The prognostic value of sleep patterns in disorders of consciousness in the sub-acute phase

OBJECTIVE: This study aimed to evaluate, through polysomnographic analysis, the prognostic value of sleep patterns, compared to other prognostic factors, in patients with disorders of consciousness (DOCs) in the sub-acute phase. METHODS: Twenty-seven patients underwent 24-h polysomnography and clinical evaluation 3.5±2months after brain injury. Their clinical outcome was assessed 18.5±9.9months later. Polysomnographic recordings were evaluated using visual and quantitative indexes. A general linear model was applied to identify features able to predict clinical outcome. Clinical status at follow-up was analysed as a function of the baseline clinical status, the interval between brain injury and follow-up evaluation, patient age and gender, the aetiology of the injury, the lesion site, and visual and quantitative sleep indexes. RESULTS: A better clinical outcome was predicted by a visual index indicating the presence of sleep integrity (p=0.0006), a better baseline clinical status (p=0.014), and younger age (p=0.031). Addition of the quantitative sleep index strengthened the prediction. CONCLUSIONS: More structured sleep emerged as a valuable predictor of a positive clinical outcome in sub-acute DOC patients, even stronger than established predictors (e.g. age and baseline clinical condition). SIGNIFICANCE: Both visual and quantitative sleep evaluation could be helpful in predicting clinical outcome in sub-acute DOCs.