Pain issues in disorders of consciousness

Background: The assessment of pain and nociception in non-communicative patients with
disorders of consciousness (DOC) is a real challenge for clinicians. It is, therefore, important to
develop sensitive standardized tools usable at the bedside.
Objectives: This review aims to provide an overview of the current knowledge about pain
processing and assessment in patients with DOC.
Methods: A search was performed on PubMed using MeSH terms including vegetative state,
unresponsive wakefulness syndrome, minimally conscious state, consciousness disorders, pain,
nociception, neuroimaging and pain assessment.
Results: Neuroimaging studies investigating pain processing in patients with DOC and their
implication for clinicians are reviewed. Current works on the development of standardized and
sensitive tools for assessing nociception are described.
Conclusion: The suggested pain perception capacity highlighted by neuroimaging studies in
patients in a MCS and in some patients in a VS/UWS supports the idea that these patients need
analgesic treatment and monitoring. The first tool which has been developed to assess
nociception and pain in patients with DOC is the NCS. Its revised version represents a rapid,
standardized and sensitive scale which can be easily implemented in a clinical setting.
Complementary pain assessments are also under validation in order to offer more options to
clinicians.