we utilized dual isotope tracer [6,6-(2)H2]glucose, that is, D2-glucose, and [3-(13)C]lactate techniques involving arm vein tracer infusion along with simultaneous cerebral (arterial [art] and jugular bulb [JB]) blood sampling. Traumatic brain injury (TBI) patients with nonpenetrating brain injuries (n=12) were entered into the study following consent of patients' legal representatives. Written and informed consent was obtained from control volunteers (n=6). Patients were studied 5.7±2.2 (mean±SD) days post-injury; during periods when arterial glucose concentration tended to be higher in TBI patients. As in previous investigations, the cerebral metabolic rate for glucose (CMRgluc, i.e., net glucose uptake) was significantly suppressed following TBI (p<0.001). However, lactate fractional extraction, an index of cerebral lactate uptake related to systemic lactate supply, approximated 11% in both healthy control subjects and TBI patients. Further, neither the CMR for lactate (CMRlac, i.e., net lactate release), nor the tracer-measured cerebral lactate uptake differed between healthy controls and TBI patients. The percentages of lactate tracer taken up and released as (13)CO2 into the JB accounted for 92% and 91% for control and TBI conditions, respectively, suggesting that most cerebral lactate uptake was oxidized following TBI. Comparisons of isotopic enrichments of lactate oxidation from infused [3-(13)C]lactate tracer and (13)C-glucose produced during hepatic and renal gluconeogenesis (GNG) showed that 75-80% of (13)CO2 released into the JB was from lactate and that the remainder was from the oxidation of glucose secondarily labeled from lactate. Hence, either directly as lactate uptake, or indirectly via GNG, peripheral lactate production accounted for ∼70% of carbohydrate (direct lactate uptake+uptake of glucose from lactate) consumed by the injured brain. Undiminished cerebral lactate fractional extraction and uptake suggest that arterial lactate supplementation may be used to compensate for decreased CMRgluc following TBI.

Thalamic atrophy in antero-medial and dorsal nuclei correlates with six-month outcome after severe brain injury

The primary and secondary damage to neural tissue inflicted by traumatic brain injury is a leading cause of death and disability. The secondary processes, in particular, are of great clinical interest because of their potential susceptibility to intervention. We address the dynamics of tissue degeneration in cortico-subcortical circuits after severe brain injury by assessing volume change in individual thalamic nuclei over the first six-months post-injury in a sample of 25 moderate to severe traumatic brain injury patients. Using tensor-based morphometry, we observed significant localized thalamic atrophy over the six-month period in antero-dorsal limbic nuclei as well as in medio-dorsal association nuclei. Importantly, the degree of atrophy in these nuclei was predictive, even after controlling for full-brain volume change, of behavioral outcome at six-months post-injury. Furthermore, employing a data-driven decision tree model, we found that physiological measures, namely the extent of atrophy in the anterior thalamic nucleus, were the most predictive variables of whether patients had regained consciousness by six-months, followed by behavioral measures. Overall, these findings suggest that the secondary non-mechanical degenerative processes triggered by severe brain injury are still ongoing after the first week post-trauma and target specifically antero-medial and dorsal thalamic nuclei. This result therefore offers a potential window of intervention, and a specific target region, in agreement with the view that specific cortico-thalamo-cortical circuits are crucial to the maintenance of large-scale network neural activity and thereby the restoration of cognitive function after severe brain injury.

•

Performed acute and chronic structural MRI in 25 severe TBI patients

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Tensor brain morphometry (TBM) shows localized thalamic acute-to-chronic atrophy.

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Anterior, medio- and lateral-dorsal nuclei are the most significant.

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Atrophy in these nuclei predicts 6-month outcome scores (GOSe).

Subclinical early posttraumatic seizures detected by continuous EEG monitoring in a consecutive pediatric cohort

PURPOSE

Traumatic brain injury (TBI) is an important cause of morbidity and mortality in children, and early posttraumatic seizures (EPTS) are a contributing factor to ongoing acute damage. Continuous video-EEG monitoring (cEEG) was utilized to assess the burden of clinical and electrographic EPTS.

METHODS

Eighty-seven consecutive, unselected (mild - severe), acute TBI patients requiring pediatric intensive care unit (PICU) admission at two academic centers were monitored prospectively with cEEG per established clinical TBI protocols. Clinical and subclinical seizures and status epilepticus (SE, clinical and subclinical) were assessed for their relation to clinical risk factors and short-term outcome measures.

KEY FINDINGS

Of all patients, 42.5% (37/87) had seizures. Younger age (p = 0.002) and injury mechanism (abusive head trauma - AHT, p < 0.001) were significant risk factors. Subclinical seizures occurred in 16.1% (14/87), while 6.9% (6/87) had only subclinical seizures. Risk factors for subclinical seizures included younger age (p < 0.001), AHT (p < 0.001), and intraaxial bleed (p < 0.001). SE occurred in 18.4% (16/87) with risk factors including younger age (p < 0.001), AHT (p < 0.001), and intraaxial bleed (p = 0.002). Subclinical SE was detected in 13.8% (12/87) with significant risk factors including younger age (p < 0.001), AHT (p = 0.001), and intraaxial bleed (p = 0.004). Subclinical seizures were associated with lower discharge King's Outcome Scale for Childhood Head Injury (KOSCHI) score (p = 0.002). SE and subclinical SE were associated with increased hospital length of stay (p = 0.017 and p = 0.041, respectively) and lower hospital discharge KOSCHI (p = 0.007 and p = 0.040, respectively).

SIGNIFICANCE

cEEG monitoring significantly improves detection of seizures/SE and is the only way to detect subclinical seizures/SE. cEEG may be indicated after pediatric TBI, particularly in younger children, AHT cases, and those with intraaxial blood on computerized tomography (CT).

Prevalence of epileptic and nonepileptic events after pediatric traumatic brain injury

Though posttraumatic epilepsy (PTE) is a prominent sequela of traumatic brain injury (TBI), other nonepileptic phenomena also warrant consideration. Within two UCLA pediatric TBI cohorts, we categorized five spell types: 1) PTE; 2) Epilepsy with other potential etiologies (cortical dysplasia, primary generalized); 3) Psychopathology; 4) Behavior misinterpreted as seizures; and 5) Other neurologic events. The two cohort subsets differed slightly in injury severity, but they were otherwise similar. Overall, PTE occurred in 40%, other epilepsy etiologies in 14%, and nonepileptic spells collectively in 46%. Among children with spells, PTE was associated with severe TBI (p=0.001), whereas psychopathology (p=0.014) and epilepsy with other etiologies (p=0.006) were associated with milder TBI severity. Posttraumatic epilepsy (p=0.002) and misinterpreted behavior (p=0.049) occurred with younger injury age. Psychopathology (p=0.020) and other neurologic events (p=0.002) occurred with older injury age. In evaluating possible PTE, clinicians should maintain a broad differential diagnosis to prevent misdiagnosis and inappropriate treatment.

Use of stent-assisted coil embolization for the treatment of wide-necked aneurysms: A systematic review

Background:

The use of stent-assisted coiling (SAC) has been shown to be a treatment option for complex aneurysms. We reviewed systematically the immediate and mid-term angiographic results following treatment of wide-necked aneurysms with self-expanding stents and coils, as well as the peri- and postprocedural rate of complications.

Methods:

A computerized database search was conducted from 01/2000 to 04/2011 using appropriate indexed terms on Pubmed. Inclusion criteria were: (1) homogeneous populations of ≥10 patients with wide-necked aneurysms; (2) use of a self-expandable neurovascular stent and coils for aneurysm treatment; (3) immediate and follow-up angiographic results; and (4) periprocedural and delayed thrombotic complications.

Results:

Seventeen studies were included, containing retrospectively collected data on 656 patients/702 aneurysms. The target aneurysm was located on the anterior circulation in 78.4% of patients. The immediate rate of complete occlusion was 46.3%, (19.3-98.1%). The intra- and postprocedural rate of intrastent thrombosis or thromboembolic event was 4.6% and 4.3%, respectively. Complete occlusion was documented in 71.9% at last angiographic follow-up. The rate of recanalization was 13.2% of aneurysms (0-28.8%). Delayed in-stent stenosis occurred in 5.3% cases (0-20.6%).

Conclusion:

SAC has been considered a treatment option for selected wide-necked aneurysms in some institutions. The use of intracranial stents should take into consideration the risk of ischemic complications, recanalization, delayed in-stent stenosis; and the currently unknown lifetime risks for stenosis, vascular injury, device failure, and aneurysm recurrence related to intracranial stenting. There is an evident need for a prospective multicenter registry for all treated patients with SAC.

Surgical treatment of Chiari malformation with and without syringomyelia: experience with 177 adult patients

Object

This study aims to show the relationship between clinical outcome in patients who underwent surgical decompression for Chiari malformation (CM) and postoperative imaging studies, with particular emphasis on the subarachnoid cisterns of the posterior fossa.

Methods

One hundred seventy-seven patients with CM, including 97 with syringomyelia, underwent posterior fossa decompressive surgery. Both the dura and arachnoid were opened in 150 of these patients, and 135 underwent reduction of the cerebellar tonsils. The patients' clinical signs and symptoms were evaluated at 2 time points after surgery. Their imaging studies were analyzed specifically for the size of the retrotonsillar and subtonsillar cisterns and the syringomyelic cavities. The authors evaluated the relationship between these imaging findings and clinical parameters.

Results

Clinical improvement correlated strongly with enlargement of the subarachnoid cisterns, and enlargement of the cisterns also correlated with reduction in size of the syrinx cavities. Symptoms related to syringomyelia responded to reduction in size of the syrinx cavities.

Conclusions

Surgical decompression of the posterior fossa should aim to create relatively large subarachnoid cisterns and reduce the size of the syrinx cavity. Reduction of the cerebellar tonsils by surgical means, together with duraplasty, achieves this goal and thereby improves the clinical outcome for patients with CM. An incidental observation of the study is that obesity increases the likelihood of headache in patients with CM.

Metabolomic analysis of cerebral spinal fluid from patients with severe brain injury

Proton nuclear magnetic resonance (H-NMR) spectroscopic analysis of cerebral spinal fluid provides a quick, non-invasive modality for evaluating the metabolic activity of brain-injured patients. In a prospective study, we compared the CSF of 44 TBI patients and 13 non-injured control subjects. CSF was screened for ten parameters: β-glucose (Glu), lactate (Lac), propylene glycol (PG), glutamine (Gln), alanine (Ala), α-glucose (A-Glu), pyruvate (PYR), creatine (Cr), creatinine (Crt), and acetate (Ace). Using mixed effects measures, we discovered statistically significant differences between control and trauma concentrations (mM). TBI patients had significantly higher concentrations of PG, while statistical trends existed for lactate, glutamine, and creatine. TBI patients had a significantly decreased concentration of total creatinine. There were no significant differences between TBI patients and non-injured controls regarding β- or α-glucose, alanine, pyruvate or acetate. Correlational analysis between metabolites revealed that the strongest significant correlations in non-injured subjects were between β- and α-glucose (r = 0.74), creatinine and pyruvate (r = 0.74), alanine and creatine (r = 0.62), and glutamine and α-glucose (r = 0.60). For TBI patients, the strongest significant correlations were between lactate and α-glucose (r = 0.54), lactate and alanine (r = 0.53), and α-glucose and alanine (r = 0.48). The GLM and multimodel inference indicated that the combined metabolites of PG, glutamine, α-glucose, and creatinine were the strongest predictors for CMRO2, ICP, and GOSe. By analyzing the CSF of patients with TBI, our goal was to create a metabolomic fingerprint for brain injury.

Early cerebral metabolic crisis after TBI influences outcome despite adequate hemodynamic resuscitation

BACKGROUND

Optimal resuscitation after traumatic brain injury (TBI) remains uncertain. We hypothesize that cerebral metabolic crisis is frequent despite adequate resuscitation of the TBI patient and that metabolic crisis negatively influences outcome.

METHODS

We assessed the effectiveness of a standardized trauma resuscitation protocol in 89 patients with moderate to severe TBI, and determined the frequency of adequate resuscitation. Prospective hourly values of heart rate, blood pressure, pulse oximetry, intracranial pressure (ICP), respiratory rate, jugular venous oximetry, and brain extracellular values of glucose, lactate, pyruvate, glycerol, and glutamate were obtained. The incidence during the initial 72 h after injury of low brain glucose <0.8 mmol/L, elevated lactate/pyruvate ratio (LPR) >25, and metabolic crisis, defined as the simultaneous occurrence of both low glucose and high LPR, were determined for the group.

RESULTS

5 patients were inadequately resuscitated and eight patients had intractable ICP. In patients with successful resuscitation and controlled ICP (n = 76), within 72 h of trauma, 76% had low glucose, 93% had elevated LPR, and 74% were in metabolic crisis. The duration of metabolic crisis was longer in those patients with unfavorable (GOSe ≤ 6) versus favorable (GOSe ≥ 7) outcome at 6 months (P = 0.011). In four multivariate models the burden of metabolic crisis was a powerful independent predictor of poor outcome.

CONCLUSIONS

Metabolic crisis occurs frequently after TBI despite adequate resuscitation and controlled ICP, and is a strong independent predictor of poor outcome at 6 months.

Differential effects of voluntary and forced exercise on stress responses after traumatic brain injury

Voluntary exercise increases levels of brain-derived neurotrophic factor (BDNF) after traumatic brain injury (TBI) when it occurs during a delayed time window. In contrast, acute post-TBI exercise does not increase BDNF. It is well known that increases in glucocorticoids suppress levels of BDNF. Moreover, recent work from our laboratory showed that there is a heightened stress response after fluid percussion injury (FPI). In order to determine if a heightened stress response is also observed with acute exercise, at post-injury days 0-4 and 7-11, corticosterone (CORT) and adrenocorticotropic hormone (ACTH) release were measured in rats running voluntarily or exposed to two daily 20-min periods of forced running wheel exercise. Forced, but not voluntary exercise, continuously elevated CORT. ACTH levels were initially elevated with forced exercise, but decreased by post-injury day 7 in the control, but not the FPI animals. As previously reported, voluntary exercise did not increase BDNF in the FPI group as it did in the control animals. Forced exercise did not increase levels of BDNF in any group. It did, however, decrease hippocampal glucocorticoid receptors in the control group. The results suggest that exercise regimens with strong stress responses may not be beneficial during the early post-injury period.

Monitoring the conjunctiva for carbon dioxide and oxygen tensions and pH during cardiopulmonary bypass

The purpose of this study was to measure, for the first time, multiple physiologic parameters of perfusion (pH, PCO2, PO2, and temperature) from the conjunctiva of adult patients during cardiopulmonary bypass while undergoing cardiothoracic surgery. Ten patients who underwent either intracardiac valve repair, atrial septal defect repair, or coronary artery bypass graft surgery had placement of a sensor which directly measured pH, PCO2, PO2, and temperature from the conjunctiva. Data were stratified into seven phases (0-5 minutes prior to bypass; 0-5, 6-10, and 11-15 minutes after initiation of bypass; 0-5 minutes prior to conclusion of bypass; and 0-5 and 6-10 minutes after bypass) and analyzed using a mixed model analysis.The change in conjunctival pH over the course of measurement was not statistically significant (p = .56). The PCO2 level followed a quadratic pattern, decreasing from a mean pre-bypass level of 37.7 mmHg at baseline prior to the initiation of cardiopulmonary bypass to a nadir of 33.2 mmHg, then increasing to a high of 39.4 mmHg at 6-10 minutes post bypass (p < .01). The PO2 declined from a mean pre-bypass level of 79.5 mmHg to 31.3 mmHg by 6-10 minutes post bypass and even post-bypass, it never returned to baseline values (p < .01). Temperature followed a pattern similar to PCO2 by returning to baseline levels as the patient was re-warmed following bypass (p < .01). There was no evidence of any eye injury or inflammation following the removal of the sensor. In the subjects studied, the conjunctival sensor yielded reproducible measurements during the various phases of cardiopulmonary bypass without ocular injury. Further study is necessary to determine the role of conjunctival measurements in critical settings.

Nonconvulsive seizures after traumatic brain injury are associated with hippocampal atrophy

OBJECTIVE

To determine if posttraumatic nonconvulsive electrographic seizures result in long-term brain atrophy.

METHODS

Prospective continuous EEG (cEEG) monitoring was done in 140 patients with moderate to severe traumatic brain injury (TBI) and in-depth study of 16 selected patients was done using serial volumetric MRI acutely and at 6 months after TBI. Fluorodeoxyglucose PET was done in the acute stage in 14/16 patients. These data were retrospectively analyzed after collection of data for 7 years.

RESULTS

cEEG detected seizures in 32/140 (23%) of the entire cohort. In the selected imaging subgroup, 6 patients with seizures were compared with a cohort of 10 age- and GCS-matched patients with TBI without seizures. In this subgroup, the seizures were repetitive and constituted status epilepticus in 4/6 patients. Patients with seizures had greater hippocampal atrophy as compared to those without seizures (21 +/- 9 vs 12 +/- 6%, p = 0.017). Hippocampi ipsilateral to the electrographic seizure focus demonstrated a greater degree of volumetric atrophy as compared with nonseizure hippocampi (28 +/- 5 vs 13 +/- 9%, p = 0.007). A single patient had an ictal PET scan which demonstrated increased hippocampal glucose uptake.

CONCLUSION

Acute posttraumatic nonconvulsive seizures occur frequently after TBI and, in a selected subgroup, appear to be associated with disproportionate long-term hippocampal atrophy. These data suggest anatomic damage is potentially elicited by nonconvulsive seizures in the acute postinjury setting.

Acute gonadotroph and somatotroph hormonal suppression after traumatic brain injury

Hormonal dysfunction is a known consequence of moderate and severe traumatic brain injury (TBI). In this study we determined the incidence, time course, and clinical correlates of acute post-TBI gonadotroph and somatotroph dysfunction. Patients had daily measurement of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, estradiol, growth hormone, and insulin-like growth factor-1 (IGF-1) for up to 10 days post-injury. Values below the fifth percentile of a healthy cohort were considered abnormal, as were non-measurable growth hormone (GH) values. Outcome measures were frequency and time course of hormonal suppression, injury characteristics, and Glasgow Outcome Scale (GOS) score. The cohort consisted of 101 patients (82% males; mean age 35 years; Glasgow Coma Scale [GCS] score <or=8 in 87%). In men, 100% had at least one low testosterone value, and 93% of all values were low; in premenopausal women, 43% had at least one low estradiol value, and 39% of all values were low. Non-measurable GH levels occurred in 38% of patients, while low IGF-1 levels were observed in 77% of patients, but tended to normalize within 10 days. Multivariate analysis revealed associations of younger age with low FSH and low IGF-1, acute anemia with low IGF-1, and older age and higher body mass index (BMI) with low GH. Hormonal suppression was not predictive of GOS score. These results indicate that within 10 days of complicated mild, moderate, and severe TBI, testosterone suppression occurs in all men and estrogen suppression occurs in over 40% of women. Transient somatotroph suppression occurs in over 75% of patients. Although this acute neuroendocrine dysfunction may not be TBI-specific, low gonadal steroids, IGF-1, and GH may be important given their putative neuroprotective functions.

Fructose induces transketolase flux to promote pancreatic cancer growth

Carbohydrate metabolism via glycolysis and the tricarboxylic acid cycle is pivotal for cancer growth, and increased refined carbohydrate consumption adversely affects cancer survival. Traditionally, glucose and fructose have been considered as interchangeable monosaccharide substrates that are similarly metabolized, and little attention has been given to sugars other than glucose. However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters. Here, we report that fructose provides an alternative substrate to induce pancreatic cancer cell proliferation. Importantly, fructose and glucose metabolism are quite different; in comparison with glucose, fructose induces thiamine-dependent transketolase flux and is preferentially metabolized via the nonoxidative pentose phosphate pathway to synthesize nucleic acids and increase uric acid production. These findings show that cancer cells can readily metabolize fructose to increase proliferation. They have major significance for cancer patients given dietary refined fructose consumption, and indicate that efforts to reduce refined fructose intake or inhibit fructose-mediated actions may disrupt cancer growth.

The risk of acute radiocontrast-mediated kidney injury following endovascular therapy for acute ischemic stroke is low

BACKGROUND AND PURPOSE

Endovascular therapy is an alternative for the treatment of AIS resulting from large intracranial arterial occlusions that depends on the use of iodinated RCM. The risk of RCM-mediated AKI following endovascular therapy for AIS may be different from that following coronary interventions because patients may not have identical risk factors.

MATERIALS AND METHODS

All consecutive patients with large-vessel AIS undergoing endovascular therapy were prospectively recorded. We recorded the baseline kidney function, and RCM-AKI was assessed according to the AKIN criteria at 48 hours after RCM administration. We compared the rate of RCM-AKI 48 hours after the procedure and sought to determine whether any preexisting factors increased the risk of RCM-AKI.

RESULTS

We identified 99 patients meeting inclusion criteria. The average volume of contrast was 189 ± 71 mL, and the average creatinine change was -4.6% at 48 hours postangiography. There were 3 patients with RCM-AKI. Although all 3 patients died as a result of their strokes, return to baseline creatinine levels occurred before death. There was a trend toward higher rates of premorbid diabetes mellitus, chronic renal insufficiency, preadmission statin and NSAID use, and a higher serum creatinine level on admission for the RCM-AKI group. The volume of procedural contrast was similar between groups (those with and those without RCM-AKI) (P = .5).

CONCLUSIONS

In this small study, the rate of RCM-AKI following endovascular intervention for AIS was very low. A much larger study is required to determine its true incidence.

Early nonischemic oxidative metabolic dysfunction leads to chronic brain atrophy in traumatic brain injury

Chronic brain atrophy after traumatic brain injury (TBI) is a well-known phenomenon, the causes of which are unknown. Early nonischemic reduction in oxidative metabolism is regionally associated with chronic brain atrophy after TBI. A total of 32 patients with moderate-to-severe TBI prospectively underwent positron emission tomography (PET) and volumetric magnetic resonance imaging (MRI) within the first week and at 6 months after injury. Regional lobar assessments comprised oxidative metabolism and glucose metabolism. Acute MRI showed a preponderance of hemorrhagic lesions with few irreversible ischemic lesions. Global and regional chronic brain atrophy occurred in all patients by 6 months, with the temporal and frontal lobes exhibiting the most atrophy compared with the occipital lobe. Global and regional reduction in cerebral metabolic rate of oxygen (CMRO(2)), cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of glucose were observed. The extent of metabolic dysfunction was correlated with the total hemorrhage burden on initial MRI (r=0.62, P=0.01). The extent of regional brain atrophy correlated best with CMRO(2) and CBF. Lobar values of OEF were not in the ischemic range and did not correlate with chronic brain atrophy. Chronic brain atrophy is regionally specific and associated with regional reductions in oxidative brain metabolism in the absence of irreversible ischemia.

Recanalization rates decrease with increasing thrombectomy attempts

BACKGROUND AND PURPOSE

Use of the Merci retriever is increasing as a means to reopen large intracranial arterial occlusions. We sought to determine whether there is an optimum number of retrieval attempts that yields the highest recanalization rates and after which the probability of success decreases.

MATERIALS AND METHODS

All consecutive patients undergoing Merci retrieval for large cerebral artery occlusions were prospectively tracked at a comprehensive stroke center. We analyzed ICA, M1 segment of the MCA, and vertebrobasilar occlusions. We compared the revascularization of the primary AOL with the number of documented retrieval attempts used to achieve that AOL score. For tandem lesions, each target lesion was compared separately on the basis of where the device was deployed.

RESULTS

We identified a total of 97 patients with 115 arterial occlusions. The median number of attempts per target vessel was 3, while the median final AOL score was 2. Up to 3 retrieval attempts correlated with good revascularization (AOL 2 or 3). When >or=4 attempts were performed, the end result was more often failed revascularization (AOL 0 or 1) and procedural complications (P = .006).

CONCLUSIONS

In our experience, 3 may be the optimum number of Merci retrieval attempts per target vessel occlusion. Four or more attempts may not improve the chances of recanalization, while increasing the risk of complications.

Proton magnetic resonance spectroscopy to evaluate spinal cord axonal injury in cervical spondylotic myelopathy

OBJECT

Magnetic resonance spectroscopy is commonly used to provide cellular and metabolic information in the management of a variety of pathological processes that affect the brain, and its application recently has been expanded to the cervical spine. The majority of radiographic investigations into the pathophysiology of cervical spondylotic myelopathy (CSM) have been focused on the spinal cord macrostructure. The authors sought to determine the feasibility of using MR spectroscopy to analyze spinal cord biochemical function in patients with CSM.

METHODS

Twenty-one patients with clinical and radiographic evidence of CSM were prospectively enrolled in this study. The patients underwent preoperative neurological examination, functional assessment, and cervical spine MR spectroscopy. Voxels were placed at the C-2 level, and the MR spectroscopy spectra peaks for N-acetylaspartate (NAA), choline, lactate (Lac), and creatine (Cr) were measured. Thirteen age-matched healthy volunteers served as controls.

RESULTS

The NAA/Cr ratio was significantly lower in patients with CSM than in controls (1.27 vs 1.83, respectively, p < 0.0001). The choline/Cr ratio was not significantly different between the 2 groups. Seven of the patients with CSM had a Lac peak, whereas no peaks were noted in the control group (p < 0.05). There was no correlation between the severity of myelopathy and the NAA/Cr ratio in the CSM cohort.

CONCLUSIONS

Data in this study demonstrated the feasibility of using MR spectroscopy to evaluate the cellular biochemistry of the spinal cord in patients with CSM. Patients with CSM had a significantly lower NAA/Cr ratio than healthy controls, likely because of axonal and neuronal loss. The presence of Lac peaks in one-third of the patients in the CSM cohort further supports the role of ischemia in the pathophysiology of CSM.

PITUITARY HORMONAL LOSS AND RECOVERY AFTER TRANSSPHENOIDAL ADENOMA REMOVAL

OBJECTIVE

Transsphenoidal adenomectomy carries the possibility of new pituitary failure and recovery. Herein, we present rates and determinants of postoperative hormonal status.

METHODS

All consecutive patients who underwent endonasal transsphenoidal adenoma removal over an 8-year period were analyzed. Those with previous sellar radiotherapy were excluded. Pre- and postoperative hormonal status (at least 3 mo after surgery) were determined and correlated with clinical parameters using a multivariate statistical model.

RESULTS

Of 444 patients (median age 45 years, 75% macroadenoma, 19% with multiple operations), 9 had preoperative panhypopituitarism. Of the remaining 435 patients, new hypopituitarism occurred in 5.5% of patients (anterior loss in 5%; permanent diabetes insipidus in 2.1%; including 2 patients who had total hypophysectomy). Of 346 patients with preoperative hormonal dysfunction, 170 (49%) had improved function. “Stalk compression” hyperprolactinemia resolved in 73% of 133 patients; recovery of at least 1 other anterior axis (excluding isolated hypogonadism associated with “stalk compression” hyperprolactinemia) occurred in 24% of 209 patients. Multivariate analysis showed that new hypopituitarism was most strongly associated with larger tumor diameter (P = 0.04). Of 223 patients with an endocrine-inactive adenoma, new hypopituitarism was seen in 0, 7.2, and 13.6% of patients with tumor diameters of &lt;20, 20 to 29, and ≥30 mm, respectively (P = 0.005). Multivariate analysis revealed that resolution of hypopituitarism was related to younger age (39 versus 52 years, P &lt; 0.0001), absence of an intraoperative cerebrospinal fluid leak and, in patients with an endocrine-inactive adenoma, absence of systemic hypertension (24% versus 6%, P = 0.009).

CONCLUSION

After transsphenoidal adenomectomy, new unplanned hypopituitarism occurs in approximately 5% of patients, whereas improved hormonal function occurs in 50% of patients. The likelihood of new hormonal loss or recovery appears to depend on several factors. New hypopituitarism occurs most commonly in patients with tumors larger than 20 mm in size, whereas hormonal recovery is most likely to occur in younger, nonhypertensive patients and those without an intraoperative cerebrospinal fluid leak.

Chronic hypopituitarism after traumatic brain injury: risk assessment and relationship to outcome

OBJECTIVE

Chronic pituitary dysfunction is increasingly recognized as a sequela of traumatic brain injury. We sought to define the incidence, risk factors, and neurobehavioral consequences of chronic hormonal deficiencies after complicated mild, moderate, or severe traumatic brain injury.

METHODS

Patients aged 14 to 80 years were prospectively enrolled at the time of injury and assessed at 3 and 6 to 9 months after injury for hormonal function and neurobehavioral consequences. Major and minor (subclinical) hormonal deficiencies, including growth hormone deficiency (GHD) and growth hormone insufficiency (GHI), were identified. Acute injury characteristics, neurobehavioral, and quality of life measures were compared in patients with and without major hormonal deficits by the use of multivariate analysis.

RESULTS

Out of 70 patients (mean age, 32 yr; median Glasgow Coma Scale score, 7; 19% women) tested at 6 to 9 months after injury, 15 (21%) had at least one major hormonal deficiency, 20 (29%) had minor deficiencies, and 30 (43%) had major and/or minor deficiencies. Patients with major deficiencies included 16% with GHD or GHI, 10.5% with hypogonadism, and 1.4% with diabetes insipidus. None of the patients required adrenal or thyroid replacement. At 6 to 9 months after injury, patients with major hormonal deficits had more abnormal acute computed tomographic findings (P = 0.014), greater acute and chronic body mass index (P < 0.01), and a worse Disability Rating Scale score (multivariate P = 0.04). Compared with the 59 growth hormone-sufficient patients, the 11 patients with GHD or GHI had worse Disability Rating Scale scores (multivariate P = 0.04), greater rates of depression, (90 versus 53%; multivariate P = 0.06), and worse quality of life in the Short Form-36 domains of energy and fatigue (multivariate P = 0.03), emotional well-being (multivariate P = 0.02), and general health (multivariate P = 0.07).

CONCLUSION

Chronic hypopituitarism warranting hormone replacement occurs in approximately 20% of patients after complicated mild, moderate, or severe traumatic brain injury and is associated with more severe brain injuries and increased disability. GHD and GHI are also associated with increased disability, poor quality of life, and a greater likelihood of depression. The clinical significance of minor hormonal deficits, which occur in almost 30% of patients, warrants further study. Given that major deficiencies are readily treatable, routine pituitary hormonal testing within 6 months of injury is indicated for this patient population.

A Short Trapezoidal Speculum for Suprasellar and Infrasellar Exposure in Endonasal Transsphenoidal Surgery

Objective:

A key limitation of the transsphenoidal approach for suprasellar and infrasellar lesions is restricted exposure. Microscope and endoscope-assisted procedures have traditionally used an oval-shaped speculum, the distal end of which restricts superior and inferior visualization. To improve visualization and use of the endoscope, shorter specula, with a trapezoidal distal end, were designed.

Methods:

The new specula have a working length of 60 mm. The proximal 20-mm segment is oval-shaped to conform to the nostril; the middle 20-mm segment has vertically oriented blades; and the distal 20-mm segment transitions to a trapezoidal orientation, with the distal blades angled 15 degrees upward and outward on the suprasellar speculum, or 15 degrees downward and outward on the infrasellar speculum. Both specula have a 5-degree distal outward flare. The upward-angled trapezoidal 60-mm speculum was compared with 70- and 80-mm oval specula in a transsphenoidal clay model. A pen light was projected from the nasal speculum end to a target 100 mm away using a blade opening width of 16 mm. Line drawings were made to quantify the impact of speculum length on the horizontal angle of exposure. The clinical utility of the trapezoidal specula was also assessed.

Results:

In the model, the 60-mm upward-angled trapezoidal speculum yielded a surface area illumination of 759 mm2, as compared with 579 and 432 mm2 with the 70-and 80-mm oval specula, an increase in exposure of 31 and 76%, respectively. In the line drawings, the 60-mm speculum provided a horizontal angle of exposure of 30 degrees, as compared with 26 and 23 degrees for the 70- and 80-mm specula, an increase of 17 and 33%, respectively. In patients, provided sufficient mucosa and bone are removed from the posterior nasal cavity, the trapezoidal specula provide an expanded working volume that facilitates endoscopy.

Conclusion:

Short upward- or downward-angled trapezoidal endonasal specula increase parasellar surface area exposure and the horizontal angle of exposure. Initial clinical experience suggests that reducing the speculum length and eliminating the distal curved blades result in greater instrument maneuverability and enhanced visibility for removing parasellar tumors.

Safety of intracranial endovascular aneurysm therapy using 3-dimensional rotational angiography: a single-center experience

BACKGROUND

Three-dimensional rotational angiography has recently been implemented in many interventional neuroradiology practices and may assist the endovascular operator in case selection and planning. The end result may be improved safety.

METHODS

We retrospectively searched our database for all aneurysms that were treated at our institution since February 1990. We identified 2 groups-those treated before and after the installation of our rotational fluoroscope on April 23, 2003. Patients with extracranial or intracavernous aneurysms were excluded. If multiple treatments were performed, only the first embolizations were considered. We then compared the 2 groups with regard to rates of immediate procedural complications. We further stratified aneurysms by number, size, and neck dimension, and performed subgroup analyses. We also conducted a post hoc comparison between chronological epochs within each group to determine whether improved safety was an epiphenomenon of advances in technology or operator skill.

RESULTS

There were a total of 876 patients treated before and 337 after the implementation of 3D-RA (total N = 1213). The overall complication rate in the pre-3D group was 5.9% and 3.0% in the post-3D group (odds ratio, 0.48; 95% CI, 0.24-0.97). Complication rates were also decreased for patients with single aneurysms. Post hoc analysis demonstrated no benefit within chronological subgroups of the pre-3D or post-3D cohorts. This suggests that the improved safety profile after 3D-RA implementation is not an epiphenomenon of factors such as technological advances or experiential improvements in technique.

CONCLUSIONS

3D-RA implemented during endovascular therapy for intracranial aneurysms improves the safety of the procedure. This may be a result of either improved aneurysm analysis and thus case selection, improved working position selection, or both.

OBSERVATIONS ON SPINE DEFORMITY AND SYRINGOMYELIA

OBJECTIVE

Spine deformities, notably scoliosis, are known to occur in conjunction with syringomyelia. This study aims to analyze the effect of laminectomies performed in the course of treatment of syringomyelia. It examines the incidence, severity, and type of spine deformity as it relates to the extent and location of laminectomies performed.

METHODS

Records of 169 patients were analyzed for evidence of spinal deformity on imaging studies for the extent of the syringomyelic cavities and for previous surgical procedures on the spine. This analysis included patients with syringomyelia related to Chiari malformation, as well as patients with primary spinal pathology.

RESULTS

Spinal deformities were encountered in 41% of Chiari-syringomyelia patients who had not undergone previous surgery and in 57% of such patients who underwent reoperation. Scoliosis, the most common type of deformity encountered, was likely to be mild in patients who had not undergone previous surgery and severe in reoperated patients. Spine deformity was significantly more common in those patients who had more extensive bone removal.

CONCLUSION

Complete laminectomy should be avoided whenever possible in patients with syringomyelia because local denervation of the axial musculature, added to loss of medial anterior horn cells from syringomyelia, favors the development of spine deformities. This is particularly true of laminectomies performed at the junctional areas of the spine, i.e., cervical-thoracic and thoracolumbar. Hemilaminectomy usually suffices for shunt placement; instrumented stabilization should be considered in patients undergoing full laminectomy, especially those considered to be at high risk of developing deformity.

Cortical synchrony changes detected by scalp electrode electroencephalograph as traumatic brain injury patients emerge from coma

BACKGROUND

Recent studies show conscious perception is correlated with firing rate synchronization across multiple neuronal assemblies. This study explores the synchrony between multiple cortical surface sites as brain injury patients emerge from coma.

METHODS

Scalp electrode EEG recordings were collected and analyzed from 13 traumatic brain injury patients during their stay in a neurosurgical intensive care unit. Neuronal synchrony was calculated between various electrode pairs during comatose and conscious periods defined by the GCS. Frequency bands from 1 to 30 Hz were evaluated in each patient.

RESULTS

As patients emerged from coma at GCS 3 to GCS scores > or =8, synchrony values from all electrode pairs revealed a global decrease in synchrony at higher GCS scores. No significant effects were detected relative to the amount of sedation given, but at higher GCS scores significantly increased neuronal synchrony was observed between occipital lobes and right parietal and temporal lobe sites. Synchrony was decreased between frontal-occipital, frontal-parietal, and parietal-occipital electrodes.

CONCLUSIONS

In frequencies from 1 to 30 Hz, synchrony between right parietal and temporal lobes, as well as bilateral occipital lobes, tends to be increased as patients emerge from comatose states. However, synchrony between most intrahemispheric cortical sites is decreased at higher GCS scores in most of the above frequency bands. Thus, brain injury patients demonstrate both increased and decreased cortical surface synchrony between different lobes during emergence from coma.

Impaired Percent Alpha Variability on Continuous Electroencephalography Is Associated with Thalamic Injury and Predicts Poor Long-Term Outcome after Human Traumatic Brain Injury

Continuous electroencephalography (cEEG) is potentially useful in determining prognosis in patients with traumatic brain injuries (TBI). The objective of this prospective, observational cohort study was to determine if the percent alpha variability (PAV) on cEEG was predictive of outcome following TBI. Injury characteristics were indexed to assess whether lesions in specific cerebral loci were correlated with PAV and patient recovery. Fifty-three TBI patients were studied using cEEG recording and serial neuroimaging. Clinical recovery was assessed at regular intervals in hospital and following discharge. The principal outcome measures included the mean 3-day PAV score, the 7-day PAV pattern, delineation of the anatomical sites of brain injury, and the 6-month clinical outcome, as measured by the Glasgow Outcome Scale (GOS). Significant univariate (p = 0.030) and multivariate (p = 0.008) relations were identified between PAV and GOS scores. PAV offered good discrimination between favorable and unfavorable 6-month outcomes (AUC 0.76) and, with a cutpoint of 0.20, had a sensitivity of 87% and negative predictive value of 82%. Multivariate modeling revealed that injuries of the thalamus (p = 0.009) and basal ganglia (p = 0.016), and the presence of diffuse edema (p = 0.009), were the key anatomical predictors of PAV. Brainstem injuries (p = 0.020) and indicators of diffuse cerebral trauma, such as deep white matter shearing (p = 0.036) and multiple subcortical lesions (p = 0.033), were the principal determinants of 6-month recovery. Inclusion of PAV enhanced the accuracy of prediction models that encompassed a selective combination of clinical and anatomical variables (adjusted R(2) = 0.458, p < 0.001). The two main results of this study are (1) PAV is a sensitive predictor of 6-month clinical outcomes following TBI, and (2) injury to the thalamus is related to impaired PAV. PAV appears best utilized as a functional adjunct to traditional clinical and anatomical predictors.

Functional Outcome in TBI II: Verbal Memory and Information Processing Speed Mediators

Following traumatic brain injury (TBI), patients often report memory difficulties, as well as reduced information processing speed. However, it remains unclear the extent to which these deficits contribute to functional impairment. In the present study, we compared the relative contribution of verbal memory and information processing speed to functional impairment at 12-month post-injury, in 87 patients with moderate-to-severe TBI. Employing structural equation modeling, we found that information processing speed, but not verbal memory functions, significantly mediated the relationship between TBI severity and post-TBI adaptive functioning. These findings suggest that despite the pervasive memory complaints among patients with TBI, it is the impact of neurotrauma on frontal systems that appears to be primarily responsible for patients' difficulties in social and occupational functioning.

Functional Outcome in TBI I: Neuropsychological, Emotional, and Behavioral Mediators

Literature exists to suggest that the severity of traumatic brain injury (TBI) is positively associated with the severity of functional impairment. However, potential mediators of this relationship have not been studied systematically. In the present study, we evaluated a model hypothesized to explain the relationship between TBI severity and functional impairment in 87 patients with moderate-to-severe TBI, studied longitudinally. Using structural equation modeling, we found that only neuropsychological status (but not emotional or behavioral difficulties) consistently mediated the relationship between TBI severity and functional outcome at 12-months post-injury. These findings suggest that, of the factors examined here, neurocognitive compromise plays the most prominent role in mediating post-TBI adaptive functioning in moderate-to-severe TBI, which has important implications for post-injury interventions.