Background: Behavioral assessment with the Coma Recovery Scale-Revised (CRS-R) is regarded as the gold standard for diagnosis of disorders of consciousness (DOC). Some patients diagnosed with the unresponsive wakefulness syndrome (UWS) based on CRS-R assessments, however, were shown to have signs of higher-level consciousness using electrophysiological and neuroimaging methods (Kondziella et al., 2016). This discrepancy could be due to the use of standard non-personalized stimuli in the key items of the scale. The benefits of including personalized stimuli in the CRS-R were shown in two recently published studies, one focusing on the assessment of auditory and visual items in UWS patients (Sternberg et al., 2018), and the other on a motor item in minimally conscious state (MCS) patients (Sun et al., 2018). 

Objective: We investigated whether personalized stimuli evoke better responses in DOC patients than standard CRS-R stimuli in the motor (object manipulation) and communication (non-functional: intentional) subscales. 

Methods: All DOC patients admitted to a neurorehabilitation hospital (Schoen Clinic Bad Aibling, Germany) between January and August 2018 (N=98) were assessed by experienced assessors every second week for the duration of their stay. Responses to personalized versus non-personalized stimuli were analyzed. Motor function subscale items were assessed by using personally relevant (e.g., pen, hair brush) and standard (tennis ball) objects during the same testing. Non-functional communication was assessed by asking patient-related (e.g., “Is your birthday in winter?”) vs. the standard (e.g., “Am I touching my nose right now?”) questions.

Results: 39 patients scored 4 or 5 (object manipulation possible but still MCS) on the motor subscale with personalized stimuli (mean age 60.3 ± 20.8 years; 20 men; 79 % non-traumatic and 21 % traumatic etiology). 46.2 % of these patients showed consistently a better response in object manipulation with personalized compared to non-personalized stimuli, whereas 38.5 % achieved consistently the same score. A consistent finding means the same response was found in each of the patient’s assessments. 15.3 % showed an inconsistent response. Similarly, 36 patients scored 1 (non-functional: intentional) on the communication subscale (mean age 56.9 ± 19.7 years; 16 men; 83 % non-traumatic and 17 % traumatic etiology). For the communication subscale, 77.8 % of patients obtained consistently a better score with personalized questions compared to non-personalized questions, and 11.1 % showed consistently no difference in performance. Mean number of assessments analyzed per patient was 6.4 ± 6.1 and 4.2 ± 3.9 in the motor and communication subscale, respectively.

Conclusion: Our results show that more responses can be consistently evoked with personalized than standard CRS-R stimuli. This difference was observed more frequently in the communication subscale. As data generated in clinical routine were analyzed in this study, we stress the need for further controlled experimental designs.

Personalized stimuli in the assessment of consciousness using the Coma Recovery Scale-Revised (CRS-R) in the motor and communication subscales