Life can be worth living in locked-in syndrome

A brain-computer interface based on bilateral transcranial Doppler ultrasound

In this study, we investigate the feasibility of a BCI based on transcranial Doppler ultrasound (TCD), a medical imaging technique used to monitor cerebral blood flow velocity. We classified the cerebral blood flow velocity changes associated with two mental tasks - a word generation task, and a mental rotation task. Cerebral blood flow velocity was measured simultaneously within the left and right middle cerebral arteries while nine able-bodied adults alternated between mental activity (i.e. word generation or mental rotation) and relaxation. Using linear discriminant analysis and a set of time-domain features, word generation and mental rotation were classified with respective average accuracies of 82.9%10.5 and 85.7%10.0 across all participants. Accuracies for all participants significantly exceeded chance. These results indicate that TCD is a promising measurement modality for BCI research.

Emotional adjustment in amyotrophic lateral sclerosis (ALS)

Despite the devastating motor impairment, a significant number of patients with amyotrophic lateral sclerosis (ALS) maintain a good psychosocial adjustment. Here we investigated whether this is specific for ALS or a more general characteristic of terminal disease. Psychosocial adjustment was investigated in 30 ALS patients, 29 cancer patients in palliative treatment and 29 age-, gender- and level of education-matched healthy controls. Subjective quality of life (sQoL), degree of depressive symptoms and coping were evaluated as measures of psychosocial adjustment. Personality factors were described. ALS and cancer patients showed a good psychosocial adjustment. Subjective QoL and depression did not differ significantly. Both patient groups presented a good sQoL. The level of mild depressive symptoms in both patient groups was similar and none showed clinically relevant depression. ALS patients expressed fewer active coping strategies than cancer patients which were explained by gender differences. Both patient groups showed comparable psychosocial adjustment to their disease. Overall, in terminally ill patients the psychological response to the prognosis is not associated with neurobiological changes (e.g., associated with subclinical deficits in ALS) or with physical decline.

Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array

The ongoing pilot clinical trial of the BrainGate neural interface system aims in part to assess the feasibility of using neural activity obtained from a small-scale, chronically implanted, intracortical microelectrode array to provide control signals for a neural prosthesis system. Critical questions include how long implanted microelectrodes will record useful neural signals, how reliably those signals can be acquired and decoded, and how effectively they can be used to control various assistive technologies such as computers and robotic assistive devices, or to enable functional electrical stimulation of paralyzed muscles. Here we examined these questions by assessing neural cursor control and BrainGate system characteristics on five consecutive days 1000 days after implant of a 4 × 4 mm array of 100 microelectrodes in the motor cortex of a human with longstanding tetraplegia subsequent to a brainstem stroke. On each of five prospectively-selected days we performed time-amplitude sorting of neuronal spiking activity, trained a population-based Kalman velocity decoding filter combined with a linear discriminant click state classifier, and then assessed closed-loop point-and-click cursor control. The participant performed both an eight-target center-out task and a random target Fitts metric task which was adapted from a human-computer interaction ISO standard used to quantify performance of computer input devices. The neural interface system was further characterized by daily measurement of electrode impedances, unit waveforms and local field potentials. Across the five days, spiking signals were obtained from 41 of 96 electrodes and were successfully decoded to provide neural cursor point-and-click control with a mean task performance of 91.3% ± 0.1% (mean ± s.d.) correct target acquisition. Results across five consecutive days demonstrate that a neural interface system based on an intracortical microelectrode array can provide repeatable, accurate point-and-click control of a computer interface to an individual with tetraplegia 1000 days after implantation of this sensor.

A survey on self-assessed well-being in a cohort of chronic locked-in syndrome patients: happy majority, miserable minority

Objectives Locked-in syndrome (LIS) consists of anarthria and quadriplegia while consciousness is preserved. Classically, vertical eye movements or blinking allow coded communication. Given appropriate medical care, patients can survive for decades. We studied the self-reported quality of life in chronic LIS patients. Design 168 LIS members of the French Association for LIS were invited to answer a questionnaire on medical history, current status and end-of-life issues. They self-assessed their global subjective well-being with the Anamnestic Comparative Self-Assessment (ACSA) scale, whose +5 and -5 anchors were their memories of the best period in their life before LIS and their worst period ever, respectively. Results 91 patients (54%) responded and 26 were excluded because of missing data on quality of life. 47 patients professed happiness (median ACSA +3) and 18 unhappiness (median ACSA -4). Variables associated with unhappiness included anxiety and dissatisfaction with mobility in the community, recreational activities and recovery of speech production. A longer time in LIS was correlated with happiness. 58% declared they did not wish to be resuscitated in case of cardiac arrest and 7% expressed a wish for euthanasia. Conclusions Our data stress the need for extra palliative efforts directed at mobility and recreational activities in LIS and the importance of anxiolytic therapy. Recently affected LIS patients who wish to die should be assured that there is a high chance they will regain a happy meaningful life. End-of-life decisions, including euthanasia, should not be avoided, but a moratorium to allow a steady state to be reached should be proposed.

A brain-computer interface for long-term independent home use

Our objective was to develop and validate a new brain-computer interface (BCI) system suitable for long-term independent home use by people with severe motor disabilities. The BCI was used by a 51-year-old male with ALS who could no longer use conventional assistive devices. Caregivers learned to place the electrode cap, add electrode gel, and turn on the BCI. After calibration, the system allowed the user to communicate via EEG. Re-calibration was performed remotely (via the internet), and BCI accuracy assessed in periodic tests. Reports of BCI usefulness by the user and the family were also recorded. Results showed that BCI accuracy remained at 83% (r = -.07, n.s.) for over 2.5 years (1.4% expected by chance). The BCI user and his family state that the BCI had restored his independence in social interactions and at work. He uses the BCI to run his NIH-funded research laboratory and to communicate via e-mail with family, friends, and colleagues. In addition to this first user, several other similarly disabled people are now using the BCI in their daily lives. In conclusion, long-term independent home use of this BCI system is practical for severely disabled people, and can contribute significantly to quality of life and productivity.

Attitudes towards end-of-life issues in disorders of consciousness: a European survey

Previous European surveys showed the support of healthcare professionals for treatment withdrawal [i.e., artificial nutrition and hydration (ANH) in chronic vegetative state (VS) patients]. The recent definition of minimally conscious state (MCS), and possibly research advances (e.g., functional neuroimaging), may have lead to uncertainty regarding potential residual perception and may have influenced opinions of healthcare professionals. The aim of the study was to update the end-of-life attitudes towards VS and to determine the end-of-life attitudes towards MCS. A 16-item questionnaire related to consciousness, pain and end-of-life issues in chronic (i.e., >1 year) VS and MCS and locked-in syndrome was distributed among attendants of medical and scientific conferences around Europe (n = 59). During a lecture, the items were explained orally to the attendants who needed to provide written yes/no responses. Chi-square tests and logistic regression analyses identified differences and associations for age, European region, religiosity, profession, and gender. We here report data on items concerning end-of-life issues on chronic VS and MCS. Responses were collected from 2,475 participants. For chronic VS (>1 year), 66% of healthcare professionals agreed to withdraw treatment and 82% wished not to be kept alive (P < 0.001). For chronic MCS (>1 year), less attendants agreed to withdraw treatment (28%, P < 0.001) and wished not to be kept alive (67%, P < 0.001). MCS was considered worse than VS for the patients in 54% and for their families in 42% of the sample. Respondents' opinions were associated with geographic region and religiosity. Our data show that end-of-life opinions differ for VS as compared to MCS. The introduction of the diagnostic criteria for MCS has not substantially changed the opinions on end-of-life issues on permanent VS. Additionally, the existing legal ambiguity around MCS may have influenced the audience to draw a line between expressing preferences for self versus others, by implicitly recognizing that the latter could be a step on the slippery slope to legalize euthanasia. Given the observed individual variability, we stress the importance of advance directives and identification of proxies when discussing end-of-life issues in patients with disorders of consciousness.

Impaired conscious recognition of negative facial expressions in patients with locked-in syndrome

The involvement of facial mimicry in different aspects of human emotional processing is widely debated. However, little is known about relationships between voluntary activation of facial musculature and conscious recognition of facial expressions. To address this issue, we assessed severely motor-disabled patients with complete paralysis of voluntary facial movements due to lesions of the ventral pons [locked-in syndrome (LIS)]. Patients were required to recognize others' facial expressions and to rate their own emotional responses to presentation of affective scenes. LIS patients were selectively impaired in recognition of negative facial expressions, thus demonstrating that the voluntary activation of mimicry represents a high-level simulation mechanism crucially involved in explicit attribution of emotions.

Towards a user-friendly brain-computer interface: initial tests in ALS and PLS patients

OBJECTIVE

Patients usually require long-term training for effective EEG-based brain-computer interface (BCI) control due to fatigue caused by the demands for focused attention during prolonged BCI operation. We intended to develop a user-friendly BCI requiring minimal training and less mental load.

METHODS

Testing of BCI performance was investigated in three patients with amyotrophic lateral sclerosis (ALS) and three patients with primary lateral sclerosis (PLS), who had no previous BCI experience. All patients performed binary control of cursor movement. One ALS patient and one PLS patient performed four-directional cursor control in a two-dimensional domain under a BCI paradigm associated with human natural motor behavior using motor execution and motor imagery. Subjects practiced for 5-10min and then participated in a multi-session study of either binary control or four-directional control including online BCI game over 1.5-2h in a single visit.

RESULTS

Event-related desynchronization and event-related synchronization in the beta band were observed in all patients during the production of voluntary movement either by motor execution or motor imagery. The online binary control of cursor movement was achieved with an average accuracy about 82.1+/-8.2% with motor execution and about 80% with motor imagery, whereas offline accuracy was achieved with 91.4+/-3.4% with motor execution and 83.3+/-8.9% with motor imagery after optimization. In addition, four-directional cursor control was achieved with an accuracy of 50-60% with motor execution and motor imagery.

CONCLUSION

Patients with ALS or PLS may achieve BCI control without extended training, and fatigue might be reduced during operation of a BCI associated with human natural motor behavior.

SIGNIFICANCE

The development of a user-friendly BCI will promote practical BCI applications in paralyzed patients.

Diagnosing consciousness: neuroimaging, law, and the vegetative state

In this paper, we review recent neuroimaging investigations of disorders of consciousness and different disciplines' understanding of consciousness itself. We consider potential tests of consciousness, their legal significance, and how they map onto broader themes in U.S. statutory law pertaining to advance directives and surrogate decision-making. In the process, we outline a taxonomy of themes to illustrate and clarify the variance in state-law definitions of consciousness. Finally, we discuss broader scientific, ethical, and legal issues associated with the advent of neuroimaging for disorders of consciousness and conclude with policy recommendations that could help to mitigate confusion in this realm.