Retrospective analysis of sleep patterns in patients with chronic disorders of consciousness

Sleep in Disorders of Consciousness: A Brief Overview on a Still under Investigated Issue

Consciousness is a multifaceted concept, involving both wakefulness, i.e., a condition of being alert that is regulated by the brainstem, and awareness, a subjective experience of any thoughts or perception or emotion. Recently, the European Academy of Neurology has published international guidelines for a better diagnosis of coma and other disorders of consciousness (DOC) through the investigation of sleep patterns, such as slow-wave and REM, and the study of the EEG using machine learning methods and artificial intelligence. The management of sleep disorders in DOC patients is an increasingly hot topic and deserves careful diagnosis, to allow for the most accurate prognosis and the best medical treatment possible. The aim of this review was to investigate the anatomo-physiological basis of the sleep/wake cycle, as well as the main sleep patterns and sleep disorders in patients with DOC. We found that the sleep characteristics in DOC patients are still controversial. DOC patients often present a theta/delta pattern, while epileptiform activity, as well as other sleep elements, have been reported as correlating with outcomes in patients with coma and DOC. The absence of spindles, as well as REM and K-complexes of NREM sleep, have been used as poor predictors for early awakening in DOC patients, especially in UWS patients. Therefore, sleep could be considered a marker of DOC recovery, and effective treatments for sleep disorders may either indirectly or directly favor recovery of consciousness.

Study of Brain Circadian Rhythms in Patients with Chronic Disorders of Consciousness and Healthy Individuals Using Microwave Radiometry

The study of circadian rhythms in the human body using temperature measurements is the most informative way to assess the viability of the body’s rhythm-organizing systems. Pathological processes can affect circadian rhythm dynamics in damaged organs. Severe brain damage that caused the development of disorders of consciousness (DOC) (strokes, traumatic brain injury) disrupts the activity of central oscillators, by directly damaging or destroying the periphery links, and the level of preservation of circadian rhythms and the dynamics of their recovery can be informative diagnostic criteria for patient’s condition assessment. This study examined 23 patients with DOC by using a non-invasive method for obtaining body and cerebral cortex temperature to compare with healthy controls. Measurements were made with a 4 h interval for 52 h beginning at 08:00 on day 1 and ending at 08:00 on day 3. The profile of patients with DOC showed complete disruption compared to healthy controls with rhythmic patterns. The results indicate that the mechanisms for maintaining brain circadian rhythms are different from general homeostasis regulation of the body. Use of microwave radio thermometry for the identification of rehabilitation potential in patients with DOC is a promising area of investigation.