Pharmacological prophylaxis of post-traumatic epilepsy

A Prospective Study of Novel Therapeutic Targets Interleukin 6, Tumor Necrosis Factor α, and Interferon γ as Predictive Biomarkers for the Development of Posttraumatic Epilepsy

Background

Posttraumatic epilepsy (PTE) is a serious and debilitating consequence of traumatic brain injury (TBI). Sometimes, the management of PTE becomes a challenging task on account of its resistance to existing antiepileptic drugs and often contributes to poor functional and psychosocial outcomes after TBI. We investigated the role of inflammatory markers interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and interferon γ (INF-γ) in predicting the development of PTE.

Methods

A prospective analysis was performed of 254 patients who were admitted with head injury to our hospital, 35 of whom had posttraumatic epilepsy (32 males and 3 females); 30 adults (28 men, 2 women) with a similar demographic profile were selected randomly as control individuals. Blood levels of TNF-α, IL-6, and INF-γ were evaluated in all participants.

Results

IL-6 levels were significantly higher in the PTE group (121.36 pg/mL; standard deviation [SD], 89.23) than in the nonseizure group (65.30 pg/mL; SD, 74.75; P = 0.01), whereas there was no significant difference between the seizure group (11.42 pg/mL; SD, 7.84) and the nonseizure groups (10.58 pg/mL; SD, 7.84) in terms of TNF-α level (P = 0.343). The level of INF-γ in the seizure group tended to be higher (mean, 1.88 pg/mL, SD, 2.13 in seizure group vs. 1.10 pg/mL, SD, 1.45 in the nonseizure group); however, no statistically significant difference was detected among the 2 groups (P = 0.09).

Conculsions

Posttraumatic epilepsy has a strong association with an increased level of IL-6 in the blood. INF-γ may or may not be associated with PTE. However, TNF-α was not associated with PTE.

Aquaporin-4 Reduces Post-Traumatic Seizure Susceptibility by Promoting Astrocytic Glial Scar Formation in Mice

Seizures are important neurological complications after traumatic brain injury (TBI) and are reported for up to 50% of patients with TBI. Despite several studies, no drug strategy has been able to alter the biological events leading to epileptogenesis. The glial water channel, aquaporin-4 (AQP4), was shown to facilitate cytotoxic cell swelling in ischemia and glial scar formation after stab wound injury. In this study, we examined post-traumatic seizure susceptibility of AQP4-deficient mice (AQP4^-/-) after injection of pentylenetetrazole (PTZ) 1 month after controlled cortical impact (CCI) and compared them to wild-type sham injury controls. After PTZ injection, AQP4^-/- mice demonstrated dramatically shortened seizure latency (120 ± 40 vs. 300 ± 70 sec; p < 0.001) and increased seizure severity (grade 7.5 ± 0.4 vs. 5.8 ± 0.4; p < 0.001) compared to their wild-type counterparts. Morphometric analysis demonstrated a significant 2-fold reduction in astrocytosis, with a concomitant increase in microgliosis in injured AQP4-null mice compared to their injured wild-type counterparts (44 ± 2 vs. 24 ± 3 cells per high power field [cells/hpf], respectively; p < 0.0001). Minocycline, an inhibitor of microglia, reversed the post-TBI epilepsy phenotype of AQP4-null mice. After minocycline treatment, AQP4^-/- mice demonstrated similar latency of seizures evoked by PTZ (723 ± 35 vs. 696 ± 38 sec; p > 0.05) and severity of seizures evoked by PTZ (grade 4.0 ± 0.5 vs. 3.81 ± 0.30; p > 0.05) compared to wild-type counterparts. Immunohistochemical analysis demonstrated decreased immunostaining of microglia to levels comparable to wild-type (12 ± 2 vs. 11 ± 4 cells/hpf, respectively; p > 0.05). Taken together, these results suggest a protective role of AQP4 in post-traumatic seizure susceptibility by promoting astrogliosis, formation of a glial scar, and preventing microgliosis.

Preventing epilepsy after traumatic brain injury: A propensity score analysis

BACKGROUND

Due to the potential consequences of post-traumatic epilepsy (PTE) exacerbating secondary injury following traumatic brain injury (TBI), the use of antiepileptic drugs (AEDs) is an accepted option for seizure prophylaxis. However, there is only a paucity of data that can be found regarding outcomes surrounding the use of AEDs. The purpose of this retrospective study is to evaluate whether the prophylactic administration of AEDs significantly decreased the incidence of PTE, when considering the severity of TBI.

METHODS

All trauma patients who had been newly diagnosed with TBI from January 1, 2010 to December 31, 2017 were retrospectively analyzed. Statistical comparisons were made using the chi-square test, Mann-Whitney U test, and Cox regression modeling. After excluding any exposed subjects with no appropriate match, patients who had received AED prophylaxis were matched by propensity score with those who did not receive AEDs. All of the TBI populations were followed up until June 30, 2018.

RESULTS

We identified 1316 patients who met the inclusion and exclusion criteria in our matched cohort through their propensity scores, where 138 patients had been receiving prophylactic AEDs and 138 patients had not. Baseline characteristics were similar in gender, age, Glasgow Coma Scale (GCS) scores, and risk factors of PTE including skull fracture, chronic alcoholism, subdural hematoma, epidural hematoma, and intracerebral hematoma. After adjusting for those risk factors, the relative incidence of seizure was not statistically significant in either of the groups (p = 0.566).

CONCLUSION

In our cohort analysis, AED prophylaxis was ineffective in preventing seizures, as the rate of seizures was similar whether patients had been receiving the drugs or not. We therefore concluded that the benefits of routine prophylactic anticonvulsant therapy in patients with TBI need to be re-evaluated.

Epidemiology of traumatic brain injury-associated epilepsy in western China: An analysis of multicenter data

OBJECTIVES

This study aims to explore the probability of developing posttraumatic epilepsy (PTE) in the following 8 years after traumatic brain injury (TBI), the risk factors associated with PTE and its cumulative prevalence.

METHODS

This is a retrospective follow-up study of patients with traumatic brain injury (TBI) discharged from the West China Hospital between January 1, 2011 and December 31, 2017, Chengdu Shang Jin Nan Fu Hospital and Sichuan Provincial People's Hospital from January 1, 2013 to March 1, 2015. We used forward stepwise method to build the final multivariate cox proportional hazard regression model to obtain estimates of hazard ratio (HR) of PTE and 95% confidence intervals (CI). We also conducted Kaplan-Meier survival analysis to investigate the cumulative prevalence of PTE.

RESULTS

The cumulative incidence of PTE rose from 6.2% in one year to 10.6% in eight years. There were more male patients in PTE group and generally older. Besides, patients with PTE tended to have abnormal CT scan results. The risk factors of PTE were male (HR = 1.6, 95% CI: 1.1-2.2, P = 0.009), early posttraumatic seizures (HR = 2.9, 95% CI: 2.2-4.1, P < 0.001), TBI severity (moderate TBI: HR = 3.0, 95% CI: 1.8-5.0, P = 0.001; severe TBI: HR = 4.3, 95% CI: 2.3-7.6, P < 0.029), loss of consciousness (LOC) more than 30 min (30 min-24 h: HR = 1.8, 95% CI: 1.02-3.1, P = 0.041; >24 h: HR = 2.4, 95% CI: 1.4-2.4, P = 0.001), subdural hematoma (SDH) (HR = 1.9, 95% CI: 1.4-2.5, P < 0.001), brain contusion sites (frontal-temporal lobe: HR = 2.7, 95% CI: 1.9-3.9, P < 0.001; other sites: HR = 1.5, 95% CI: 1.01-2.3, P = 0.042) and cranial surgery (HR = 1.7, 95% CI: 1.3-2.3, P < 0.001).

SIGNIFICANCE

The probability of developing PTE increased during the study period. In addition, the risk of developing PTE was significantly associated with gender, EPTS, LOC time, SDH, brain contusion sites, surgery and TBI severity. However, further researches may be needed to predict the risk of PTE in combination with quantitative factors.

Advances and Future Directions of Diagnosis and Management of Pediatric Abusive Head Trauma: A Review of the Literature

Abusive head trauma (AHT) is broadly defined as injury of the skull and intracranial contents as a result of perpetrator-inflicted force and represents a persistent and significant disease burden in children under the age of 4 years. When compared to age-matched controls with typically single occurrence accidental traumatic brain injury (TBI), mortality after AHT is disproportionately high and likely attributable to key differences between injury phenotypes. This article aims to review the epidemiology of AHT, summarize the current state of AHT diagnosis, treatment, and prevention as well as areas for future directions of study. Despite neuroimaging advances and an evolved understanding of AHT, early identification remains a challenge for contemporary clinicians. As such, the reported incidence of 10–30 per 100,000 infants per year may be a considerable underestimate that has not significantly decreased over the past several decades despite social campaigns for public education such as “Never Shake a Baby.” This may reflect caregivers in crisis for whom education is not sufficient without support and intervention, or dangerous environments in which other family members are at risk in addition to the child. Acute management specific to AHT has not advanced beyond usual supportive care for childhood TBI, and prevention and early recognition remain crucial. Moreover, AHT is frequently excluded from studies of childhood TBI, which limits the precise translation of important brain injury research to this population. Repeated injury, antecedent abuse or neglect, delayed medical attention, and high rates of apnea and seizures on presentation are important variables to be considered. More research, including AHT inclusion in childhood TBI studies with comparisons to age-matched controls, and translational models with clinical fidelity are needed to better elucidate the pathophysiology of AHT and inform both clinical care and the development of targeted therapies. Clinical prediction rules, biomarkers, and imaging modalities hold promise, though these have largely been developed and validated in patients after clinically evident AHT has already occurred. Nevertheless, recognition of warning signs and intervention before irreversible harm occurs remains the current best strategy for medical professionals to protect vulnerable infants and toddlers.

Antiepileptic Drugs Elevate Astrocytic Kir4.1 Expression in the Rat Limbic Region

Inwardly rectifying potassium (Kir) channel subunits Kir4.1 are specifically expressed in astrocytes and regulate neuronal excitability by mediating spatial potassium buffering. In addition, it is now known that astrocytic Kir4.1 channels are closely involved in the pathogenesis of epilepsy. Here, to explore the role of Kir4.1 channels in the treatment of epilepsy, we evaluated the effects of the antiepileptic drugs, valproate, phenytoin, phenobarbital and ethosuximide, on Kir4.1 expression in astrocytes using immunohistochemical techniques. Repeated treatment of rats with valproate (30–300 mg/kg, i.p., for 1–10 days) significantly elevated the Kir4.1 expression levels in the cerebral cortex, amygdala and hippocampus. Up-regulation of Kir4.1 expression by valproate occurred in a dose- and treatment period-related manner, and did not accompany an increase in the number of astrocytes probed by glial fibrillary acidic protein (GFAP). In addition, repeated treatment with phenytoin (30 mg/kg, i.p., for 10 days) or phenobarbital (30 mg/kg, i.p., for 10 days) also elevated Kir4.1 expression region-specifically in the amygdala. However, ethosuximide (100 mg/kg, i.p., for 10 days), which can alleviate absence but not convulsive seizures, showed no effects on the astrocytic Kir4.1 expression. The present results demonstrated for the first time that the antiepileptic drugs effective for convulsive seizures (valproate, phenytoin, and phenobarbital) commonly elevate the astrocytic Kir4.1 channel expression in the limbic regions, which may be related to their antiepileptic actions.

Posttraumatic epilepsy: long-term follow-up of children with mild traumatic brain injury

OBJECTIVE Posttraumatic epilepsy (PTE) is a known complication of traumatic brain injury (TBI). The true incidence of PTE in children is still uncertain, because most research has been based primarily on adults. This study aimed to determine the true incidence of PTE in a pediatric population with mild TBI (MTBI) and to identify risk factors for the development of epileptic events. METHODS Data were collected from electronic medical records of children 0-17 years of age, who were admitted to a single medical center between 2007 and 2009 with a diagnosis of MTBI. This prospective research consisted of a telephone survey between 2015 and 2016 of children or their caregivers, querying for information about epileptic episodes and current seizure and neurological status. The primary outcome measure was the incidence of epilepsy following TBI, which was defined as ≥ 2 unprovoked seizure episodes. Posttraumatic seizure (PTS) was defined as a single, nonrecurrent convulsive episode that occurred > 24 hours following injury. Seizures within 24 hours of the injury were defined as immediate PTS. RESULTS Of 290 children eligible for this study, 191 of them or their caregivers were reached by telephone survey and were included in the analysis. Most injuries (80.6%) were due to falls. Six children had immediate PTS. All children underwent CT imaging; of them, 72.8% demonstrated fractures and 10.5% did not demonstrate acute findings. The mean follow-up was 7.4 years. Seven children (3.7%) experienced PTS; of them, 6 (85.7%) developed epilepsy and 3 (42.9%) developed intractable epilepsy. The overall incidence of epilepsy and intractable epilepsy in this cohort was 3.1% and 1.6%, respectively. None of the children who had immediate PTS developed epilepsy. Children who developed epilepsy spent an average of 2 extra days in the hospital at the time of the injury. The mean time between trauma and onset of seizures was 3.1 years. Immediate PTS was not correlated with PTE. CONCLUSIONS In this analysis of data from medical records and long-term follow-up, MTBI was found to confer increased risk for the development of PTE and intractable PTE, of 4.5 and 8 times higher, respectively. As has been established in adults, these findings confirm that MTBI increases the risk for PTE in the pediatric population.

Stem cells and combination therapy for the treatment of traumatic brain injury

TBI is a nondegenerative, noncongenital insult to the brain from an external mechanical force; for instance a violent blow in a car accident. It is a complex injury with a broad spectrum of symptoms and has become a major cause of death and disability in addition to being a burden on public health and societies worldwide. As such, finding a therapy for TBI has become a major health concern for many countries, which has led to the emergence of many monotherapies that have shown promising effects in animal models of TBI, but have not yet proven any significant efficacy in clinical trials. In this paper, we will review existing and novel TBI treatment options. We will first shed light on the complex pathophysiology and molecular mechanisms of this disorder, understanding of which is a necessity for launching any treatment option. We will then review most of the currently available treatments for TBI including the recent approaches in the field of stem cell therapy as an optimal solution to treat TBI. Therapy using endogenous stem cells will be reviewed, followed by therapies utilizing exogenous stem cells from embryonic, induced pluripotent, mesenchymal, and neural origin. Combination therapy is also discussed as an emergent novel approach to treat TBI. Two approaches are highlighted, an approach concerning growth factors and another using ROCK inhibitors. These approaches are highlighted with regard to their benefits in minimizing the outcomes of TBI. Finally, we focus on the consequent improvements in motor and cognitive functions after stem cell therapy. Overall, this review will cover existing treatment options and recent advancements in TBI therapy, with a focus on the potential application of these strategies as a solution to improve the functional outcomes of TBI.

Late Post-traumatic Epilepsy in Children and Young Adults: Impropriety of Long-Term Antiepileptic Prophylaxis and Risks in Tapering

BACKGROUND

After traumatic brain injury, epilepsy affects up to 20 % of children. It is a risk factor, for both clinical recovery and cognitive performance; therefore pharmacological therapy is advisable. Current guidelines recommend prophylaxis to be initiated as soon as possible and tapered 1 week after trauma. However, no guideline exists for paediatric patients and the clinical practice is heterogeneous.

OBJECTIVE

In our institute, prophylaxis was routinely tapered 6 months after trauma. Therefore we investigated whether this prophylaxis or its tapering influenced the development of post-traumatic epilepsy, together with several clinical-demographic factors.

METHODS

The study population comprised all patients with post-traumatic brain injury referred to this institute between 2002 and 2009 who consented to participate. Clinical, epileptological and pharmacological data were collected. The role of prophylaxis and several other predictors on occurrence of post-traumatic epilepsy was analysed through logistic regressions.

RESULTS

Two hundred and three patients (145 paediatric) were followed for 57 months on average. Risk factors for epilepsy were past neurosurgery [odds ratio (OR) = 2.61, 95 % confidence interval (CI) 1.15-5.96], presence of epileptiform anomalies (OR = 6.92, 95 % CI 3.02-15.86) and the presence of prophylaxis (OR = 2.49, 95 % CI 1.12-5.52), while higher intelligence quotient (IQ) was protective (OR = 0.96, 95 % CI 0.95-0.98). While evaluating possible different effects within and after 6 months (tapering, for those under prophylaxis), we found that epileptiform anomalies (OR = 7.61, 95 % CI 2.33-24.93, and OR = 8.21, 95 % CI 3.00-22.44) and IQ (OR = 0.96, 95 % CI 0.94-0.98, and OR = 0.97, 95 % CI 0.95-0.98) were always significant predictors of epilepsy, while neurosurgery (OR = 4.38, 95 % CI 1.10-17.45) was significant only within 6 months from trauma, and prophylaxis (OR = 3.98, 95 % CI 1.62-9.75) only afterwards.

CONCLUSIONS

These results suggest that prophylaxis was irrelevant when present; furthermore its tapering increased the risk of epilepsy. Since the presence of epileptiform anomalies was the main predictor of post-traumatic epilepsy, such anomalies may be useful to better direct the choice of prophylaxis.

Post-traumatic epilepsy in children-experience from a tertiary referral center

BACKGROUND

Post-traumatic epilepsy after a traumatic brain injury occurs in 10%-20% of children. Unfortunately, a biomarker that could provide prognostic information about both post-traumatic epilepsy and cognitive development is lacking. In this first of a series of studies, we have reviewed and analyzed clinical variables in children following traumatic brain injury to understand the epidemiologic and clinical characteristics of post-traumatic epilepsy in our urban population.

METHODS

We performed a retrospective electronic chart review of patients who had suffered traumatic brain injury and subsequently evaluated at Children's Hospital of Michigan from 2002 to 2012. Various epidemiologic and clinical variables were analyzed.

RESULTS

Patients who had severe traumatic brain injury and post-traumatic epilepsy had an abnormal acute head computed tomography. These patients had increased number of different seizure types, increased risk of intractability of epilepsy, and were on multiple antiepileptic drugs. Hypomotor seizure was the most common seizure type in these patients. There was a high prevalence of patients who suffered nonaccidental trauma, all of whom had severe traumatic brain injury.

CONCLUSIONS

This study demonstrates a need for biomarkers in children following traumatic brain injury to reliably evaluate the risk of post-traumatic epilepsy.

Traumatic brain injury induces rapid enhancement of cortical excitability in juvenile rats

AIMS

Following a traumatic brain injury (TBI), 5-50% of patients will develop posttraumatic epilepsy (PTE) with children being particularly susceptible. Currently, PTE cannot be prevented and there is limited understanding of the underlying epileptogenic mechanisms. We hypothesize that early after TBI the brain undergoes distinct cellular and synaptic reorganization that facilitates cortical excitability and promotes the development of epilepsy.

METHODS

To examine the effect of pediatric TBI on cortical excitability, we performed controlled cortical impact (CCI) on juvenile rats (postnatal day 17). Following CCI, animals were monitored for the presence of epileptiform activity by continuous in vivo electroencephalography (EEG) and/or sacrificed for in vitro whole-cell patch-clamp recordings.

RESULTS

Following a short latent period, all animals subjected to CCI developed spontaneous recurrent epileptiform activity within 14 days. Whole-cell patch-clamp recordings of layer V pyramidal neurons showed no changes in intrinsic excitability or spontaneous excitatory postsynaptic currents (sEPSCs) properties. However, the decay of spontaneous inhibitory postsynaptic currents (sIPSCs) was significantly increased. In addition, CCI induced over a 300% increase in excitatory and inhibitory synaptic bursting. Synaptic bursting was prevented by blockade of Na(+)-dependent action potentials or select antagonism of glutamate or GABA-A receptors, respectively.

CONCLUSION

Our results demonstrate that CCI in juvenile rats rapidly induces epileptiform activity and enhanced cortical synaptic bursting. Detection of epileptiform activity early after injury suggests it may be an important pathophysiological component and potential indicator of developing PTE.

A Critical Look at Phenytoin Use for Early Post-Traumatic Seizure Prophylaxis

Backround:

The American Academy of Neurology recommended using phenytoin or carbamazepine to prevent early post-traumatic seizures (PTS) in severe traumatic brain injuries (TBI). In this study, we examined the effects of using phenytoin prophylaxis on mild, moderate, and severe TBIs. There have been no studies looking at compliance rate and side effects of systematic use of phenytoin at a large population scale. The goal of this study is to determine 1) the proportion of TBI patients receiving phenytoin prophylaxis; 2) which parameters decided when to decide administer phenytoin; 3) prophylaxis efficacy and complication rate.

Methods:

We retrospectively studied all patients admitted with a TBI over a two year-period and collected the following information: age, GCS score, CT-scan Marshall grade, incidence of early PTS, incidence of phenytoin use and time delay, side effects, and incidence of over-dosage or under-dosage.

Results:

1008 patients were included. 5.4 % had early PTS, 2.3 % while on prophylaxis and 3.1% while not on prophylaxis, 1.9% before reaching the hospital and 1.2% prior to phenytoin administration while in hospital. Delay of administration was 5 hours. 64.8% received prophylaxis and physicians used positive CT scan as the primary decision-making parameter (p<.001). Compliance with guidelines was 99.7%. Adverse reactions occurred in 0.5%. Levels were drawn in 42.2% (52% therapeutic, 41% low, 7% high).

Conclusions:

Phenytoin is used according to guidelines, with CT scan being the main decision factor for its use. The frequency of early PTS rate is low and side effects are rare. However, earlier administration of phenytoin and adequate levels could further prevent early PTS.

Traumatic brain injury with and without late posttraumatic seizures: what are the impacts in the post-acute phase: a NIDRR Traumatic Brain Injury Model Systems study

OBJECTIVE

To compare and contrast the levels of impairment, disability, and community participation of individuals with traumatic brain injury (TBI) with or without late posttraumatic seizures (LPTS).

DESIGN

Prospective survey study.

SETTING

Community.

PARTICIPANTS

Two groups of 91 individuals with TBI, with and without LPTS, were enrolled in the TBI Model Systems National Database between 1989 and 2002 and interviewed at years 1, 2, and 5 postinjury.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Demographic, injury severity, productivity, and psychosocial outcomes.

RESULTS

The majority of the demographic and productivity outcomes up to 5 years postinjury were similar between individuals in the LPTS and non-LPTS groups. Both the LPTS and non-LPTS groups showed an increasing percentage of individuals who began to live alone after the first year postinjury and a decreasing percentage of individuals who were living with family members at 5 years postinjury compared with the first year post-TBI. A higher percentage of individuals in the LPTS group reported using more dependent forms of transportation such as riding with others or using public transportation. Individuals in the LPTS group had higher Disability Rating Scale scores at all time points, denoting greater functional disability, than individuals in the non-LPTS group, despite the 2 groups having similar Disability Rating Scale scores at discharge from rehabilitation. Satisfaction With Life Scale scores showed no changes over time but were significantly different between both groups at all time points, with individuals in the LPTS group reporting lower Satisfaction With Life Scale score than individuals in the non-LPTS group.

CONCLUSIONS

It does appear that the development of LPTS following a TBI is associated with poorer functional and psychosocial outcomes in the first 5 years after injury. It remains to be determined whether there are other factors that also may account for these differences and that may be amenable to intervention.

Dosing and therapeutic monitoring of phenytoin in young adults after neurotrauma: are current practices relevant?

Anticonvulsant drugs are commonly used to treat and prevent seizures after neurotrauma. However, many physiological changes occur in the neurotrauma patient, which alter the pharmacokinetics of drugs such as phenytoin. This raises concerns relating to the dosage and monitoring of phenytoin in these patients compared with its routine use in epileptic patients. Examples of pharmacokinetic alterations within the neurotrauma patient include changes in hepatic metabolism, protein binding alterations, and disruption of the blood-brain barrier. Drug interactions and genetic factors may also contribute to pharmacokinetic variations. Many studies have reported that neurotrauma patients often present with either subtherapeutic or highly variable phenytoin serum concentrations. When phenytoin doses recommended for the epileptic patient are used in the neurotrauma patient, efficacy is limited to early posttraumatic seizures, with no effect on morbidity, mortality, or the onset of late posttraumatic seizures. This review examines the effect of neurotrauma on the pharmacokinetics of phenytoin alongside clinical outcomes and questions the current dosing and therapeutic monitoring practices within this area.

The impact of prophylactic treatment on post-traumatic epilepsy after severe traumatic brain injury

AIM

To assess the incidence of late post-traumatic epilepsy (PTE) in patients with very severe traumatic brain injury (TBI) who either received or did not receive anti-epileptic prophylactic treatment.

METHODS

Two populations were studied: 55 patients retrospectively and 82 subjects prospectively.

RESULTS

Ten patients (18%) in the first population showed late PTE. Although the incidence was lower in patients who did not receive prophylactic treatment, the difference between the treated and the non-treated group was not statistically significant. Sixty-nine patients in the second group (84%) had prophylactic treatment. Twenty-seven patients (39%) suffered from late PTE during the 2-year follow-up period and 17 of them (63%) showed EEG epileptic abnormalities. No patient who did not receive preventive therapy suffered from late PTE during the observation period.

CONCLUSIONS

Due to the negative cognitive effects of anti-epileptic drugs, the preliminary results are of considerable interest for the rehabilitation of patients with very severe TBI.

Prevention and treatment of post-traumatic epilepsy

Post-traumatic epilepsy is reported after 2-5% of closed head injuries but up to 50% or more following penetrating head injury. Despite several studies, no drug strategy has been able, to date, to quench the biochemical events leading to epileptogenesis. One possibility is that treatment with available antiepileptic drugs has been implemented too late, and thus, ultra-early treatment might still be able to stop the neurochemical epileptogenic cascade dead in its tracks. However, currently drug therapy should be instituted only after the first late unprovoked seizure.

Post-traumatic epilepsy: an overview

Post-traumatic epilepsy (PTE) is a recurrent seizure disorder secondary to brain injury following head trauma. PTE is not a homogeneous condition and can appear several years after the head injury. The mechanism by which trauma to the brain tissue leads to recurrent seizures is unknown. Cortical lesions seem important in the genesis of the epileptic activity, and early seizures are likely to have a different pathogenesis than late seizures. Anti-epileptic drugs available for treatment are phenytoin, sodium valproate, and carbamazepine. Newer anti-epileptics are helpful, particularly in patients with associated post-traumatic stress disorders; however, no randomized controlled studies are available to prove that one of these drugs is better than the other. Current evidence is that the treatment of early post-traumatic seizures does not influence the incidence of post-traumatic epilepsy. Routine preventive anticonvulsants are not indicated for patients with head injuries, and treatment in the acute phase does not reduce death or disability rates.

Traumatic brain injury in children--clinical implications

Traumatic brain injury (TBI) is the leading cause of death in childhood; however only very few studies focusing on the specific pathophysiology and treatment have been published to date. Head trauma is more likely in young children than in adults given the same deceleration of the body due to their large and heavy heads and weak cervical ligaments and muscles. Resulting brain injury is more severe due to their thin, pliable skulls and the yet unfused sutures. Accordingly, children below the age of 4 years have lower chances of a full recovery after severe TBI, although in general, neurologic recovery after severe brain injury in children is better than in adults. The time course of brain injury can be divided into two steps: primary and secondary injury. Primary brain injury exclusively results from the initial impact. In contrast, adverse physiologic conditions during recovery after head trauma may account for additional brain damage, which is then referred to as secondary brain injury. As primary brain injury can only be influenced by preventive measures, all therapeutic efforts during the post-injury period focus on the reduction of secondary injury to the traumatized brain. Several mechanisms have been identified to be involved in the development of post-traumatic secondary brain injury, which render the rationale for the key treatment strategies. Three evidence based measures are of critical importance to prevent or minimize secondary brain injury: (1) avoid hypoxemia, (2) avoid post-traumatic arterial hypotension, and (3) refer the traumatized child to an experienced trauma team at a center that provides the availability of special equipment, e.g. for surgical procedures and airway management, for this age group. For several other therapeutical means, e.g. hypothermia or specific surgical interventions, clinical evidence to date is insufficient to allow recommendation as rescue treatment for children at risk of severe neurological sequelae following TBI. This review discusses the clinical implication of pathophysiologic mechanisms of TBI in the developing brain according to the recent literature and current guidelines. It follows the clinical approach to a head injured child, that can be divided into three phases, i.e. initial assessment and stabilization, followed by first tier, and if necessary second tier therapeutic interventions to assure adequate oxygenation and perfusion of the brain.

Neurobiology of Seizures and Behavioral Abnormalities

Seizures are both caused by and induce a complex set of neurobiological alterations and adaptations. The animal model of amygdala kindling provides insight into the spatiotemporal evolution of these changes as a function of seizure development and progression. Intracellular, synaptic, and microstructural changes are revealed as related to both the primary pathophysiology of kindled seizure evolution and compensatory secondary, or endogenous anticonvulsant adaptations. At the level of gene expression, the balance of these pathological and adaptive processes (as augmented by exogenous medications) probably determines whether seizures will be manifest or suppressed and could account for aspects of their intermittency. As anxiety and emotion modulation are subserved by many of the same neuroanatomic substrates involved in the evolution of complex partial seizures, particularly those of the medial temporal lobe, it is readily conceptualized how vulnerability to a range of psychiatric disorders could be related to the primary or secondary neurochemical alterations associated with seizure disorders. The discrete and methodologically controlled elucidation of the cascades and spatiotemporal distributions of neurobiological alterations that accompany seizure evolution in the kindling model may help resolve some of the difficulty and complexity of elucidating these biobehavioral relationships in the clinic.

Convergences in course of illness and treatments of the epilepsies and recurrent affective disorders

The failure to achieve and maintain remission is a critical problem for a high percentage of patients with epilepsy and the primary affective disorders. Early illness onset and delayed initiation of treatment may contribute to primary treatment resistance or that associated with loss of efficacy (tolerance phenomenon). Neurobiological data and principles drawn from the amygdala kinding model of seizure progression are reviewed for their heuristic value in conceptualizing molecular mechanisms of illness progression and its prevention with pharmacological agents in the epilepsies and, indirectly, the recurrent affective disorders. Caveats in the use of this model and convergences and divergences in its predictive validity for seizures and affective disorders are noted.

Review of the role of anticonvulsant prophylaxis following brain injury

Anticonvulsants were once routinely used as prophyllaxis for all head injuries. There has been a decline in their recent use. The evidence for use of prophylaxis is reviewed. Questions postulated will be answered with the best available evidence.

Randomized Controlled Trial of Prophylactic Phenytoin after Neurosurgery for Brain Tumor

Add-on Phenytoin Fails to Prevent Early Seizures after Surgery for Supratentorial Brain Tumors: A Randomized Controlled Study

De Santis A, Villani R, Sinisi M, Stocchetti N, Perucca E

Epilepsia 2002;43:175–182

Purpose

To determine the potential effectiveness of phenytoin (PHT) in preventing early postoperative seizures in patients undergoing craniotomy for supratentorial brain tumors. Two hundred patients requiring elective craniotomy for supratentorial brain tumors were randomized to two groups of equal size, with a prospective, open-label, controlled design. One group received PHT (18 mg/kg as an intravenous intraoperative load, followed by additional daily doses aimed at maintaining serum PHT concentrations within the 10- to 20-age/ml range) for 7 consecutive days. In the other group, PHT was not administered. More than 90% of patients in both groups continued to take preexisting anticonvulsant medication (AEDs) with carbamazepine or phenobarbital throughout the study. The primary efficacy end point was the number of patients remaining free from seizures during the 7-day period after the operation. Of 100 patients allocated to PHT, 13 experienced seizures during the 7-day observation period, compared with 11 of 100 patients in the placebo group (p > 0.05). Most seizures occurred in the first day after surgery in both groups. There were no differences between groups in the proportion of patients experiencing more than one seizure, but there was a trend for generalized seizures to be more common in PHT-treated patients than in controls (11 vs. five patients, respectively). Status epilepticus occurred in one patient in the PHT group and in two patients in the control group. Of the 13 PHT-treated seizure patients, 11 had serum PHT concentrations within the target range, and only two had concentrations below range on the days their seizures occurred. PHT, given at dosages producing serum concentrations within the target range, failed to prevent early postoperative seizures in patients treated with concomitant AEDs. Prophylactic administration of PHT cannot be recommended in these patients.

Add-on phenytoin fails to prevent early seizures after surgery for supratentorial brain tumors: a randomized controlled study

PURPOSE

To determine the potential effectiveness of phenytoin (PHT) in preventing early postoperative seizures in patients undergoing craniotomy for supratentorial brain tumors.

METHODS

Two hundred patients requiring elective craniotomy for supratentorial brain tumors were randomized to two groups of equal size, with a prospective, open-label, controlled design. One group received PHT (18 mg/kg as an intravenous intraoperative load, followed by additional daily doses aimed at maintaining serum PHT concentrations within the 10- to 20-aeg/ml range) for 7 consecutive days. In the other group, PHT was not administered. More than 90% of patients in both groups continued to take preexisting anticonvulsant medication (AEDs) with carbamazepine or phenobarbital throughout the study. The primary efficacy end point was the number of patients remaining free from seizures during the 7-day period after the operation.

RESULTS

Of 100 patients allocated to PHT, 13 experienced seizures during the 7-day observation period, compared with 11 of 100 patients in the placebo group (p > 0.05). Most seizures occurred in the first day after surgery in both groups. There were no differences between groups in the proportion of patients experiencing more than one seizure, but there was a trend for generalized seizures to be more common in PHT-treated patients than in controls (11 vs. five patients, respectively). Status epilepticus occurred in one patient in the PHT group and in two patients in the control group. Of the 13 PHT-treated seizure patients, 11 had serum PHT concentrations within the target range, and only two had concentrations below range on the days their seizures occurred.

CONCLUSIONS

PHT, given at dosages producing serum concentrations within the target range, failed to prevent early postoperative seizures in patients treated with concomitant AEDs. Prophylactic administration of PHT cannot be recommended in these patients.

The promise of new antiepileptic drugs

Epilepsy is the most common serious disorder of the brain and comprises a wide range of different conditions with varying aetiologies. The long-established antiepileptic drugs (AEDs) control seizures in 50% of patients developing partial seizures, and 60-70% of those developing generalized seizures. Several AEDs were made available in the 1990s. These drugs have efficacy, but have had only a modest impact on those with refractory epilepsies. A 50% seizure reduction, which is commonly used as an endpoint in clinical trials, confers little benefit to a patient. Of the newer AEDs, lamotrigine and oxcarbazepine are now licensed for use as monotherapy and vigabatrin has a monotherapy licence for infantile spasms. Careful and prolonged postmarketing surveillance is essential to detect adverse effects, which may not be evident in premarketing clinical trials. At this time, there are 10 AEDs currently in varying stages of clinical development. Current strategies for selecting an AED for a particular patient are crude. Magnetic resonance spectroscopic measures of cerebral neuro-transmitters and genetic analysis may allow better prediction of which drug is most likely to be efficacious and to have low risk of adverse effects. Present AEDs suppress the occurrence of seizures. Agents that prevent the development of epilepsy and which protect the brain from the consequences of seizures would be of great value, but it will be difficult to prove their effectiveness. At present AEDs are given continually and systemically. Local drug delivery is feasible and could avoid the adverse effects of AEDs. The combination of local drug delivery with prediction of seizure occurrence could revolutionize the treatment of currently refractory epilepsies.