Olfactory discrimination in disorders of consciousness: A new sniff protocol

Abstract Background The identification of salient stimuli useful for rehabilitation purposes is important in patients with disorders of consciousness (DOC): among these, olfactory stimuli might play an important role due to the functional coupling between olfactory and emotional processing. However, a high percentage of post brain injury patients present anosmia. Aims of the Study The aim of this pilot research is to present an innovative approach to test olfactory functions at the bedside using four selected odors in patients with DOC. Methods Sixteen patients with DOC were tested with two assessment techniques the new olfactory discrimination protocol (ODP) and a functional magnetic resonance imaging paradigm to evaluate olfactory neural process. The Frequentist and Bayesian methods were used to analyze reliability properties of the new tool. Results Analysis showed a good agreement between assessment techniques and a substantial test‐retest reliability of the ODP. Cohen's Ks were equal to 0.814 (95% CI = 0.471, 1) and 0.607 (0.118; 1) respectively, using the Frequentist approach, while they were 0.762 (95% HPD = 0.470; 0.966) and 0.650 (0.320; 0.913) with the Bayesian approach in the 11 patients analyzed. Conclusions Despite the limits of this preliminary research, the ODP can be useful for clinicians for the preliminary assessment of the olfactory discrimination in patients with DOC.