Dopamine agonist therapy in low-response children following traumatic brain injury

Amantadine for Traumatic Brain Injury-Supporting Evidence and Mode of Action

Traumatic brain injury (TBI) is an important global clinical issue, requiring not only prevention but also effective treatment. Following TBI, diverse parallel and intertwined pathological mechanisms affecting biochemical, neurochemical, and inflammatory pathways can have a severe impact on the patient's quality of life. The current review summarizes the evidence for the utility of amantadine in TBI in connection to its mechanism of action. Amantadine, the drug combining multiple mechanisms of action, may offer both neuroprotective and neuroactivating effects in TBI patients. Indeed, the use of amantadine in TBI has been encouraged by several clinical practice guidelines/recommendations. Amantadine is also available as an infusion, which may be of particular benefit in unconscious patients with TBI due to immediate delivery to the central nervous system and the possibility of precise dosing. In other situations, orally administered amantadine may be used. There are several questions that remain to be addressed: can amantadine be effective in disorders of consciousness requiring long-term treatment and in combination with drugs approved for the treatment of TBI? Do the observed beneficial effects of amantadine extend to disorders of consciousness due to factors other than TBI? Well-controlled clinical studies are warranted to ultimately confirm its utility in the TBI and provide answers to these questions.

Does amantadine improve cognitive recovery in severe disorders of consciousness after aneurysmal subarachnoid hemorrhage? A double-blind placebo-controlled study

BACKGROUND

Severe disorders of consciousness (sDoC) are a common sequela of aneurysmal subarachnoid hemorrhages (aSAH), and amantadine has been used to improve cognitive recovery after traumatic brain injury.

OBJECTIVE

This study evaluated the effect of amantadine treatment on consciousness in patients with sDoC secondary to aSAH.

METHODS

This double-center, randomized, prospective, cohort study included patients ≥ 18 years old with sDoC after aSAH from February 2020 to September 2023. Individual patient data of patients were pooled to determine the effect of amantadine, in comparison to placebo. The primary outcomes at 3 and 6 months after the ictus were evaluated using the modified Rankin scale (mRS) and Glasgow outcome scale (GOS). In addition to all-cause mortality, secondary endpoints were assessed weekly during intervention by scores on Rappaport's Disability Rating Scale (RDRS) and Coma Recovery Scale-Revised (CRSR).

RESULTS

Overall, 37 patients with sDoC and initial Glasgow Coma Scale (GCS) varying between 3 and 11 were recruited and randomized to amantadine (test group, n = 20) or placebo (control group, n = 17). The average age was 59.5 years (28 to 81 year-old), 24 (65%) were women, and the mean GCS at the beginning of intervention was 7.1. Most patients evolved to vasospasm (81%), with ischemia in 73% of them. The intervention was started between 30 to 180 days after the ictus, and administered for 6 weeks, with progressively higher doses. Neither epidemiological characteristics nor considerations regarding the treatment of the aneurysm and its complications differed between both arms. Overall mortality was 10.8% (4 deaths). During the study, four patients had potential adverse drug effects: two presented seizures, one had paralytic ileus, and another evolved with tachycardia; the medication was not suspended, only the dose was not increased. At data opening, 2 were taking amantadine and 2 placebo.

CONCLUSION

Despite some good results associated with amantadine in the literature, this study did not find statistically significant positive effects in cognitive recovery in patients with delayed post-aSAH sDoC. Further large randomized clinical trials in patients' subgroups are needed to better define its effectiveness and clarify any therapeutic window where it can be advantageous.

Scoping Review on the Diagnosis, Prognosis, and Treatment of Pediatric Disorders of Consciousness

BACKGROUND AND OBJECTIVES

Comprehensive guidelines for the diagnosis, prognosis, and treatment of disorders of consciousness (DoC) in pediatric patients have not yet been released. We aimed to summarize available evidence for DoC with >14 days duration to support the future development of guidelines for children, adolescents and young adults aged 6 months-18 years.

METHODS

This scoping review was reported based on Preferred Reporting Items for Systematic reviews and Meta-Analyses-extension for Scoping Reviews guidelines. A systematic search identified records from 4 databases: PubMed, Embase, Cochrane Library, and Web of Science. Abstracts received 3 blind reviews. Corresponding full-text articles rated as "in-scope" and reporting data not published in any other retained article (i.e., no double reporting) were identified and assigned to 5 thematic evaluating teams. Full-text articles were reviewed using a double-blind standardized form. Level of evidence was graded, and summative statements were generated.

RESULTS

On November 9, 2022, 2,167 documents had been identified; 132 articles were retained, of which 33 (25%) were published over the past 5 years. Overall, 2,161 individuals met the inclusion criteria; female patients were 527 of 1,554 (33.9%) cases included, whose sex was identifiable. Of 132 articles, 57 (43.2%) were single case reports and only 5 (3.8%) clinical trials; the level of evidence was prevalently low (80/132; 60.6%). Most studies included neurobehavioral measures (84/127; 66.1%) and neuroimaging (81/127; 63.8%); 59 (46.5%) were mainly related to diagnosis, 56 (44.1%) to prognosis, and 44 (34.6%) to treatment. Most frequently used neurobehavioral tools included the Coma Recovery Scale-Revised, Coma/Near-Coma Scale, Level of Cognitive Functioning Assessment Scale, and Post-Acute Level of Consciousness scale. EEG, event-related potentials, structural CT, and MRI were the most frequently used instrumental techniques. In 29/53 (54.7%) cases, DoC improvement was observed, which was associated with treatment with amantadine.

DISCUSSION

The literature on pediatric DoCs is mainly observational, and clinical details are either inconsistently presented or absent. Conclusions drawn from many studies convey insubstantial evidence and have limited validity and low potential for translation in clinical practice. Despite these limitations, our work summarizes the extant literature and constitutes a base for future guidelines related to the diagnosis, prognosis, and treatment of pediatric DoC.

N-methyl-D-aspartate receptor antagonists in improving cognitive deficits following traumatic brain injury: a systematic review

OBJECTIVE

To review the role of N-methyl-D-aspartate receptor (NMDAR) antagonists in managing post-TBI cognitive deficits.

METHODS

A search of PubMed, Embase, and Cochrane was conducted on Jan 12, 2021 without publication date or language restriction.

RESULTS

Forty-seven studies were included, involving 20 (42.6%) randomized controlled trials. Four (8.5%) studies had a low risk of bias (RoB), while 34 (72.3%) had unclear and nine (19.2%) had high RoB. Six NMDAR antagonists had been investigated: amantadine (n = 32), memantine (n = 4), magnesium (n = 4), traxoprodil (n = 3), selfotel (n = 2), and dextromethorphan (n = 2).

CONCLUSION

Although some benefits were observed, there are still some concerns regarding the efficacy and safety of NMDAR antagonists in improving post-TBI cognitive deficits. Further research is required to examine whether (i) these agents, notably amantadine, could accelerate cognitive improvement and shorten the hospital stay, (ii) these agents affect different cognitive domains/subdomains in the same direction, (iii) an optimal therapeutic time window exists, (iv) a member of this drug class can be proved to be effective without interfering in non-excitotoxic actions of glutamate, (v) they can be more effective as part of combination therapies or in particular subgroups of patients with TBI.

Prescribing Patterns of Amantadine During Pediatric Inpatient Rehabilitation After Traumatic Brain Injury: A Multicentered Retrospective Review From the Pediatric Brain Injury Consortium

OBJECTIVES

To describe dosing practices for amantadine hydrochloride and related adverse effects among children and young adults with traumatic brain injury (TBI) admitted to pediatric inpatient rehabilitation units.

SETTING

Eight pediatric acute inpatient rehabilitation units located throughout the United States comprising the Pediatric Brain Injury Consortium.

PARTICIPANTS

Two-hundred thirty-four children and young adults aged 2 months to 21 years with TBI.

DESIGN

Retrospective data revie.

MAIN OUTCOME MEASURES

Demographic variables associated with the use of amantadine, amantadine dose, and reported adverse effects.

RESULTS

Forty-nine patients (21%) aged 0.9 to 20 years received amantadine during inpatient rehabilitation. Forty-five percent of patients admitted to inpatient rehabilitation with a disorder of consciousness (DoC) were treated with amantadine, while 14% of children admitted with higher levels of functioning received amantadine. Children with DoC who were not treated with amantadine were younger than those with DoC who received amantadine (median 3.0 vs 11.6 years, P = .008). Recorded doses of amantadine ranged from 0.7 to 13.5 mg/kg/d; the highest total daily dose was 400 mg/d. Adverse effects were reported in 8 patients (16%); nausea/abdominal discomfort and agitation were most common, each reported in 3 patients. The highest reported dose without an adverse effect was 10.1 mg/kg/d.

CONCLUSION

During pediatric inpatient rehabilitation, amantadine was prescribed to children across a range of ages and injury severity and was most commonly prescribed to older children with DoC. Dosing varied widely, with weight-based dosing for younger/smaller children at both lower and higher doses than what had been previously reported. Prospective studies are needed to characterize the safety and tolerability of higher amantadine doses and optimize amantadine dosing parameters for children with TBI.

Assessment of the effect of amantadine in patients with traumatic brain injury: A meta-analysis

BACKGROUND

Traumatic brain injury is a global burden. We aimed to perform a meta-analysis to determine the efficacy of amantadine for cognitive performance after traumatic brain injury.

METHODS

The systematic review was prospectively registered on the International Prospective Register of Systematic Reviews website under the registration number CRD42017080044. We used Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines to report the steps of meta-analysis. The search included electronic databases (PubMed, PsycINFO, Embase, Cochrane Library databases, CENTRAL, ProQuest and ClinicalTrials.gov trial registry). Critical care medicine journals and clinical neurology specialty were searched using www.scimagojr.com. There was no publication date restriction. Two authors assessed studies' relevance and extracted data. Studies were assessed for quality using the Cochrane risk of bias tool. Data were analyzed using Comprehensive Meta-analysis Program versions 2.0 and 3.0.

RESULTS

Twenty-six studies out of 3,440 records were included in the systematic review, of which only 14 clinical trials and 6 observational studies were included in the meta-analysis. Amantadine significantly enhanced the cognitive function relative to control group (mean difference [MD], 0.50; 95% confidence interval [CI], 0.33-0.66; p < 0.001, 16 studies, 1,127 participants, low certainty evidence). Consistent significant difference in favor of amantadine relative to control group was found (MD of 0.79 [95% CI, 0.34-1.24], very low certainty evidence, for cohort studies vs. MD of 0.40 [95% CI, 0.25-0.56], moderate certainty evidence, for RCTS). Starting amantadine in the first week after TBI had a significant effect on improving cognitive function (MD, 0.97; 95% CI, 0.45-1.49; 16 studies, 1,127 participants, low certainty). Amantadine showed a better effect when administered for less than 1 month (MD, 0.83; 95% CI, 0.56-1.11; low certainty) and to patients below 18 years of age (MD, 0.66; 95% CI, 0.32-0.99; low certainty) or to patients with less severe traumatic brain injury (MD, 0.40; 95% CI, 0.18-0.62; low certainty). No statistically significant difference existed between amantadine and the control concerning the adverse events (OR, 1.74; 95% CI, 0.88-3.44; p = 0.11, moderate certainty). Metaregression of the different clinical parameters, which are onset of treatment, age, and severity of traumatic brain injury, showed a statistically significant relation between onset of treatment and the effect size of amantadine. The relation between the other two parameters and the effect size of amantadine showed a marginal statistical significance.

CONCLUSION

Amantadine may improve the cognitive function when used after TBI. Further research with high validity is needed to reach a solid conclusion about the use of amantadine in traumatic brain injury.

LEVEL OF EVIDENCE

Systematic review/meta-analysis, level III.

Emerging Treatments for Disorders of Consciousness in Paediatric Age

The number of paediatric patients living with a prolonged Disorder of Consciousness (DoC) is growing in high-income countries, thanks to substantial improvement in intensive care. Life expectancy is extending due to the clinical and nursing management achievements of chronic phase needs, including infections. However, long-known pharmacological therapies such as amantadine and zolpidem, as well as novel instrumental approaches using direct current stimulation and, more recently, stem cell transplantation, are applied in the absence of large paediatric clinical trials and rigorous age-balanced and dose-escalated validations. With evidence building up mainly through case reports and observational studies, there is a need for well-designed paediatric clinical trials and specific research on 0-4-year-old children. At such an early age, assessing residual and recovered abilities is most challenging due to the early developmental stage, incompletely learnt motor and cognitive skills, and unreliable communication; treatment options are also less explored in early age. In middle-income countries, the lack of rehabilitation services and professionals focusing on paediatric age hampers the overall good assistance provision. Young and fast-evolving health insurance systems prevent universal access to chronic care in some countries. In low-income countries, rescue networks are often inadequate, and there is a lack of specialised and intensive care, difficulty in providing specific pharmaceuticals, and lower compliance to intensive care hygiene standards. Despite this, paediatric cases with DoC are reported, albeit in fewer numbers than in countries with better-resourced healthcare systems. For patients with a poor prospect of recovery, withdrawal of care is inhomogeneous across countries and still heavily conditioned by treatment costs as well as ethical and cultural factors, rather than reliant on protocols for assessment and standardised treatments. In summary, there is a strong call for multicentric, international, and global health initiatives on DoC to devote resources to the paediatric age, as there is now scope for funders to invest in themes specific to DoC affecting the early years of the life course.

Organizing a Rational Approach to Treatments of Disorders of Consciousness Using the Anterior Forebrain Mesocircuit Model

SUMMARY

Organizing a rational treatment strategy for patients with multifocal structural brain injuries and disorders of consciousness (DOC) is an important and challenging clinical goal. Among potential clinical end points, restoring elements of communication to DOC patients can support improved patient care, caregiver satisfaction, and patients' quality of life. Over the past decade, several studies have considered the use of the anterior forebrain mesocircuit model to approach this problem because this model proposes a supervening circuit-level impairment arising across DOC of varying etiologies. We review both the conceptual foundation of the mesocircuit model and studies of mechanisms underlying DOC that test predictions of this model. We consider how this model can guide therapeutic interventions and discuss a proposed treatment algorithm based on these ideas. Although the approach reviewed originates in the evaluation of patients with chronic DOC, we consider some emerging implications for patients in acute and subacute settings.

Amantadine: reappraisal of the timeless diamond-target updates and novel therapeutic potentials

The aim of the current review was to provide a new, in-depth insight into possible pharmacological targets of amantadine to pave the way to extending its therapeutic use to further indications beyond Parkinson's disease symptoms and viral infections. Considering amantadine's affinities in vitro and the expected concentration at targets at therapeutic doses in humans, the following primary targets seem to be most plausible: aromatic amino acids decarboxylase, glial-cell derived neurotrophic factor, sigma-1 receptors, phosphodiesterases, and nicotinic receptors. Further three targets could play a role to a lesser extent: NMDA receptors, 5-HT3 receptors, and potassium channels. Based on published clinical studies, traumatic brain injury, fatigue [e.g., in multiple sclerosis (MS)], and chorea in Huntington's disease should be regarded potential, encouraging indications. Preclinical investigations suggest amantadine's therapeutic potential in several further indications such as: depression, recovery after spinal cord injury, neuroprotection in MS, and cutaneous pain. Query in the database http://www.clinicaltrials.gov reveals research interest in several further indications: cancer, autism, cocaine abuse, MS, diabetes, attention deficit-hyperactivity disorder, obesity, and schizophrenia.

Associations Between Amantadine Usage, Gait, and Cognition in PSP: A post-hoc Analysis of the Davunetide Trial

Introduction: Amantadine anecdotally improves gait in progressive supranuclear palsy (PSP) but definitive data is lacking. We investigated associations between amantadine usage, gait, cognition, and activities of daily living in 310 subjects with PSP using data from the davunetide trial.

Method: We compared baseline demographics, PSP Rating Scale (PSPRS), Repeat Battery for the Assessment of Neuropsychological Status (RBANS), and Schwab and England Activities of Daily Living (SEADL) scores between subjects taking vs. not taking amantadine using chi-square tests for categorical variables and independent sample t-tests for continuous variables. Using the general linear model (GLM), we tested whether group status predicted total PSPRS, PSPRS-gait and midline, total RBANS, RBANS-attention, and SEADL before and after the 52-weeks follow-up.

Results: Subjects taking vs. not taking amantadine were similar at baseline, except subjects taking amantadine had a higher Clinical Global Impression (CGI) Score (p = 0.01). However, the CGI change score did not differ between groups at week 52 (p = 0.10). Using GLM models (controlling for covariates), we found that subjects taking vs. not taking amantadine did not significantly predict total PSPRS, PSPRS-gait and midline, total RBANS, RBANS-attention, or SEADL at baseline, week 52, or the change score between baseline and week 52.

Discussion: This post-hoc analysis of the davunetide trial did not find an association between amantadine and gait or cognitive measures in PSP, but was not powered to find such a difference. Future studies should still examine amantadine for symptomatic benefit in multiple PSP subtypes.

Joint Neuropsychological Assessment through Coma/Near Coma and Level of Cognitive Functioning Assessment Scales Reduces Negative Findings in Pediatric Disorders of Consciousness

The present study aimed to: (a) characterize the emergence to a conscious state (CS) in a sample of children and adolescents with severe brain injury during the post-acute rehabilitation and through two different neuropsychological assessment tools: the Rappaport Coma/Near Coma Scale (CNCS) and Level of Cognitive Functioning Assessment Scale (LOCFAS); (b) compare the evolution in patients with brain lesions due to traumatic and non-traumatic etiologies; and (c) describe the relationship between the emergence to a CS and some relevant clinical variables. In this observational prospective longitudinal study, 92 consecutive patients were recruited. Inclusion criteria were severe disorders of consciousness (DOC), Glasgow Coma Scale (GCS) score ≤8 at insult, age 0 to 18 years, and direct admission to inpatient rehabilitation from acute care. The main outcome measures were CNCS and LOCFAS, both administered three and six months after injury. The cohort globally shifted towards milder DOC over time, moving from overall 'moderate/near coma' at three months to 'near/no coma' at six months post-injury. The shift was captured by both CNCS and LOCFAS. CNCS differentiated levels of coma at best, while LOCFAS was superior in characterizing the emergence from coma. Agreement between scales was fair, and reduced negative findings at less than 10%. Patients with traumatic brain injury (TBI) vs. non-traumatic brain injury (NTBI) were older and had neurosurgical intervention more frequently. No relation between age and the level of consciousness was found overall. Concurrent administration of CNCS and LOCFAS reduced the rate of false negatives and better detected signs of arousal and awareness. This provides indication to administer both tools to increase measurement precision.

Neurostimulant Prescribing Patterns in Children Admitted to the Intensive Care Unit after Traumatic Brain Injury

Neurostimulant medications are commonly prescribed following traumatic brain injury (TBI) in adults; little is known about their use in children with TBI. Our objective was to analyze neurostimulant prescribing practices from 2005 to 2015 in children admitted to the intensive care unit (ICU) with TBI. We hypothesized that neurostimulant prescriptions have increased over time and are associated with older age and injury severity. A retrospective cohort study of patients age 1 month to 18 years with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) discharge diagnosis code for TBI admitted to the ICU between 2005 and 2015 in 37 pediatric hospitals included in the Pediatric Health Information System was conducted. Variables examined include patient and injury characteristics and neurostimulant medication use. Descriptive statistics and multi-variable logistic regression testing were used to determine variables associated with neurostimulant prescription. Of 30,881 patients with TBI, most were male (64%) and age 0-4 years (43%). In patients with mechanism of injury reported (n = 21,998), TBI was most frequently due to falls (36%) and motor vehicle collisions (36%). One thousand sixty-four neurostimulants were prescribed to 878 (3%) patients with 41% of prescriptions for amantadine and 38% for methylphenidate. Neurostimulants were prescribed a median (interquartile range) of 17 (8-35) days post-injury and increased over the study decade (R² = 0.806). In a multi-variable analysis, variables most strongly associated with receipt of a neurostimulant were age 14-18 years (odds ratio 5.8, 95% confidence interval [4.3,7.8]), motor vehicle collision (3.1, [2.4,4.2]), intracranial pressure (ICP) monitor (3.8, [3.1,4.5]), and mechanical ventilation (3.4, [2.7,4.3]). Use of neurostimulants following pediatric TBI is uncommon, has increased over time, and is associated with indicators of higher severity of illness. Knowledge of prescribing practices may assist in optimizing the design of efficacy and outcome studies that will inform clinical guidelines.

The effects of amantadine on traumatic brain injury outcome: a double-blind, randomized, controlled, clinical trial

INTRODUCTION

Amantadine, as a dopamine receptor agonist, may stimulate and help the recovery of the nervous system after traumatic brain injury (TBI).

METHODS

We performed this study as a double-blind, randomized, controlled clinical trial with target population including all patients with TBI who scored nine or lower on the Glasgow Coma Scale (GCS), admitted to our hospital between January 2013 and April 2014. The protocol included administration of the drug (placebo or amantadine) for 6 weeks and patient evaluation using the GCS and FOUR score on the first, third and seventh days after the drug was started. After 6 months from starting study drug, the patients were evaluated on the Mini-Mental State Examination, Glasgow Outcome Study, Disability Rating Scale and Karnofsky Performance Scale.

RESULTS

We included 40 patients in the study. The mean age of the patients was 36.77 ± 18.21. As an only important finding, the amantadine group registered an important rise between the first and the seventh day of study drug (∆GCS7-GCS1) with p-value = 0.044.

CONCLUSION

Based on our findings during the first week and the 6 months (since starting drug) follow-ups, prescribing amantadine did not lead to reportable effects on the patients' level of consciousness, memory, disability, cognition, mortality and performance.

A retrospective analysis of paroxysmal sympathetic hyperactivity following severe pediatric brain injury

BACKGROUND

There are several gaps in the literature related to the prognosis and care of children who have experienced a brain injury then develop paroxysmal sympathetic hyperactivity (PSH).

OBJECTIVE

The objective of the present study was to explore the characteristics and prognosis of children who have experienced severe brain injury and developed PSH.

METHODOLOGY

A secondary analysis was conducted using an established clinical dataset of children who had experienced severe brain injury and were admitted to an academic children's rehabilitation center (n= 83).

RESULTS

Those children with PSH had a significantly longer acute care length of stay (p= 0.024) and total length of stay (p= 0.034) compared with those without PSH. There was no significant difference in cognitive and motor function or transition to rehabilitation between those with and those without PSH after controlling for age and etiology of injury.

IMPLICATIONS

The findings from the present study reveal factors regarding the elusive phenomenon of PSH among children.

Neurostimulant use is associated with improved survival in comatose patients after cardiac arrest regardless of electroencephalographic substrate

AIM

Identify EEG patterns that predict or preclude favorable response in comatose post-arrest patients receiving neurostimulants.

METHODS

We examined a retrospective cohort of consecutive electroencephalography (EEG)-monitored comatose post-arrest patients. We classified the last day of EEG recording before neurostimulant administration based on continuity (continuous/discontinuous), reactivity (yes/no) and malignant patterns (periodic discharges, suppression burst, myoclonic status epilepticus or seizures; yes/no). In subjects who did not receive neurostimulants, we examined the last 24h of available recording. For our primary analysis, we used logistic regression to identify EEG predictors of favorable response to treatment (awakening).

RESULTS

In 585 subjects, mean (SD) age was 57 (17) years and 227 (39%) were female. Forty-seven patients (8%) received a neurostimulant. Neurostimulant administration independently predicted improved survival to hospital discharge in the overall cohort (adjusted odds ratio (aOR) 4.00, 95% CI 1.68-9.52) although functionally favorable survival did not differ. No EEG characteristic predicted favorable response to neurostimulants. In each subgroup of unfavorable EEG characteristics, neurostimulants were associated with increased survival to hospital discharge (discontinuous background: 44% vs 7%, P=0.004; non-reactive background: 56% vs 6%, P<0.001; malignant patterns: 63% vs 5%, P<0.001).

CONCLUSION

EEG patterns described as ominous after cardiac arrest did not preclude survival or awakening after neurostimulant administration. These data are limited by their observational nature and potential for selection bias, but suggest that EEG patterns alone should not affect consideration of neurostimulant use.

Pediatric Traumatic Brain Injury and Autism: Elucidating Shared Mechanisms

Pediatric traumatic brain injury (TBI) and autism spectrum disorder (ASD) are two serious conditions that affect youth. Recent data, both preclinical and clinical, show that pediatric TBI and ASD share not only similar symptoms but also some of the same biologic mechanisms that cause these symptoms. Prominent symptoms for both disorders include gastrointestinal problems, learning difficulties, seizures, and sensory processing disruption. In this review, we highlight some of these shared mechanisms in order to discuss potential treatment options that might be applied for each condition. We discuss potential therapeutic and pharmacologic options as well as potential novel drug targets. Furthermore, we highlight advances in understanding of brain circuitry that is being propelled by improved imaging modalities. Going forward, advanced imaging will help in diagnosis and treatment planning strategies for pediatric patients. Lessons from each field can be applied to design better and more rigorous trials that can be used to improve guidelines for pediatric patients suffering from TBI or ASD.

A Narrative Review of Pharmacologic and Non-pharmacologic Interventions for Disorders of Consciousness Following Brain Injury in the Pediatric Population

Traumatic brain injury (TBI) is the most common cause of long-term disability in the United States. A significant proportion of children who experience a TBI will have moderate or severe injuries, which includes a period of decreased responsiveness. Both pharmacological and non-pharmacological modalities are used for treating disorders of consciousness after TBI in children. However, the evidence supporting the use of potential therapies is relatively scant, even in adults, and overall, there is a paucity of study in pediatrics. The goal of this review is to describe the state of the science for use of pharmacologic and non-pharmacologic interventions for disorders of consciousness in the pediatric population.

Establishing a Clinically Relevant Large Animal Model Platform for TBI Therapy Development: Using Cyclosporin A as a Case Study

We have developed the first immature large animal translational treatment trial of a pharmacologic intervention for traumatic brain injury (TBI) in children. The preclinical trial design includes multiple doses of the intervention in two different injury types (focal and diffuse) to bracket the range seen in clinical injury and uses two post-TBI delays to drug administration. Cyclosporin A (CsA) was used as a case study in our first implementation of the platform because of its success in multiple preclinical adult rodent TBI models and its current use in children for other indications. Tier 1 of the therapy development platform assessed the short-term treatment efficacy after 24 h of agent administration. Positive responses to treatment were compared with injured controls using an objective effect threshold established prior to the study. Effective CsA doses were identified to study in Tier 2. In the Tier 2 paradigm, agent is administered in a porcine intensive care unit utilizing neurological monitoring and clinically relevant management strategies, and intervention efficacy is defined as improvement in longer term behavioral endpoints above untreated injured animals. In summary, this innovative large animal preclinical study design can be applied to future evaluations of other agents that promote recovery or repair after TBI.

Catecholaminergic based therapies for functional recovery after TBI

Among the many pathophysiologic consequences of traumatic brain injury are changes in catecholamines, including dopamine, epinephrine, and norepinephrine. In the context of TBI, dopamine is the one most extensively studied, though some research exploring epinephrine and norepinephrine have also been published. The purpose of this review is to summarize the evidence surrounding use of drugs that target the catecholaminergic system on pathophysiological and functional outcomes of TBI using published evidence from pre-clinical and clinical brain injury studies. Evidence of the effects of specific drugs that target catecholamines as agonists or antagonists will be discussed. Taken together, available evidence suggests that therapies targeting the catecholaminergic system may attenuate functional deficits after TBI. Notably, it is fairly common for TBI patients to be treated with catecholamine agonists for either physiological symptoms of TBI (e.g. altered cerebral perfusion pressures) or a co-occuring condition (e.g. shock), or cognitive symptoms (e.g. attentional and arousal deficits). Previous clinical trials are limited by methodological limitations, failure to replicate findings, challenges translating therapies to clinical practice, the complexity or lack of specificity of catecholamine receptors, as well as potentially counfounding effects of personal and genetic factors. Overall, there is a need for additional research evidence, along with a need for systematic dissemination of important study details and results as outlined in the common data elements published by the National Institute of Neurological Diseases and Stroke. Ultimately, a better understanding of catecholamines in the context of TBI may lead to therapeutic advancements. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Neuromodulation of the conscious state following severe brain injuries

Disorders of consciousness (DOC) following severe structural brain injuries globally affect the conscious state and the expression of goal-directed behaviors. In some subjects, neuromodulation with medications or electrical stimulation can markedly improve the impaired conscious state present in DOC. We briefly review recent studies and provide an organizing framework for considering the apparently widely disparate collection of medications and approaches that may modulate the conscious state in subjects with DOC. We focus on neuromodulation of the anterior forebrain mesocircuit in DOC and briefly compare mechanisms supporting recovery from structural brain injuries to those underlying facilitated emergence from unconsciousness produced by anesthesia. We derive some general principles for approaching the problem of restoration of consciousness after severe structural brain injuries, and suggest directions for future research.

Therapeutic options to enhance coma arousal after traumatic brain injury: state of the art of current treatments to improve coma recovery

Traumatic brain injury is a leading cause of death and disability. Optimizing the recovery from coma is a priority in seeking to improve patients' functional outcomes. Standards of care have not been established: pharmacological interventions, right median nerve and sensory stimulation, dorsal column stimulation (DCS), deep brain stimulation, transcranial magnetic stimulation, hyperbaric oxygen therapy and cell transplantation have all been utilized with contrasting results. The aim of this review is to clarify the indications for the various techniques and to guide the clinical practice towards an earlier coma arousal. A systematic bibliographic search was undertaken using the principal search engines (Pubmed, Embase, Ovid and Cochrane databases) to locate the most pertinent studies. Traumatic injury is a highly individualized process, and subsequent impairments are dependent on multiple factors: this heterogeneity influences and determines therapeutic responses to the various interventions.

Update on pharmaceutical intervention for disorders of consciousness and agitation after traumatic brain injury in children

Responsiveness and agitation are common targets for pharmaceutical intervention after traumatic brain injury (TBI) in children. This focused review presents a critical discussion of the limited literature available on the use of medications for disorders of consciousness and agitation in children with TBI. For disorders of consciousness, evidence from several small studies supports a potential benefit of dopaminergic agents for improving responsiveness in some children with lower levels of function after TBI. Larger studies, likely requiring multicenter collaborations, are needed to more definitively address questions regarding the use of medications for responsiveness in children with TBI. The literature regarding use of pharmaceutical agents for agitation in children with TBI is even more limited. The dearth of literature regarding the effects of medications used for agitation in children with TBI highlights the need for additional basic and clinical science contributions in this area.

Movement disorder in ataxia-telangiectasia: treatment with amantadine sulfate

Ataxia-telangiectasia is a cerebellar neurodegenerative disorder presenting with ataxia, chorea, myoclonus, and bradykinesia. Literature on treatment of movement disorders is scarce. We treated 17 children (aged 11.2 ± 3.9 years) for 8 weeks with the dopaminergic and anti-N-methyl-d-aspartate (NMDA) agent amantadine sulfate 6.3 ± 0.87 mg/kg/d. Ataxia was assessed by using the International Cooperative Ataxia Scale, parkinsonism by the Unified Parkinson Disease Rating Scale, and chorea/myoclonus by the Abnormal Involuntary Movement Scale. Responders were considered those patients who had at least 20% improvement in the summation of the 3 scales. Overall, 76.5% of patients were responders, with a mean 29.3% improvement. Ataxia, involuntary movements, and parkinsonism improved significantly (25.3%, 32.5%, and 29.5%, respectively); (P < .001, t test). Side effects were mild and transient, and they did not lead to drug discontinuation. Amantadine is a well-tolerated and effective treatment for motor symptoms in ataxia telangiectasia. Assessment of long-term effects and a double-blind study should follow.

Methylphenidate and amantadine to stimulate reawakening in comatose patients resuscitated from cardiac arrest

BACKGROUND

Despite critical-care packages including therapeutic hypothermia (TH), neurologic injury is common after cardiac arrest (CA) resuscitation. Methylphenidate and amantadine have treated coma in traumatically-brain-injured patients with mixed success, but have not been explored in post-arrest patients.

OBJECTIVE

Compare the outcome of comatose post-arrest patients treated with neurostimulants to a matched cohort.

METHODS

Retrospective cohort study from 6/2008 to 12/2011 in a tertiary university hospital. We included adult patients treated with methylphenidate or amantadine after resuscitation from in-hospital or out-of-hospital CA (OHCA) of any rhythm, excluding patients with traumatic/surgical etiology of arrest, terminal re-arrest within 6h, or withdrawal of care by family within 6h. Primary outcome was following commands; secondary outcomes included survival to hospital discharge, cerebral performance category (CPC), and modified Rankin scale (mRS). We compared characteristics and outcomes to a control cohort matched on TH and 72 h FOUR score ± 1.

RESULTS

Of 588 patients, 8 received methylphenidate, 6 received amantadine, and 2 both. Most were female suffering OHCA with median age 61 years. All received TH and a multi-modal neurological evaluation. Initial exam revealed median GCS 6 and FOUR 7, which was unchanged at 72 h. Six patients (38%) followed commands prior to discharge at median 2.5 days (range: 1-18 days) after treatment. Patients receiving neurostimulants trended toward improved rate of following commands, survival to hospital discharge, and distribution of CPC and mRS scores.

CONCLUSIONS

Neurostimulants may be considered to stimulate wakefulness in selected post-cardiac arrest patients, but a prospective trial is needed to evaluate this therapy.

Cyclosporin A preserves mitochondrial function after traumatic brain injury in the immature rat and piglet

Cyclosporin A (CsA) has been shown to be neuroprotective in mature animal models of traumatic brain injury (TBI), but its effects on immature animal models of TBI are unknown. In mature animal models, CsA inhibits the opening of the mitochondrial permeability transition pore (MPTP), thereby maintaining mitochondrial homeostasis following injury by inhibiting calcium influx and preserving mitochondrial membrane potential. The aim of the present study was to evaluate CsA's ability to preserve mitochondrial bioenergetic function following TBI (as measured by mitochondrial respiration and cerebral microdialysis), in two immature models (focal and diffuse), and in two different species (rat and piglet). Three groups were studied: injured+CsA, injured+saline vehicle, and uninjured shams. In addition, we evaluated CsA's effects on cerebral hemodynamics as measured by a novel thermal diffusion probe. The results demonstrate that post-injury administration of CsA ameliorates mitochondrial dysfunction, preserves cerebral blood flow (CBF), and limits neuropathology in immature animals 24 h post-TBI. Mitochondria were isolated 24 h after controlled cortical impact (CCI) in rats and rapid non-impact rotational injury (RNR) in piglets, and CsA ameliorated cerebral bioenergetic crisis with preservation of the respiratory control ratio (RCR) to sham levels. Results were more dramatic in RNR piglets than in CCI rats. In piglets, CsA also preserved lactate pyruvate ratios (LPR), as measured by cerebral microdialysis and CBF at sham levels 24 h after injury, in contrast to the significant alterations seen in injured piglets compared to shams (p<0.01). The administration of CsA to piglets following RNR promoted a 42% decrease in injured brain volume (p<0.01). We conclude that CsA exhibits significant neuroprotective activity in immature models of focal and diffuse TBI, and has exciting translational potential as a therapeutic agent for neuroprotection in children.

Amantadine treatment following traumatic brain injury in children

PRIMARY OBJECTIVE

The focus of this paper is to review the current literature on the use of amantadine in children who have sustained a head injury.

MAIN OUTCOMES AND RESULTS

A MEDLINE search was conducted and yielded five papers. They were composed of prospective, retrospective and case study designs. Dosage use and side effect profiles were consistent with expected norms. Efficacy was measures primarily by alertness and arousal and positive results were found for all studies on these dimensions. Behavioural and cognitive measures of outcome yielded mixed results.

CONCLUSIONS

The studies reviewed for this paper suggest that amantadine is clinically beneficial for children who have sustained head injuries. Double blind placebo controlled trials with larger sample sizes are needed to further substantiate these findings.

Assessing the relationship between the WNSSP and therapeutic participation in adolescents in low response states following severe traumatic brain injury

PRIMARY OBJECTIVE

This study examines the relationship between scores on the Western Neuro Sensory Stimulation Profile (WNSSP) and therapeutic participation as it relates to rehabilitation readiness (RR) in adolescents with low response following severe traumatic brain injury (TBI).

RESEARCH DESIGN

This is a serial observational design using multiple measures of clinical status and participation.

METHODS AND PROCEDURES

Ten children, mean age 16.7 years, who remained in a low response state (30 days or more) were assessed with the WNSSP and videotaped during physical and occupational therapy sessions. Associations were evaluated between WNSSP scores and participation scores related to arousal, awareness and communication.

MAIN OUTCOMES AND RESULTS

The WNSSP was only associated with the communication score (p < 0.0001). The arousal and awareness scores had no significant impact on the WNSSP score.

CONCLUSIONS

These results suggest that scores on the WNSSP may be related to the return of communication skills in adolescents in low response states as one part of assessing their therapeutic participation and ultimate rehabilitation readiness. This ability may assist in making decisions regarding care planning.

Is there anybody in there? Detecting awareness in disorders of consciousness

The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and electrophysiological tools in search for objective markers of consciousness is being employed. However, such tools cannot be considered as diagnostic per se, but as assistants to the clinical evaluation, which, at present, remains the gold standard. Regarding therapeutic management in DOC, no evidence-based recommendations can be made in favor of a specific treatment. The present review summarizes clinical and paraclinical studies that have been conducted with neuroimaging and electrophysiological techniques in search of residual awareness in DOC. We discuss the medical, scientific and ethical implications that derive from these studies and we argue that, in the future, the role of neuroimaging and electrophysiology will be important not only for the diagnosis and prognosis of DOC but also in establishing communication with these challenging patients.

Status epilepticus in a pediatric patient with amantadine overdose

A 2-year-old boy who ingested 0.8-1.5 g of amantadine developed status epilepticus. One hour later, the child presented with agitation, diaphoresis, and vomiting. He was admitted to the pediatric emergency department 2 hours later. Generalized seizures evolved to status epilepticus, with alternating generalized tonic-clonic and partial seizures, over a period of 7 hours. Other initial clinical signs were sinusal tachycardia and reactive bilateral mydriasis. All symptoms resolved within 20 hours, with a good recovery; the child was released from the hospital on day 3.

Pharmacotherapy to enhance arousal: what is known and what is not

Severe brain injury results in a disturbance among a wide range of critical neurotransmitter systems. Each neurotransmitter system places its own functional role while being interconnected to a multitude of other systems and functions. This chapter seeks to review the major neurotransmitter systems involved after severe acquired brain injury. While limited in their construct, animal models of brain injury have demonstrated agents that may assist in the recovery process and those that may further slow recovery. We review further the issue of laboratory evidence and what is transferable to the clinic. Lastly, this chapter reviews published clinical pharmacotherapy studies or trials in the arena of arousal for those with clinical severe brain injury. We discuss limitations as well as findings and present the available evidence in a table-based format. While no clear evidence exists to suggest a defined and rigid pharmacotherapeutic approach, interesting data does suggest that several medications have been associated with enhanced arousal. Several studies are underway or about to begin that will shed more light on the utility of such agents in improving function after severe brain injury. For now, clinicians must employ their own judgment and what has been learned from the limited literature to the care of a challenging group of persons.

MRI patterns in prolonged low response states following traumatic brain injury in children and adolescents

OBJECTIVES

To explore the relationship between location and pattern of brain injury identified on MRI and prolonged low response state in children post-traumatic brain injury (TBI).

METHODS

This observational study compared 15 children who spontaneously recovered within 30 days post-TBI to 17 who remained in a prolonged low response state.

RESULTS

92.9% of children with brain stem injury were in the low response group. The predicted probability was 0.81 for brain stem injury alone, increasing to 0.95 with a regional pattern of injury to the brain stem, basal ganglia, and thalamus.

CONCLUSIONS

Low response state in children post-TBI is strongly correlated with two distinctive regions of injury: the brain stem alone, and an injury pattern to the brain stem, basal ganglia, and thalamus. This study demonstrates the need for large-scale clinical studies using MRI as a tool for outcome assessment in children and adolescents following severe TBI.

Open-label amantadine in children with attention-deficit/hyperactivity disorder

OBJECTIVES

The purpose of this study was to explore the possible efficacy and tolerability of amantadine in the treatment of attention-deficit/hyperactivity disorder (ADHD) in stimulant-naïve children.

METHODS

Twenty four children (5-13 years old) with Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) ADHD (4 inattentive, 2 hyperactive, and 18 combined type) entered a 6-week open-label treatment with amantadine (50-150 mg) given as a single morning dose. Parent and teacher ADHD rating scales and the parent Child Behavior Checklist (CBCL) were administered at baseline and at week 6.

RESULTS

Twenty three subjects completed the 6-week treatment. One child dropped out at week 2 because of persistent headache, and another 12 children reported adverse effects, most commonly transient appetite decrease. The parent ADHD score decreased from mean 41.04 +/- D 6.9 at baseline to 28.9 +/- 8.7 at week 6 (p < 0.001, effect size d = 1.5), and the teacher ADHD score from 35.8 +/- 9.6 to 26.2 +/- 9.5 (p < 0.001, effect size d = 1.0). Response rate (a 25% or greater decline in ADHD score) was 58% based on parents and 46% based on teachers.

CONCLUSIONS

These data suggest that amantadine has acceptable acute tolerability at single doses up to 150 mg/day and is possibly efficacious in decreasing ADHD symptoms, although its activity appears to be more modest than that of stimulant medications.