The perception of pain and its management in disorders of consciousness

Empirical comparison of deep learning models for fNIRS pain decoding

Introduction

Pain assessment is extremely important in patients unable to communicate and it is often done by clinical judgement. However, assessing pain using observable indicators can be challenging for clinicians due to the subjective perceptions, individual differences in pain expression, and potential confounding factors. Therefore, the need for an objective pain assessment method that can assist medical practitioners. Functional near-infrared spectroscopy (fNIRS) has shown promising results to assess the neural function in response of nociception and pain. Previous studies have explored the use of machine learning with hand-crafted features in the assessment of pain.

Methods

In this study, we aim to expand previous studies by exploring the use of deep learning models Convolutional Neural Network (CNN), Long Short-Term Memory (LSTM), and (CNN-LSTM) to automatically extract features from fNIRS data and by comparing these with classical machine learning models using hand-crafted features.

Results

The results showed that the deep learning models exhibited favourable results in the identification of different types of pain in our experiment using only fNIRS input data. The combination of CNN and LSTM in a hybrid model (CNN-LSTM) exhibited the highest performance (accuracy = 91.2%) in our problem setting. Statistical analysis using one-way ANOVA with Tukey's (post-hoc) test performed on accuracies showed that the deep learning models significantly improved accuracy performance as compared to the baseline models.

Discussion

Overall, deep learning models showed their potential to learn features automatically without relying on manually-extracted features and the CNN-LSTM model could be used as a possible method of assessment of pain in non-verbal patients. Future research is needed to evaluate the generalisation of this method of pain assessment on independent populations and in real-life scenarios.

Study protocol: Developing telephone follow-up scale for patients with disorders of consciousness

Background

The significant lack of rehabilitation prognostic data is the main reason that affects the treatment decision-making and ethical issues of patients with disorders of consciousness (DoC). Currently, the clinic's consciousness assessment tools cannot satisfy DoC patients' follow-up needs.

Objective

The purpose of this study is to construct a sensitive, professional, and simple telephone follow-up scale for DoC patients to follow up on the prognosis, especially the recovery of consciousness, of prolonged DoC patients transferred to community hospitals or at home.

Methods

This study is to adopt expert consultation to construct and to verify the validity and feasibility of the scale on-site.

Conclusion

At present, there is a strong demand for portable, accurate, and easily operated scales. It is helpful to improve the rehabilitation data of prolonged DoC patients and provide more basis for their treatment and rehabilitation.

Towards a New Assessment Tool for Caregivers of Patients with Disorders of Consciousness: The Social and Family Evaluation Scale (SAFE)

Monitoring the level of responsiveness of patients with Disorders of Consciousness (DoCs) represents an issue in all the settings where there is not the daily presence of clinicians, such as long-term and domestic settings. The involvement of patients’ informal caregivers (i.e., patients’ family) in such a monitoring process is thus fundamental. However, to date, no standardized tailored-made instruments exist that informal caregivers can use without the presence of clinicians, despite evidence illustrating the good accuracy of caregivers when expressing their opinions about the level of responsiveness of DoC patients. The present work aims to set the foundational knowledge, to create a standardized instrument that is able to assess the level of responsiveness of patients with DoCs by their informal caregivers. After selecting and modifying the items to be included in the new scale from the gold standard to diagnose DoCs (i.e., the Coma Recovery Scale-revised), and following a consensus process, we created the Social and Family Evaluation (SAFE) scale for caregivers of patients with DoCs. Although the SAFE needs a validation process, with the present work we provided its preliminary description along with insights into its clinical utility.

Pain in Persons with Disorders of Consciousness

Pain and suffering in persons with disorders of consciousness (DoC) remain poorly understood, frequently unaddressed or inadequately addressed, and controversial on numerous levels. This narrative literature review will address a number of critical issues germane to pain and suffering in this challenging group of patients, providing an introductory overview of the topic, perspectives on current knowledge regarding pain pathoanatomy and pathophysiology, and a review of common pain generators and factors that can lead to the chronifcation of pain. Caveats on bedside pain assessment challenges, as well as electrophysiologic and neuroimaging findings in these patients, will also be explored. Pain management techniques, including non-pharmacological and pharmacological, will be reviewed. Ethical considerations in the context of pain and suffering in persons with disorders of consciousness will round out the review prior to our concluding comments.

Consciousness Beyond Neural Fields: Expanding the Possibilities of What Has Not Yet Happened

In the field theories in physics, any particular region of the presumed space-time continuum and all interactions between elementary objects therein can be objectively measured and/or accounted for mathematically. Since this does not apply to any of the field theories, or any other neural theory, of consciousness, their explanatory power is limited. As discussed in detail herein, the matter is complicated further by the facts than any scientifically operational definition of consciousness is inevitably partial, and that the phenomenon has no spatial dimensionality. Under the light of insights from research on meditation and expanded consciousness, chronic pain syndrome, healthy aging, and eudaimonic well-being, we may conceive consciousness as a source of potential energy that has no clearly defined spatial dimensionality, but can produce significant changes in others and in the world, observable in terms of changes in time. It is argued that consciousness may have evolved to enable the human species to generate such changes in order to cope with unprecedented and/or unpredictable adversity. Such coping could, ultimately, include the conscious planning of our own extinction when survival on the planet is no longer an acceptable option.

The influence of the CRS-R score on functional outcome in patients with severe brain injury receiving early rehabilitation

Background

The aim of the study was to determine the role of the Coma Recovery Scale-Revised (CRS-R) in the prediction of functional status at the end of neurological early rehabilitative treatment.

Methods

Patients consecutively admitted to intensive or intermediate care units of a neurological rehabilitation center were enrolled in the study. Consciousness and functional status were assessed with the Coma Recovery Scale-Revised (CRS-R) and the Early Rehabilitation Barthel Index (ERBI), respectively. Both assessments were carried out weekly within the first month and at the end of early rehabilitation. Patient and clinical data were entered into a binary logistic regression model to predict functional status at discharge.

Results

327 patients (112 females, 215 males) with a median age of 63 years (IQR = 53–75) and a median disease duration of 18 days (IQR = 12–28) were included. Most patients suffered from stroke (59 %), followed by traumatic brain injury (31 %), and hypoxic ischemic encephalopathy (10 %). Upon admission, 12 % were diagnosed as comatose, 31 % as unresponsive wakefulness syndrome (UWS), 35 % as minimally conscious state (MCS) and 22 % already emerged from MCS (eMCS). Of all patients undergoing complete early rehabilitative treatment (n = 180), 72 % showed improvements in level of consciousness (LOC). In this group, age, initial CRS-R score and gains in CRS-R score after four weeks independently predicted functional outcome at discharge.

Conclusions

The study confirms the relevance of the CRS-R score for functional outcome prediction. High CRS-R scores and young age facilitate functional improvements and increase the probability to continue treatment in subsequent rehabilitation phases. Moreover, results indicate that recovery might occur over a period of time that extends beyond acute care.

Effects of intrathecal baclofen therapy in subjects with disorders of consciousness: a reappraisal

Baclofen is a structural analogue of gamma-amino-butyric acid (GABA), which reduces spastic hypertonia of striated muscle due to a mechanism of GABA_B-ergic inhibition of mono- and polysynaptic reflexes at the spinal level. There are reports of patients with severe disorders of consciousness that presented a substantial improvement following intrathecal baclofen (ITB) administration for severe spasticity. The neural mechanisms underlying the clinical recovery after ITB have not yet been clarified. Baclofen could modulate sleep-wake cycles that may be dysregulated and thus interfere with alertness and awareness. The diminished proprioceptive and nociceptive sensory inputs may relieve thalamo-cortical neural networks involved in maintaining the consciousness of the self and the world. ITB treatment might also promote the recovery of an impaired GABAergic cortical tone, restoring the balance between excitatory and inhibitory cortical activity. Furthermore, glutamatergic synapses are directly or indirectly modulated by GABA_B-ergic receptors. Neurophysiological techniques (such as transcranial magnetic stimulation, electroencephalography, or the combination of both) can be helpful to explore the effects of intrathecal or oral baclofen on the modulation of neural cortical circuits in humans with disorders of consciousness.

Development of a Measure of Nociception for Patients With Severe Brain Injury

OBJECTIVES

Severe brain injury is often accompanied by painful comorbidities and by concurrent limitations in the ability to report pain. Assessment of nociception aids diagnosis and helps balance reduction in suffering with avoidance of sedating medications. Existing assessment methods confound patients' level of consciousness with the intensity of nociception, complicating pain assessment as consciousness evolves. We sought to develop a measure of nociception that is independent of the level of consciousness.

MATERIALS AND METHODS

We identified 15 behavioral and physiological items likely to be sensitive to nociception. We rated noncommunicative patients with traumatic brain injury in 4 different activities predicted to modulate nociception, on each of 2 days, one randomly chosen for acetaminophen administration. The level of consciousness and level of agitation were also measured.

RASCH ANALYSIS

Rasch analysis was used to assess item fit to an underlying dimension of nociception.

RESULTS

Five items that demonstrated poor fit to the dimension were removed. The 10 remaining items demonstrated acceptable fit. Scores were significantly influenced by activity and analgesic treatment and were largely independent of measures of consciousness and agitation. Accurate scores could be obtained in about 10 minutes and were robust to missing data.

DISCUSSION

The results provide evidence that the Brain Injury Nociception Assessment Measure (BINAM) is reliable and feasible to administer. It can assess the intensity of nociception largely independent of the level of consciousness. Further research is warranted on the impact of BINAM use on the care of patients with severe traumatic brain injury.

Evidence of altered pressure pain thresholds in persons with disorders of consciousness as measured by the Nociception Coma Scale-Italian version

Pain assessment in patients with disorders of consciousness (DoC) is a controversial issue for clinicians, who require tools and standardised procedures for testing nociception in non-communicative patients. The aims of the present study were, first, to analyse the psychometric properties of the Italian version of the Nociception Coma Scale and, second, to evaluate pressure pain thresholds in a group of patients with DoC. The authors conducted a multi-centre study on 40 healthy participants and 60 DoC patients enrolled from six hospitals in Italy. For each group an electronic algometer was used to apply all nociceptive pressure stimuli. Our results show that the Italian version of the NCS retains the good psychometric properties of the original version and is therefore suitable for standardised pain assessment in clinical practice. In our study, pressure pain thresholds measured in a group of patients in vegetative and minimally conscious state were relatively lower than pain threshold values found in a group of healthy participants. Such findings motivate additional investigation on possible pain sensitisation in patients with severe brain injury and multiple co-morbidities, and on application of tailored therapeutic approaches useful for pain management in patients unable verbally to communicate their feelings.

Disorders of Consciousness: Painless or Painful Conditions?-Evidence from Neuroimaging Studies

The experience of pain in disorders of consciousness is still debated. Neuroimaging studies, using functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), multichannel electroencephalography (EEG) and laser-evoked potentials, suggest that the perception of pain increases with the level of consciousness. Brain activation in response to noxious stimuli has been observed in patients with unresponsive wakefulness syndrome (UWS), which is also referred to as a vegetative state (VS), as well as those in a minimally conscious state (MCS). However, all of these techniques suggest that pain-related brain activation patterns of patients in MCS more closely resemble those of healthy subjects. This is further supported by fMRI findings showing a much greater functional connectivity within the structures of the so-called pain matrix in MCS as compared to UWS/VS patients. Nonetheless, when interpreting the results, a distinction is necessary between autonomic responses to potentially harmful stimuli and conscious experience of the unpleasantness of pain. Even more so if we consider that the degree of residual functioning and cortical connectivity necessary for the somatosensory, affective and cognitive-evaluative components of pain processing are not yet clear. Although procedurally challenging, the particular value of the aforementioned techniques in the assessment of pain in disorders of consciousness has been clearly demonstrated. The study of pain-related brain activation and functioning can contribute to a better understanding of the networks underlying pain perception while addressing clinical and ethical questions concerning patient care. Further development of technology and methods should aim to increase the availability of neuroimaging, objective assessment of functional connectivity and analysis at the level of individual cases as well as group comparisons. This will enable neuroimaging to truly become a clinical tool to reliably investigate pain in severely brain-injured patients as well as an asset for research.

An Innovative Model of a Home-Like Environment for People in Vegetative and Minimally Conscious States

BACKGROUND AND PURPOSE

Many forms of assisted living have been proposed for people who have a loss of autonomy in activities of daily living. Despite the increasing prevalence of vegetative and minimally conscious states, no dedicated residential accommodation has been implemented for patients with chronic disorders of consciousness (DOCs).

METHODS

This is a descriptive study addressing an innovative model of in-house assistance, named Casa Iride, which has recently been implemented in the attempt to ensure health, safety, and well-being for people with DOCs and their families.

RESULTS

Our findings show that Casa Iride enables severely disabled individuals to live with dignity within a customized domestic environment. At the same time, it provides support for caregivers from both a practical and a psychological point of view.

CONCLUSIONS

The results so far indicate a virtuous cycle that brings health, social, psychological, ethical, and economic advantages: the individuals receive all the assistance needed; the families share a place with other people with similar challenges, become more aware of their situation, and learn to cope with it and to maintain their productivity at work; and the care flow of patients through intensive care units and intensive rehabilitation wards is not delayed by a lack of post discharge services.

Intrathecal baclofen: effects on spasticity, pain, and consciousness in disorders of consciousness and locked-in syndrome

Disorders of consciousness (DOCs) include coma, vegetative state (VS), and minimally conscious state (MCS). Coma is characterized by impaired wakefulness and consciousness, while VS and MCS are defined by lacking or discontinuous consciousness despite recovered wakefulness. Conversely, locked-in syndrome (LIS) is characterized by quadriplegia and lower cranial nerve paralysis with preserved consciousness. Intrathecal baclofen (ITB) is a useful treatment to improve spasticity both in patients with DOCs and LIS. Moreover, it supports the recovery of consciousness in some patients with VS or MCS. The precise mechanism underlying this recovery has not yet been elucidated. It has been hypothesized that ITB may act by reducing the overload of dysfunctional sensory stimuli reaching the injured brain or by stabilizing the imbalanced circadian rhythms. Although the current indication of ITB is the management of severe spasticity, its potential use in speeding the recovery of consciousness merits further investigation.