Olfactory Bulb Volume Research Articles

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 bulb volume in patients with normal-pressure hydrocephalus: an MRI evaluation

To investigate changes in olfactory bulb (OB) volume in patients with idiopathic normal-pressure hydrocephalus (NPH). This multicentric retrospective study included a test group of 23 patients with NPH (10 male and 13 female patients) and a control group of 27 healthy participants without hydrocephalus. The OB volume in all participants had been measured using cranial magnetic resonance imaging (MRI). In the NPH group, positivity for disproportionately enlarged subarachnoid space hydrocephalus (DESH) was also evaluated. The OB volumes of the NPH group (R 38.29±9.34 mm3 and L37.52±9.59 mm3) were significantly lower than those of the control group (R 45.87±7.33 mm3 and L48.41±7.62 mm3) bilaterally. There were no significant differences between right and left OB volumes in the NPH group. Nine of the 23 patients were DESH positive and 14 were DESH negative. There were no significant differences between OB volumes of the DESH positive and DESH vpatients in the NPH group. In both groups, there was a positive correlation between right and left OB volumes. There were no significant correlations between OB volumes and age or gender. In the NPH group, there were no significant correlations between DESH positivity and OB volumes. OB volume decrease and olfactory problems should be taken into account in idiopathic NPH patients. When expanded ventricles and decreased OB volume are observed at cranial MRI, a diagnosis of idiopathic NPH should be considered.

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.

Quantitative analysis of healthy olfactory sulcus depth, olfactory tract length and olfactory bulb volume in the paediatric population: a magnetic resonance study.

The aim of this study was to determine the normal reference values for olfactory sulcus depth, olfactory tract length and olfactory bulb volume in the paediatric population with routine magnetic resonance imaging (MRI) and determine the relationship, if any, between these values and patient sex and age. Ninety patients with a median age of 8 years (age range: 3-17 years), consisting of 45 males and 45 females with normal brain MRI scans were evaluated. The patients were divided into three subgroups based on age range, with n = 30 per subgroup; group 1: young children (3-6 years), group 2: children (7-11 years) and group 3: adolescents (12-17 years). In the cranial MRI examination of all groups, the right, left and total olfactory bulb volume values were measured in mm3, the right and left olfactory tract length values and the right and left olfactory sulcus depth values were calculated manually in mm. Demographic data including sex and age were recorded. There was no significant difference between the age groups in terms of sex. Right-left olfactory sulcus depth; right-left olfactory tract length and right-left total olfactory bulb volume values increased significantly when they are compared in terms of age groups (p < 0.0001, = 0.028; < 0.0001, < 0.0001; < 0.0001, < 0.0001; < 0.0001, respectively). There was no significant difference between right and left olfactory tract length and olfactory bulb volumes in all groups (p = 0.792 and p = 0.478), but the right olfactory sulcus depth was significantly larger than the left (p = 0.003). Especially as the age progresses, olfactory tract length and olfactory bulb volume dimensions of olfactory nerve and olfactory sulcus depth should be checked during diagnosis of respective illnesses in paediatric population.

Astrogliosis and sexually dimorphic neurodegeneration and microgliosis in the olfactory bulb in Parkinson\u2019s disease

Hyposmia is prodromal, and male sex is a risk marker for an enhanced likelihood ratio of Parkinson’s disease. The literature regarding olfactory bulb volume reduction is controversial, although the olfactory bulb has been largely reported as an early and preferential site for α-synucleinopathy. These pathological deposits have been correlated with neural loss in Nissl-stained material. However, microgliosis has rarely been studied, and astrogliosis has been virtually neglected. In the present report, α-synucleinopathy (α-synuclein), neurodegeneration (Neu-N), astrogliosis (GFAP), and microgliosis (Iba-1) were quantified, using specific markers and stereological methods. Disease, sex, age, disease duration, and post-mortem interval were considered variables for statistical analysis. No volumetric changes have been identified regarding disease or sex. α-Synucleinopathy was present throughout the OB, mainly concentrated on anterior olfactory nucleus. Neurodegeneration (reduction in Neu-N-positive cells) was statistically significant in the diseased group. Astrogliosis (increased GFAP labeling) and microgliosis (increased Iba-1 labeling) were significantly enhanced in the Parkinson’s disease group. When analyzed per sex, neurodegeneration and microgliosis differences are only present in men. These data constitute the demonstration of sex differences in neurodegeneration using specific neural markers, enhanced astrogliosis and increased microgliosis, also linked to male sex, in the human olfactory bulb in Parkinson’s disease.

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.

First histopathological bridging of the distance between Onuf's nucleus and substantia nigra after olfactory bulbectomy-new ideas about the urinary dysfunction in cerebral neurodegenerative disease: an experimental study.

Olfactory bulbectomy (OBX) in experimental studies induces neurochemical, neurodegenerative changes in various parts of the body. But no information is available about how OBX affects the spinal cord in rats. Our study aims to investigate this question. Twenty-eight male rats were used. The rats were divided into three groups: six as the control, six as the SHAM, and 16 as the study group in which OBX was performed. The animals were followed for 10 weeks. After decapitation of the animals, olfactory bulb (OB) volumes, the olfactory glomerulus (OG), and the neuron density of the ON (Onuf nucleus) per cubic centimeter at the L4-S4 level were examined histopathologically and analyzed stereologically. The mean OB volume, remaining normal OG density, and degenerated neuron density (DND) of the ON was measured as 4.32 ± 0.21/mm3 , 1842 ± 114/mm3 , and 4 ± 1/mm3 in the control (group I); 3.3 ± 0.14/mm3 , 1321 ± 114/mm3 , and 43 ± 8/mm3 in the SHAM (group II); and 1.672 ± 0.12/mm3 , 852 ± 93/mm3 , and 154 ± 11/mm3 in the study group (group III). There was a statistically significant difference between the SHAM and the study group (P < .05). In this study, histopathological bridging between ON-related lower urinary tract symptoms (LUTS) and OBX was shown the first time. According to the findings, LUTS may be reversed by the protection of the affected spinal cord through the correction of olfaction impairment in neurodegenerative disease.

Reduced Olfactory Bulb Volume in Obesity and Its Relation to Metabolic Health Status.

Smell perception plays an important role in eating behavior and might be involved in body weight gain. Since a body of literature implies that olfactory perception and function is hampered in obesity, we here investigate neuroanatomical correlates of this phenomenon. We assessed olfactory bulb (OB) volume with magnetic resonance imaging in 67 healthy participants with a body mass index (BMI) from 18.9 to 45.4 kg/m2 (mean = 28.58 ± 6.64). Moreover, we obtained psychophysiological data on olfactory ability (Sniffin’ Sticks, Food associated odor test) and self-report measurements on eating behavior. Additionally, we collected parameters associated with metabolic health in obesity (waist-hip ratio, waist-height ratio, leptin levels, body fat percentage, fat mass index, insulin resistance) to investigate recently proposed mechanistic explanatory models of why olfaction may be altered in obesity. We showed that OB volume was significantly lower in participants with obesity when compared to those of normal weight. Moreover, we found weak to moderate negative correlations between OB volume and BMI and related measures of metabolic health, especially leptin, body fat percentage, waist-height ratio and insulin resistance. However, neither OB volume nor BMI were related to olfactory function in our young and healthy sample. Nevertheless, our results provide first indications that obesity is associated with brain anatomical changes in the OBs.

Convergence of Olfactory Inputs within the Central Nervous System of a Cartilaginous and a Bony Fish: An Anatomical Indicator of Olfactory Sensitivity

The volume of the olfactory bulbs (OBs) relative to the brain has been used previously as a proxy for olfactory capabilities in many vertebrate taxa, including fishes. Although this gross approach has predictive power, a more accurate assessment of the number of afferent olfactory inputs and the convergence of this information at the level of the telencephalon is critical to our understanding of the role of olfaction in the behaviour of fishes. In this study, we used transmission electron microscopy to assess the number of first-order axons within the olfactory nerve (ON) and the number of second-order axons in the olfactory peduncle (OP) in established model species within cartilaginous (brownbanded bamboo shark, Chiloscyllium punctatum [CP]) and bony (common goldfish, Carassius auratus [CA]) fishes. The total number of axons varied from a mean of 18.12 ± 7.50 million in the ON to a mean of 0.38 ± 0.21 million in the OP of CP, versus 0.48 ± 0.16 million in the ON and 0.09 ± 0.02 million in the OP of CA. This resulted in a convergence ratio of approximately 50:1 and 5:1, respectively, for these two species. Based on astroglial ensheathing, axon type (unmyelinated [UM] and myelinated [M]) and axon size, we found no differentiated tracts in the OP of CP, whereas a lateral and a medial tract (both of which could be subdivided into two bundles or areas) were identified for CA, as previously described. Linear regression analyses revealed significant differences not only in axon density between species and locations (nerves and peduncles), but also in axon type and axon diameter (p < 0.05). However, UM axon diameter was larger in the OPs than in the nerve in both species (p = 0.005), with no significant differences in UM axon diameter in the ON (p = 0.06) between species. This study provides an in-depth analysis of the neuroanatomical organisation of the ascending olfactory pathway in two fish taxa and a quantitative anatomical comparison of the summation of olfactory information. Our results support the assertion that relative OB volume is a good indicator of the level of olfactory input and thereby a proxy for olfactory capabilities.

Olfactory Bulb MRI and Paranasal Sinus CT Findings in Persistent COVID-19 Anosmia

Background and purposeThere is limited literature consisting of case reports or series on olfactory bulb imaging in COVID-19 olfactory dysfunction. An imaging study with objective clinical correlation is needed in COVID-19 anosmia in order to better understand underlying pathogenesis.Material and methodsWe evaluated 23 patients with persistent COVID-19 olfactory dysfunction. Patients included in this study had a minimum 1-month duration between onset of olfactory dysfunction and evaluation. Olfactory functions were evaluated with Sniffin’ Sticks Test. Paranasal sinus CTs and MRI dedicated to olfactory nerves were acquired. On MRI, quantitative measurements of olfactory bulb volumes and olfactory sulcus depth and qualitative assessment of olfactory bulb morphology, signal intensity, and olfactory nerve filia architecture were performed.ResultsAll patients were anosmic at the time of imaging based on olfactory test results. On CT, Olfactory cleft opacification was seen in 73.9% of cases with a mid and posterior segment dominance. 43.5% of cases had below normal olfactory bulb volumes and 60.9% of cases had shallow olfactory sulci. Of all, 54.2% of cases had changes in normal inverted J shape of the bulb. 91.3% of cases had abnormality in olfactory bulb signal intensity in the forms of diffusely increased signal intensity, scattered hyperintense foci or microhemorrhages. Evident clumping of olfactory filia was seen in 34.8% of cases and thinning with scarcity of filia in 17.4%. Primary olfactory cortical signal abnormality was seen in 21.7% of cases.ConclusionOur findings indicate olfactory cleft and olfactory bulb abnormalities are seen in COVID-19 anosmia. There was a relatively high percentage of olfactory bulb degeneration. Further longitudinal imaging studies could shed light on the mechanism of olfactory neuronal pathway injury in COVID-19 anosmia.

Olfactory Cleft Measurements and COVID-19-Related Anosmia.

ObjectiveThis study aimed to investigate the differences in olfactory cleft (OC) morphology in coronavirus disease 2019 (COVID-19) anosmia compared to control subjects and postviral anosmia related to infection other than severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).Study DesignProspective.SettingThis study comprises 91 cases, including 24 cases with anosmia due to SARS-CoV-2, 38 patients with olfactory dysfunction (OD) due to viral infection other than SARS-CoV-2, and a control group of 29 normosmic cases.MethodsAll cases had paranasal sinus computed tomography (CT), and cases with OD had magnetic resonance imaging (MRI) dedicated to the olfactory nerve. The OC width and volumes were measured on CT, and T2-weighted signal intensity (SI), olfactory bulb volumes, and olfactory sulcus depths were assessed on MRI.ResultsThis study showed 3 major findings: the right and left OC widths were significantly wider in anosmic patients due to SARS-CoV-2 (group 1) or OD due to non–SARS-CoV-2 viral infection (group 2) when compared to healthy controls. OC volumes were significantly higher in group 1 or 2 than in healthy controls, and T2 SI of OC area was higher in groups 1 and 2 than in healthy controls. There was no significant difference in olfactory bulb volumes and olfactory sulcus depths on MRI among groups 1 and 2.ConclusionIn this study, patients with COVID-19 anosmia had higher OC widths and volumes compared to control subjects. In addition, there was higher T2 SI of the olfactory bulb in COVID-19 anosmia compared to control subjects, suggesting underlying inflammatory changes. There was a significant negative correlation between these morphological findings and threshold discrimination identification scores.Level of EvidenceLevel 4.

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.

A new perspective on imaging of olfactory dysfunction: Does size matter?

PurposeThis study assesses the diagnostic utility of olfactory nerve and bulb morphologies in addition to volumetric analysis in classification of different olfactory dysfunction etiologies. Methods106 patients presenting with olfactory loss and 17 control subjects were included. Based on detailed anamnesis, smell test and ear-nose-throat examination; patients were categorized into four groups as post-viral, post-traumatic, idiopathic, and obstructive olfactory dysfunction. Olfactory region was imaged with paranasal sinus CT and MRI dedicated to olfactory nerve. Olfactory bulb volume and olfactory sulcus depths were calculated on MRI. The olfactory bulb was assessed for morphology, contour lobulations and T2-signal intensity; and olfactory nerve for uniformity and clumping. ResultsVolumetric analysis showed decreased olfactory bulb volume in idiopathic and obstructive group compared to control subjects. Olfactory sulci were shallower in post-viral, post-traumatic, idiopathic, and obstructive group compared to the control group.In post-viral group; olfactory bulbs had lobulated contour and focal T2-hyperintense regions in 67 % of cases, and olfactory nerves had a clumped and thickened appearance in 66 % of cases. In idiopathic group, olfactory bulbs were rectangular shaped with minimally deformed contours, and olfactory nerves were thin and hard to delineate. No specific olfactory bulb or nerve pattern was identified in obstructive and post-traumatic groups, however closed olfactory cleft and siderotic frontobasal changes were helpful clues in obstructive and post-traumatic groups, respectively. ConclusionIn addition to olfactory cleft patency, olfactory sulcus depth and olfactory bulb volume; bulb and nerve morphologies may provide diagnostic information on different etiologies of olfactory dysfunction.

Letter: Anosmia in COVID-19: Severe Acute Respiratory Syndrome Coronavirus 2 Through the Nasoliary Epithelium and a Possible Spreading Way to the Central Nervous System-A Purpose to Study.

To the Editor: Italy is currently one of the countries most affected by the global emergency of COVID-19, a lethal disease of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).1 A lot of emergency centers from China,2 United Kingdom, and Italy,3 including our Department of Policlinic Umberto I of Rome, reported a significant number of COVID-19 patients presenting anosmia and ageusia as onset symptoms,4 and it is reported that anosmia appear at an early stage of the disease.2-4 There are 3 well-described syndromes in the current SARS-CoV-2 outbreak: asymptomatic, mild upper respiratory disease, and severe systemic disease. This minor and nonspecific symptomatology can represent the only manifestation of the disease in asymptomatic or in the mild form of the disease, but we have also noticed an asymptomatic anosmia during the early stages of COVID-19. These data poorly correlate with other studies reporting anosmia as the onset manifestation of the disease in only 5.1% of patients.2 It seems that this chemosensory dysfunction is present in 30% to 40% of all symptomatic patients.3,5 It is not possible to understand with certainty whether SARS-CoV-2 causes olfactory dysfunction through mechanisms other than nasal obstruction (a subsequent postviral olfactory dysfunction [PVOD] onset) or it may persist in resident cells, olfactory cells, and may become a factor or cofactor of a possible recurrence and a source of spread of the disease. Based on a recent work,5 it seems to be that the olfactory system (OS), despite being highly efficient at controlling neuroinvasion in normal conditions, is the main route of propagation within the central nervous system (CNS) used by human coronaviruses and respiratory viruses.6 PURPOSE OF STUDY Considering that the evidence of a specific virus in the nasal cavity is not equal to the persistence of the virus within the olfactory cells and that it has been shown that epithelium can be safely biopsied,7 we aim at withdrawing a sample of nasal mucosa of patients with proven serological diagnosis of COVID-19, in order to investigate the involvement of the upper nasal (ethmoidal) mucosa by SARS-CoV-2, through a minimally invasive endoscopic nasal procedure. Mucous fresh-frozen samples are taken to be sent for transmission nuclear magnetic resonance (NMR) microscopy study. With a reduction in olfactory function, we would have expected to also find a reduction in olfactory bulb volume, as it has been found to positively correlate with the performance of OS in healthy subjects.8 We also wanted to determine the clinical outcome of patients affected by SARS-CoV-2 experiencing alteration of taste and smell in order to better characterize these clinical manifestations and acquire information on the pathogenesis. In order to postulate a possible clinical screening tool to orientate testing of paucisymptomatic individuals, we aim at studying a correlation between progression of anosmia, clinical status, radiological pulmonary status, and presence and quantity of the virus in the nasal mucosa. DISCUSSION There is now a well-recognized association of a complete subjective loss of smell and taste over 24 to 72 h without other significant symptoms of a respiratory influence with SARS-CoV-2 in the current pandemic with multiple reports of smell loss with the infection,2-5 but we cannot recognize it as a typical isolated sudden onset anosmia (ISOA) or as a rhinological/neurological symptom of SARS-CoV-2. We do not know if this indeterminate symptom may or may not have a diagnostic or prognostic significance on the pathology. We prompt all healthcare practitioners with patients presenting with onset of anosmia to treat these patients as possible COVID-19 positive with appropriate precautions and to avoid the use of immunosuppressants and intranasal steroids, which although seem to be of relatively low risk can have an impact on the presumed neurological cause of the anosmia and increased risks of immunosuppression in the current pandemic. Disclosures The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Brain TRODAT-SPECT Versus MRI Morphometry in Distinguishing Early Mild Parkinson's Disease from Other Extrapyramidal Syndromes.

The clinical differentiation of Parkinson's disease (PD) from other extrapyramidal syndromes has made a challenge in neurology. This study aimed to compare the specificity and sensitivity of brain MRI volumetry and dopamine transporter scans in differentiating PD from other extrapyramidal syndromes in the early stages of the disease. This study included 34 patients younger than 70 years old with less than 3 years of extrapyramidal symptoms. Demographic and clinical history of the patients, including age, sex, and disease duration, was gathered. Disease severity was assessed using Unified Parkinson's Disease Rating Scale III (UPDRS III). For all patients, 99m Tc-TRODAT single-photon emission computed tomography (SPECT) and MRI volumetry were performed. Patients were followed up for 1 year and examined for final diagnosis. According to the quantitative 99m Tc-TRODAT analysis, all of the specific binding ratio (SBR) parameters, including right, left, and bilateral SBRs, were significantly higher in the non-Parkinsonian patients. Also, the results indicated a high diagnostic accuracy for both quantitative 99m Tc-TRODAT analysis (about 88% for SBR parameters) and MRI volumetry (71% for bilateral olfactory bulbs volume) in diagnosing PD. Regarding the diagnosis of PD, there were no significant differences between quantitative scan results and olfactory bulb volumetry according to the area under the receiver operating characteristic curves. 99m Tc-TRODAT has a higher accuracy in differentiation of early PD from non-Parkinsonian conditions, particularly essential tremor. Olfactory bulbs volumetry by using MRI can also serve as a potential alternative method in this regard.

The effect of olfactory training on olfactory bulb volumes in patients with idiopathic olfactory loss.

Olfactory loss impacts around 20% of the population and is associated with the reduction of pleasure from eating and drinking, sex and depression (1). Encouragingly, research findings have consistently demonstrated that olfactory training (OT) can improve olfactory function in people with olfactory loss due to various aetiologies (2). The most commonly used method for OT involves smelling four different odours (lemon, eucalyptus, rose and cloves), twice daily, for 12 weeks.

Bilateral transient olfactory bulb edema during COVID-19–related anosmia

An asymptomatic 27-year-old man was diagnosed with coronavirus disease 2019 (COVID-19) by occupational medicine after contagion (reverse transcription polymerase chain reaction [ RT - PCR ]). Four days after the diagnosis, he experienced complete anosmia and dysgeusia.1 On day 7, 1.5T MRI showed signs of bilateral olfactory bulb edema on 3D constructive interference in steady state T2-weighted imaging, demonstrated by severe enlargement2 (left: 73 mm3, right: 64 mm3) and an abnormally high signal intensity (figure). Olfactory clefts showed mild edema. The olfactory pathways, including the cortical projections (fluid-attenuated inversion recovery and diffusion-weighted imaging not shown), were normal. Sensory recovery and negative RT-PCR (positive on days 1, 2, and 10) appeared on day 14. MRI on day 24 confirmed the normalization of olfactory bulb signal and volumes (left: 22 mm3, right: 17 mm3).

Evaluation of olfactory bulbus volume and olfactory sulcus depth by 3T MR.

The aim of this study was to evaluate olfactory bulbus volume (OBV) and olfactory sulcus depth (OSD) according to age and sex with 3T MRI in a healthy Turkish population. In the current study, 200 patients who had cranial MRI were retrospectively evaluated. They were divided into the following groups to examine the effects of age: group 1: 18-30 years old; group 2: 31-40 years old; group 3: 41-50 years old; group 4: 51-60 years old; and group 5: >60 years old. OBV and OSD measurements were performed on coronal T2-weighted brain MR images. The mean right and left olfactory bulb volume and sulcus depths were used for evaluation. The mean age was 46.5 ± 18.1 (range 18-86) years. The mean OBV value of both sides was 91.17 ± 7.8 mm 3 in all patients. The mean OSD value of both sides was 8.62 ± 0.84 mm in all patients. There was no statistically significant difference in OBV and OSD between sexes (P < 0.236; P < 0.482). Group 5 (>60 years old) was found to have significantly lower OBV and OSD values than the other groups (all P < 0.001). The normal values of OBV and OSD should be established according to age to determine decreased OBV and OSD values.

A new experimental evidence that olfactory bulb lesion may be a causative factor for substantia nigra degeneration; preliminary study

Background: Anosmia has been considered as the first diagnostic criteria of Parkinson disease (PD), we investigated the effect of the olfactory bulbectomy (OBX) on histopathological features of the substantia nigra in an animal model.Methods: Twenty-seven male rats were used in this study. Animals were divided into three groups as five (control), six SHAM and sixteen study (OBL) groups. Nothing was done in the control group, the only burr hole was done in the SHAM group, OBL was not applied, and bilateral OBL was performed in the study group, and followed ten weeks, then animals were decapitated. Olfactory bulb volumes were measured by macro anatomically. The olfactory bulbs and substantia nigra sections were analyzed by a stereological method to evaluate olfactory glomerulus and neuron density of substantia nigra per cubic centimeter and compared with statistically.Results: The mean olfactory bulb volume, degenerated olfactory glomerulus density and degenerated neuron density of substantia nigra were measured as:(4.14 ± 0.20) mm3, (1 ± 1)/mm3 and (7 ± 2)/mm3 in control (Group I); (3.6 ± 0.16)/mm3, (4 ± 1)/mm3 and(32 ± 7)/mm3 in SHAM (Group II) and (2.2 ± 0.9)/mm3, (112 ± 18)/mm3 and (1543 ± 115)/mm3in study group (Group III). Diminished olfactory bulb volume was observed in Group III animals.Conclusions: We concluded that OBL may lead to the degeneration of substantia nigra.

Diffusion tensor imaging: a smart move to olfactory pathway imaging; comparative study of chronic sinonasal polyposis patients and normal control

BackgroundOlfaction is critically important for a good quality of life and incorporated in many physiological domains such as attention, emotion, memory, and airflow motor control. Olfactory researches have been expanded in the last decade due to close relation between the olfactory disorders and different brain diseases. Diagnosis of anosmia and hyposmia are based on history, smell tests, and physical examination which rely on the patient’s response without an objective measure of impairment. This study assessed the value of volumetry and DTI parameters as objective measurements for olfactory dysfunction.Fourteen patients with chronic sinonasal polyposis for at least 6 months were included in this study; all of them underwent tailored MRI examination including volumetry and DTI for olfactory bulbs and tracts. The results were compared to the same number of age and sex-matched healthy control group.ResultsThe study results showed that olfactory bulb and tract (OB/T) volume, FA and ADC could distinguish between patients and healthy controls. Statistically significant differences were noticed between the FA & ADC values of patient and control groups (p < 0.05) and a highly significant one was noticed as regarding the OT volume (p < 0.001).ConclusionMR volumetry and DTI parameters can be used as objective measurements for the olfactory dysfunction for patients with chronic sinonasal polyposis.