We investigated the relationship between three language-dependent behaviors (i.e., command-following, intelligible verbalization, and intentional communication) and the functional status of patients with disorders of consciousness (DoC). We hypothesized that patients in minimally conscious state (MCS) who retain behavioral evidence of preserved language function would have similar levels of functional disability, while patients who lack these behaviors would demonstrate significantly greater disability. We reasoned that these results could then be used to establish empirically-based diagnostic criteria for MCS+.
In this retrospective cohort study we included rehabilitation inpatients diagnosed with DoC following severe-acquired brain injury (MCS = 57; vegetative state/unresponsive wakefulness syndrome [VS/UWS] = 63); women: 46; mean age: 47 ± 19 years; traumatic etiology: 68; time post-injury: 40 ± 23 days). We compared the scores of the Disability Rating Scale score (DRS) at time of transition from VS/UWS to MCS or from MCS– to MCS+, and at discharge between groups.
Level of disability on the DRS was similar in patients with any combination of the three language-related behaviors. MCS patients with no behavioral evidence of language function (i.e., MCS–) were more functionally impaired than patients with MCS+ at time of transition and at discharge.
Command-following, intelligible verbalization, and intentional communication are not associated with different levels of functional disability. Thus, the MCS+ syndrome can be diagnosed based on the presence of any one of these language-related behaviors. Patients in MCS+ may evidence less functional disability compared to those in MCS who fail to demonstrate language function (i.e., MCS–).
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Coma recovery scale-revised
Disorders of consciousness
Disability rating scale
Minimally conscious state
Traumatic brain injury
Unresponsive wakefulness syndrome/vegetative state
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Dr. Aurore Thibaut is a FNRS is a post-doctoral research fellow and has been supported by the Wallonie Brussel International (WBI) scholarship, the Belgian American Educational Foundation (BAEF), and the Leon Fredericq Foundation. Dr. Bodien is supported by the National Institute on Disability, Independent Living and Rehabilitation Research (NIDILRR), Administration for Community Living (90DP0039, Spaulding-Harvard TBI Model System). Dr. Giacino received support from NIDILRR (90DP0039, Spaulding-Harvard TBI Model System) and the James S. McDonnell Foundation (Understanding Human Cognition-Collaborative). The authors thank the clinical staff at Spaulding Hospital Cambridge and Spaulding Rehabilitation Hospital for acquiring the clinical metrics used in this study.
Conflicts of interest
The authors report no conflict of interest.
The REDCap database was approved by the local Institutional Review Board. Data were acquired during routine clinical care by trained clinicians.
Electronic supplementary material
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Supplementary figure 2: DRS at transition and at discharge for non-TBI and TBI. DRS total scores (means and SEs) at transition from UWS to MCS– (black columns) or at transition from UWS or MCS– to MCS+ (grey columns) and at discharge for the same groups. The graph on the left shows the results for the non-TBI subgroup and the graph on the right shows the results for the TBI subgroup (JPG 86 kb)
Supplementary figure 3: DRS without the communication subscale at time of transition. DRS total scores removing the communication subscale (means and SEs) for each group at transition from UWS to MCS– (black column) or at transition from UWS or MCS– to MCS+ (six grey columns). A3 = command following; C1 = intentional communication; DRS= Disability Rating Scale, MCS = minimally conscious state minus; O3 = intelligible verbalization. Black asterisks represent statistical differences between groups (JPG 88 kb)
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Thibaut, A., Bodien, Y.G., Laureys, S. et al. Minimally conscious state “plus”: diagnostic criteria and relation to functional recovery. J Neurol 267, 1245–1254 (2020). https://doi.org/10.1007/s00415-019-09628-y
- Minimally conscious state
- Disorders of consciousness
- Coma recovery scale-revised
- Disability rating scale
- Intentional communication
- Intelligible verbalization