Pharmacological and electrical stimulation in chronic disorders of consciousness: New insights and future directions

Persistent vegetative state after severe cerebral hemorrhage treated with amantadine: A retrospective controlled study

Amantadine is currently recommended for use in patients of posttraumatic brain injury with unconsciousness. However, the application of amantadine in consciousness disturbance after cerebral hemorrhage has only been rarely reported. This allows for a further exploration of the role of amantadine in the treatment of PVS resulting from severe cerebral hemorrhage.Retrospective cohort study from 1/2015 to 7/2019 in Beijing Chaoyang hospital. We included adult patients treated with amantadine after severe cerebral hemorrhage in PVS. Primary outcome was time of consciousness recovery and Glasgow Out Scale scores after 5 months from onset. We compared characteristics and outcomes to a control cohort. matched on age, Coma Recovery Scale-Revised score, volume and location of hemorrhage.Among the 12 patients who received amantadine treatment, 6 patients regained consciousness (50%) after 5 months of disease onset, but were still severely disabled. Besides, the time for regaining consciousness was within 3 months of disease onset. The remaining 6 patients were still in a PVS. Compared with the amantadine group, the consciousness recovery rate (50% vs 33.3%, P = .68) after 5 months in the nested control group was not significantly different. The awakening time for patients in the amantadine group was earlier than the control group (100% vs 25%, P = .03).In this study, amantadine can accelerate the recovery of consciousness in patients following severe cerebral hemorrhage. We recommend further randomized controlled studies to determine the efficacy of amantadine.

The use of amantadine in patients with unresponsive wakefulness syndrome after severe cerebral hemorrhage

BACKGROUND

Amantadine is currently recommended for use in patients of post-traumatic brain injury with unresponsive wakefulness syndrome (UWS). However, the application of amantadine in UWS after cerebral hemorrhage has only been rarely reported. This allows for a further exploration of the role of amantadine in the treatment of UWS resulting from a severe cerebral hemorrhage.

METHODS

We observed the changes of seven patients with UWS of intracerebral hemorrhage after taking amantadine. We also carried out a detailed neurological examination of the patient with disorders of consciousness to include or exclude subjects for the study. CRS-R score was used to evaluate the neurological recovery.

RESULTS

An improvement in consciousness was observed within 3-6 days after the start of amantadine administration in all seven cases (n = 7/7; 100%). Five patients recovered conscious and left aphasia, hemiplegia and other sequelae, and two patients recovered from UWS to minimally conscious state (MCS).

CONCLUSIONS

In this study, amantadine administration showed substantial positive effects on recovery following severe cerebral hemorrhage. We recommend further randomized controlled studies to determine the efficacy of amantadine.

Effect of acoustic stimuli in patients with disorders of consciousness: a quantitative electroencephalography study

Auditory stimuli are proposed as beneficial neurorehabilitation methods in patients with disorders of consciousness. However, precise and accurate quantitative indices to estimate their potential effect remain scarce. Fourteen patients were recruited from the Neuro-Rehabilitation Unit of Hangzhou Hospital of Zhejiang Armed Police Corps of China. Altogether, there were seven cases of unresponsive wakefulness syndrome (five males and two females, aged 45.7 ± 16.8 years) and seven cases of minimally conscious state (six males and one female, aged 42.3 ± 20.8 years). Simultaneously, fourteen healthy controls (10 males and 4 females, aged 51.7 ± 9.7 years) also participated in this case-control experiment. Brain response to music, subjects’ own name, and noise was monitored by quantitative electroencephalography (QEEG) in the resting state and with acoustic stimulation. Predictive QEEG values in various brain regions were investigated. Our results show that cerebral activation was high in subjects stimulated by their own name, especially in the temporal lobe in patients with disorders of consciousness, and the frontal lobe in the control group. Further, during resting and stimulation, QEEG index (δ + θ/α + β ratio) negatively correlated with the Coma Recovery Scale-Revised score in traumatic disorders of consciousness patients. Hence, we speculate that a subject's own name might be an effective awakening therapy for patients with disorders of consciousness. Moreover, QEEG index in specific stimulation states may be used as a prognostic indicator for disorders of consciousness patients (sensitivity, 75%; specificity, 50%). This clinical study has been registered at ClinicalTrials.gov (identifier: NCT03385291).

Chronic disorders of consciousness

Over the last 20 years, studies have provided greater insight into disorders of consciousness (DOC), also known as altered state of consciousness. Increased brain residual functions have been identified in patients with DOC due to the successful application of novel next-generation imaging technologies. Many unconscious patients have now been confirmed to retain considerable cognitive functions. It is hoped that greater insight regarding the psychological state of patients may be achieved through the use of functional magnetic resonance imaging and brain-computer interfaces. However, issues surrounding the research and treatment of DOC remain problematic. These include differing opinions on the definition of consciousness, difficulties in diagnosis, assessment, prognosis and/or treatment, and newly emerging ethical, legal and social issues. To overcome these, appropriate care must be offered to patients with DOC by clinicians and families, as DOC patients may now be considered to live in more than just a vegetative state. The present article reviews the controversy surrounding the definition of consciousness and the reliability of novel technologies, prognostic prediction, communication with DOC patients and treatment methods. The ethical and social issues surrounding the treatment of DOC and future perspectives are also considered.

Neurologic complications of acute environmental injuries

Environmental injuries can result in serious neurologic morbidity. This chapter reviews neurologic complications of thermal burns, smoke inhalation, lightning strikes, electric injury, near drowning, decompression illness, as well as heat stroke and accidental hypothermia. Knowing the pathophysiology and clinical presentation of such injuries is essential to proper management of primary and secondary medical complications. This chapter highlights the most frequently encountered neurologic injuries secondary to common environmental hazards, divided into the topics: injuries related to fire, electricity, water, and the extremes of temperature.

Recovery from Chronic Diseases of Consciousness: State of the Art in Neuromodulation for Persistent Vegetative State and Minimally Conscious State

Chronic diseases of consciousness (CDC) can still be considered a challenging frontier for modern medicine, probably because of their not completely understood physiopathological mechanisms. Following encouraging evidence on cerebral hemodynamics, some authors have hypothesized a role for neuromodulation in the treatment of CDC patients. In the past 40 years, spinal cord stimulation (SCS) and deep brain stimulation (DBS) have been used experimentally for the treatment of patients in a severe altered state of consciousness, with some interesting but not conclusive results. The present review summarizes the data currently available in the literature on this particular and debated topic. On these grounds, further clinical studies are needed to better understand the altered dynamics of neuronal network circuits in CDC patients as a step towards novel therapeutic strategies.

Does Modafinil improve the level of consciousness for people with a prolonged disorder of consciousness? a retrospective pilot study

BACKGROUND AND AIM

Modafinil is best known as a sleep regulator among healthy individuals, but studies suggest that it reduces excessive daytime sleepiness in patients with brain injury. This retrospective pilot study evaluated the effectiveness of Modafinil for people with a prolonged disorder of consciousness and whether those with a traumatic brain injury did better than those with a non-traumatic brain injury.

METHOD

Twenty four prolonged disorder of consciousness patients who were prescribed Modafinil, were assessed at least four times both before and during treatment. The Coma Recovery Scale-Revised was used to determine if patients had a disorder of consciousness and the Wessex Head Injury Matrix was used to monitor behavior during baseline and treatment periods. Patients with a traumatic brain injury (N = 12) were compared with those with non-traumatic brain injury (N = 12). A chi-square test with significance at 0.05 was used and when frequencies were below 5 a Fisher's Exact Test was used.

RESULTS

Cognitive improvements were noted in domains of wakefulness, awareness, concentration, tracking and following commands. Significant differences were found for the whole group between baseline and Modafinil (x²=9.80; p = 0.002). Eleven of the 12 traumatic brain injury patients had higher Wessex Head Injury Matrix scores when on Modafinil (x²=8.33, p < 0.004). Six non-traumatic brain injury patients had higher scores with Modafinil, two had lower scores and four showed no change. There was no significant difference in the number of patients showing an increase compared to those showing a decrease (Fisher's exact test p = 0.29).

CONCLUSION

Modafinil appears to be beneficial for enhancing cognition in prolonged disorder of consciousness patients. Traumatic brain injury patients benefited more than non-traumatic brain injury patients. Implications for Rehabilitation People with prolonged disorders of consciousness are those in coma, a vegetative state or a minimally conscious state. Sensorimotor and neuromodulations (pharmacological and brain stimulation) are the available treatment strategies to this group. Modafinil promotes attention, concentration and maintains wakefulness in a patient with narcolepsy, obstructive sleep apnea and shift work sleep disorders. In a relatively small sample, this retrospective pilot study shows the effectiveness of Modafinil in conjunction with good care, suitable medications and multidisciplinary rehabilitation in enhancing arousal in prolonged disorders of consciousness patients.

Longitudinal changes in functioning and disability in patients with disorders of consciousness: the importance of environmental factors

Disorders of consciousness are neurological conditions associated with low levels of functioning which pose a serious challenge to public health systems. The current study aimed to examine longitudinal changes in functioning in patients with disorders of consciousness and to identify associated biopsychosocial factors using the International Classification of Functioning, Disability, and Health. An Italian sample of 248 patients was assessed longitudinally. Differences in relative variability (an index of change that controls for baseline levels) between acute and chronic patients and predictors of relative variability in "Activities &amp; Participation" were examined. Results showed that there were subgroups of patients whose functioning improved over time. The number of problems in "Activities &amp; Participation" decreased in acute patients over time, whereas in chronic patients, an increase was found. The significant difference in relative variability for the environmental factor "support and relationships" reflects the increase in facilitators in acute patients, whereas the number of facilitators in chronic patients remained unchanged over time. Age at event, time from event, and relative variability in "Environmental Factors" were significant predictors of relative variability in "Activities &amp; Participation". It is of clinical relevance that patients with disorders of consciousness are kept in a supportive and facilitative environment, in order to prevent a decline in their functioning. Moreover, caregivers should receive tailored support in order to enhance and facilitate appropriate care of patients with disorders of consciousness.

Clinical utility of brain stimulation modalities following traumatic brain injury: current evidence

Traumatic brain injury (TBI) remains the main cause of disability and a major public health problem worldwide. This review focuses on the neurophysiology of TBI, and the rationale and current state of evidence of clinical application of brain stimulation to promote TBI recovery, particularly on consciousness, cognitive function, motor impairments, and psychiatric conditions. We discuss the mechanisms of different brain stimulation techniques including major noninvasive and invasive stimulations. Thus far, most noninvasive brain stimulation interventions have been nontargeted and focused on the chronic phase of recovery after TBI. In the acute stages, there is limited available evidence of the efficacy and safety of brain stimulation to improve functional outcomes. Comparing the studies across different techniques, transcranial direct current stimulation is the intervention that currently has the higher number of properly designed clinical trials, though total number is still small. We recognize the need for larger studies with target neuroplasticity modulation to fully explore the benefits of brain stimulation to effect TBI recovery during different stages of recovery.

Pharmacotherapy for disorders of consciousness: are 'awakening' drugs really a possibility?

Disorders of consciousness, including the coma state, vegetative state and minimally conscious state, are among the least understood and least curable conditions in modern neurology. Structural or functional injuries may produce impairments in the neuronal circuits (the ascending reticular activating system and thalamocortical loops) responsible for maintaining the wakefulness state and awareness, associated with a change in neurotransmitter concentrations. Pharmacological agents that are able to restore the levels of neurotransmitters and, consequently, neural synaptic plasticity and functional connectivity of consciousness networks, may play an important role as drugs useful in improving the consciousness state. Currently, there is growing interest in the scientific community with regard to pharmacological agents that act on the gamma amino-butyric acid (GABA) system, such as zolpidem and baclofen, and monoamine systems, such as dopaminergic agents and some antidepressants. The purpose of this article is to provide a comprehensive overview of these potential 'awakening' drugs in patients with disorders of consciousness. The possible mechanisms by which these drugs may exert their effects in promoting recovery of consciousness are discussed, highlighting how many findings are often the result of sporadic events rather than prospective controlled trials or implementation of standard treatment guidelines.

Clinically significant response to zolpidem in disorders of consciousness secondary to anti-N-methyl-D-aspartate receptor encephalitis in a teenager: a case report

BACKGROUND

Anti-N-methyl-d-aspartate receptor encephalitis has been associated with a prolonged neuropsychiatric phase that may last for months to years.

PATIENT

We report the case of a 16-year-old girl who was diagnosed with anti-N-methyl-d-aspartate receptor encephalitis resulting from left ovarian mature teratoma 2 weeks after presentation with psychosis. Following tumor removal and immunotherapy, recovery from a minimally conscious state was accelerated significantly by zolpidem that was used for her sleep disturbance. Our patient was discharged home 8 weeks after admission with marked improvement in her neurological function. Zolpidem has been reported to improve arousal in disorders of consciousness but there are no previous reports of its benefit among patients with anti-N-methyl-d-aspartate receptor encephalitis.

CONCLUSION

Zolpidem would be a reasonable consideration as an adjunctive treatment in anti-N-methyl-d-aspartate receptor encephalitis after tumor removal and immunotherapy to accelerate recovery and rehabilitation.

Technology-based intervention programs to promote stimulation control and communication in post-coma persons with different levels of disability

Post-coma persons in a minimally conscious state and with extensive motor impairment or emerging/emerged from such a state, but affected by lack of speech and motor impairment, tend to be passive and isolated. A way to help them develop functional responding to control environmental events and communication involves the use of intervention programs relying on assistive technology. This paper provides an overview of technology-based intervention programs for enabling the participants to (a) access brief periods of stimulation through one or two microswitches, (b) pursue stimulation and social contact through the combination of a microswitch and a sensor connected to a speech generating device (SGD) or through two SGD-related sensors, (c) control stimulation options through computer or radio systems and a microswitch, (d) communicate through modified messaging or telephone systems operated via microswitch, and (e) control combinations of leisure and communication options through computer systems operated via microswitch. Twenty-six studies, involving a total of 52 participants, were included in this paper. The intervention programs were carried out using single-subject methodology, and their outcomes were generally considered positive from the standpoint of the participants and their context. Practical implications of the programs are discussed.

Modality-based organization of ascending somatosensory axons in the direct dorsal column pathway

The long-standing doctrine regarding the functional organization of the direct dorsal column (DDC) pathway is the "somatotopic map" model, which suggests that somatosensory afferents are primarily organized by receptive field instead of modality. Using modality-specific genetic tracing, here we show that ascending mechanosensory and proprioceptive axons, two main types of the DDC afferents, are largely segregated into a medial-lateral pattern in the mouse dorsal column and medulla. In addition, we found that this modality-based organization is likely to be conserved in other mammalian species, including human. Furthermore, we identified key morphological differences between these two types of afferents, which explains how modality segregation is formed and why a rough "somatotopic map" was previously detected. Collectively, our results establish a new functional organization model for the mammalian direct dorsal column pathway and provide insight into how somatotopic and modality-based organization coexist in the central somatosensory pathway.

Disorders of consciousness: responding to requests for novel diagnostic and therapeutic interventions

Severe brain injury can leave patients with chronic disorders of consciousness. Because of impaired responsiveness, many of these patients have traditionally been regarded as unaware. However, findings from recent clinical studies herald a potential paradigm shift: functional imaging and neurophysiological studies have identified ways to assess awareness and have revealed astounding cases of awareness despite clinical unresponsiveness. Hence, diagnostic classifications have been rewritten, prognostic knowledge is improving, and therapeutic studies have regained momentum, showing for the first time some therapeutic effects on responsiveness. Clinicians must increasingly respond to requests by patients' families and surrogate decision makers to use novel techniques for diagnosis, prognosis, and treatment, and in doing so several ethical and social issues need to be considered. Such requests provide an opportunity for clinicians to learn about patients' values and preferences and to maintain clinical acumen for changes in patient status with the patients' best interests in mind.

A learning assessment procedure as a test supplement for monitoring progress with two post-coma persons with a diagnosis of vegetative state

OBJECTIVE

Evaluating a learning assessment procedure for monitoring progress with two post-coma adults with a diagnosis of vegetative state.

METHOD

ABABCBCB and ABABCB designs were used for the two participants, with A representing baseline, B intervention and C control conditions. Participants' activation of an optic microswitch by eyelid closure produced stimulation during B phases.

RESULTS

One participant increased responding during B phases and decreased it during the C condition, suggesting a non-reflective minimal level of consciousness. She showed P300 and mismatch negativity responses and scored at the vegetative level on the Coma Recovery Scale-Revised (CRS-R). The other participant increased responding during the initial B phases without decline during the first (viable) part of the C condition, suggesting a pre-conscious level. He showed indistinct P300 and mismatch negativity responses and vegetative-level scores on the CRS-R.

CONCLUSION

Learning data seemed reconcilable with neurophysiological measures and more positive than CRS-R scores.

Transcranial focused ultrasound to the thalamus alters anesthesia time in rats

A pulsed application of focused ultrasound (FUS) to the regional brain tissue alters the state of tissue excitability and thus provides the means for noninvasive functional neuromodulation. We report that the application of transcranial FUS to the thalamus of anesthetized rats reduced the time to emergence of voluntary movement from intraperitoneal ketamine/xylazine anesthesia. Low-intensity FUS was applied to the thalamus of anesthetized animals. The times required for the animals to show distinct physiological/behavioral changes were measured and compared with those times required in a control session without sonication. The sonication significantly reduced the time to show pinch response and voluntary movement. The modulatory effects of FUS on anesthesia suggest potential therapeutic applications for disorders of consciousness such as minimally consciousness states.