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Review
. 2023 Mar 20:17:1112206.
doi: 10.3389/fnsys.2023.1112206. eCollection 2023.

Assessment and management of pain/nociception in patients with disorders of consciousness or locked-in syndrome: A narrative review

Estelle A C Bonin  1   2 , Nicolas Lejeune  1   3   4 , Emilie Szymkowicz  1   2 , Vincent Bonhomme  5   6 , Charlotte Martial  1   2 , Olivia Gosseries  1   2 , Steven Laureys  1   2   7 , Aurore Thibaut  1   2
Affiliations
Review

Assessment and management of pain/nociception in patients with disorders of consciousness or locked-in syndrome: A narrative review

Estelle A C Bonin et al. Front Syst Neurosci. .

Abstract

The assessment and management of pain and nociception is very challenging in patients unable to communicate functionally such as patients with disorders of consciousness (DoC) or in locked-in syndrome (LIS). In a clinical setting, the detection of signs of pain and nociception by the medical staff is therefore essential for the wellbeing and management of these patients. However, there is still a lot unknown and a lack of clear guidelines regarding the assessment, management and treatment of pain and nociception in these populations. The purpose of this narrative review is to examine the current knowledge regarding this issue by covering different topics such as: the neurophysiology of pain and nociception (in healthy subjects and patients), the source and impact of nociception and pain in DoC and LIS and, finally, the assessment and treatment of pain and nociception in these populations. In this review we will also give possible research directions that could help to improve the management of this specific population of severely brain damaged patients.

Keywords: disorders of consciousness; locked-in syndrome; nociception; pain; pain assessment; pain management; theories of pain.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Variation in diagnosis of patients with pathological states of consciousness according to the level of recovery of cognitive and motor functions. UWS, unresponsive wakefulness syndrome; MCS, minimally conscious state; LIS, locked-in syndrome; in red, patients able to process nociceptive inputs and able to experience pain; in blue, patients processing nociceptive inputs but without evidence of pain experience; in purple, patients able to process nociceptive inputs and having the (probable) neural basis for pain experience (created with BioRender.com, based on Thibaut et al. (2019) and recent empirical literature).
FIGURE 2
FIGURE 2
Ascending and descending nociceptive pathways (created with BioRender.com). Based on Brown et al. (2018).
FIGURE 3
FIGURE 3
Cortical and subcortical regions involved in the pain-related neuromatrix (created with BioRender.com). In healthy subjects and MCS or LIS patients the functional connections (red lines) are preserved whereas in “true” UWS patients the somatosensory cortex is activated in isolation [based on Bouhassira et al. (2005) and Bagnato et al. (2021)].
FIGURE 4
FIGURE 4
Pain treatment options in DoC and LIS patients (created with BioRender.com). Based on Posadzki and Ernst (2011), Klein et al. (2015), Chatelle et al. (2016), Vickers et al. (2018), Rice et al. (2019), Bicego et al. (2021), and de Pedro Negri et al. (2022).
See this image and copyright information in PMC

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