Subjective and Objective Assessments of Post-traumatic Olfactory Dysfunction

Abstract

Introduction: Traumatic brain injuries are the most common cause of olfactory dysfunction. Deficits in olfaction may be conductive or neurosensory in nature, with varying degrees of impairment resulting in a diminished quality of life and an increased risk for personal injury among patients. The aim of this research is to evaluate the results of the subjective and objective quantitative examinations of olfactory function in a group of patients with post-traumatic anosmia in order to predict its value in identifying olfactory deficits in clinical practice. Materials and Methods: The present study included 38 patients who reported anosmia or hyposmia caused by a traumatic head injury, and a group of 31 age- and sex-matched controls without olfactory dysfunction or prior history of head injury. The comparison of odor perception and identification of two oils (mint and anise) was assessed with the use of blast olfactometry with cortical olfactory event-related potentials. Results: Subjective olfactory tests revealed anosmia or hyposmia in 94% of patients with head injury-related olfactory dysfunction. Objective tests revealed olfactory event-related potentials from cranial nerve I produced by the stimulation with both mint and anise in 20 patients (52.6%). Olfactory event-related potentials from cranial nerve V produced by the stimulation with mint were registered in 26 patients (68.4%). The lack of any responses, from both cranial nerve I and V, was found in 12 patients (32% of cases). Conclusions: Findings from our study indicate the application of both subjective and objective examinations in the evaluation of patients with olfactory impairment. In the diagnosis of post-traumatic anosmia or hyposmia, objective examinations are particularly useful when the patients' level of cognition may be impaired or when subjects may be exaggerating their olfactory defects for a secondary gain. The diagnosis of damage to the olfactory system, specifically in the receptive part of the olfactory pathway, can be established in patients who showed reduced amplitudes or absent cortical responses in addition to absent odor identification and perception threshold in the subjective examination.

The diagnostic value of the olfactory evaluation for congenital hypogonadotropic hypogonadism

“…Although olfactory event-related potentials (OERPs) are considered as the gold standard of olfactory function evaluation, they are rarely used in clinical practice because they are complex and time-consuming (11). The OB plays a relay station role in the processing of olfactory information.…”

Food Neophobia, Odor and Taste Sensitivity, and Overall Flavor Perception in Food

“…Also, in a study by Lo and colleagues [ 129 ], anise was found to be predictive of smell ability. In a study by Limphaibool et al [ 130 ], subjective olfactory tests revealed that 94% of subjects with olfactory dysfunction were not able to identify anise whereas all of the subjects in the control group, without olfactory dysfunction, were able to identify it.…”

Assessment and Scientific Progresses in the Analysis of Olfactory Evoked Potentials

“…Additionally, the analysis on the control group and the patient group showed higher OERP amplitudes and shorter latencies in healthy subjects compared with patients. More recently, in [ 52 ], comparing the perception of odors with traditional olfactometry and the amplitude of evoked potentials, the correlations between the two types of tests, subjective and objective, were evaluated in patients with post-traumatic anosmia. Results in [ 52 ] were in good agreement with the previous studies.…”

“…More recently, in [ 52 ], comparing the perception of odors with traditional olfactometry and the amplitude of evoked potentials, the correlations between the two types of tests, subjective and objective, were evaluated in patients with post-traumatic anosmia. Results in [ 52 ] were in good agreement with the previous studies. The authors demonstrated, also through the support of subjective tests, a marked reduction in the OERP amplitude or the total absence of the OERP component, possibly associated to a serious olfactory dysfunction.…”