Olfactory Discrimination in Disorders of Consciousness: A New Sniff Protocol

Brain Behav. 2019 Aug;9(8):e01273. doi: 10.1002/brb3.1273. Epub 2019 Jun 28.


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.

Keywords: Bayesian approach; disorders of consciousness; neuroimaging; olfactory test; vegetative state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bayes Theorem
  • Brain Injuries / complications
  • Consciousness Disorders* / diagnosis
  • Consciousness Disorders* / etiology
  • Consciousness Disorders* / physiopathology
  • Female
  • Functional Neuroimaging / methods*
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Olfaction Disorders* / diagnosis
  • Olfaction Disorders* / etiology
  • Olfactory Perception / physiology*
  • Point-of-Care Testing
  • Reproducibility of Results