A persistent change in subcellular distribution of calcineurin following fluid percussion injury in the rat

The Role of Estradiol in Traumatic Brain Injury: Mechanism and Treatment Potential

Patients surviving traumatic brain injury (TBI) face numerous neurological and neuropsychological problems significantly affecting their quality of life. Extensive studies over the past decades have investigated pharmacological treatment options in different animal models, targeting various pathological consequences of TBI. Sex and gender are known to influence the outcome of TBI in animal models and in patients, respectively. Apart from its well-known effects on reproduction, 17β-estradiol (E2) has a neuroprotective role in brain injury. Hence, in this review, we focus on the effect of E2 in TBI in humans and animals. First, we discuss the clinical classification and pathomechanism of TBI, the research in animal models, and the neuroprotective role of E2. Based on the results of animal studies and clinical trials, we discuss possible E2 targets from early to late events in the pathomechanism of TBI, including neuroinflammation and possible disturbances of the endocrine system. Finally, the potential relevance of selective estrogenic compounds in the treatment of TBI will be discussed.

Variation in PPP3CC Genotype Is Associated with Long-Term Recovery after Severe Brain Injury

After experimental traumatic brain injury (TBI), calcineurin is upregulated; blocking calcineurin is associated with improved outcomes. In humans, variation in the calcineurin A-gamma gene (PPP3CC) has been associated with neuropsychiatric disorders, though any role in TBI recovery remains unknown. This study examines associations between PPP3CC genotype and mortality, as well as gross functional status assessed at admission using the Glasgow Coma Scale (GCS) and at 3, 6, and 12 months after severe TBI using the Glasgow Outcome Score (GOS). The following tagging single nucleotide polymorphisms (tSNPs) in PPP3CC were genotyped: rs2443504, rs2461491, rs2469749, and rs10108011. The rs2443504 AA genotype was univariately associated with GCS (p = 0.022), GOS at 3, 6, and 12 months (p = 0.002, p = 0.034, and p = 0.004, respectively), and mortality (p = 0.007). In multivariate analysis controlling for age, sex, and GCS, the AA genotype of rs2443504 was associated with GOS at 3 (p = 0.02), and 12 months (p = 0.01), with a trend toward significance at 6 months (p = 0.05); the AA genotype also was associated with mortality in the multivariate model (p = 0.04). Further work is warranted to better understand the role of calcineurin, as well as the genes encoding it and their relevance to outcomes after brain injury.

NMDA receptor triggered molecular cascade underlies compression-induced rapid dendritic spine plasticity in cortical neurons

Compression causes the reduction of dendritic spines of underlying adult cortical pyramidal neurons but the mechanisms remain at large. Using a rat epidural cerebral compression model, dendritic spines on the more superficial-lying layer III pyramidal neurons were found quickly reduced in 12h, while those on the deep-located layer V pyramidal neurons were reduced slightly later, starting 1day following compression. No change in the synaptic vesicle markers synaptophysin and vesicular glutamate transporter 1 suggest no change in afferents. Postsynaptically, N-methyl-d-aspartate (NMDA) receptor trafficking to synaptic membrane was detected in 10min and lasting to 1day after compression. Translocation of calcineurin to synapses and enhancement of its enzymatic activity were detected within 10min as well. These suggest that compression rapidly activated NMDA receptors to increase postsynaptic calcium, which then activated the phosphatase calcineurin. In line with this, dephosphorylation and activation of the actin severing protein cofilin, and the consequent depolymerization of actin were all identified in the compressed cortex within matching time frames. Antagonizing NMDA receptors with MK801 before compression prevented this cascade of events, including NR1 mobilization, calcineurin activation and actin depolymerization, in the affected cortex. Morphologically, MK801 pretreatment prevented the loss of dendritic spines on the compressed cortical pyramidal neurons as well. In short, we demonstrated, for the first time, mechanisms underlying the rapid compression-induced cortical neuronal dendritic spine plasticity. In addition, the mechanical force of compression appears to activate NMDA receptors to initiate a rapid postsynaptic molecular cascade to trim dendritic spines on the compressed cortical pyramidal neurons within half a day.

Differential effect of traumatic brain injury on the nuclear factor of activated T Cells C3 and C4 isoforms in the rat hippocampus

The interaction between the phosphatase calcineurin and transcription factor nuclear factor of activated T cells (NFAT) plays an important role numerous signaling and the regulatory events. Although NFAT is mostly known for its transcription function in the immune system, NFAT also has essential functions even in the central nervous system (CNS). The effects of traumatic brain injury (TBI) on NFAT are currently unknown. To determine if there is an alteration in NFAT after TBI, we examined NFATc3 and c4 levels at 6 h, 1 day, 1 week, 2 weeks and 4 weeks post injury. Rats were anesthetized and surgically prepared for controlled cortical impact (CCI) injury or sham surgery. Semi-quantitative measurements of NFATc3 and c4 in the hippocampal homogenates from injured and sham rats sacrificed at the appropriate time after injury were assessed using Western blot analysis. After TBI insult, in the hippocampus ipsilateral to the injury, NFATc3 expression levels were decreased both in the cytoplasmic and nuclear fractions. However, NFATc4 expression levels were increased in the cytoplasmic fraction but decreased in the nuclear fraction. Double labeling (with NeuN and GFAP) immunohistochemistry revealed that NFATc3 was expressed in subset of astrocytes and NFATc4 was expressed primarily in neurons. These differential responses in NFATc3 and c4 expression after TBI insult may indicate long-term changes in hippocampal excitability and may contribute to behavioral deficits. Further study is warranted to illustrate the role of NFATc3 and c4 in the setting of TBI.

Molecular mechanisms of cognitive dysfunction following traumatic brain injury

Traumatic brain injury (TBI) results in significant disability due to cognitive deficits particularly in attention, learning and memory, and higher-order executive functions. The role of TBI in chronic neurodegeneration and the development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and most recently chronic traumatic encephalopathy (CTE) is of particular importance. However, despite significant effort very few therapeutic options exist to prevent or reverse cognitive impairment following TBI. In this review, we present experimental evidence of the known secondary injury mechanisms which contribute to neuronal cell loss, axonal injury, and synaptic dysfunction and hence cognitive impairment both acutely and chronically following TBI. In particular we focus on the mechanisms linking TBI to the development of two forms of dementia: AD and CTE. We provide evidence of potential molecular mechanisms involved in modulating Aβ and Tau following TBI and provide evidence of the role of these mechanisms in AD pathology. Additionally we propose a mechanism by which Aβ generated as a direct result of TBI is capable of exacerbating secondary injury mechanisms thereby establishing a neurotoxic cascade that leads to chronic neurodegeneration.

Differential effects of FK506 on structural and functional axonal deficits after diffuse brain injury in the immature rat

Diffuse axonal injury is a major component of traumatic brain injury in children and correlates with long-term cognitive impairment. Traumatic brain injury in adult rodents has been linked to a decrease in compound action potential (CAP) in the corpus callosum, but information on trauma-associated diffuse axonal injury in immature rodents is limited. We investigated the effects of closed head injury on CAP in the corpus callosum of 17-day-old rats. The injury resulted in CAP deficits of both myelinated and unmyelinated fibers in the corpus callosum between 1 and 14 days postinjury (dpi). These deficits were accompanied by intra-axonal dephosphorylation of the 200-kDa neurofilament subunit (NF200) at 1 and 3 dpi, a decrease in total NF200 at 3 dpi and axonal degeneration at 3 and 7 dpi. Although total phosphatase activity decreased at 1 dpi, calcineurin activity was unchanged. The calcineurin inhibitor, FK506, significantly attenuated the injury-induced NF200 dephosphorylation of NF200 at 3 dpi and axonal degeneration at 3 and 7 dpi but did not affect the decrease in NF200 protein levels or impaired axonal transport. FK506 had no effect on CAP deficits at 3 dpi but exacerbated the deficit in only the myelinated fibers at 7 dpi. Thus, in contrast to adult animals, FK506 treatment did not improve axonal function in brain-injured immature animals, suggesting that calcineurin may not contribute to impaired axonal function.

In vitro stretch injury induces time- and severity-dependent alterations of STEP phosphorylation and proteolysis in neurons

Striatal-enriched tyrosine phosphatase (STEP) has been identified as a component of physiological and pathophysiological signaling pathways mediated by N-methyl-d-aspartate (NMDA) receptor/calcineurin/calpain activation. Activation of these pathways produces a subsequent change in STEP isoform expression or activation via dephosphorylation. In this study, we evaluated changes in STEP phosphorylation and proteolysis in dissociated cortical neurons after sublethal and lethal mechanical injury using an in vitro stretch injury device. Sublethal stretch injury produces minimal changes in STEP phosphorylation at early time points, and increased STEP phosphorylation at 24 h that is blocked by the NMDA-receptor antagonist APV, the calcineurin-inhibitor FK506, and the sodium channel blocker tetrodotoxin. Lethal stretch injury produces rapid STEP dephosphorylation via NR2B-containing NMDA receptors, but not calcineurin, and a subsequent biphasic phosphorylation pattern. STEP(61) expression progressively increases after sublethal stretch with no change in calpain-mediated STEP(33) formation, while lethal stretch injury results in STEP(33) formation via a NR2B-containing NMDA receptor pathway within 1 h of injury. Blocking calpain activation in the initial 30 min after stretch injury increases the ratio of active STEP in cells and blocks STEP(33) formation, suggesting that STEP is an early substrate of calpain after mechanical injury. There is a strong correlation between the amount of STEP(33) formed and the degree of cell death observed after lethal stretch injury. In summary, these data demonstrate that previously characterized pathways of STEP regulation via the NMDA receptor are generally conserved in mechanical injury, and suggest that calpain-mediated cleavage of STEP(33) should be further examined as an early marker of neuronal fate after stretch injury.

Hypoxia enhances high-voltage-activated calcium currents in rat primary cortical neurons via calcineurin

Hypoxia regulates neuronal ion channels, sometimes resulting in seizures. We evaluated the effects of brief sustained hypoxia (1% O(2), 4h) on voltage-gated calcium channels (VGCCs) in cultured rat primary cortical neurons. High-voltage activated (HVA) Ca(2+) currents were acquired immediately after hypoxic exposure or after 48h recovery in 95% air/5% CO(2). Maximal Ca(2+) current density increased 1.5-fold immediately after hypoxia, but reverted to baseline after 48h normoxia. This enhancement was primarily due to an increase in L-type VGCC activity, since nimodipine-insensitive residual Ca(2+) currents were unchanged. The half-maximal potentials of activation and steady-state inactivation were unchanged. The calcineurin inhibitors FK-506 (in the recording pipette) or cyclosporine A (during hypoxia) prevented the post-hypoxic increase in HVA Ca(2+) currents, while rapamycin and okadaic acid did not. L-type VGCCs were the source of Ca(2+) for calcineurin activation, as nimodipine during hypoxia prevented post-hypoxic enhancement. Hypoxia transiently potentiated L-type VGCC currents via calcineurin, suggesting a positive feedback loop to amplify neuronal calcium signaling that may contribute to seizure generation.

Molecular mechanisms underlying effects of neural stem cells against traumatic axonal injury

Transplantation of neural stem cells (NSCs) improves functional outcomes following traumatic brain injury (TBI). Previously we demonstrated that human NSCs (hNSCs) via releasing glial cell line-derived neurotrophic factor (GDNF), preserved cognitive function in rats following parasagittal fluid percussion. However, the underlying mechanisms remain elusive. In this study, we report that NSC grafts significantly reduce TBI-induced axonal injury in the fimbria and other brain regions by blocking abnormal accumulation of amyloid precursor protein (APP). A preliminary mass spectrometry proteomics study revealed the opposite effects of TBI and NSCs on many of the cytoskeletal proteins in the CA3 region of the hippocampus, including α-smooth muscle actin (α-SMA), the main stress fiber component. Further, Western blot and immunostaining studies confirmed that TBI significantly increased the expression of α-SMA in hippocampal neurons, whereas NSC grafts counteracted the effect of TBI. In an in vitro model, rapid stretch injury significantly shortened lengths of axons and dendrites, increased the expression of both APP and α-SMA, and induced actin aggregation, effects offset by GDNF treatment. These GDNF protective effects were reversed by a GDNF-neutralizing antibody or a specific calcineurin inhibitor, and were mimicked by a specific Rho inhibitor. In summary, we demonstrate for the first time that hNSC grafts and treatment with GDNF acutely reduce traumatic axonal injury and promote neurite outgrowth. Possible mechanisms underlying GDNF-mediated neurite protection include balancing the activity of calcineurin, whereas GDNF-induced neurite outgrowth may result from the reduction of the abnormal α-SMA expression and actin aggregation via blocking Rho signals. Our study also suggests the necessity of further exploring the roles of α-SMA in the central nervous system (CNS), which may lead to a new avenue to facilitate recovery after TBI and other injuries.

Mechanisms of dendritic spine remodeling in a rat model of traumatic brain injury

Traumatic brain injury (TBI), a leading cause of death and disability in the United States, causes potentially preventable damage in part through the dysregulation of neural calcium levels. Calcium dysregulation could affect the activity of the calcium-sensitive phosphatase calcineurin (CaN), with serious implications for neural function. The present study used both an in vitro enzymatic assay and Western blot analyses to characterize the effects of lateral fluid percussion injury on CaN activity and CaN-dependent signaling in the rat forebrain. TBI resulted in an acute alteration of CaN phosphatase activity and long-lasting alterations of its downstream effector, cofilin, an actin-depolymerizing protein. These changes occurred bilaterally in the neocortex and hippocampus, appeared to persist for hours after injury, and coincided with synapse degeneration, as suggested by a loss of the excitatory post-synaptic protein PSD-95. Interestingly, the effect of TBI on cofilin in some brain regions was blocked by a single bolus of the CaN inhibitor FK506, given 1 h post-TBI. Overall, these findings suggest a loss of synapse stability in both hemispheres of the laterally-injured brain, and offer evidence for region-specific, CaN-dependent mechanisms.

Strain-related differences after experimental traumatic brain injury in rats

The present study directly compares the effects of experimental brain injury in two commonly used rat strains: Fisher 344 and Sprague-Dawley. We previously found that Fisher rats have a higher mortality rate and more frequent seizure attacks at the same injury level than Sprague-Dawley rats. Although strain differences in rats are commonly accepted as contributing to variability among studies, there is a paucity of literature addressing strain influence in experimental neurotrauma. Therefore this study compares outcome measures in two rat strains following lateral fluid percussion injury. Fisher 344 and Sprague-Dawley rats were monitored for changes in physiological measurements, intracranial pressure, and electroencephalographic activity. We further analyzed neuronal degeneration and cell death in the injured brain using Fluoro-Jade-B (FJB) histochemistry and caspase-3 immunostaining. Behavioral studies using the beam walk and Morris water maze were conducted to characterize strain differences in both motor and cognitive functional recovery following injury. We found that Fisher rats had significantly higher intracranial pressure, prolonged seizure activity, increased FJB-positive staining in the injured cortex and thalamus, and increased caspase-3 expression than Sprague-Dawley rats. On average, Fisher rats displayed a greater amount of total recording time in seizure activity and had longer ictal durations. The Fisher rats also had increased motor deficits, correlating with the above results. In spite of these results, Fisher rats performed better on cognitive tests following injury. The results demonstrate that different rat strains respond to injury differently, and thus in preclinical neurotrauma studies strain influence is an important consideration when evaluating outcomes.

Excitatory synaptic transmission and network activity are depressed following mechanical injury in cortical neurons

In vitro and in vivo traumatic brain injury (TBI) alter the function and expression of glutamate receptors, yet the combined effect of these alterations on cortical excitatory synaptic transmission is unclear. We examined the effect of in vitro mechanical injury on excitatory synaptic function in cultured cortical neurons by assaying synaptically driven intracellular free calcium ([Ca(2+)](i)) oscillations in small neuronal networks as well as spontaneous and miniature excitatory postsynaptic currents (mEPSCs). We show that injury decreased the incidence and frequency of spontaneous neuronal [Ca(2+)](i) oscillations for at least 2 days post-injury. The amplitude of the oscillations was reduced immediately and 2 days post-injury, although a transient rebound at 4 h post-injury was observed due to increased activity of N-methyl-d-aspartate (NMDARs) and calcium-permeable α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (CP-AMPARs). Increased CP-AMPAR function was abolished by the inhibition of protein synthesis. In parallel, mEPSC amplitude decreased immediately, 4 h, and 2 days post-injury, with a transient increase in the contribution of synaptic CP-AMPARs observed at 4 h post-injury. Decreased mEPSC amplitude was evident after injury, even if NMDARs and CP-AMPARs were blocked pharmacologically, suggesting the decrease reflected alterations in synaptic Glur2-containing, calcium-impermeable AMPARs. Despite the transient increase in CP-AMPAR activity that we observed, the overriding effect of mechanical injury was long-term depression of excitatory neurotransmission that would be expected to contribute to the cognitive deficits of TBI.

Regional calcineurin subunit B isoform expression in rat hippocampus following a traumatic brain injury

Calcineurin subunit isoforms are implicated in long term potentiation, long term depression, and structural plasticity. Calcineurin inhibitors benefit axonal damage, cellular dysfunction, and cognitive outcomes in animal models of traumatic brain injury (TBI). Distribution of the catalytic calcineurin A subunit is altered and calcineurin activity increased following fluid percussion injury. Alterations in calcineurin subunit A isoform distribution within the hippocampus also occur post controlled cortical impact (CCI) demonstrating a reduction in catalytic subunit distribution in CA1-2 dendritic fields. Furthermore the effect of TBI on the regulatory subunit, calcineurin B, is unknown. Understanding the role of both subunits is necessary to effectively target alterations in calcineurin signaling as current calcineurin inhibitors, such as cyclosporin A and FK-506, rely upon binding sites on both subunits for complete inhibition. The effect of moderate CCI on the expression and distribution of calcineurin B isoforms within the hippocampus was examined at 2h and 2weeks post injury. Calcineurin B isoforms showed increased expression throughout the CA1 and CA2 while there was a decrease in expression within the ipsilateral dentate gyrus. Alterations in CnB isoform expression within the CA1, CA1-2, and dentate gyrus have significant implications for persistent hippocampal dysfunction following TBI. Regional changes in regulatory subunit expression may alter the effect of calcineurin inhibitors regionally following a traumatic brain injury.

Expression of protein phosphatase 2B (calcineurin) subunit A isoforms in rat hippocampus after traumatic brain injury

Calcineurin (CaN) is a calcium/calmodulin-dependent phosphatase directly activated by calcium as a result of neuronal activation that is important for neuronal function. CaN subunit isoforms are implicated in long-term potentiation (LTP), long-term depression (LTD), and structural plasticity. CaN inhibitors are also beneficial to cognitive outcomes in animal models of traumatic brain injury (TBI). There are known changes in the CaN A (CnA) subunit following fluid percussion injury (FPI). The CnA subunit has two isoforms: CnAalpha and CnAbeta. The effect of moderate controlled cortical impact (CCI) on distribution of CnA isoforms was examined at 2 h and 2 weeks post-injury. CnA distribution was assayed by immunohistochemistry and graded for non-parametric analysis. Acutely CnA isoforms showed reduced immunoreactivity in stratum radiatum processes of the ipsilateral CA1 and CA1-2. There was also a significant alteration in the immunoreactivity of both CnA isoforms in the ipsilateral dentate gyrus, predominantly within the hidden blade. Alterations in CnA isoform regional distribution within the CA1, CA1-2, and dentate gyrus may have significant implications for persistent hippocampal dysfunction following TBI, including dysfunction in hippocampal plasticity. Understanding alterations in CnA isoform distribution may help improve the targeting of current therapeutic interventions and/or the development of new treatments for TBI.

A cellular mechanism for dendritic spine loss in the pilocarpine model of status epilepticus

PURPOSE

Previous studies have documented a synaptic translocation of calcineurin (CaN) and increased CaN activity following status epilepticus (SE); however, the cellular effect of these changes in CaN in the pathology of SE remains to be elucidated. This study examined a CaN-dependent modification of the dendritic cytoskeleton. CaN has been shown to induce dephosphorylation of cofilin, an actin depolymerization factor. The ensuing actin depolymerization can lead to a number of physiological changes that are of interest in SE.

METHODS

SE was induced by pilocarpine injection, and seizure activity was monitored by video-EEG. Subcellular fractions were isolated by differential centrifugation. CaN activity was assayed using a paranitrophenol phosphate (pNPP) assay protocol. Cofilin phosphorylation was assessed using phosphocofilin-specific antibodies. Cofilin-actin binding was determined by coimmunoprecipitation, and actin polymerization was measured using a triton-solubilization protocol. Spines were visualized using a single-section rapid Golgi impregnation procedure.

RESULTS

The immunoreactivity of phosphocofilin decreased significantly in hippocampal and cortical synaptosomal samples after SE. SE-induced cofilin dephosphorylation could be partially blocked by the preinjection of CaN inhibitors. Cofilin activation could be further demonstrated by increased actin-cofilin binding and a significant depolymerization of neuronal actin, both of which were also blocked by CaN inhibitors. Finally, we demonstrated a CaN-dependent loss of dendritic spines histologically.

DISCUSSION

The data demonstrate a CaN-dependent, cellular mechanism through which prolonged seizure activity results in loss of dendritic spines via cofilin activation. Further research into this area may provide useful insights into the pathology of SE and epileptogenic mechanisms.

Phosphorylation of Calcium Calmodulin—Dependent Protein Kinase II following Lateral Fluid Percussion Brain Injury in Rats

Traumatic brain injury (TBI) can dramatically increase levels of intracellular calcium ([Ca(2+)](i)). One consequence of increased [Ca(2+)](i) would be altered activity and function of calcium-regulated proteins, including calcium-calmodulin-dependent protein kinase II (CaMKII), which is autophosphorylated on Thr(286)(pCaMKII(286)) in the presence of calcium and calmodulin. Therefore, we hypothesized that TBI would result in increased levels of pCaMKII(286), and that such increases would occur early after injury in brain regions known to be damaged following lateral fluid percussion TBI (i.e., hippocampus and cortex). In order to test this hypothesis, immunostaining of CaMKII was examined in rat hippocampus and cortex after lateral fluid percussion (LFP) injury using an antibody directed against pCaMKII(286). LFP injury produced a marked increase in pCaMKII(286) immunostaining in the hippocampus and overlying cortex 30 min after TBI. The pattern of increased immunostaining was uneven, and unexpectedly absent in some hippocampal CA3 pyramidal neurons. This suggests that phosphatase activity may also increase following TBI, resulting in dephosphorylation of pCaMKII(286) in subpopulations of CA3 pyramidal neurons. Western blotting confirmed a rapid increase in levels of pCaMKII(286) at 10 and 30 min after brain injury, and that it was transient and no longer significantly elevated when examined at 3, 8, and 24 h. These results demonstrate that TBI alters the autophosphorylation state of CaMKII, an important neuronal regulator of critical cell functions, including enzyme activities, cell structure, gene expression, and neuronal plasticity, and provide a molecular mechanism that is likely to contribute to cell injury and impaired plasticity after TBI.

Tacrolimus depresses local immune cell infiltration but fails to reduce cortical contusion volume in brain-injured rats

The immunosuppressant drug tacrolimus (FK-506) failed to show an anti-edematous effect despite suppressing pro-inflammatory cytokines in cerebrospinal fluid following focal traumatic brain injury. By questioning the role of the inflammatory response as a pharmacological target, we investigated the effects of FK-506 on immune cell infiltration in brain-injured rats. Following induction of a cortical contusion, male Sprague-Dawley rats received FK-506 or physiological saline intraperitoneally. Brains were removed at 24 h, 72 h or 7 days, respectively. Frozen brain sections (7 microm) were stained immunohistologically for markers of endothelial activation (intercellular adhesion molecule-1--ICAM-1), neutrophil infiltration (His-48), and microglial and macrophage activation (Ox-6; ED-1), respectively. Immunopositive cells were counted microscopically. Contusion volume (CV) was quantified morphometrically 7 days after trauma. Inflammatory response was confined to the ipsilateral cortex and hippocampal formation, predominating in the contusion and pericontusional cortex. Strongest ICAM-1 expression coincided with sustained granulocyte accumulation at 72h which was suppressed by FK-506. Ox-6+ cells prevailing at 72 h were also significantly reduced by FK-506. ED-1+ cells reaching highest intensity at 7 days were significantly attenuated at 72 h. Cortical CV was not influenced. FK-506 significantly decreased post-traumatic local inflammation which, however, was not associated with a reduction in cortical CV. These results question the importance of post-traumatic local immune cell infiltration in the secondary growth of a cortical contusion.

Pediatric posttraumatic seizures: epidemiology, putative mechanisms of epileptogenesis and promising investigational progress

Posttraumatic seizures and epilepsy are common in children experiencing traumatic brain injury and portend worse functional outcome. Unfortunately, the pathogenesis of pediatric posttraumatic seizures and epilepsy remains poorly understood, and no efficacious preventive therapy for post-traumatic epilepsy has been identified. This article reviews the epidemiology of pediatric posttraumatic seizures, discusses prominent putative mechanisms of posttraumatic epileptogenesis and highlights recent promising progress in experimental investigations of posttraumatic seizures and epilepsy.