Christian Niyonkuru

Acute Serum Hormone Levels: Characterization and Prognosis after Severe Traumatic Brain Injury

Experimental traumatic brain injury (TBI) studies report the neuroprotective effects of female sex steroids on multiple mechanisms of injury, with the clinical assumption that women have hormonally mediated neuroprotection because of the endogenous presence of these hormones. Other literature indicates that testosterone may exacerbate injury. Further, stress hormone abnormalities that accompany critical illness may both amplify or blunt sex steroid levels. To better understand the role of sex steroid exposure in mediating TBI, we 1) characterized temporal profiles of serum gonadal and stress hormones in a population with severe TBI during the acute phases of their injury; and 2) used a biological systems approach to evaluate these hormones as biomarkers predicting global outcome. The study population was 117 adults (28 women; 89 men) with severe TBI. Serum samples (n=536) were collected for 7 days post-TBI for cortisol, progesterone, testosterone, estradiol, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Hormone data were linked with clinical data, including acute care mortality and Glasgow Outcome Scale (GOS) scores at 6 months. Hormone levels after TBI were compared to those in healthy controls (n=14). Group based trajectory analysis (TRAJ) was used to develop temporal hormone profiles that delineate distinct subpopulations in the cohort. Structural equations models were used to determine inter-relationships between hormones and outcomes within a multivariate model. Compared to controls, acute serum hormone levels were significantly altered after severe TBI. Changes in the post-TBI adrenal response and peripheral aromatization influenced hormone TRAJ profiles and contributed to the abnormalities, including increased estradiol in men and increased testosterone in women. In addition to older age and greater injury severity, increased estradiol and testosterone levels over time were associated with increased mortality and worse global outcome for both men and women. These findings represent a paradigm shift when thinking about the role of sex steroids in neuroprotection clinically after TBI.

S100b as a Prognostic Biomarker in Outcome Prediction for Patients with Severe Traumatic Brain Injury

As an astrocytic protein specific to the central nervous system, S100b is a potentially useful marker in outcome prediction after traumatic brain injury (TBI). Some studies have questioned the validity of S100b, citing the extracerebral origins of the protein as reducing the specificity of the marker. This study evaluated S100b as a prognostic biomarker in adult subjects with severe TBI (sTBI) by comparing outcomes with S100b temporal profiles generated from both cerebrospinal fluid (CSF) (n = 138 subjects) and serum (n = 80 subjects) samples across a 6-day time course. Long-bone fracture, Injury Severity Score (ISS), and isolated head injury status were variables used to assess extracerebral sources of S100b in serum. After TBI, CSF and serum S100b levels were increased over healthy controls across the first 6 days post-TBI (p ≤ 0.005 and p ≤ 0.031). Though CSF and serum levels were highly correlated during early time points post-TBI, this association diminished over time. Bivariate analysis showed that subjects who had temporal CSF profiles with higher S100b concentrations had higher acute mortality (p < 0.001) and worse Glasgow Outcome Scale (GOS; p = 0.002) and Disability Rating Scale (DRS) scores (p = 0.039) 6 months post-injury. Possibly as a result of extracerebral sources of S100b in serum, as represented by high ISS scores (p = 0.032), temporal serum profiles were associated with acute mortality (p = 0.015). High CSF S100b levels were observed in women (p = 0.022) and older subjects (p = 0.004). Multivariate logistic regression confirmed CSF S100b profiles in predicting GOS and DRS and showed mean and peak serum S100b as acute mortality predictors after sTBI.

YKL-40 expression in traumatic brain injury - an initial analysis

YKL-40 (chitinase 3-like protein 1) is expressed in a broad spectrum of inflammatory conditions and cancers. We have previously reported that YKL-40 levels are elevated in the cerebrospinal fluid (CSF) of macaques and humans with lentiviral encephalitis, as well as multiple sclerosis (MS). The current study assessed temporal CSF YKL-40 levels in subjects with severe traumatic brain injury (TBI; Glasgow Coma Scale [GCS] score <or=8). We also evaluated temporal expression of YKL-40 after parasagittal controlled cortical impact (CCI) injury over the parietal cortex (2.8 mm deep, 4 m/sec). We demonstrate that CSF YKL-40 levels are elevated after acute TBI, and that YKL-40 levels are higher in patients who died following injury than in patients who survived. YKL-40 levels significantly correlate with CSF levels of inflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), as well as the inflammatory marker C-reactive protein (CRP). After CCI, in situ hybridization (ISH) showed that YKL-40 transcription is primarily associated with reactive astrocytes in pericontusional cortex. Tissue YKL-40 transcription time course analysis after CCI showed that YKL40 transcription in astrocytes began 1 day after injury, remained elevated for several days, and then declined by day 12. Similarly to our temporal CSF measurements in humans, YKL-40 induction after CCI is coincident with IL-1beta expression. Taken together these findings demonstrate that YKL-40 is induced in astrocytes during acute neuroinflammation, is temporally related to inflammatory mediator expression, and may be a useful biomarker for understanding secondary injury and for patient prognosis.

Quantitative electromyography improves prediction in vocal fold paralysis

Quantitative laryngeal electromyography (LEMG) using turns analysis can differentiate acute vocal fold paralysis from normal controls. The objective of this study is to determine if using both traditional qualitative LEMG measurements in addition to turns analysis improves prognostic accuracy in patients with acute vocal fold paralysis who demonstrate voluntary motor activity.

Neuroprotective, Neuroplastic, and Neurobehavioral Effects of Daily Treatment With Levetiracetam in Experimental Traumatic Brain Injury

Background. Prophylactic treatment with antiepileptic drugs (AEDs) has been recommended to prevent early seizure onset in patients with traumatic brain injury (TBI). However, the potential neuroprotective and/or detrimental effects of prophylactic AED treatment on behavioral and cognitive function after TBI are not well studied. Objective. To investigate the effects of a novel AED, levitiracetam (LEV), on behavioral and cognitive function after experimental TBI in rats. Methods. Adult male rats were administered LEV (intraperitoneal 50 mg/kg) or vehicle (saline; SL) daily for 20 days beginning 1 day after controlled cortical impact (CCI; 2.8 mm; 4 m/s) or sham surgery. Beam performance (days 1-6), Y-maze (day 7), and Morris water maze (days 14-19) postinjury testing was assessed. Results. Daily LEV treatment improved motor function, increased novel arm exploration in the Y-maze, elicited greater hippocampal cell sparing, and decreased contusion volumes compared with CCI/SL rats. Daily LEV administration also reversed a TBI-induced decrease in regional glutamate transporter expression and neuroplastic marker proteins present 20 days post-CCI. Also, daily LEV treatment decreased regional IL-1β expression after TBI. Conclusions. These results suggest that daily LEV treatment has beneficial effects on histological, molecular, and behavioral elements of neurological recovery after TBI, in part, via modulation of neuroinflammatory and excitatory pathways.

Group-based trajectory analysis applications for prognostic biomarker model development in severe TBI: a practical example.

Over the last decade, biomarker research has identified potential biomarkers for the diagnosis, prognosis, and management of traumatic brain injury (TBI). Several cerebrospinal fluid (CSF) and serum biomarkers have shown promise in predicting long-term outcome after severe TBI. Despite this increased focus on identifying biomarkers for outcome prognostication after a severe TBI, several challenges still exist in effectively modeling the significant heterogeneity observed in TBI-related pathology, as well as the biomarker-outcome relationships. Biomarker data collected over time are usually summarized into single-point estimates (e.g., average or peak biomarker levels), which are, in turn, used to examine the relationships between biomarker levels and outcomes. Further, many biomarker studies to date have focused on the prediction power of biomarkers without controlling for potential clinical and demographic confounders that have been previously shown to affect long-term outcome. In this article, we demonstrate the application of a practical approach to delineate and describe distinct subpopulations having similar longitudinal biomarker profiles and to model the relationships between these biomarker profiles and outcomes while taking into account potential confounding factors. As an example, we demonstrate a group-based modeling technique to identify temporal S100 calcium-binding protein B (S100b) profiles, measured from CSF over the first week post-injury, in a sample of adult subjects with TBI, and we use multivariate logistic regression to show that the prediction power of S100b biomarker profiles can be superior to the prediction power of single-point estimates.

Comparison of Surface and Ultrasound Localization to Identify Forearm Flexor Muscles for Botulinum Toxin Injections

To determine if ultrasound (US) localization is equivalent to surface landmark localization to identify botulinum toxin injection targets for forearm muscle spasticity.

Cerebrospinal Fluid Cortisol and Progesterone Profiles and Outcomes Prognostication after Severe Traumatic Brain Injury

Despite significant advances in the management of head trauma, there remains a lack of pharmacological treatment options for traumatic brain injury (TBI). While progesterone clinical trials have shown promise, corticosteroid trials have failed. The purpose of this study was to (1) characterize endogenous cerebrospinal fluid (CSF) progesterone and cortisol levels after TBI, (2) determine relationships between CSF and serum profiles, and (3) assess the utility of these hormones as predictors of long-term outcomes. We evaluated 130 adults with severe TBI. Serum samples (n=538) and CSF samples (n=746) were collected for 6 days post-injury, analyzed for cortisol and progesterone, and compared with healthy controls (n=13). Hormone data were linked with clinical data, including Glasgow Outcome Scale (GOS) scores at 6 and 12 months. Group based trajectory (TRAJ) analysis was used to develop temporal hormone profiles delineating distinct subpopulations. Compared with controls, CSF cortisol levels were significantly and persistently elevated during the first week after TBI, and high CSF cortisol levels were associated with poor outcome. As a precursor to cortisol, progesterone mediated these effects. Serum and CSF levels for both cortisol and progesterone were strongly correlated after TBI relative to controls, possibly because of blood-brain barrier disruption. Also, differentially impaired hormone transport and metabolism mechanisms after TBI, potential de novo synthesis of steroids within the brain, and the complex interplay of cortisol and pro-inflammatory cytokines may explain these acute hormone profiles and, when taken together, may help shed light on why corticosteroid trials have previously failed and why progesterone treatment after TBI may be beneficial.

Persistent hypogonadism influences estradiol synthesis, cognition and outcome in males after severe TBI

Objective: Acute hypogonadotropic hypogonadism (AHH) occurs frequently after TBI, as does chronic hypogonadotropic hypogonadism. However, AHH and persistent hypogonadotropic hypogonadism (PHH) after TBI are not well studied. The objective of this study was to characterize longitudinal hormone profiles and the impact of AHH and PHH on outcome. Methods: In this prospective cohort study, men with severe TBI (n = 38) had serum gonadal and gonadotropic hormones measured during weeks 1–52 post-injury. AHH, PHH and/or early resolving hypogonadotropic hypogonadism (ERHH) were based on temporal hormone assessments. PHH and hormone profiles were then compared to multiple outcome measures 6–12 months post-TBI. Results: AHH affected 100% of the population, while 37% subsequently developed PHH. Acute testosterone (TEST) and estradiol/testosterone (E2/TEST) ratios were associated with PHH and outcome. Over time, post-acute TEST and E2 levels for the ERHH group approached normal range, while levels for the PHH group remained low. Post-acute gonadotrophin levels were within the normal range for both groups. PHH, along with lower post-acute TEST and E2 profiles, was associated with worse functional and cognitive outcomes at 6 and 12 months post-injury. Conclusions: These results support screening for post-acute secondary hypogonadism and further research to assess the mechanisms underlying PHH and associated functional and cognitive deficits.

CSF Bcl-2 and cytochrome C temporal profiles in outcome prediction for adults with severe TBI.

The biochemical cascades associated with cell death after traumatic brain injury (TBI) involve both pro-survival and pro-apoptotic proteins. We hypothesized that elevated cerebrospinal fluid (CSF) Bcl-2 and cytochrome C (CytoC) levels over time would reflect cellular injury response and predict long-term outcomes after TBI. Cerebrospinal fluid Bcl-2 and CytoC levels were measured for 6 days after injury for adults with severe TBI (N = 76 subjects; N = 277 samples). Group-based trajectory analysis was used to generate distinct temporal biomarker profiles that were compared with Glasgow Outcome Scale (GOS) and Disability Rating Scale (DRS) scores at 6 and 12 months after TBI. Subjects with persistently elevated temporal Bcl-2 and CytoC profiles compared with healthy controls had the worst outcomes at 6 and 12 months (P ≤ 0.027). Those with CytoC profiles near controls had better long-term outcomes, and those with declining CytoC levels over time had intermediate outcomes. Subjects with Bcl-2 profiles that remained near controls had better outcomes than those with consistently elevated Bcl-2 profiles. However, subjects with Bcl-2 values that started near controls and steadily rose over time had 100% good outcomes by 12 months after TBI. These results show the prognostic value of Bcl-2 and CytoC profiles and suggest a dynamic apoptotic and pro-survival response to TBI.