Fostering participation: Including animals in therapy for patients in a minimally conscious state

Minimally conscious states, which occur after severe brain injuries, represent a significant burden and can lead to long-term disability. Patients in minimally conscious states are a vulnerable patient group that needs early and effective treatments. Animal-assisted therapy is a possible treatment for minimally conscious patients and is applied for various reasons. The stimulation provided by animals is multisensory and emotional. Interactions with animals function nonverbally, and these situations are easy to understand. First studies have shown that animal-assisted therapy can increase active movements, awareness, and brain activity. However, the evidence base for animal-assisted therapy in treatments of minimally conscious states is minimal. We conducted three studies to better understand the effect of animal interaction on minimally conscious patients. First, we wanted to investigate how animal-assisted therapy affects behavior, physiological parameters, and the level of consciousness of minimally conscious patients. For this purpose, we conducted a randomized two-treatment multiperiod crossover study that measured patients during eight animal-assisted and eight conventional therapies (study I). Second, we were interested in the mechanisms involved in the interaction between minimally conscious patients and animals. For this purpose, we measured brain activity in two experimental studies with healthy adults and minimally conscious patients (studies II and III). We compared the responses to different forms of contact with a dog and a plush animal. We also analyzed patients’ heart rates and heart-rate variability in study III. The crossover study revealed that the minimally conscious patients showed more behavioral responses, more awareness, and higher physiological arousal in the animal-assisted therapy sessions compared to conventional sessions (study I). Healthy participants in the experimental study showed higher brain activity when interacting with a dog than with a plush animal. The closer the interaction with the dog or plush animal was, the higher the brain activity became. Minimally conscious patients also had increased brain activity with increased proximity to a dog or a plush animal. But the patients reacted equally strongly to the dog and the plush animal. However, the patients’ heart rates were higher during interaction with the dog than with the plush animal. The three studies indicate that interactions with animals have the potential to arouse minimally conscious patients physiologically and emotionally. This arousal allows these patients to participate more fully in therapy through a higher level of consciousness. The three studies make an important contribution to better understanding the influence of animals on minimally conscious patients. However, one of many new questions is how animal-assisted therapy should be delivered and which patients can benefit most from this therapy approach. More studies will be needed to enable a safe, evidence-based application of animal-assisted therapy in minimally conscious patients

Shining a Light on Awareness::A Review of Functional Near-Infrared Spectroscopy for Prolonged Disorders of Consciousness

Qualitative clinical assessments of the recovery of awareness after severe brain injury require an assessor to differentiate purposeful behavior from spontaneous behavior. As many such behaviors are minimal and inconsistent, behavioral assessments are susceptible to diagnostic errors. Advanced neuroimaging tools can bypass behavioral responsiveness and reveal evidence of covert awareness and cognition within the brains of some patients, thus providing a means for more accurate diagnoses, more accurate prognoses, and, in some instances, facilitated communication. The majority of reports to date have employed the neuroimaging methods of functional magnetic resonance imaging, positron emission tomography, and electroencephalography (EEG). However, each neuroimaging method has its own advantages and disadvantages (e.g., signal resolution, accessibility, etc.). Here, we describe a burgeoning technique of non-invasive optical neuroimaging—functional near-infrared spectroscopy (fNIRS)—and review its potential to address the clinical challenges of prolonged disorders of consciousness. We also outline the potential for simultaneous EEG to complement the fNIRS signal and suggest the future directions of research that are required in order to realize its clinical potential

Shedding Light on Hearing in Coma: Investigating the Applicability of Functional Near-infrared Spectroscopy for Assessing Auditory Function and Aiding Prognosis in Patients with Acute Disorders of Consciousness

There is a critical need for a bedside neuroimaging tool to aid in the prediction of functional recovery outcomes for patients with acute disorders of consciousness (DoC) in the early days following severe brain injury. Current neurobehavioral examinations and prognosis tools have limitations in predicting good outcomes, leading to potential mistreatment or premature withdrawal of life support. Functional near-infrared spectroscopy (fNIRS) is a viable candidate for such purposes due to its portability and cost-effectiveness. Auditory processing, viewed as a multi-level and multifaceted brain function, could provide a sensitive and specific marker of residual cognitive function in unresponsive patients. This study aimed to investigate the effectiveness of fNIRS for hierarchical assessment of auditory function and evaluate its applicability for predicting recovery outcomes in acute DoC. The capability of fNIRS for such an application was demonstrated by validating it against fMRI in a healthy population and cross-validating it in an entirely unresponsive patient with cognitive-motor dissociation. An innovative fNIRS-focused method was developed to quantify patients’ auditory function, and a data-driven method was explored to improve the sensitivity and specificity of auditory scores. Using these analytical tools, a direct association was found between auditory function and recovery outcome in a small patient cohort. Based on the study’s findings, the crucial role of methodological considerations in the use of fNIRS was discussed, and specific modifications in the stimulus and optical montage designs were suggested to enhance the method’s reliability

Near Infrared Spectroscopy and Electroencephalography For an Assessment of Brain Function in patients with Disorders of Consciousness

There is growing evidence that some of the patients presenting with the Vegetative State (VS), also known as Unresponsive Wakefulness State, can respond to environmental stimuli. This response can be detected by using functional brain imaging, including electroencephalography (EEG) or Near Infrared Spectroscopy (NIRS). By definition, the VS patients are awake but not aware, unlike the patients in the Minimally Conscious State (MCS), who have some fluctuating awareness. Since consciousness is impaired in both conditions, these states are also referred as Disorders of Consciousness (DOC) or prolonged Disorders of Consciousness (pDOC) This thesis aims to develop a bedside applicable tool using the EEG and NIRS for brain function assessment in VS and MCS patients. In this study, two experimental protocols have been developed and validated on healthy subjects. The results showed that using the motor imagery and own subject name stimuli, some of the VS patients were able to wilfully modulate their brain activity in response to those stimuli. The results presented in this thesis can be implemented as a part of a protocol for brain function assessment in pDOC patients and can be used for the further studies for better understanding of the brain function in these patients

Towards simultaneous electroencephalography and functional near-infrared spectroscopy for improving diagnostic accuracy in prolonged disorders of consciousness: a healthy cohort study

Qualitative clinical assessments of the recovery of awareness after severe brain injury require an assessor to differentiate purposeful behaviour from spontaneous behaviour. As many such behaviours are minimal and inconsistent, behavioural assessments are susceptible to diagnostic errors. Advanced neuroimaging tools such as functional magnetic resonance imaging and electroencephalography (EEG) can bypass behavioural responsiveness and reveal evidence of covert awareness and cognition within the brains of some patients, thus providing a means for more accurate diagnoses, more accurate prognoses, and, in some instances, facilitated communication. As each individual neuroimaging method has its own advantages and disadvantages (e.g., signal resolution, accessibility, etc.), this thesis studies on healthy individuals a burgeoning technique of non-invasive electrical and optical neuroimaging—simultaneous EEG and functional near-infrared spectroscopy (fNIRS)—that can be applied at the bedside. Measuring reliable covert behaviours is correlated with participant engagement, instrumental sensitivity and the accurate localisation of responses, aspects which are further addressed over three studies. Experiment 1 quantifies the typical EEG changes in response to covert commands in the absence and presence of an object. This is investigated to determine whether a goal-directed task can yield greater EEG control accuracy over simple monotonous imagined single-joint actions. Experiment 2 characterises frequency domain NIRS changes in response to overt and covert hand movements. A method for reconstructing haemodynamics using the less frequently investigated phase parameter is outlined and the impact of noise contaminated NIRS measurements are discussed. Furthermore, classification performances between frequency-domain and continuous-wave-like signals are compared. Experiment 3 lastly applies these techniques to determine the potential of simultaneous EEG-fNIRS classification. Here a sparse channel montage that would ultimately favour clinical utility is used to demonstrate whether such a hybrid method containing rich spatial and temporal information can improve the classification of covert responses in comparison to unimodal classification of signals. The findings and discussions presented within this thesis identify a direction for future research in order to more accurately translate the brain state of patients with a prolonged disorder of consciousness