Recent advances in disorders of consciousness: focus on the diagnosis

Abstract

Background: Over the last two decades, there has been a considerable increase in knowledge of brain function in patients with disorders of consciousness following a coma. Differentiating between patients in unresponsive wakefulness syndrome and in minimally conscious state still represents a major clinical, legal and ethical challenge.

Objectives: This review focuses on recent behavioural and neuroimaging studies in this specific population.

Results: The growing interest in the use of neuroimaging techniques as new diagnostic tools has stimulated research in this area and created further challenges to clinical categorization and management. This study proposes a diagnostic procedure combining the use of behavioural scales and neuroimaging techniques. In cases of dissociation between behavioural and ancillary test results, it is suggested that a diagnostic label of 'non-behavioural MCS' (MCS*) be used to provide a more clinically accurate diagnosis (and, in theory, prognosis) when the bedside exam shows no evidence of consciousness, yet the neurodiagnostic work-up does.

Conclusion: More neuroimaging research is needed before clinical implementation to reach the single-subject diagnosis level, as well as to address the sensitivity and specificity of each technique, whether single or combined.

Keywords: Clinical assessment; diagnosis; disorders of consciousness; minimally conscious state; neuroimaging techniques; unresponsive wakefulness syndrome; vegetative state.