Post-traumatic olfactory dysfunction: a scoping review of assessment and rehabilitation approaches

Post-traumatic Olfactory Dysfunction (PTOD) consists of a complete or partial loss of olfactory function that may occur after a traumatic brain injury (TBI). PTOD may be linked to some neuropsychiatric features, such as social, cognitive and executive dysfunction, as well as behavioral symptoms, especially when TBI involves the orbito-frontal cortex. The diagnosis of PTOD is based on medical history and clinical data and it is supported by psychometric tests (i.e., subjective tools) as well as electrophysiological and neuroimaging measures (i.e., objective methods). The assessment methods allow monitoring the changes in olfactory function over time and help to establish the right therapeutic and rehabilitative approach. In this context, the use of the olfactory training (OT), which is a non-pharmacological and non-invasive treatment option, could promote olfactory function through top-down (central) and bottom-up (peripheral) processes. To better manage patients with TBI, PTOD should be detected early and properly treated using the various therapeutic rehabilitative possibilities, both conventional and advanced, also taking into consideration the emerging neuromodulation approach.

[Differences in clinical features of post-traumatic olfactory dysfunction and non-post-traumatic olfactory dysfunction: a follow-up study]

Objective:To analyze the clinical features and recovery rate of post-traumatic olfactory dysfunction (PTOD) in Chinese adults in a case control follow-up study. Method:The clinical data of 202 patients who were diagnosed with olfactory dysfunction between January 2015 and December 2016 and followed up for 14 to 473 days were analyzed in this retrospective study. The patients were divided into those with PTODs (PTOD group) and those without PTODs (non-PTOD group). The two groups were compared with regard to age (years), sex, olfactory function (Sniffin' sticks), gustatory function (triple drop method), chemosensory evoked potentials, and magnetic resonance imaging (MRI) characteristics of olfactory pathways. The recovery rate of PTOD was evaluated by Sniffin' sticks and triple drop method. Result:Patients in the PTOD group (40±11 years) were significantly younger than those in the non-PTOD group (47±15 years), whereas the number of men and women was similar in both groups. The mean TDI score (Sniffin' sticks) was significantly different between the PTOD (12±5) and non-PTOD (19±8) groups (P<0.05). The mean oERP P2 latency was significantly shorter for the non-PTOD group (418±64 ms) than for the PTOD group (483±82 ms, P<0.05). There were no significant differences in the mean oERP N1 latency, N1 amplitude, P2 amplitude, mean tERP P2 latency and MRI between the two groups. After the follow-up period, 8.9% (5/56) and 5.4% (3/56) patients in the PTOD group exhibited an improvement in olfactory function and gustatory function, respectively. Conclusion:PTOD should be considered a type of disability that can lead to serious accidents, and an adequate understanding of its clinical features and etiologies is critical for appropriate diagnosis and treatment and for improving the prognosis of treatment. The rate of recovery of olfactory function is higher than that of gustatory function in patients with PTOD; further investigations are required in this regard.