Actigraphy in brain-injured patients – A valid measurement for assessing circadian rhythms?

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Actigraphy has received increasing attention in classifying rest-activity cycles. However, in patients with disorders of consciousness (DOC), actigraphy data may be considerably confounded by passive movements, such as nursing activities and therapies. Consequently, this study verified whether circadian rhythmicity is (still) visible in actigraphy data from patients with DOC after correcting for passive movements.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Wrist actigraphy was recorded over 7-8 consecutive days in patients with DOC (diagnosed with unresponsive wakefulness syndrome [UWS; <jats:italic>n</jats:italic>=19] and [exit] minimally conscious state [MCS/EMCS; <jats:italic>n</jats:italic>=11]). Presence and actions of clinical and research staff as well as visitors were indicated using a tablet in the patient’s room. Following removal and interpolation of passive movements, non-parametric rank-based tests were computed to identify differences between circadian parameters of uncorrected and corrected actigraphy data.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Uncorrected actigraphy data overestimated the <jats:italic>inter</jats:italic>daily stability and <jats:italic>intra</jats:italic>daily variability of patients’ activity and underestimated the deviation from a circadian 24h rhythm. Only 5/30 (17%) patients deviated more than 1h from 24h in the uncorrected data, whereas this was the case for 17/30 (57%) patients in the corrected data. When contrasting diagnoses based on the corrected dataset, stronger circadian rhythms and higher activity levels were observed in MCS/EMCS as compared to UWS patients. Day-to-night differences in activity were evident for both patient groups.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Our findings indicate that uncorrected actigraphy data overestimates the circadian rhythmicity of patients’ activity, as nursing activities, therapies, and visits by relatives follow a circadian pattern itself. Therefore, we suggest correcting actigraphy data from patients with reduced mobility.</jats:p></jats:sec>

A Heartbeat Away From Consciousness: Heart Rate Variability Entropy Can Discriminate Disorders of Consciousness and Is Correlated With Resting-State fMRI Brain Connectivity of the Central Autonomic Network

“…Furthermore, the preliminary results from an ongoing work investigating the day-to-night variations of the HRV in disorders of consciousness seem to indicate that the circadian cycle impacts directly the HRV, with more difference between groups being highlighted during the day. If this is confirmed on a bigger sample, this would indicate that ECG acquisition should be preferentially done during the day, as was done in our study ( 128 ).…”

Sleep and Circadian Disturbance in Disorders of Consciousness: Current Methods and the Way towards Clinical Implementation

“…However, without correction for activity not initiated by the patient, the presence of circadian rhythmicity in DoC patients might be overestimated. 67 Whereas 83% of patients show a circadian rhythm when not corrected for external movements, only 43% of DoC patients retain a circadian rhythm in their body movements after correction. This could highlight the limited circadian rhythmicity, especially in VS/UWS patients who still display it less than MCS patients.…”