Olfactory Bulb Volume Changes Research Articles

Effects of Endoscopic Sinus Surgery on Olfactory Bulb Volume among Patients with Chronic Rhinosinusitis: A Systematic Review and Meta-Analysis.

Endoscopic sinus surgery (ESS) could significantly improve olfactory function among patients with chronic rhinosinusitis (CRS). This study aimed to perform a meta-analysis to evaluate the effect of ESS on the olfactory bulb volume (OBV) among patients with CRS. A systemic search of PubMed, Medline, Embase, Web of Science, and other databases was conducted to identify studies assessing OBV changes in patients with CRS after ESS utilizing magnetic resonance imaging. A total of four studies with 168 participants were included. Comparing the changes in OBV of patients with CRS before and after surgery within 3-6 months, the ESS significantly improved the overall OBV (P = 0.005, I2 = 66%), with the left OBV increased by 5.57mm3 (P = 0.84, I2 = 0%), and the right OBV increased by 8.63mm3 (P = 0.09, I2 = 53%). A difference in OBV persists between healthy controls and patients with CRS 3-6 months after ESS. The overall OBV of patients with CRS after ESS was significantly smaller than controls (mean difference = -3.84, P = 0.04), with a mean difference of 4.13mm3 on the left side (P = 0.72, I2 = 0%), and a mean difference of 3.22mm3 on the right side (P = 0.0001, I2 = 89%). ESS significantly increases the OBV among patients with CRS.

Altered structural connectivity in olfactory disfunction after mild COVID-19 using probabilistic tractography

We aimed to investigate changes in olfactory bulb volume and brain network in the white matter (WM) in patients with persistent olfactory disfunction (OD) following COVID-19. A cross-sectional study evaluated 38 participants with OD after mild COVID-19 and 24 controls, including Sniffin' Sticks identification test (SS-16), MoCA, and brain magnetic resonance imaging. Network-Based Statistics (NBS) and graph theoretical analysis were used to explore the WM. The COVID-19 group had reduced olfactory bulb volume compared to controls. In NBS, COVID-19 patients showed increased structural connectivity in a subnetwork comprising parietal brain regions. Regarding global network topological properties, patients exhibited lower global and local efficiency and higher assortativity than controls. Concerning local network topological properties, patients had reduced local efficiency (left lateral orbital gyrus and pallidum), increased clustering (left lateral orbital gyrus), increased nodal strength (right anterior orbital gyrus), and reduced nodal strength (left amygdala). SS-16 test score was negatively correlated with clustering of whole-brain WM in the COVID-19 group. Thus, patients with OD after COVID-19 had relevant WM network dysfunction with increased connectivity in the parietal sensory cortex. Reduced integration and increased segregation are observed within olfactory-related brain areas might be due to compensatory plasticity mechanisms devoted to recovering olfactory function.

Changes in olfactory bulbus volume and olfactory sulcus depth in the chronic period after COVID-19 infection

Background Although there are a limited number of studies investigating the changes in olfactory bulb volume (OBV) and olfactory sulcus depth (OSD) values in the acute and subacute periods after COVID-19 infection, there are no studies conducted in the chronic period. Purpose The aim of this study is to reveal the changes in OBV and OSD after COVID-19 in the chronic period. Material and methods A total of 83 people were included in our study, including 42 normal healthy individuals (control group) and 41 patients with COVID-19 infection (10–12 months after infection). Results The COVID-19 group included 41 patients with the mean age 40.27 ± 14.5 years and the control group included 42 individuals with the mean age 40.27 ± 14.4. The mean OBV was 67.97 ± 14.27 mm3 in the COVID-19 group and 94.21 ± 7.56 mm3 in the control group. The mean OSD was 7.98 ± 0.37 mm in the COVID-19 group and 8.82 ± 0.74 mm in the control group. Left, right, and mean OBVs and OSD were significantly lower in patients with COVID- 19 than the control individuals (all p < .05). Conclusion Our findings show that COVID-19 infection causes a significant decrease in the OBV and OSD measurements in the chronic period.

Olfactory rehabilitation and olfactory bulb volume changes in patients after total laryngectomy: a prospective randomized study

IntroductionAfter total laryngectomy, decreased olfactory function and olfactory bulb volume shrinkage have been reported to occur due to olfactory deprivation caused by nasal airflow interruption. There is evidence that the olfactory system can be modulated by repeated exposure to odors in a procedure called olfactory training. However, it is not known whether any recovery of the lost olfactory bulb volume is possible by eliminating olfactory deprivation via olfactory rehabilitation long after laryngectomy. ObjectiveThis study examined the recovery of olfactory function and the change in olfactory bulb volume via long-term olfactory rehabilitation after total laryngectomy. MethodsPossible causes of olfactory dysfunction in the study participants were evaluated by collecting detailed anamnesis. As olfactory tests, orthonasal butanol threshold and odor discrimination tests were performed. Three-dimensional olfactory bulb volumes were calculated using manual segmentation on T2-weighted coronal magnetic resonance images. In olfactory rehabilitation, four different odors were applied to all patients orthonasally, using a larynx bypass technique for 30 min per day for 6 months. Olfactory tests were performed before the rehabilitation and after 6 months of rehabilitation, and olfactory bulb volume measurements were performed using magnetic resonance images. ResultsEleven patients diagnosed with advanced laryngeal cancer who underwent total laryngectomy and postoperative radiotherapy with a follow-up of 5–10 years were included in the study. All patients were male, and the mean age was 58.18 ± 4.17 years. In total laryngectomized patients, the olfactory bulb volumes measured on magnetic resonance images were 42.25 ± 12.8 mm3 before and 55.5 ± 11.22 mm3 after rehabilitation, and this increase was highly significant. Olfactory test scores were 2.3 ± 1.27 before and 4.39 ± 0.86 after rehabilitation, and this increase was also highly significant. ConclusionAs a result of the olfactory rehabilitation applied by providing orthonasal air flow, the olfactory function lost after total laryngectomy was improved considerably, and the olfactory bulb volume was significantly increased. The increase in olfactory bulb volume in total laryngectomy patients via olfactory rehabilitation to eliminate olfactory deprivation due to nasal airflow interruption was demonstrated for the first time in this prospective longitudinal study.

Radiological evidence to changes in the olfactory bulb volume depending on body mass index in the childhood

ObjectiveEnergy balance is preserved through the exchange between body weight and adipose tissue across the multi-faceted complex network that is composed of the sensorial, metabolic, and neuro-endocrine circuits. The olfactory control of energy homeostasis is maintained through the interplay between the olfactory bulb (OB) and adipose tissue. While extremely studied, most researches still report controversial results and sensorial regulation of obesity is not fully understood. This study aims to investigate the interplay between olfactory bulb volume (OBV) as a radiological clue of sensorial control and obesity in children. Subjects and methodChildren (n = 195) were classified into four groups based on body mass index (BMI) percentiles: normal weight (n = 89), overweight (n = 31), obese (n = 32) and morbidly obese (n = 43). OBV were calculated using MRI. ResultsMean OBV was higher in children with obesity than in those of normal weights. The means of OBV are found higher in the overweight and obese children (43.76 ± 9.50–49.29 ± 8.61 mm3) than in those of morbidly obese (38.23 ± 11.52 mm3) (p < 0.001). In overweight and obese children, a positive correlation were found between the BMI and OBV (roverweigh = 0.275-robese = 0.377), while in the morbidly obese group, there was a negative correlation (rseverelyobese = −0.445). ConclusionThis study reveals that OBV is higher in obese children. Also, it shows that there is a positive correlation between OBV and BMI in overweight and obese children and a negative correlation in the morbidly obese group. These radiological bimodal changes in OBV indicate that olfactory control acts to provide energy balance, mediated by positive in the overweight and obese children, negative feedback in the morbidly obese group.

Olfactory bulb volume changes associated with trans-sphenoidal pituitary surgery.

ObjectiveThe trans-sphenoidal approach is most frequently used for pituitary adenoma (PA) enucleation. However, effects of this surgery on neighboring structures have received little attention so far. In particular, no investigations on olfactory bulb (OB) anatomy after trans-sphenoidal surgery have been reported. Because impairment of olfaction has been shown in small groups following trans-sphenoidal surgery we hypothesized that the transnasal approach is likely to alter OB volume which is associated with changes of olfactory function.MethodsThe study comprised 33 patients with pituitary adenoma (14 women and 19 men, mean age 50 years). Comprehensive assessment of olfactory function was conducted with the "Sniffin' Sticks" test kit. Based on magnetic resonance imaging scans OBs were measured before and approximately one year after trans-sphenoidal PA enucleation.ResultsOwing to postoperative non-compliance and MRI artifacts partly due to drill friction complete evaluation of “Sniffin' Sticks” in term of obtaining the TDI score was possible pre- and postoperatively in 21 patients whereas OB volumes were available in 32 patients. Approximately one year after surgery olfactory function was not significantly different from baseline. However, left- and right-sided OB volume in patients treated via trans-sphenoidal surgery decreased (p = 0.001). The side of the surgical approach did not affect OB volume in a side-specific manner. Changes in odor threshold were significantly correlated to changes in right-sided OB volume (r = 0.45, p = 0.024).ConclusionOverall olfactory performance one year after surgery was not significantly different from baseline. However, changes in OB volume are associated with changes in olfactory performance and OB volumes decreased in patients.

Olfactory Bulb Volume Changes in Patients With Nasal Septal Deviation.

The olfactory bulb (OB) plays a pivotal role in the processing of olfactory information. The aim of this study was to investigate the OB volume changes and its possible associations with nasal septal deviation. Cross-sectional study. Otolaryngology Department of Bozok University School of Medicine and Neurology Department of Yozgat State Hospital. Ninety patient's cranial magnetic resonance imaging (MRI) studies (46 males and 44 females, mean age 36 ± 13.4 years; range 18-56 years) with isolated nasal septal deviations were recruited for the study. Olfactory bulb volumes in all study subjects were evaluated in T2-weighted coronal MRI images by planimetric manual contouring. Nasal septal deviation angles were found to range between 5° and 23.21° (mean 13.6° ± 3.58°). The right-sided deviations included 17 mild (<9°, Group I), 20 moderate (9°-15°, Group II), and 16 severe (15° and up, Group III) patients. The left-sided deviations included 14 mild (<9°, Group I), 13 moderate (9°-15°, Group II), and 10 severe (15° and up, Group III) subjects. Olfactory bulb volumes were calculated in both right- and left-sided deviation groups. In the patients with left-sided septal deviations of Groups I, II, and III, the left OB volumes of Groups I, II, and III were 46.49 ± 3.87, 47.46 ± 3.36, and 60.68 ± 5.65 mm and the right OB volumes were 53.37 ± 3.76, 56.47 ± 4.43, and 76.69 ± 6.84 mm, respectively. The statistical evaluation of the right OB volumes did not produce significant difference between Groups I and II (P = 0.73). The authors demonstrated statistically significant differences in comparison of Groups I to III and Groups II to III (P = 0.002 and P = 0.016, respectively). In the right septal deviation group for Groups I, II, and III, mean volumes of right OB volumes were 45.59 ± 4.46, 48.63 ± 3.78, and 61.35 ± 5.84 mm, respectively, and the left OB volumes were 54.67 ± 4.73, 57.65 ± 4.53, and 75.84 ± 7.67 mm, respectively. There was no statistically significant difference between Groups I and II (P = 0.95) left OB volumes in the right-sided deviation group, but statistically significant difference was demonstrated in Groups I to III and Groups II to III compartments (P = 0.002 and P = 0.003). In our study, while mild and moderate septal deviations lacked any significant affect on OB volumes, severe deviations were found to have significant impact on these parameter. Additionally the contralateral OB volumes in the severe septum deviation group were significantly bigger when compared to the ipsilateral OB volumes. Further multidisciplinary studies are required to evaluate the clinical significance of OB volume changes in diagnosis and follow-up of several otolaryngologic or nonotolaryngologic diseases.

Changes in olfactory bulb volume following lateralized olfactory training.

Repeated exposure to odors modifies olfactory function. Consequently, "olfactory training" plays a significant role in hyposmia treatment. In addition, numerous studies show that the olfactory bulb (OB) volume changes in disorders associated with olfactory dysfunction. Aim of this study was to investigate whether and how olfactory bulb volume changes in relation to lateralized olfactory training in healthy people. Over a period of 4months, 97 healthy participants (63 females and 34 males, mean age: 23.74±4.16years, age range: 19-43years) performed olfactory training by exposing the same nostril twice a day to 4 odors (lemon, rose, eucalyptus and cloves) while closing the other nostril. Before and after olfactory training, magnetic resonance imaging (MRI) scans were performed to measure OB volume. Furthermore, participants underwent lateralized odor threshold and odor identification testing using the "Sniffin' Sticks" test battery.OB volume increased significantly after olfactory training (11.3% and 13.1% respectively) for both trained and untrained nostril. No significant effects of sex, duration and frequency of training or age of the subjects were seen. Interestingly, PEA odor thresholds worsened after training, while olfactory identification remained unchanged.These data show for the first time in humans that olfactory training may involve top-down process, which ultimately lead to a bilateral increase in olfactory bulb volume.

Magnetic resonance imaging study; does the olfactory bulb volume change in major depression?

Abstract Goal: The olfactory region function disorders and olfactory bulb volume changes in neurodegenerative and neuropsychiatric disorders are defined. In this study, the olfactory bulb values of patients diagnosed with major depression in accordance with DMS-IV criteria, are measured with MRI, and these values are compared with the values of healthy volunteers to see if there are any statistically significant changes. Method: The study was carried out with 20 healthy volunteers and 20 patients who had been diagnosed with acute major depression in accordance with ‘diagnostic and statistical manual of mental disorders’ (DMS) IV criteria and have been getting treatment for more than 2 years in Istanbul Education and Research Hospital. 1,5 Tesla MRI were used in 40 cases, and the olfactory bulb volume on two hemispheres were measured separately. Results: Contrary to the former studies, we found no statistically significant difference between the olfactory bulb volume measurements of the control group and the group diagnosed with major depression.

Changes in Olfactory Bulb Volume in Parkinson's Disease: A Systematic Review and Meta-Analysis.

ObjectiveThe changes in olfactory bulb (OB) volume in Parkinson’s disease (PD) patients have not yet been comprehensively evaluated. The purpose of this meta-analysis was to explore whether the OB volume was significantly different between PD patients and healthy controls.MethodsPubMed and Embase were searched up to March 6, 2015 with no language restrictions. Two independent reviewers screened eligible studies and extracted data on study characteristics and OB volume. Additionally, a systematic review and meta-analysis using a random-effects model were conducted. Publication bias was determined by using funnel plots and Begg’s and Egger’s tests. Subgroup analyses were performed to assess possible sources of heterogeneity.ResultsSix original case-control studies of 216 PD patients and 175 healthy controls were analyzed. The pooled weighted mean difference (WMD) in the OB volume between the PD patients and the healthy participants was -8.071 for the right OB and -10.124 for the left OB; these values indicated a significant difference among PD patients compared with healthy controls. In addition, a significant difference in the lateralized OB volume was observed in PD patients, with a pooled WMD of 1.618; these results indicated a larger right OB volume than left OB volume in PD patients. In contrast, no difference in the lateralized OB volume was found in healthy controls. No statistical evidence of publication bias among studies was found based on Egger’s or Begg’s tests. Sensitivity analyses revealed that the results were consistent and robust.ConclusionsOverall, both the left and the right OB volume were significantly smaller in PD patients than in healthy controls. However, significant heterogeneity and an insufficient number of studies underscore the need for further observational research.

Relation of the volume of the olfactory bulb to psychophysical measures of olfactory function.

The aim of this review is to investigate whether changes in olfactory bulb volume relate to changes in specific olfactory functions. We studied currently available peer-reviewed articles on the volume of the human olfactory bulb that also included a psychophysical measure of olfactory function. In the present review, we observed a very clear and consistent correlation between general olfactory function and olfactory bulb (OB) volume. We were not able to find a clear relationship between a specific smell component and OB volume, even when analyzing pathologic conditions separately. In some cases, changes were observed for different subtests, but these changes did not significantly correlate with OB volume or had only a borderline correlation. In other cases, we found contradictory data. Several factors may contribute to the difficulties in finding correlations with the different components of smell: (1) the OB volume may be influenced by information from olfactory receptor neurons (bottom-up effect), information from central nervous system (top-down effect) and by direct damage; (2) most pathologic conditions affect more than one area of the olfactory pathway; (3) small sample sizes of hyposmic subjects were used. We believe that it is necessary to do further studies with larger numbers of subjects to answer the currently investigated question.

Olfactory bulb volume and olfactory function in patients with multiple sclerosis

Some studies reported olfactory dysfunction in patients with multiple sclerosis (MS). There is no agreement about the most suitable testing method for measuring olfactory function (OF) in MS patients. Recent studies showed that olfactory bulb volume changes with the degree of olfactory dysfunction. We assessed olfactory bulb volume of MS patients with magnetic resonance imaging (MRI) and related it to the OF. Volumetric measurements of the right and left olfactory bulb (OB) were performed by manual segmentation within 36 MS patients. Psychophysical testing of the orthonasal OF was performed using threshold-discrimination-identification (TDI) score in MS patients. Of all MS patients, 44.4% displayed olfactory dysfunction. The TDI score of all 36 MS patients, especially the score of the Identification subtest correlated strongly with neurological scores typical of MS. In patients with a decreased OB volume, there was a positive correlation between volumetry of the OB and OF. OB volumes may provide valuable information about MS patients with olfactory dysfunction. The TDI test and Identification subtest were very sensitive in detecting olfactory dysfunction in MS patients.

Reduced olfactory bulb volume in total laryngectomy patients: a magnetic resonance imaging study

The olfactory bulb (OB) is a remarkably plastic structure with highly active afferent neurons, which is partly reflected by its volume. Although deterioration of olfaction after total laryngectomy is reported by many patients, this problem has not received widespread attention. There has been no study that had addresses this loss olfactory ability as a function of OB volume. The aim of this study was to determine OB volume changes after laryngectomy. Twenty one patients post-total laryngectomy and 17 subjects with normal olfactory function underwent magnetic resonance imaging (MRI) for volumetric measurement of the OB. The history of all participants was taken in detail to exclude other possible causes of smell dysfunction. Volumetric measurement of the OB was performed by manual segmentation of the OB into coronal slices. Olfactory function was assessed with the orthonasal olfaction test. There was no statistically significant difference in volume between the right and left sides of the OB in the study and control groups. However, the study group had smaller OB volumes than the control group. In our assessment of orthonasal olfaction, patients who were post-total laryngectomy had worse orthonasal olfactory function than the control group. There were significant correlations between OB volumes and orthonasal test scores. Our MRI study showed that post-total laryngectomy patients had higher rates of olfactory bulb atrophy than the control subjects. Laryngectomy is associated with measurable decreases in olfactory function and this study hopes to further clarify this association by demonstrating that patients with total laryngectomy have reduced OB volumes when compared to the normal population.

Olfactory Bulb Volume in Patients with Sinonasal Disease

The aim of this study was to assess the volume of the olfactory bulb (OB) in patients with chronic rhinosinusitis (without nasal polyposis at the endoscopic evaluation) and to evaluate the correlation between this measure and the degree of sinonasal inflammation. Patients with sinonasal disease (SND; n = 22) were compared with healthy controls (n = 16) using orthonasal and retronasal olfactory test results and OB volumes measurement calculated by planimetric manual contouring using standardized methods. The Lund-Mackay score (originally described for CT scan) was also used to gauge sinonasal inflammation (SND score). The two groups were not significantly different in terms of age or distribution of sex. Patients had significantly higher right- and left-sided SND scores than controls. There was no significant group difference between patients and controls with regard to OB volume. However, patients with an SND score < or =12 had larger OB volumes than patients with higher SND scores (p < 0.001). Even when controlling for the subjects' age, a significant correlation was present between OB volume and SND score (r = -0.52; p = 0.001) with smaller OB volumes being associated with a higher degree of sinonasal pathology. OB volume correlated with the SND score, which is an indicator of the degree of sinonasal inflammation. SND patients with a slight decrease or even normal olfactory function may already exhibit changes in their OB volume. This study also seems to emphasize the idea that OB volume changes are more sensitive to subtle changes in the olfactory system than results from psychophysical testing.

Correlation of Olfactory Function With Changes in the Volume of the Human Olfactory Bulb

To investigate changes of olfactory bulb (OB) volume over time in relation to olfactory function. Prospective, before-after trial. Outpatient clinic of a university clinic for otorhinolaryngology. A total of 20 patients with olfactory loss participated in the study. The duration of olfactory deficits ranged from 3 months to 6 years. Olfactory function was assessed for phenyl ethyl alcohol odor threshold, odor discrimination, and odor identification. Olfactory bulb volume was determined using magnetic resonance imaging. In initially hyposmic patients (n = 13), changes in OB volume were found to correlate with odor threshold changes (r = 0.82; P = .001); no such correlation was found for odor discrimination or odor identification. As demonstrated in a longitudinal study for the first time to our knowledge, the human OB is a highly plastic structure that responds to individual changes in olfactory status.