Prevention and treatment of post-traumatic epilepsy

Neuroprotection and anti-seizure effects of levetiracetam in a rat model of penetrating ballistic-like brain injury

PURPOSE

We assessed the therapeutic efficacy of FDA-approved anti-epileptic drug Levetiracetam (LEV) to reduce post-traumatic nonconvulsive seizure (NCS) activity and promote neurobehavioral recovery following 10% frontal penetrating ballistic-like brain injury (PBBI) in male Sprague-Dawley rats.

METHODS

Experiment 1 anti-seizure study: 50 mg/kg LEV (25 mg/kg maintenance doses) was given twice daily for 3 days (LEV3D) following PBBI; outcome measures included seizures incidence, frequency, duration, and onset. Experiment 2 neuroprotection studies: 50 mg/kg LEV was given twice daily for either 3 (LEV3D) or 10 days (LEV10D) post-injury; outcome measures include motor (rotarod) and cognitive (water maze) functions.

RESULTS

LEV3D treatment attenuated seizure activity with significant reductions in NCS incidence (54%), frequency, duration, and delayed latency to seizure onset compared to vehicle treatment. LEV3D treatment failed to improve cognitive or motor performance; however extending the dosing regimen through 10 days post-injury afforded significant neuroprotective benefit. Animals treated with the extended LEV10D dosing regimen showed a twofold improvement in rotarod task latency to fall as well as significantly improved spatial learning performance (24%) in the MWM task.

CONCLUSIONS

These findings support the dual anti- seizure and neuroprotective role of LEV, but more importantly identify the importance of an extended dosing protocol which was specific to the therapeutic targets studied.

Neurobehavioral effects of levetiracetam in patients with traumatic brain injury

Moderate to severe traumatic brain injury (TBI) is one of the leading causes of acquired epilepsy. Prophylaxis for seizures is the standard of care for individuals with moderate to severe injuries at risk for developing seizures, though relatively limited comparative data is available to guide clinicians in their choice of agents. There have however been experimental studies which demonstrate potential neuroprotective qualities of levetiracetam after TBI, and in turn there is hope that eventually such agents may improve neurobehavioral outcomes post-TBI. This mini-review summarizes the available studies and suggests areas for future studies.

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

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

Current approaches to the treatment of head injury in children

Head trauma is one of the most challenging fields of traumatology and demands immediate attention and intervention by first-line clinicians. Symptoms can vary from victim to victim and according to the victim's age, leading to difficulties in making timely and accurate decisions at the point of care. In children, falls, accidents while playing, sports injuries, and abuse are the major causes of head trauma. Traffic accidents are the main cause of disability and death in adolescents and adults. Injury sites include facial bones, muscles, ligaments, vessels, joints, nerves, and focal or whole-brain injuries. Of particular importance are cranial and intracranial injuries. A closed injury occurs when the head suddenly and violently hits an object but the object does not break through the skull. A penetrating injury occurs when an object pierces the skull and affects the brain tissue. Early diagnosis and proper management are crucial to treat patients with potentially life-threatening head and neck trauma. In this review, we discuss the different cases of traumatic brain injury and summarize the current therapies and neuroprotective strategies as well as the related outcomes for children with traumatic brain injury.

Neuroimaging biomarkers of epileptogenesis

Much progress has been made in the field studying the process of epileptogenesis via neuroimaging techniques. Conventional imaging methods include magnetic resonance imaging with morphometric analysis, magnetic resonance spectroscopy and positron emission tomography. Newer network-based methods such as diffusion tensor imaging and functional magnetic resonance imaging with resting functional connectivity are being developed and applied to clinical use. This review provides a brief summary of the major human and animal studies in both partial and generalized epilepsies that demonstrate the potential of these imaging modalities to serve as biomarkers of epileptogenesis.

Correlates of posttraumatic epilepsy 35 years following combat brain injury

BACKGROUND

The Vietnam Head Injury Study (VHIS) is a prospective, longitudinal follow-up of 1,221 Vietnam War veterans with mostly penetrating head injuries (PHIs). The high prevalence (45%-53%) of posttraumatic epilepsy (PTE) in this unique cohort makes it valuable for study.

METHODS

A standardized multidisciplinary neurologic, cognitive, behavioral, and brain imaging evaluation was conducted on 199 VHIS veterans plus uninjured controls, some 30 to 35 years after injury, as part of phase 3 of this study.

RESULTS

The prevalence of seizures (87 patients, 43.7%) was similar to that found during phase 2 evaluations 20 years earlier, but 11 of 87 (12.6%) reported very late onset of PTE after phase 2 (more than 14 years after injury). Those patients were not different from patients with earlier-onset PTE in any of the measures studied. Within the phase 3 cohort, the most common seizure type last experienced was complex partial seizures (31.0%), with increasing frequency after injury. Of subjects with PTE, 88% were receiving anticonvulsants. Left parietal lobe lesions and retained ferric metal fragments were associated with PTE in a logistic regression model. Total brain volume loss predicted seizure frequency.

CONCLUSIONS

Patients with PHI carry a high risk of PTE decades after their injury, and so require long-term medical follow-up. Lesion location, lesion size, and lesion type were predictors of PTE.

Global expression profiling in epileptogenesis: does it add to the confusion?

Since the inception of global gene expression profiling platforms in the mid-1990s, there has been a significant increase in publications of differentially expressed genes in the process of epileptogenesis. In particular for mesial temporal lobe epilepsy, the presence of a latency period between the first manifestation of seizures to chronic epilepsy provides the opportunity for therapeutic interventions at the molecular biology level. Using global expression profiling techniques, approximately 2000 genes have been published demonstrating differential expression in mesial temporal epilepsy. The majority of these changes, however, are specific to laboratory or experimental conditions with only 53 genes demonstrating changes in more than two publications. To this end, we review the current status of gene expression profiling in epileptogenesis and suggest standard guidelines to be followed for greater accuracy and reproducibility of results.

Pathology and pathophysiology of the amygdala in epileptogenesis and epilepsy

Acute brain insults, such as traumatic brain injury, status epilepticus, or stroke are common etiologies for the development of epilepsy, including temporal lobe epilepsy (TLE), which is often refractory to drug therapy. The mechanisms by which a brain injury can lead to epilepsy are poorly understood. It is well recognized that excessive glutamatergic activity plays a major role in the initial pathological and pathophysiological damage. This initial damage is followed by a latent period, during which there is no seizure activity, yet a number of pathophysiological and structural alterations are taking place in key brain regions, that culminate in the expression of epilepsy. The process by which affected/injured neurons that have survived the acute insult, along with well-preserved neurons are progressively forming hyperexcitable, epileptic neuronal networks has been termed epileptogenesis. Understanding the mechanisms of epileptogenesis is crucial for the development of therapeutic interventions that will prevent the manifestation of epilepsy after a brain injury, or reduce its severity. The amygdala, a temporal lobe structure that is most well known for its central role in emotional behavior, also plays a key role in epileptogenesis and epilepsy. In this article, we review the current knowledge on the pathology of the amygdala associated with epileptogenesis and/or epilepsy in TLE patients, and in animal models of TLE. In addition, because a derangement in the balance between glutamatergic and GABAergic synaptic transmission is a salient feature of hyperexcitable, epileptic neuronal circuits, we also review the information available on the role of the glutamatergic and GABAergic systems in epileptogenesis and epilepsy in the amygdala.