Possible applications for dopaminergic agents following traumatic brain injury: part 1

Transcranial direct current stimulation combined with amantadine in repetitive mild traumatic brain injury in rats

BACKGROUND

Balance and memory deficits are common in patients with repetitive mild traumatic brain injury (mTBI).

OBJECTIVE

To investigate the combined effects of amantadine and transcranial direct current stimulation (tDCS) on balance and memory in repetitive mTBI rat models.

METHODS

In this prospective animal study, 40 repetitive mTBI rats were randomly assigned to four groups: tDCS, amantadine, combination of amantadine and anodal tDCS, and control. The tDCS group received four sessions of anodal tDCS for four consecutive days. The amantadine group received four intraperitoneal injections of amantadine for four consecutive days. The combination group received four intraperitoneal injections of amantadine and anodal tDCS for four consecutive days. Motor-evoked potential (MEP), rotarod test, and novel object test results were evaluated before mTBI, before treatment, and after treatment.

RESULTS

All groups showed significant improvements in the rotarod and novel object tests, particularly the combination group. The combination group showed a significant improvements in duration (p < 0.01) and maximal speed in the rotarod test (p < 0.01), as well as an improvement in novel object ratio (p = 0.05) and MEP amplitude (p = 0.05) after treatment. The combination group exhibited a significant increase in novel object ratio compared to the tDCS group (p = 0.04). The GFAP integral intensity of the left motor cortex and hippocampus was the lowest in the combination group.

CONCLUSION

Combination treatment with amantadine and tDCS had positive effects on balance and memory recovery after repetitive mTBI in rats. Therefore, we expect that the combination of amantadine and tDCS may be a treatment option for patients with repetitive mTBIs.

Placebo-controlled trial of oral amantadine and zolpidem efficacy on the outcome of patients with acute severe traumatic brain injury and diffuse axonal injury

BACKGROUND

A constituent of diffuse axonal injury (DAI) is supposed to be present in about 1/3 of all severe traumatic brain injury (TBI) as specified by pathologic documents. Diffuse axonal injury is categorized by extensive injury to axons in the brain. A rise in the incidences of TBI, and the limited study to verified effect of drugs like amantadine and zolpidem in improving the consciousness levels of patients with acute traumatic brain injury with axonal injury enthused us to initiate this study in the acute TBI patients.

METHODS

In our randomized, controlled trial involving patients with acute severe TBI, we studied 66 patients in 3 groups. Group 1 (n=22) received oral amantadine, Group 2 (n=22) received oral zolpidem, whereas group 3 (n=22) received placebo, the first 8 days after injury respectively. The primary outcome measures included GCS (Glashow coma scale) through the initial admission, a complete medical history was recorded, and each patient had a meticulous physical and neurological investigation.

RESULTS

We found that the administration of amantadine in an acute phase after injury improved the rate of patients GCS and GOS (Glasgow Outcome Scale) compared with zolpidem and placebo groups, but without any significant statistical difference.

CONCLUSION

Our results has emphasized that because amantadine has intense biochemical effects on several ways, it appears to be beneficial in acute period after DAI-associated TBI.

Treating Disorders of Consciousness With Apomorphine: Protocol for a Double-Blind Randomized Controlled Trial Using Multimodal Assessments

Background: There are few available therapeutic options to promote recovery among patients with chronic disorders of consciousness (DOC). Among pharmacological treatments, apomorphine, a dopamine agonist, has exhibited promising behavioral effects and safety of use in small-sample pilot studies. The true efficacy of the drug and its neural mechanism are still unclear. Apomorphine may act through a modulation of the anterior forebrain mesocircuit, but neuroimaging and neurophysiological investigations to test this hypothesis are scarce. This clinical trial aims to (1) assess the treatment effect of subcutaneous apomorphine infusions in patients with DOC, (2) better identify the phenotype of responders to treatment, (3) evaluate tolerance and side effects in this population, and (4) examine the neural networks underlying its modulating action on consciousness. Methods/Design: This study is a prospective double-blind randomized parallel placebo-controlled trial. Forty-eight patients diagnosed with DOC will be randomized to receive a 30-day regimen of either apomorphine hydrochloride or placebo subcutaneous infusions. Patients will be monitored at baseline 30 days before initiation of therapy, during treatment and for 30 days after treatment washout, using standardized behavioral scales (Coma Recovery Scale-Revised, Nociception Coma Scale-Revised), neurophysiological measures (electroencephalography, body temperature, actigraphy) and brain imaging (magnetic resonance imaging, positron emission tomography). Behavioral follow-up will be performed up to 2 years using structured phone interviews. Analyses will look for changes in behavioral status, circadian rhythmicity, brain metabolism, and functional connectivity at the individual level (comparing before and after treatment) and at the group level (comparing apomorphine and placebo arms, and comparing responder and non-responder groups). Discussion: This study investigates the use of apomorphine for the recovery of consciousness in the first randomized placebo-controlled double-blind trial using multimodal assessments. The results will contribute to define the role of dopamine agonists for the treatment of these challenging conditions and identify the neural correlates to their action. Results will bring objective evidence to further assess the modulation of the anterior forebrain mesocircuit by pharmacological agents, which may open new therapeutic perspectives. Clinical Trial Registration: EudraCT n°2018-003144-23; Clinicaltrials.gov n°NCT03623828 (https://clinicaltrials.gov/ct2/show/NCT03623828).

Psychotropic Medication Use During Inpatient Rehabilitation for Traumatic Brain Injury

OBJECTIVE

To describe psychotropic medication administration patterns during inpatient rehabilitation for traumatic brain injury (TBI) and their relation to patient preinjury and injury characteristics.

DESIGN

Prospective observational cohort.

SETTING

Multiple acute inpatient rehabilitation units or hospitals.

PARTICIPANTS

Individuals with TBI (N=2130; complicated mild, moderate, or severe) admitted for inpatient rehabilitation.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Not applicable.

RESULTS

Most frequently administered were narcotic analgesics (72% of sample), followed by antidepressants (67%), anticonvulsants (47%), anxiolytics (33%), hypnotics (30%), stimulants (28%), antipsychotics (25%), antiparkinson agents (25%), and miscellaneous psychotropics (18%). The psychotropic agents studied were administered to 95% of the sample, with 8.5% receiving only 1 and 31.8% receiving ≥6. Degree of psychotropic medication administration varied widely between sites. Univariate analyses indicated younger patients were more likely to receive anxiolytics, antidepressants, antiparkinson agents, stimulants, antipsychotics, and narcotic analgesics, whereas those older were more likely to receive anticonvulsants and miscellaneous psychotropics. Men were more likely to receive antipsychotics. All medication classes were less likely administered to Asians and more likely administered to those with more severe functional impairment. Use of anticonvulsants was associated with having seizures at some point during acute care or rehabilitation stays. Narcotic analgesics were more likely for those with history of drug abuse, history of anxiety and depression (premorbid or during acute care), and severe pain during rehabilitation. Psychotropic medication administration increased rather than decreased during the course of inpatient rehabilitation in each of the medication categories except for narcotics. This observation was also true for medication administration within admission functional levels (defined by cognitive FIM scores), except for those with higher admission FIM cognitive scores.

CONCLUSIONS

Many psychotropic medications are used during inpatient rehabilitation. In general, lower admission FIM cognitive score groups were administered more of the medications under investigation compared with those with higher cognitive function at admission. Considerable site variation existed regarding medications administered. The current investigation provides baseline data for future studies of effectiveness.

Review of Awakening Agents

Brain injuries are a serious burden of illness to Canada and the US. Advances in managing head trauma have allowed more patients to emerge from decreased levels of consciousness and helped them cope with neurocognitive, neurobehavioural, and neuropsychiatric deficits. In this article, we review the current (1986-2002) evidence surrounding the pharmacological management of arousal states and the aforementioned neurological sequelae of head injury in either acute or chronic conditions. This article will review the evidence for the use of psychostimulants (methylphenidate), antidepressants (amitriptyline, selective serotonin reuptake inhibitors, and buproprion), Parkinson’s medications (amantadine, bromocriptine, carbidopa/levodopa), anticonvulsants (valproic acid), modafinil (Provigil), lactate, hyperbaric oxygen chamber, electroconvulsive therapy, and transmagnetic stimulation, in patients following a head injury. The review did not include all anticonvulsants, neuroleptics, beta-blockers, benzodiazepines, azospirones or cognitive enhancers. Unfortunately, the quality of the evidence is generally poor, and sometimes conflicting, which in turn results in indecisive guidelines for treating patients. Accepting the inherent flaws in the evidence we feel that this paper may serve as a stepping-stone for future researchers to improve data gathering that targets neurocognitive, neurobehavioural and neuropsychiatric symptoms following a head injury.

BPSD following traumatic brain injury

Annually, 700,000 people are hospitalized with brain injury acquired after traumatic brain injury (TBI) in Brazil.

OBJECTIVE

We aim to review the basic concepts related to TBI, and the most common Behavioral and Psychological Symptoms of Dementia (BPSD) findings in moderate and severe TBI survivors. We also discussed our strategies used to manage such patients in the post-acute period.

METHODS

Fifteen TBI outpatients followed at the Center for Cognitive Rehabilitation Post-TBI of the Clinicas Hospital of the University of São Paulo were submitted to a neurological, neuropsychological, speech and occupational therapy evaluation, including the Mini-Mental State Examination. Rehabilitation strategies will then be developed, together with the interdisciplinary team, for each patient individually. Where necessary, the pharmacological approach will be adopted.

RESULTS

Our study will discuss options of pharmacologic treatment choices for cognitive, behavioral, or affective disorders following TBI, providing relevant information related to a structured cognitive rehabilitation service and certainly will offer an alternative for patients and families afflicted by TBI.

CONCLUSION

Traumatic brain injury can cause a variety of potentially disabling psychiatric symptoms and syndromes. Combined behavioral and pharmacological strategies, in the treatment of a set of highly challenging behavioral problems, appears to be essential for good patient recovery.

Continuous subcutaneous apomorphine for severe disorders of consciousness after traumatic brain injury

BACKGROUND

The prognosis of long-term severe disorders of consciousness due to traumatic brain injury is discouraging. There is little definitive evidence of the underlying mechanisms, but a deficiency of the dopaminergic system may be involved.

METHODS

In a prospective open-labelled clinical study, the feasibility, relative efficacy and safety of continuous subcutaneous (s.c.) administration of apomorphine in Vegetative State (VS) or Minimally Conscious State (MCS) patients due to severe traumatic brain injury (TBI) was tested. Apomorphine was administered to eight patients. Outcome measures were the Coma Near-Coma Scale (CNCS) and Disability Rating Scale (DRS).

RESULTS

Drug management was implemented without any problems. There was improvement in the primary outcomes for all patients. Awakening was seen as rapidly as within the first 24 hours of drug administration and as late as 4 weeks. Seven of the patients had completely recovered consciousness. All improvements were sustained for at least 1 year, even after apomorphine was discontinued. Drug-related adverse events were all anticipated and resolved after the dose was reduced.

CONCLUSION

Based on this open-label pilot study, continuous s.c. apomorphine infusion appears to be feasible, safe and potentially effective in improving consciousness in patients in VS and MCS due to severe TBI.

Fast awakening from minimally conscious state with apomorphine

BACKGROUND

Traumatic brain injury (TBI) can induce long-term severe disorders of consciousness. Evidence suggests an underlying dopaminergic deficit. Dopamine agonists may therefore play an important role in recovery of consciousness.

OBJECTIVE

To explore the response to continuous subcutaneous administration of apomorphine in a patient who had remained in minimally conscious state for 104 days and to evaluate the anatomical substrate of the effect.

DESIGN

A prospective, open-label, daily treatment, dose-escalation single case clinical study, with retrospective diffusion tensor image (DTI) evaluation.

RESULTS

On the fist day of treatment, the patient was able to move his limbs on command and answer yes/no questions which had not been the case prior to apomorphine administration. Subsequently there was a full recovery of consciousness and substantial functional recovery that was sustained even after apomorphine discontinuation. At the highest dose, mild dyskinesias were observed. These resolved with a lowering of the dose. DTI demonstrated a decrease of thalamocortical and corticothalamic projections in this MCS patient compared to normal volunteers.

CONCLUSION

Although this is an open-label single-patient case report, the data are consistent with the theory that a dopaminergic deficit underlies MCS and that it may be overcome with apomorphine administration.

Dopamine D2-receptor-mediated increase in vascular and endothelial NOS activity ameliorates cerebral vasospasm after subarachnoid hemorrhage in vitro

INTRODUCTION

Cerebral vasospasm after subarachnoid hemorrhage (SAH) is a serious complication resulting in delayed neurological deficit, increased morbidity, mortality, longer hospital stays, and rehabilitation time. It afflicts approximately 35 per 100,000 Americans per year, and there is currently no effective therapy. We present in vitro data suggesting that increasing intrinsic nitric oxide relaxation pathways in vascular smooth muscle via dopaminergic agonism ameliorates cerebral vasospasm after SAH.

METHODS

Cerebrospinal fluid (CSF) from patients with cerebral vasospasm after SAH (CSF(V)) was used to induce vasospasm in porcine carotid artery in vitro. Dopamine was added to test its ability to reverse spasm, and specific dopamine receptor antagonists were used to determine which receptor mediated the protection. Immunohistochemical techniques confirmed the presence of dopamine receptor subtypes and the involvement of NOS in the mechanism of dopamine protection.

RESULTS

Dopamine receptor 1, 2, and 3 subtypes are all present in porcine carotid artery. Dopamine significantly reversed spasm in vitro (67% relaxation), and this relaxation was prevented by Haloperidol, a D(2)R antagonist (10% relaxation, P < 0.05), but not by D(1) or D(3)-receptor antagonism. Both eNOS and iNOS expression were increased significantly in response to CSF(V) alone, and this was significantly enhanced by addition of dopamine, and blocked by Haloperidol.

CONCLUSION

Cerebral vasospasm is significantly reversed in a functional measure of vasospasm in vitro by dopamine, via a D(2)R-mediated pathway. The increase in NOS protein seen in both the endothelium and vascular smooth muscle in response to CSF(V) is enhanced by dopamine, also in a D(2)R-dependent mechanism.

[Indications, efficacy and tolerance of drug therapy in view of improving recovery of consciousness following a traumatic brain injury]

OBJECTIVE

To review the literature about the indications, efficacy, limits and tolerance problems of drugs used with the aim of improving recovery of consciousness after a traumatic coma.

METHODS

Query using Medline, Embase, Neurosciences and Pascal databases. Thirty-two references were selected, including:articles proposing a synthesis of recent knowledge concerning neurotransmitters involved in vigilance, the pathophysiological mechanisms of impairment and the related pharmacology;clinical studies examining the efficacy of large categories of pharmacological agents (dopaminergic drugs, psychostimulants, tricyclic antidepressants and others) on vigilance and on alteration of consciousness following brain lesions.

RESULTS

The synthesis provides evidence about the theoretical actions and efficacy of the available pharmacological agents. The clinical studies are less convincing: indications and therapeutic choices are empirical. Studies report often single cases. Randomised studies are rare, often heterogeneous concerning the aetiology of the brain lesions. The evaluation scales are varied and too wide. In this context, amantadin, amphetamine, methylphenidate and bromocryptin showed some positive effects. Despite a pessimist general feeling, some cases of unexpected recovery as well as relapses during breaks in treatment were arguments in favour of the drug that was administered.

DISCUSSION/CONCLUSION

This review suggests that drug treatments for awakening might become a useful and perhaps even indispensable, complement in case management. It is therefore urgent to design multicentre studies in order to set rational indications and to develop realistic therapeutic protocols.

Amantadine to improve neurorecovery in traumatic brain injury-associated diffuse axonal injury: a pilot double-blind randomized trial

BACKGROUND

Traumatic brain injury (TBI) caused by a high-speed transportation accident results in a mechanism of injury commonly described as diffuse axonal injury (DAI), which is associated with a reduction in dopamine turnover in the brain. Because of its affect on both dopamine and N-methyl-D-aspartate (NMDA) channels, amantadine has been the subject of considerable interest and clinical use in acute TBI.

PARTICIPANTS

In this study, 35 subjects, who had a TBI in a transportation accident and were initially seen with a Glasgow Coma Scale score of 10 or less within the first 24 hours after admission, were randomly assigned to a double-blind, placebo-controlled, crossover design trial.

MAIN OUTCOME MEASURES

Amantadine, 200 mg, or placebo was each administered for 6 weeks (12 weeks total) to patients who were recruited consecutively.

RESULTS

There was an improvement in the Mini-Mental Status (MMSE) scores of 14.3 points (P =.0185), Disability Rating Scale (DRS) score of 9.8 points (P =.0022), Glasgow Outcome Scale (GOS) score of 0.8 points (P =.0077), and in the FIM Cognitive score (FIM-cog) of 15.1 points (P =.0033) in the group that received amantadine during the first 6 weeks (group 1), but there was no improvement in the second 6 weeks on placebo (P >.05). In group 2 (active drug second 6 weeks), there was an improvement in the MMSE of 10.5 points, in the DRS of 9.4 points (P =.0006), in the GOS of 0.5 points (P =.0231), and in the FIM-cog of 11.3 points (P =.0030, Wilcoxon signed rank) spontaneously in the first 6 weeks on placebo (P =.0015). However, group 2 gained a statistically significant additional 6.3 points of recovery in the MMSE (P =.0409), 3.8 points in the DRS (P =.0099), 0.5 points in the GOS (P =.4008), and 5.2 points in the FIM-cog (P =.0173, Wilcoxon signed rank) between the sixth week and the twelfth week of treatment on the active drug.

CONCLUSIONS

There was a consistent trend toward a more rapid functional improvement regardless of when a patient with DAI-associated TBI was started on amantadine in the first 3 months after injury.