Fast ripple-delta coupling as an early biomarker for post-traumatic epileptogenesis in repetitive brain injury.

Traumatic brain injury (TBI) can induce post-traumatic epilepsy (PTE), but early biomarkers for epileptogenesis are lacking. We used a repetitive diffuse TBI (rdTBI) model in mice with continuous video-EEG monitoring up to 4½ months post-injury to investigate electrographic biomarkers before and during post-traumatic seizure development. 25% of mice developed post-traumatic seizures with highly variable latency (5–126 days post-injury). Most significantly, we identified fast ripple-delta DOWN state coupling as an early biomarker that was detectable at 4 days post-TBI and appeared before seizure onset in all seizure-experiencing mice. This EEG signature distinguished seizure-experiencing from seizure-free TBI mice with high specificity. Power spectrum analysis revealed elevated delta and theta power, reduced physiological fast oscillations (alpha, beta, gamma) and increased pathological high-frequency oscillations (fast ripples) in seizure-experiencing animals, indicating network hyperexcitability. Spike analysis showed that while TBI itself increased cortical excitability, seizure onset triggered a dramatic further escalation in interictal activity. These electrographic signatures were remarkably consistent across all seizure-experiencing animals regardless of single or recurrent seizure pattern. Our results demonstrate that fast ripple-delta coupling represents a promising early biomarker detectable at 4 days post-TBI, before seizure onset, offering potential for early identification of post-traumatic seizure susceptibility. Importantly, this biomarker identified all seizure-prone animals regardless of whether they developed single or recurrent seizures, suggesting shared underlying mechanisms and clinical relevance for any post-traumatic seizure occurrence. These findings emphasize the utility of temporal EEG analysis for detecting early electrographic changes in post-traumatic epileptogenesis and may inform future intervention strategies.

Human posttraumatic epilepsy (PTE), the most common acquired epilepsy in teenagers and young adults1, is an unfortunate natural experiment that may provide insight into epileptogenesis and anti-epileptogenic interventions. In PTE, epilepsy develops weeks to months after traumatic brain injury (TBI), and often in a previously nonepileptic and otherwise healthy brain. Particularly in severe TBI, the injury timing is well-documented, and by necessity for critical care, the patients are closely monitored with access to imaging, electrophysiologic, blood and cerebrospinal fluid (CSF) biomarkers. Yet, the neurobiology of events that take place in the time between TBI and the first seizure of PTE, remains incompletely understood. This gap in knowledge about the mechanisms of posttraumatic epileptogenesis limits our capacity to develop successful antiepileptogenic interventions. As intriguing as the fundamental question of why PTE follows TBI after a seizure-free latent period, are the questions of why only a minority of patients with severe TBI, approximately 20%, develop PTE, and whether a biomarker measure may predict individual PTE likelihood. The selection for the 2015 Epilepsia Prize form Diamond et al., “IL-1β associations with posttraumatic epilepsy development: A genetics and biomarker cohort study2,” addresses these important questions. The authors studied a sizeable (n=256) and relatively homogenous cohort of patients with moderate-to-severe TBI who were part of an otherwise larger group enrolled in a study aimed to evaluate the contributions of genetics and related biomarkers to post-TBI outcomes. PTE developed in 16.4% of this group. Based on a growing literature that implicates autoimmune and inflammatory mechanisms in post-TBI pathophysiology, including in posttraumatic epileptogenesis, they formulated and tested a hypothesis that IL-1β concentrations in the CSF and in serum are predictive of PTE. IL-1β, a proinflammatory cytokine produced by activated microglia and astrocytes, is increased in the CNS after TBI, and may mark a sustained proinflammatory state that contributes to PTE. Further, to study genetic susceptibility to IL-1β-mediated post-traumatic epileptogenesis, the investigators tested whether individual genotypes at selected small nuclear polymorphism (SNPs) of the gene coding for IL-1β (IL-1β) also predicted PTE likelihood. With this approach of studying both the gene and gene product in PTE the authors demonstrate that both a high CSF:serum IL-1β concentration ratio and the specific heterozygous CT genotype in one SNP in the IL-1B gene promoter region, rs1143634, are associated with increased PTE risk. This was the first study to investigate the contributions of both IL-1β levels and IL-1B genetics in a single large TBI patient cohort. While IL-1β has been previously implicated in nontraumatic epilepsy and epileptogenesis, neither its role, nor the role of a specific IL-1β polymorphism as PTE biomarkers have been measured. Interestingly, CSF IL-1β was elevated in all TBI subjects relative to an uninjured control population and did not by itself mark a PTE risk. Thus rather than high CSF IL-1β, a low serum IL-1β concentration in the PTE vs. non-PTE patients with TBI accounted for the increased CSF:serum ratio. This finding underscores the complexity of TBI and PTE biomarker biology where one-dimensional metrics, individual measures that predict the likelihood of PTE with adequate specificity and sensitivity have been elusive. An appropriately cautious discussion in this article suggests an intriguing blood-to-brain IL-1β transport that may account for proinflammatory accumulation of peripheral IL-1β in the CNS. If validated, this would be in contrast to other cytokines and reactive proteins that follow a brain-to-blood transport and concentration gradient. These data thereby suggest that peripheral IL-1β production and transport may present novel therapeutic targets. IL-1β is representative of the larger class of signaling molecules that likely contribute to immune-mediated posttraumatic neuronal dysfunction, and this article expands on its contribution to PTE. The authors also add to their group's prior preclinical research which indicates that levetiracetam, a common first-line antiepileptic drug, suppresses regional posttraumatic IL-1β production and by this mechanism may suppress posttraumatic seizures3. These new data support future design and testing of antiepileptic and antiepileptogenic strategies that target IL-1β-related immune signaling pathways. The authors do not speculate as to the mechanistic contributions to PTE of the rs1143634 SNP CT heterozygous state, and indeed the experiment was not designed to address this question. However, the targeted approach to look simultaneously at the prognostic values IL-1β levels and IL-1B genetics suggests future work that will also incorporate measures of both the gene and the gene product in TBI research. The clinical TBI field and growing body of science dedicated to PTE and post-traumatic epileptogenesis will benefit from this report which is a step toward practical gene and protein biomarkers that predict post-TBI outcomes. These results implicating IL-1β protein and gene in PTE are particularly versatile as they can be incorporated either into future basic preclinical research aimed to elucidate PTE mechanisms and test novel therapies, or into the design of prospective clinical trials.

Objective To establish a stable reproducible repeated traumatic brain injury (TBI) animal model to study the neuron loss after TBI. Methods Sixty-four male SD rats were randomly divided into single TBI control group, the single TBI group, repetitive TBI control group, and repetitive TBI group, and each group was divided into four subgroups: 3 d group, 7 d group, 14 d group and 30 d group, each subgroup of 4 rats. Single TBI group was hit only once after craniotomy, repetitive TBI group hit four times in intervals of 24 h, and the control group was only given anesthesia to remove bone flap. After TBI model was established, the modified neurological severity score (mNSS) was detected at 1st, 3rd, 7th, 14th and 30th day, and Morris water maze test was used to examine spatial learning and memory ability at 30th day. The hematoxylin and eosin (HE) staining was used to observe the brain damage after the injury, and immunofluorescence to test neurons NeuN missing after injury. Results (1) As compared with the single TBI group, the mNSS results showed that the neurobehavioral injury was more serious at different time points after injury (1, 3 d: P=0.013, 7 d: P=0.003, 14 d: P=0.008, 21, 30 d: P=0.000). Morris water maze latency training results showed that the time to reach the target platform was prolonged at the second day after the start of training when compared with single TBI group (P=0.000). The percentage of target quadrant showed that the single injury group [(33.33±6.80)%] was higher than that in the repeated injury group [(16.34±3.76)%] in the same injury time (P=0.029). (2) Immunofluorescence showed that the neurons in the repetitive TBI group around the damaged area and those in the area of hippocampal dentate gyrus were lost seriously over time, more significant than in single TBI group (damaged area: 14 d: P=0.007, 30 d: P=0.003; hippocampal dentate gyrus: 14 d: P=0.009, 30 d: P=0.007). Conclusion As compare with the single TBI group, repetitive TBI leads to severe neurological defect and neuron loss. This repetitive TBI model can provide replicable rat model to study the neuropathology mechanism of neurodegeneration after repetitive brain injury. Key words: Traumatic brain injury; Neurodegenerative disease; Rat; Neuron; Model, animal

Background: Traumatic brain injury (TBI) is one of the most leading causes of deaths and disability among youth worldwide. Post-traumatic seizures (PTS) and post-traumatic epilepsy (PTE) are important catastrophic complications of TBI. Epilepsy has important medico-legal aspects for both the patient and the physician. Aim of the study: to identify forms of post traumatic seizures (generalized, focal, or focal followed by secondary generalized), site of epileptic focus, nature of brain injury that caused their occurrence, risk factors for epilepsy occurrence and medico-legal importance of PTS. Methods: A prospective cross-sectional study was conducted including patients with PTS and PTE who presented to El Demerdash and Ain shams Specialized Hospitals during the study period. Data were collected from patients by a questionnaire and from clinical sheets. Patients were classified into three groups according to time of occurrence of PTS. Results: A total of 77 patients were included. Cases were mostly in the age group less than 45 years old. Male patients were more represented in the study (64.9%). Transportation injuries were the most prominent pattern of TBI followed by blunt trauma (29.9%), open head injuries (13%), fall from height (13%) and polytrauma (1.3%). The most common affected site was frontal area of the brain (51.9%) followed by temporal region (45.5%). Associated complications included intra-cranial hemorrhage (87%) and skull fracture (35.1%). Immediate seizures were recorded in 9.1 % of the studied patients compared to 26% with early PTS. Patients with late PTS were the majority accounting for 64.9% of study patients of whom 50% with late PTS from the start. Most cases experienced generalized seizures attacks (59.7%) followed by focal with secondary generalization seizures attacks in (27.3%) and the least were with focal seizures attacks (13.0%). EEG showed abnormal activity in (62.3%) of patients and normal activity in (37.7%). Conclusion: Post-traumatic seizures and epilepsy are an important well-known sequel of traumatic brain injury with important medico-legal aspects. Pattern of head injury and site of traumatic area are important risk factors in occurrence of PTS and EEG abnormal activity is an important predictor for occurrence of PTS as well.

The accumulation of brain injury leads to severe neuropathological and neurobehavioral changes after repetitive mild traumatic brain injury

Repetitive mild traumatic brain injuries in children of abuse

ObjectiveThe development of post-traumatic epilepsy (PTE) following traumatic brain injury (TBI) is associated with unfavorable functional outcomes, and the global function of PTE patients might change dynamically overtime. Predicting the long-term functional outcomes of patients with PTE may help to develop accurate rehabilitation programs and improve their quality of life. Based on this, the objective of this study is to use clinical data to derive and validate a model for predicting the functional outcomes of patients with PTE after moderate-to-severe TBI.MethodsThis study retrospectively analyzed 721 patients with PTE after moderate-to-severe TBI in the Epilepsy Centre, Beijing Tiantan Hospital, from January 2013 to December 2018. All patients had favorable global function as indicated by the Glasgow Outcome Scale-Extended (GOSE) at the time of their first late post-traumatic seizure (PTS) onset, and the 5-year global function after the first late PTS onset was chosen as the principal outcome of interest. To identify possible predictors for the global functional outcomes, univariate and multivariate logistic regression techniques were used. A prognostic model was established using these identified predictors, the internal validation with the bootstrapping method was performed, and the model was then visualized as a graphical score chart.ResultsThe 5-year global functional outcome of 98 (13.59%) patients was unfavorable, and the temporal lobe lesion was found as the strongest predictor of unfavorable outcomes. The final prognostic model also included the following other predictors: gender, age at TBI, multiple injuries, the severity of TBI, and latency of PTE. Discrimination was satisfactory with C-statistic of 0.754 (0.707 – 0.800), the goodness-of-fit test indicated good calibration (P = 0.137), and the C-statistic was 0.726 for internal validation. A graphical score chart was also constructed to provide the probability of an unfavorable 5-year global functional outcomes more readily.ConclusionsClearer treatment strategies are essential to help ameliorate the global functional outcomes of patients with PTE. Our proposed prognostic model has significant potential to be used in the clinic for predicting global functional outcomes among patients with PTE after moderate-to-severe TBI.

Contusion brain damage in mice for modelling of post-traumatic epilepsy with contralateral hippocampus sclerosis: Comprehensive and longitudinal characterization of spontaneous seizures, neuropathology, and neuropsychiatric comorbidities

Are enlarged perivascular spaces a predictor of early post-traumatic seizures after traumatic brain injury?- A pilot study.

Study Objectives Traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) commonly cooccur. Approaches to research and treatment of these disorders have been segregated, despite overlapping symptomology. We and others have hypothesized that comorbid TBI + PTSD generates worse symptoms than either condition alone. We present a mouse model of comorbid TBI + PTSD to further explore this condition. Methods A mouse model of TBI + PTSD was generated using the single prolonged stress (SPS) protocol in combination with the controlled cortical impact (CCI) protocol. This resulted in four experimental groups: control, TBI, PTSD, and TBI + PTSD. Behavioral phenotyping included gait analysis, contextual fear conditioning, acoustic startle response, and prepulse inhibition. Results Mice in the TBI + PTSD group showed a significantly impaired gait compared to their counterparts with TBI alone as well as control mice. Mice in the TBI + PTSD group showed significantly impaired contextual fear recall compared to controls. Prepulse inhibition testing revealed intact acoustic startle and auditory sensory gating. Conclusions These results indicate that SPS paired with CCI in mice produces unique behavioral impairments in gait and fear recall that are not present in either condition alone. Further studies are underway to examine additional behavioral, physiological, and pathological phenotypes in this combined model of TBI + PTSD.

Traumatic brain injury (TBI) is defined as an impact to the head by an external force that causes brain alterations and subsequent long‐term functional deficits. TBI contributes to an economic burden of $17 billion USD annually and is a leading cause of death and disability for individuals under 45. The severity of TBI varies from mild to severe with repetitive and mild (rm) TBI, and accounts for the highest percentage of TBI‐cases, leading to long‐term cognitive impairment. There are no current treatment(s) for repetitive and mild TBI, therefore, we sought to identify novel signaling molecules/pathways that could contribute to TBI.We employed a clinically relevant (non‐surgical) closed‐head impact model of engineered rotational acceleration (CHIMERA) that allows free rotation of the head upon impact generated from an air‐compressed piston. Our data suggest a novel role for PRMT7 (protein arginine methyltransferases) in the disease progression as indicated by the temporal decrease in protein expression post‐rmTBI. Our central hypothesis is that the loss of PRMT7, due to repetitive and mild TBI, mediates excitotoxicity, increased cellular death, disturbed mitochondrial dynamics and contributes to behavioral deficits. PRMTs are novel targets that catalyze the methylation of arginine residues (a constitutive post‐translational modification) involved in transcription, translation, receptor trafficking, and protein stability. There are currently 11 known PRMT isoforms (PRMT1‐11), with PRMT7 gene deletion in human patients causing neurological deficits such as intellectual disability, microcephaly, and brachydactyly, along with hyperexcitability and impaired social behaviors in murine in vivo models.We assessed diffuse axonal injury in our model of mild and repetitive TBI (via CHIMERA) to suggest enhanced silver deposition (dark stained regions) throughout the brain, similar to human pathology. Next, we measured PRMT7 protein levels that were decreased in the cortex and hippocampus 7‐days post‐rmTBI. Relative PRMT7 mRNA (via real‐time qPCR) was enhanced in the cortex 1‐day post‐rmTBI. Using LC‐MS, we measured excitatory neurotransmitters to suggest that glutamate was enhanced in the hippocampus 3‐day post‐rmTBI. In addition, mitochondrial fission and fusion was assessed by measuring DRP1 and OPA1 and our results indicated increased polarization towards fission as indicated by significant increase of DRP1 protein expression 1,3,7 days post rmTBI. Furthermore, mitochondrial oxygen consumption rates were analyzed via Seahorse XF analyzer and indicated dynamic changes in ATP‐linked respiration and maximal respiration 1 and 3 days post‐rmTBI. Finally, learning, working memory, and locomotor skills were significantly impaired as indicated by decreased alternation ratios via T‐maze, novel object recognition, and rotarod assessment. Overall, our results suggest that PRMT7 can mediate neuronal hyperexcitability, altered mitochondrial dynamics and can affect functional outcomes post‐rmTBI.

Early posttraumatic seizures (EPS) that may occur following a traumatic brain injury (TBI) are associated with poorer outcomes and development of posttraumatic epilepsy (PTE). To evaluate risk factors for EPS, associated morbidity and mortality, and contribution to PTE. Data were collected from an Australian registry-based cohort study of adults (age ≥18 years) with moderate to severe TBI from January 2005 to December 2019, with 2-year follow-up. The statewide trauma registry, conducted on an opt-out basis in Victoria (population 6.5 million), had 15 152 patients with moderate to severe TBI identified via Abbreviated Injury Scale (AIS) head severity score, with an opt-out rate less than 0.5% (opt-out n = 136). EPS were identified via International Statistical Classification of Diseases, Tenth Revision, Australian Modification (ICD-10-AM) codes recorded after the acute admission. Outcome measures also included in-hospital metrics, 2-year outcomes including PTE, and post-discharge mortality. Adaptive least absolute shrinkage and selection operator (LASSO) regression was used to build a prediction model for risk factors of EPS. Among the 15 152 participants (10 457 [69%] male; median [IQR] age, 60 [35-79] y), 416 (2.7%) were identified with EPS, including 27 (0.2%) with status epilepticus. Significant risk factors on multivariable analysis for developing EPS were younger age, higher Charlson Comorbidity Index, TBI sustained from a low fall, subdural hemorrhage, subarachnoid hemorrhage, higher Injury Severity Score, and greater head injury severity, measured using the AIS and Glasgow Coma Score. After adjustment for confounders, EPS were associated with increased ICU admission and ICU length of stay, ventilation and duration, hospital length of stay, and discharge to inpatient rehabilitation rather than home, but not in-hospital mortality. Outcomes in TBI admission survivors at 24 months, including mortality (relative risk [RR] = 2.14; 95% CI, 1.32-3.46; P = .002), development of PTE (RR = 2.91; 95% CI, 2.22-3.81; P < .001), and use of antiseizure medications (RR = 2.44; 95% CI, 1.98-3.02; P < .001), were poorer for cases with EPS after adjustment for confounders. The prediction model for EPS had an area under the receiver operating characteristic curve of 0.72 (95% CI, 0.66-0.79), sensitivity of 66%, and specificity of 73% in the validation set. We identified important risk factors for EPS following moderate to severe TBI. Early posttraumatic seizures were associated with longer ICU and hospital admissions, ICU ventilation, and poorer 24-month outcomes including mortality and development of PTE.

Introduction. Posttraumatic epilepsy: treatable epileptogenesis.

Posttraumatic seizures (PTS) and posttraumatic epilepsy (PTE) are common and debilitating consequences of traumatic brain injury (TBI). Early PTS result in secondary brain injury by raising intracranial pressure and worsening cerebral edema and metabolic crisis. PTE is a localization-related epilepsy strongly associated with TBI severity, but risk factors for PTE and epileptogenesis are incompletely understood and are active areas of research. Medical management of PTS in adults and children is reviewed. Surgical options for posttraumatic drug-resistant epilepsy are also discussed. Continuous electroencephalography is indicated for children and adults with TBI and coma because of the high incidence of nonconvulsive seizures, periodic discharges, and associated secondary brain injury in this population. Neuroinflammation is a central component of secondary brain injury and appears to play a key role in epileptogenesis. Levetiracetam is increasingly used for seizure prophylaxis in adults and children, but variability remains. PTS occur commonly after TBI and are associated with secondary brain injury and worse outcomes in adults and children. Current medical and surgical management options for PTS and PTE are reviewed.

Abstracts from The 37^th Annual National Neurotrauma Symposium June 29–July 3, 2019 Pittsburgh, Pennsylvania