Nonconvulsive seizures in traumatic brain injury: what you don't see can hurt you

Case Report: Non-convulsive seizure following traumatic brain injury - a significant occurrence that needs to be considered due to potential long-term sequelae

Introduction/background

Non convulsive seizures (NCS) following traumatic brain injury (TBI) may remain undiagnosed due to lack of overt clinical manifestation and can have long-term sequelae due to delay in timely treatment. Occurrence of early NCS is known to have subsequent neurologic sequelae due to excitotoxic neuronal injury.

Case report

This is a case report of a young girl who sustained a TBI due to a motor vehicle accident (MVA) and was admitted with a fluctuating level of consciousness. Her clinical presentation was attributed to TBI; however as her conscious level did not recover, an electroencephalogram (EEG) was requested, which detected non convulsive status epilepticus (NCSE). Anti-seizure medication (ASM) was started. Her follow-up EEG and magnetic resonance imaging (MRI) were suggestive of the potential adverse effects of prolonged NCSE.

Conclusion

NCS may remain undiagnosed in TBI due to a paucity of overt clinical manifestations. Every patient with TBI and altered consciousness at presentation should be evaluated by continuous EEG monitoring immediately, if possible, in the emergency department to avoid long-term sequelae of NCS in such cases.

Dual Therapeutic Effects of C-10068, a Dextromethorphan Derivative, Against Post-Traumatic Nonconvulsive Seizures and Neuroinflammation in a Rat Model of Penetrating Ballistic-Like Brain Injury

Post-traumatic seizures can exacerbate injurious outcomes of severe brain trauma, yet effective treatments are limited owing to the complexity of the pathology underlying the concomitant occurrence of both events. In this study, we tested C-10068, a novel deuterium-containing analog of (+)-N-methyl-3-ethoxymorphinan, in a rat model of penetrating ballistic-like brain injury (PBBI) and evaluated the effects of C-10068 on PBBI-induced nonconvulsive seizures (NCS), acute neuroinflammation, and neurofunctional outcomes. NCS were detected by electroencephalographic monitoring. Neuroinflammation was evaluated by immunohistochemical markers, for example, glial fibrillary acidic protein and major histocompatibility complex class I, for activation of astrocytes and microglia, respectively. Neurofunction was tested using rotarod and Morris water maze tasks. Three infusion doses of C-10068 (1.0, 2.5, and 5.0 mg/kg/h × 72 h) were tested in the antiseizure study. Neuroinflammation and neurofunction were evaluated in animals treated with 5.0 mg/kg/h × 72 h C-10068. Compared to vehicle treatment, C-10068 dose dependently reduced PBBI-induced NCS incidence (40-50%), frequency (20-70%), and duration (30-82%). The most effective antiseizure dose of C-10068 (5.0 mg/kg/h × 72 h) also significantly attenuated hippocampal astrocyte activation and perilesional microglial reactivity post-PBBI. Within C-10068-treated animals, a positive correlation was observed in reduction in NCS frequency and reduction in hippocampal astrocyte activation. Further, C-10068 treatment significantly attenuated astrocyte activation in seizure-free animals. However, C-10068 failed to improve PBBI-induced motor and cognitive functions with the dosing regimen used in this study. Overall, the results indicating that C-10068 exerts both potent antiseizure and antiinflammatory effects are promising and warrant further investigation.

Delayed thalamic astrocytosis and disrupted sleep-wake patterns in a preclinical model of traumatic brain injury

Traumatic brain injury (TBI) involves diffuse axonal injury and induces subtle but persistent changes in brain tissue and function and poses challenges for early detection of neurological injury. The present study uses an automated behavioral analysis system to assess alterations in rodent behavior in the subacute phase in a preclinical mouse model of TBI, controlled cortical impact (CCI) injury. In the first few weeks following CCI, mice demonstrated normal exploratory behaviors and other typical home-cage behaviors. However, beginning 4 weeks post-injury, CCI mice developed disruptions in sleep-wake patterns, including an increased number of awakenings from sleep. Such impaired sleep maintenance was accompanied by an increased latency to reach peak sleep in CCI mice. These sleep disruptions implicate involvement of the thalamocortical network, the activity of which must be tightly regulated to control sleep maintenance. After injury, there was an increase in reactive microglia in thalamic regions as well as delayed reactive astrocytosis that was evident in the thalamic reticular nucleus, which preceded the development of sleep disruptions. These data suggest that cortical injury may trigger inflammatory responses in deeper neuroanatomical structures, including the thalamic reticular nucleus. Such engagement of the thalamus may perturb the thalamocortical network that regulates sleep/awake patterns and contribute to sleep disruptions observed in this model as well as those documented in patients with TBI.

Multimodal Cerebral Monitoring in Traumatic Brain Injury

Traumatic brain injury presents a significant impact on patients in terms of morbidity and mortality. Pathology is heterogeneous and is often associated with secondary deterioration. This paper reviews both clinical and research modes of monitoring to detect deterioration and compares what is available to the ideal. Intracranial pressure measurement, jugular venous oxygen saturation, microdialysis and cerebral oxygen monitoring are among the variables described and future research-based modalities are explored.

Evaluation of an easy, standardized and clinically practical method (SurePrep) for the preparation of electrode-skin contact in neurophysiological recordings

The aim of this study was to assess the practicality, reliability and safety of a recently introduced method of skin preparation for EEG recordings. We compared the traditional skin abrasion (SA) method to a method called SurePrep (SP), which creates tiny incisions through the upper epithelial layers. The study comprised three parts. In part 1, forearm recordings (n = 400; ten healthy volunteers) were conducted to examine acute and late (24 h) impedances, skin reactions, as well as the effects on electrode movement artefacts. In part 2, the effect of repeated (up to nine) SP sticks on impedances was examined on the forearm skin in two subjects (n = 99). In part 3, preparation speed and skin impedances were measured from preparation of a standard EEG cap in four subjects (n = 74). Immediately after preparation, skin impedances were a little lower (n.s.) after SA, but the variability in impedances was significantly less after SP (p < 0.01). After one day, there was no mean impedance difference but a greater proportion of SP sites were >10 kOmega. The frequency of immediate skin irritations (93.5%) was much higher after SA compared to 42.5% after SP, but there was no clinically significant difference observed after one day. The SP method exposed interstitial fluid in 5% of cases, while SA caused a wound-like lesion in 4.5% of the sites. No macroscopic blood was observed in any case (n = 400). Three sticks with the SP device produced clinically sufficient (<10 kOmega) impedances in 85% of the cases, and a total of five to six sticks secured a sufficient skin contact in all skin sites examined (n = 99). Preparation of skin contacts in the EEG cap was faster by SP compared to SA in all four study subjects. Our results demonstrate that skin contacts of sufficient quality can be reliably, easily and quickly prepared by the SP method. SP is a useful alternative for EEG recordings in general, although SA may provide the slightly better preserved skin contacts needed for long-term recordings. Notably, SP could facilitate emergency care units, peripheral hospitals and after-hours EEG acquisition by people without special EEG training.

Induced hypothermia for trauma: current research and practice

Induction of hypothermia with the goal of providing therapeutic benefit has been accepted for use in the clinical setting of adult cardiac arrest and neonatal hypoxic-ischemic encephalopathy (HIE). However, its potential as a treatment in trauma is not as well defined. This review discusses potential benefits and complications of induced hypothermia (IH) with emphasis on the current state of knowledge and practice in various types of trauma. There is excellent preclinical research showing that in cases of penetrating trauma with cardiac arrest, inducing hypothermia to 10 degrees C using cardiopulmonary bypass (CPB) could possibly save those otherwise likely to die without causing neurologic sequelae. A human trial of this intervention is about to get underway. Preclinical studies suggest that inducing hypothermia may be useful to delay cardiac arrest in penetrating trauma victims who are hypotensive. There is potential for IH to be used in cases of blunt trauma, but it has not been well studied. In the case of traumatic brain injury (TBI), clinical trials have shown conflicting results, despite almost uniform efficacy seen in preclinical experiments. Major studies are analyzed and ways to standardize its use and optimize future clinical trials are discussed. More preclinical and clinical research is needed to better define whether there could be a role for IH in the case of spinal cord injuries.

Microdialysis: is it ready for prime time?

PURPOSE OF REVIEW

This review highlights recent advances in cerebral microdialysis for investigational and clinical neurochemical monitoring in patients with critical neurological conditions.

RECENT FINDINGS

Use of microdialysis with other methods, including PET, electrophysiological monitoring and brain tissue oximetry in traumatic brain injury, subarachnoid hemorrhage with vasospasm, and infarction with refractory increased intracranial pressure have been reported. Potentially adverse neurochemical effects of nonconvulsive status epilepticus and cortical slow depolarization waves, both of which are increasingly recognized in traumatic brain injury and stroke patients, have been reported. The explosive growth in the use of cerebral oximetry with targeted management of brain tissue oxygen levels is leading to greater understanding of derangements of cerebral bioenergetics in the critically ill brain, but there remain unresolved basic issues. Understanding of the analytes that are measurable at the bedside - glucose, lactate, pyruvate, glutamate and glycerol - continues to evolve with glucose, lactate, pyruvate and the lactate-pyruvate ratio taking center stage. Analytes including inflammatory biomarkers such as cytokines and metabolites of nitric oxide are presently investigational, but hold promise for future application in advancing our understanding of basic pathophysiology, therapeutic target selection and prognostication. Growing consensus on indications for use of clinical microdialysis and advances in commercially available equipment continue to make microdialysis increasingly 'ready for prime time.'

SUMMARY

Cerebral microdialysis is an established tool for neurochemical research in the ICU. This technique cannot be fruitfully used in isolation, but when combined with other monitoring methods provides unique insights into the biochemical and physiological derangements in the injured brain.