Pain assessment and management in disorders of consciousness

Pain and suffering controversies in persons with disorders of consciousness continue to be debated by the scientific, legal and medical ethics communities. This review examines the current knowledge base for guiding decisions regarding assessment and management of pain in persons with disorders of consciousness.

Studies have shown that brain processing linked to pain in persons in a vegetative state is incomplete and is processed only at a primary and not higher secondary level. Therefore, such painful stimuli would not reach the threshold for conscious experience. In contrast, persons in a minimally conscious state have been shown to have brain activation patterns to pain similar to controls. Therefore, these patients may have sufficient cortical integration and access to afferent information to allow for nociceptive stimuli to be consciously processed. Data to date do not allow for differentiation of the degree of any conscious pain experience or determination of whether individuals with disorders of consciousness are able to suffer.

Pain and suffering should be considered in all persons with disorders of consciousness and adequately treated. Behavioural assessment scales developed for patients unable to speak could be used to assess pain. Future studies should focus on methodologies for specific pain measures relevant to this unique and challenging patient population.