Post-traumatic Olfactory Dysfunction Research Articles

Olfactory function after mild traumatic brain injury in children-a longitudinal case control study.

The prevalence of posttraumatic olfactory dysfunction in children after mild traumatic brain injury ranges from 3 to 58%, with potential factors influencing this variation, including traumatic brain injury severity and assessment methods. This prospective longitudinal study examines the association between mild traumatic brain injury and olfactory dysfunction in children. Seventy-five pediatric patients with mild traumatic brain injury and an age-matched healthy control group were enrolled. Olfactory function was assessed using the Sniffin' Sticks battery, which focuses on olfactory threshold and odor identification. The study found that children with mild traumatic brain injury had impaired olfactory function compared with healthy controls, particularly in olfactory threshold scores. The prevalence of olfactory dysfunction in the patient group was 33% and persisted for 1yr. No significant association was found between traumatic brain injury symptoms (e.g. amnesia, loss of consciousness) and olfactory dysfunction. The study highlights the importance of assessing olfactory function in children after mild traumatic brain injury, given its potential impact on daily life. Although most olfactory dysfunction appears transient, long-term follow-up is essential to fully understand the recovery process. The findings add valuable insights to the limited literature on this topic and urge the inclusion of olfactory assessments in the management of pediatric mild traumatic brain injury.

Can MRI predict olfactory loss and improvement in posttraumatic olfactory dysfunction?

Although most patients with post-traumatic olfactory dysfunction (PTOD) undergo MRI, there is no consensus about its diagnostic or prognostic value. The aims were: 1) to classify the extent of post-traumatic neurodegeneration; 2) to determine its relationship with chemosensory dysfunction (smell, taste, trigeminal); and 3) to establish whether MRI can predict olfactory improvement. We conducted a retrospective cohort study based on a series of 56 patients with PTOD. All patients underwent validated psychophysical tests of their smell, taste, and trigeminal functions, otorhinolaryngologic evaluation, and MRI. An experienced radiologist blinded to patient data evaluated 40 chemosensory-relevant brain regions according to a four-point scale (0=no lesion to 3=large lesion). Follow up data after 4 years (on average) were available in 46 patients. The cluster analysis showed 4 brain lesion patterns that differed in lesion localization and severity. They are associated with diagnostic categories: anosmia, hyposmia and normosmia. Two clusters were highly specific for anosmia (100% specificity)and could accurately predict this condition (100% positive predictive value). No clusters were associated with trigeminal or taste dysfunction. Regarding improvement, 72.7% of patients in the cluster with mild lesions experienced subjective and measurable olfactory improvement whereas this was only the case in 21.7-37.5% of patients with larger lesions. The odds of subjective smell improvement were 5.9 times higher in patients within the milder cluster compared to larger ones. The analysis of brain lesions in PTOD allows corroboration of smell test results and prediction of subjective and measurable improvement.

Heterogeneous Damage to the Olfactory Epithelium in Patients with Post-Viral Olfactory Dysfunction.

Post-viral olfactory dysfunction (PVOD) is a neurogenic disorder caused by a common cold virus. Based on the homology of deduced amino acid sequences, olfactory sensory neurons (OSNs) in both mice and humans express either class I or class II odorant receptor genes encoding class I and class II OSNs. The purpose of this study was to determine whether OSN damage in PVOD occurs uniformly in both neuron types. The characteristics of PVOD patients were compared with those of patients with chronic rhinosinusitis (CRS) or post-traumatic olfactory dysfunction (PTOD). Briefly, subjects underwent orthonasal olfaction tests using five different odors (T&T odors) and a retronasal olfaction test using a single odor (IVO odor). The regions in the mouse olfactory bulb (OB) activated by the T&T and the IVO odors were also examined. Multivariate analysis of 307 cases of olfactory dysfunction (PVOD, 118 cases; CRS, 161 cases; and PTOD, 28 cases) revealed that a combination of responses to the IVO odor, but not to the T&T odors, is characteristic of PVOD, with high specificity (p < 0.001). Imaging analysis of GCaMP3 mice showed that the IVO odor selectively activated the OB region in which the axons of class I OSNs converged, whereas the T&T odors broadly activated the OB region in which axons of class I and class II OSNs converged. A response to T&T odors, but not IVO odor, in PVOD suggests that class I OSNs are injured preferentially, and that OSN damage in PVOD may occur heterogeneously in a neuron-type-dependent manner.

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.

Olfactory Dysfunction Following Moderate to Severe Traumatic Brain Injury: A Systematic Review and Meta-Analysis.

Reports of smell loss following traumatic brain injury (TBI) are a well-documented but understudied phenomenon. Given the broad consequences of olfactory loss, we characterized psychophysical olfactory dysfunction in individuals with moderate to severe TBI using systematic review and meta-analytic methods. Following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) protocol, five databases (PubMed, EMBASE, Cochrane Library, Web of Science, Scopus) were reviewed for studies investigating olfactory dysfunction in persons with moderate to severe TBI. Of the 5,223 studies reviewed, 19 met our inclusion criteria for the systematic review and 11 met inclusion criteria for meta-analysis. We calculated effect sizes (Hedges' g) to characterize the degree of olfactory dysfunction between patients with moderate to severe TBI and controls. A total of 951 moderate-severe TBI patients from 19 studies were included in the systematic review, which largely demonstrated poorer olfactory psychophysical performances in this patient population. Meta-analysis demonstrated a large effect size for olfactory dysfunction in moderate-severe TBI relative to healthy controls (g=-2.43, 95%CI: -3.16 < δ<-1.69). The magnitude of the effect was moderated by age and patient sex, with larger effect sizes associated with older age (following exclusion of a pediatric population) and larger compositions of women in the patient group. Moderate to severe TBI is associated with prominent olfactory dysfunction. Significant research gaps remain regarding the mechanism, recovery and natural history of olfactory dysfunction following moderate to severe TBI, which has significant clinical implications for the identification and treatment for those with post-traumatic olfactory dysfunction.

Gustatory dysfunction in patients with olfactory dysfunction and the associated factors.

Little is known about the occurrence of gustatory dysfunction (GD) in relation to different aetiologies of olfactory dysfunction (OD) as assessed by psychophysical chemosensory tests. The aim of this study was to analyse gustatory function in patients with OD and to investigate clinical factors associated with GD. A total of 742 individuals who underwent both olfactory and gustatory function tests at a tertiary medical centre from November 2019 to March 2021 were retrospectively enrolled. Olfactory and gustatory function were assessed by the YSK olfactory and gustatory function tests, respectively. Patients with OD were classified into four groups according to the aetiology: sinonasal disease, post-infection OD (PIOD), post-traumatic OD (PTOD), and others. Secondary outcomes included age, sex, smoking history, and alcohol history. Among the 488 patients with OD, 93 (19.1%) showed GD and 395 (80.9%) had normal gustatory function. Only 25 (9.8%) among 254 individuals with normosmia showed GD. Analyses of these frequencies revealed a significant association between OD and GD. In addition, the taste score was significantly lower in patients with OD than individuals with normosmia. The frequency of GD was significantly higher in patients with PTOD (53.6%) than in those with OD of other aetiologies (sinonasal disease, 6.7%; PIOD, 13.0%; others, 24.4%). In the multivariate analysis, age >=5 years and PTOD were associated with a high frequency of GD among patients with OD. The current study show that GD is significantly associated with OD. In particular, GD is more common in patients with PTOD than in those with OD of other aetiologies.

A study of depression, partnership and sexual satisfaction in patients with post-traumatic olfactory disorders

Post-traumatic olfactory dysfunction (PTOD) is associated with a significant decrease in quality of life. The present study aimed to explore whether PTOD is associated with depression and changes in sexuality. There were two groups in this case–control study. The patient group consisted of patients with PTOD (n = 55), and the control group comprised healthy individuals without the olfactory disorder (n = 115). Olfactory function, depression, partnership, and sexual satisfaction were assessed using the Iranian version of the Sniffin’ Sticks test (Ir-SST), Beck Depression Inventory (BDI), Enrich Couple Scale (ECS) and Sexual Satisfaction Scale for Women (SSSW). The BDI scores were higher in the patient group than in the control group (p < 0.001). The SSSW score was lower in the patient group than in controls (p < 0.01), although the ECS score was not significantly different between patients and controls. Also, there was no significant difference in the severity of trauma between marital satisfaction and sexual satisfaction. However, the analysis showed a statistically significant difference in depression scores in connection with the head trauma severity. In the PTOD group, depression was increased and sexual satisfaction declined. Understanding the association of olfactory dysfunction with depression and sexuality allows patients and doctors to deal with less notable consequences of this disorder.

Altered glucose metabolism of the olfactory-related cortices in anosmia patients with traumatic brain injury.

Impaired brain cortices contribute significantly to the pathophysiological mechanisms of post-traumatic olfactory dysfunction (PTOD). This study aimed to use 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to measure cerebral cortices' metabolism activity and then to explore their associations with olfaction in patients with PTOD. Ethics committee-approved prospective studies included 15 patients with post-traumatic anosmia and 11 healthy volunteers. Olfactory function was assessed using the Sniffin' Sticks. Participants underwent 18F-FDG PET/CT scan and the image data were collected for the voxel-based whole brain analysis. Furthermore, the standardized uptake value ratio (SUVR) of the whole brain regions was measured and correlated with olfactory function. Patients with post-traumatic anosmia showed significantly reduced glucose metabolism in bilateral rectus, bilateral superior and medial orbitofrontal cortex (OFC), bilateral thalamus, left hippocampus and parahippocampus and left superior temporal pole (all p < 0.001). In contrast, patients with post-traumatic anosmia had significantly increased glucose metabolism in the bilateral insula (all p < 0.001). SUVR values among a total of 17 cerebral cortices including frontal, limbic, and temporal regions were significantly and positively correlated with olfactory function. The cerebral cortices with the top three correlations were the right middle frontal OFC (r = 0.765, p = 0.001), right caudate (r = 0.652, p = 0.010) and right putamen (r = 0.623, p = 0.002). Patients with post-traumatic anosmia presented with distinct patterns of brain metabolism and key cortices that highly associated with the retained olfactory function were identified. The preliminary results further support the potential use of PET imaging for precisely assessing brain metabolism in patients with PTOD.

Effects of olfactory training on posttraumatic olfactory dysfunction: a systematic review and meta-analysis.

BackgroundPosttraumatic olfactory dysfunction is a clinical challenge due to refractory characteristics and limited therapeutic options. Olfactory training has been proved to be effective for olfactory dysfunction with varied etiologies. We pooled existing studies to evaluate the effects of olfactory training in patients with posttraumatic olfactory dysfunction.MethodsA systematic literature review using PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify studies assessing olfactory change in patients with posttraumatic olfactory dysfunction after olfactory training.ResultsOf the initial 812 abstracts reviewed, 13 full‐text articles were included. Clinically significant results after olfactory training were defined as an improvement of threshold, discrimination, and identification (TDI) score ≥6 or University of Pennsylvania Smell Identification Test (UPSIT) score ≥4. Six studies were included in the meta‐analysis, 36.31% (95% confidence interval [CI], 0.28 to 0.45) of posttraumatic patients would achieve clinically significant results after olfactory training with a mean increase of TDI score of 4.61.ConclusionOlfactory training might be a promising modality for the treatment of posttraumatic olfactory dysfunction. More high‐quality studies with controls are needed to clarify the effect of olfactory training on total olfactory performance and subcomponents of olfaction.

Imaging Features to Predict Response to Olfactory Training in Post-Traumatic Olfactory Dysfunction.

Prognosis of post-traumatic olfactory dysfunction is poor, with medical treatment options showing limited success rates. Olfactory training (OT) has been introduced as a potential therapeutic option in olfactory dysfunction. We aimed to identify the imaging features that would predict a better response to OT and create an imaging-based prognostic scale. We retrospectively reviewed 52 patients that underwent OT at our center for post-traumatic olfactory dysfunction. Olfactory functions at the time of initial presentation and at completion of OT were evaluated using Sniffin' Sticks test and threshold discrimination identification (TDI) scores were calculated. Patients were divided into responders (ROT group: 16 cases) and non-responders (n-ROT group: 36 cases) to OT based on TDI score change (cut-off 5.5 point). Morphological measurements of olfactory fossa, olfactory bulb volume and signal abnormalities, olfactory nerve filia integrity, siderosis, encephalomalacic changes in olfactory cortex, and other cortical regions were reviewed. There was no significant difference between the two groups in terms of age, gender distribution, olfactory dysfunction duration, head-trauma severity, and initial TDI scores. A model incorporating five variables: cribriform plate fracture, olfactory fossa depth (cut-off: 4.9 mm), olfactory bulb encephalomalacia, olfactory bulb volume (cut-off: 27.1 mm3 ), and siderosis was developed. This model had an area under the curve (AUC) of 0.950, and a cut-off value of 1 had 76.5% sensitivity and 97.1% specificity in prediction of response to OT. We developed an imaging-based scoring system with good specificity that can be used as an adjunctive tool for patient counseling, and optimal selection of management options. 4 Laryngoscope, 131:E2243-E2250, 2021.

Subjective and Objective Assessments of Post-traumatic Olfactory Dysfunction.

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.

Treatment of posttraumatic olfactory dysfunction with corticosteroids and olfactory training

Background: Few have investigated long-term effect of treatment of posttraumatic olfactory dysfunction (OD).Aims/objectives: To explore if sequential treatment with corticosteroids and olfactory training (OT) improved smell in patients with OD after moderate and severe traumatic brain injury (TBI).Material and methods: Twenty-two patients with persistent OD, mean 62 months after trauma, completed an open uncontrolled intervention study of treatment for 10 d with oral corticosteroids and thereafter for 3 months with OT twice daily. Olfaction was assessed by Sniffin’ Sticks. They were tested at four-time points, with the last assessment 12 months after baseline measurements.Results: Mean age at trauma was 45 (SD 14) years. Mean threshold, discrimination and identification (TDI) score at baseline was 14.4 (SD 7.3) and increased to mean 20.8 (SD 7.4) after 1 year (minimum −3.0; maximum 19.5, p value <.001). Analysed separately, each TDI component increased significantly after 1 year. Half of the patients (11/22) experienced a clinically significant improvement of ≥6.0 TDI points. Improvement was not associated with any sociodemographic or trauma-related characteristics or with olfactory function at baseline.Conclusions and significance: Treatment with corticosteroids and OT was promising in persistent OD after TBI and should be further studied.

4347 Bimodal Visual-Olfactory Training for Post-Surgical or Post-Traumatic Olfactory Dysfunction (VOLT Trial)

OBJECTIVES/GOALS: 1) Assess the patient-reported, perceived change in olfactory function after bimodal visual-olfactory training (OT) 2) Assess change in olfactory function after bimodal visual-olfactory training with a smell identification test 3) Assess which scents are most important to people with olfactory dysfunction (OD) METHODS/STUDY POPULATION: The participants are adults with subjective or clinically diagnosed OD with post-surgical or traumatic etiologies within the last 5 years. At the first of two study visits, participants complete the University of Pennsylvania Smell Identification Test (UPSIT) and complete general health (SF-36) and olfactory-related quality-of-life questionnaires. From a list of 34 scents, participants chose the 4 scents most important to them and smelled the scents twice daily for 3 months. Olfactory testing and the quality-of-life questionnaires were repeated at the final visit. RESULTS/ANTICIPATED RESULTS: 10 participants have enrolled in the study. There was one screen fail and one withdrawal. Six participants are currently undergoing OT and two have completed the study. Seven participants have post-surgical etiology and three have post-traumatic etiology of their OD. Of the two participants who have completed the study, one had an UPSIT score improvement from 25 to 33 out of the 40 questions correct. The minimally clinically important difference on the UPSIT is 4. She reports improvement subjectively. The second participant had a UPSIT score change from 25 to 24 and reports ability to smell is neither better nor worse. DISCUSSION/SIGNIFICANCE OF IMPACT: Traumatic and post-surgical, particularly post-transphenoidal hypophysectomy, are common etiologies of OD and no effective treatments exist. The results from our pilot study will help better inform the best way to undergo OT, how effective it is, and the planning of future studies.

Effects of olfactory training on resting-state effective connectivity in patients with posttraumatic olfactory dysfunction

The present study investigated if and how the smell training scheme affects resting‑state effective connectivity. We focused on connectivity among brain regions that participate in olfactory‑related processes, including the piriform cortex, amygdala, orbitofrontal cortex (OFC), insula, and cingulate cortex. Sixteen patients with posttraumatic olfactory dysfunctions between the ages of 18 and 36 years participated in this study. Olfactory performance of subjects was evaluated using the Sniffin' Sticks test kit and then, resting‑state functional magnetic resonance imaging (fMRI) was performed. Of the 16 participants, 8 underwent olfactory training for 16 weeks and the remaining 8 did not receive the treatment (the control group). After 16 weeks, participants in both groups underwent the same procedure (smell testing and the MRI examination). Olfactory performance scores were compared between groups using an independent samples t‑test. Spectral dynamic causal modeling was applied to resting‑state fMRI data to identify alterations in effective connectivity due to the smell training. We found that patients in the treatment group improved in the odor discrimination task and overall olfactory function as compared to the control group. Compared to the control group, patients in the treatment group had increased self‑inhibitory connectivity of the OFC and increased excitatory connectivity from the cingulate cortex to the insula. Moreover, the excitatory connectivity from the OFC to the cingulate cortex was found to be weaker following the olfactory training scheme. This study shows that a smell training scheme can cause changes in resting‑state effective connectivity parameters that can be attributed to improvements in the odor discrimination task.

Efficacy and associated factors of olfactory training in the treatment of olfactory dysfunction

Objective: To explore the clinical effects and the influence factors of olfactory training in the treatment of olfactory dysfunction. Methods: A total of 86 patients with olfactory dysfunction (49 post-infectious and 37 post-traumatic) in Beijing Anzhen Hospital during Dec 2016 to May 2017 were recruited in this prospective study. The clinical data of patients were analyzed, including gender, age, body mass index (BMI), course of disease, smoking history, drinking history, diabetes history, hypertension history, hyperlipidemia history, and anxiety visual analogue score (VAS). All patients were treated with olfactory training for 16 weeks, and all of them underwent Sniffin' Sticks olfactory test before and after treatment, which was evaluated by composite threshold-discrimination-identification score (TDI). SPSS 23.0 software, paired t test and univariate and multivariate Logistic regression analysis were used to analyze the data. Results: Eighty patients received treatment, including 46 post-infectious olfactory dysfunction and 34 post-traumatic olfactory dysfunction. After olfactory training, the total scores of TDI increased with statistically significant (18.3±8.6 vs 13.6±7.4, t=-6.158, P<0.05). The overall efficacy was 40% (32/80). The effective rate were 45.7% (21/46) in post-infectious olfactory dysfunction and 32.4% (11/34) in post-traumatic olfactory dysfunction respectively, with no statistically significant difference (χ(2)=1.441, P=0.230). Logistic regression analysis showed that the course of disease was an influence factor in the clinical curative effect (OR=0.881, 95%CI: 0.799-0.973, P=0.012). In patients with less than a year of olfactory dysfunction, the olfactory function improved obviously with the efficiency of 50.9% (29/57). Conclusion: Sixteen weeks of olfactory training provides a significant therapeutic effect on the post-infectious and post-traumatic olfactory dysfunction, and the olfactory training can achieve better therapeutic effects at the early stage.

Frequency and prognostic factors of olfactory dysfunction after traumatic brain injury

ABSTRACTObjective: To assess the frequency and factors associated with posttraumatic olfactory dysfunction, including anosmia, in a follow-up of patients with moderate and severe traumatic brain injury (TBI).Methods: The setting was a cross-sectional study of patients that were consecutively included in the Trondheim TBI database, comprising injury-related variables. Eligible participants 18–65 years were contacted 9–104 months post trauma and asked olfactory-related questions. Those reporting possible posttraumatic change of olfaction were invited to further examination using the Sniffin’ Sticks panel.Results: Of 211 eligible participants, 182 (86.3%) took part in telephone interviews and 25(13.7%) were diagnosed with olfactory dysfunction. 60% of these, or 8.2% of all participants, had anosmia. In age-adjusted logistic regression analyses, fall (OR 2.5, 95% CI 1.0–6.2), skull base fracture (OR 2.9, 95% CI 1.2–7.1) and cortical contusion(s) (OR 6.0, 95% CI 2.1–17.3) were associated with olfactory dysfunction. In an analysis of anosmia, fall (OR 3.4, 95% CI 1.1–10.6) and cortical contusion(s) (OR 19.7, 95% CI 2.5-156.0) were associated with the outcome.Conclusion: Of the study participants 13.7% had olfactory dysfunction and 8.2% had anosmia. Higher age, trauma caused by fall and CT displaying skull base fracture and cortical contusion(s) were related to olfactory dysfunction.

Morphological evaluation using MRI of the olfactory filaments (fila) in a post-traumatic olfactory rat model.

ObjectiveTo investigate whether magnetic resonance imaging (MRI) can be used to directly assess olfactory bulb (OB) lesions and quantify the associated morphological changes of olfactory filaments (OF), also known as fila, in an in vivo OB-lesion rat model of the brain.MethodsA surgical group (n = 5) of male Sprague–Dawley rats was subjected to the unilateral damage of the OB by a steel needle. The control group (n = 5) did not receive surgery. To assess olfactory system injury in vivo, T2-weighted MRI images were acquired in an oblique plane at a 30° angle from transverse plane one day after surgery. These brain regions were also assessed in the controls. The olfactory function was evaluated using the buried food pellet test (BFPT) 5 days before and after surgery.ResultsThe OF could be clearly observed on the MRI images from all animals. The left and right OF mean lengths (mm) were similar in the control group (0.81 ± 0.18 vs 0.89 ± 0.17, P > 0.05). In the surgical group, the OB was partially injured in all rats. These rats did not show differences in OF length between left- and right-side (0.83 ± 0.18 vs 0.93 ± 0.24, P > 0.05) at the time of measurement. The time (sec) required to find the food pellets in the BFPT was longer after than before the surgery (83.80 ± 34.37 vs 231.44 ± 53.23, P < 0.05).ConclusionsMicroMRI may be a feasible tool to evaluate the OF and OBs in rat models. The unilateral partial OB lesion model appears to be an effective post-traumatic olfactory dysfunction model.

Head trauma and olfactory function.

Olfactory impairment is a well-established sequela of head injury. The presence and degree of olfactory dysfunction is dependent on severity of head trauma, duration of posttraumatic amnesia, injuries obtained, and as more recently established, age. Deficits in smell can be conductive or neurosensory, contingent on location of injury. The former may be amenable to medical or surgical treatment, whereas the majority of patients with neurosensory deficits will not recover. Many patients will not seek treatment for such deficits until days, weeks, or even months after the traumatic event due to focus on more pressing injuries. Evaluation should start with a comprehensive history and physical exam. Determination of the site of injury can be aided by CT and MRI scanning. Verification of the presence of olfactory deficit, and assessment of its severity requires objective olfactory testing, which can be accomplished with a number of methods. The prognosis of posttraumatic olfactory dysfunction is unfortunate, with approximately only one third improving. Emphasis must be placed on identification of reversible causes, such as nasal bone fractures, septal deviation, or mucosal edema/hematoma. Olfactory loss is often discounted as an annoyance, rather than a major health concern by both patients and many healthcare providers. Patients with olfactory impairment have diminished quality of life, decreased satisfaction with life, and increased risk for personal injury. Paramount to the management of these patients is counseling with regard to adoption of compensatory strategies to avoid safety risks and maximize quality of life. Practicing otolaryngologists should have a thorough understanding of the mechanisms of traumatic olfactory dysfunction in order to effectively diagnose, manage, and counsel affected patients.

Factors Contributing to Therapeutic Improvement of Post-traumatic Olfactory Dysfunction

Factors Contributing to Therapeutic Improvement of Post-traumatic Olfactory Dysfunction

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.