1175 SLEEP-WAKE CYCLE AND EARLY NEUROLOGICAL RECOVERY AFTER MODERATE TO SEVERE TRAUMATIC BRAIN INJURY

Abstract

Introduction: We recently demonstrated that the sleep-wake cycle is severely altered in the acute stage of moderate to severe traumatic brain injuries (TBI). In general, these patients have short sleep and wake bouts dispersed over the 24 h. This study aimed to explore whether early markers of TBI severity predict acute sleep-wake cycle disturbances. Moreover, it aimed to verify the relationship between the sleep-wake cycle and the acute cognitive recovery. Method(s): We included 37 non-sedated patients (age 30 +/- 14 yo, 25 males) hospitalized for moderate to severe TBI. We used two severity markers that are available in the first hours following TBI, namely the initial Glasgow Coma Scale (GCS) score and the delay to recover the ability to sustain visual fixation. Once patients had reached medical stability, we used continuous actigraphy to document the sleep-wake cycle, and a consolidated sleep-wake cycle was defined by a daytime activity ratio > 80%. A short neuropsychological assessment was performed in a subsample of 13 patients. Correlation analyses were conducted between sleep-wake variables, TBI severity markers and performance on neuropsychological tests. Result(s): Patients had a median GCS score of 7 (range 3-13) and spent 6 +/- 6 days without visual fixation in the intensive care unit. Once patient had reached medical stability, they had 5 +/- 4 days of non-consolidated sleep-wake cycle. The number of days without sleep-wake cycle consolidation correlated with the initial GCS score (rho=0.35; p=0.04) and the delay before recovering visual fixation (r=0.45; p<0.01). Moreover, more altered sleep-wake cycle was associated with poorer performance on cognitive screening, episodic memory, language and logical reasoning tests carried before hospital discharge (r varying from -0.5 to -0.7, p<0.05, n=13). Conclusion(s): Our results support emerging evidence showing that early markers of TBI severity gathered in the first few hours after TBI can predict acute sleep-wake cycle alterations. The reappearance of consolidated sleep-wake cycle was associated with better cognitive recovery; still the directionality (or bidirectionality) of this relationship needs to be further investigated.