Olfactory Bulb Volume In Patients Research Articles

Assessment of factors influencing the olfactory bulb volume in patients with post-viral olfactory dysfunction.

To investigate the factors influencing the volume of the olfactory bulb (OB) in patients with post-viral olfactory dysfunction (PVOD). We collected 92 olfactory bulb volumes from patients with PVOD who underwent a sinus computed tomographic and magnetic resonance imaging (MRI) scan of the head and collected clinical information including gender, age, disease course, minimal cross-sectional area, nasal airway resistance, and olfactory function. OB volume was measured in MRI and the scans were evaluated according to the Lund-Mackay (LM) scoring system. Male patients with PVOD had a larger OB volume (β = 0.284, P < 0.05). OB volume was smaller in patients with a longer course of olfactory dysfunction (β = -0.254, P < 0.05). According to the LM scoring system, patients with a higher anterior ethmoidal sinus score had smaller OB volume (β = -0.476, P < 0.05). The study revealed that gender, disease course, and the score of anterior ethmoidal sinusitis can affect the OB volume in patients with PVOD.

Training with Odors Impacts Hippocampal Thickness in Patients with Mild Cognitive Impairment.

The olfactory system is affected early in Alzheimer's disease and olfactory loss can already be observed in patients with mild cognitive impairment (MCI). Olfactory training is effective for improving olfactory and cognitive function by stimulating the olfactory pathway, but its effect on patients with MCI remains unclear. The aim of this randomized, prospective, controlled, blinded study was to assess whether a 4-month period of olfactory training (frequent short-term sniffing various odors) may have an effect on olfactory function, cognitive function, and morphology of medial temporal lobe (MTL) subregions and olfactory bulb in MCI patients. A total of thirty-seven MCI patients were randomly assigned to the training group or a placebo group, which were performed twice a day for 4 months. Olfactory assessments, cognitive tests and magnetic resonance imaging were performed at the baseline and follow-up period. After the training, there was an increase in odor discrimination, and increased cortical thickness of bilateral hippocampus (CA23DG and CA1) and mean MTL. Additionally, the change of olfactory score was positively associated with change of volume of olfactory bulb and hippocampus; the change of global cognition was positively associated with change of cortical thickness of hippocampus, entorhinal cortex and mean MTL; the change of cortical thickness of entorhinal cortex was positively associated with change of executive function. Olfactory training was associated with an increase in cortical thickness of the hippocampus but not olfactory bulb volume in patients with MCI. Olfactory training may serve as an early intervention of preventing hippocampal atrophy.

Evaluation of olfactory bulb volume and olfactory sulcus depth in patients with panic disorder and depressive disorder: An MRI study.

Background:Although some studies have shown decreases in the olfactory bulb (OB) volume and olfactory function in depressive disorder, there are no studies investigating OB volume in patients with panic disorder.Aim:The aim of this study was to investigate whether there was a change in OB volume and olfactory sulcus (OS) depth in patients with panic and depressive disorder when compared with the control group, and which group was more affected by comparing the two disease groups.Methods:Data of 51 patients with panic disorder and 56 patients with depressive disorder were obtained by scanning the database of the hospital retrospectively. The control group consisted of 56 subjects without panic and depressive disorder. OB volume and OS depth measurements were performed on cranial magnetic resonance imaging (MRI).Results:Bilateral OB volume of the panic and depressive disorder groups were significantly lower than those of the control group. The lowest volume was found in depressive patients. There was no significant difference between the groups with respect to OS measurements. When OB volume and OS depth differences between the genders were evaluated, a statistically significant difference was not determined.Conclusion:Reduced OB volume was determined in both panic and depressive disorder patients, and clarification of these preliminary findings may contribute to the pathophysiology of panic and depressive disorders.

Olfactory dysfunction and olfactory bulb volume in patients with deviated nasal septum

The purpose of the study is to demonstrate the possibility and information content of olfactory bulb volume measuring in healthy volunteers and patients with deviated nasal septum, as well as the relationship between the volume of the olfactory bulb and olfactory function. Material and methods. 28 men with deviated nasal septum aged 24 to 35 years (main group) and 21 clinically healthy volunteers, men aged 23 to 33 years (control group) were examined. All patients underwent checkup of the ENT organs and examinations on a 1.5 T MRI machine with 12-channel head coil. The sense of smell was examined using the extended Sniffin Sticks test (SST) (“Buerhard”, Hamburg, Germany) with the definition of 3 parameters: threshold, identification and discrimination. Results. In accordance with the design of the work, threshold, discrimination, identification subtests and MRI examination of the head were performed with the measurement of the olfactory bulb volume of patients in the main group and volunteers in the control group. In all participants in the control group was diagnosed normosmia in accordance with the TDI indicator, and in patients with deviated nasal septum – hyposmia. Olfactory function in patients deviated nasal septum was significantly lower on the narrower side as indicated for odor thresholds, odor recognition, and odor identification (P&lt;0.01). It was found that olfactory bulb volumes are larger on the wider side than on the narrower side (P&lt;0.01). Conclusion. Asymmetry in the size and volume of OB is observed only in patients with deviated nasal septum, it is absent in healthy volunteers. MRI visualization and morphometry of olfactory bulb, in addition to identifying of the nasal cavity, paranasal sinuses state, are informative in the process of preoperative examination of patients with deviated nasal septum. Olfactory bulb volume definition should be used for personalized diagnosis and quantitative assessment of olfactory dysfunction.

Prognostic value of olfactory bulb volume in patients with post-viral olfactory dysfunction

Objective:The purpose of this study was to compare the olfactory function examination results of patients with post-viral olfactory dysfunction（PVOD） in different prognostic groups and analyze prognostic factors, especially the influence of olfactory bulb volume（OBV） on prognosis, so as to provide objective basis for clinical diagnosis and treatment. Methods:After approval by the hospital ethics committee, the patients with PVOD admitted to Beijing Anzhen Hospital's outpatient department from January 2019 to December 2019 were followed up for at least 1 year. These patients completed the Sniffin' Sticks test and MRI examination of the olfactory pathway before treatment. According to the results of the Sniffin' Sticks test after 1 year follow-up（threshold-discrimination-identification（TDI） score of the patients was increased at least 6 points）, the patients were divided into two groups as the improvement group and the non-improvement group. The prognostic factors of PVOD patients were preliminarily determined by comparing the differences of various factors and the results of olfactory function examination between the two groups. Results:In this study, 47 patients with PVOD were included, with the smell improvement rate was 53.2%. Compared with the improvement group, the patients in the non-improvement group had longer duration, poorer initial olfactory function, higher olfactory threshold, and poorer olfactory discrimination and recognition ability（All P<0.01）. There was no statistical difference in terms of gender, age, allergic rhinitis and smoking between the two groups（All P>0.05）.The OBV of the non-improvement group was （59.48±23.92） mm³, which was significantly lower than that in the improvement group（[92.77±14.35]mm³, P<0.001）. Multiple logistic regression analysis showed that prognostic factors included course of disease（OR 0.677, 95%CI 0.461-0.993, P=0.046）, initial T value（OR 263.806, 95%CI 1.028-67 675.884, P=0.049） and OBV（OR 1.160, 95%CI 1.002-1.343, P=0.047）. The area under the receiver operating characteristic curve（ROC curve） of OBV was 0.888（0.797-0.979, P<0.001）. The correct diagnostic index of OBV≥78.50 mm³was used to determine the prognosis of olfactory function, with a specificity of 0.818 and a sensitivity of 0.840. The ROC curve analysis showed that the area under the ROC curve of duration was 0.822（0.703-0.940, P<0.001）. The correct diagnostic index of the duration ≤6 months was used to determine the prognosis of olfactory function, with a specificity of 0.727 and a sensitivity of 0.800. The area of T score was 0.793（0.662-0.924, P=0.001）. T score ≥1.25 was used as the correct diagnostic index to determine the prognosis of olfactory function. The specificity and sensitivity were 0.818 and 0.680, respectively. Conclusion:The prognosis of olfactory function in PVOD patients is related to the course of disease, the degree of olfactory loss and OBV. Those with no improvement in olfactory function have a longer disease course, aggravated olfactory damage and reduced OBV than those with improved olfactory function. The factors of Duration ≤6 months, T value ≥1.25 and OBV≥78.50 mm³suggested better prognosis, and the results of objective olfactory examination have greater value in evaluating the prognosis of olfactory function.

Evaluation of olfactory bulb volume in patients with diabetic olfactopathy and comparison with healthy individuals

Evaluation of olfactory bulb volume in patients with diabetic olfactopathy and comparison with healthy individuals

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.

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.

Decreased olfactory bulb volume in patients with restless legs syndrome

Objective: Restless legs syndrome (RLS) is a chronic progressive movement disorder with a pathophysiology that is still not fully known. In recent years, a growing number of studies have suggested that the disease may be of a neurodegenerative nature. We aimed to measure olfactory bulb volume (OBv) in RLS using cranial magnetic resonance imaging (MRI). Methods: The study included 24 patients (11 males, 13 females) aged 18-60 years who were diagnosed with idiopathic RLS according to the criteria of the Restless Legs Syndrome Study Group (IRLSSG) 2014 and followed up by our neurology clinic, and 26 age-matched controls (12 males, 14 females). In the cranial MRI examination of both groups, the right, left and total OBv values were manually calculated in mm3. Results: While there was no significant difference between the right and left OBv values of the patient and control groups, the total OBv value of the patient group was found to be significantly lower compared to the control group (p=0.041). There was no significant difference between disease severity and OBv values. It was seen that right, left and total OBv values decreased significantly as the duration of the disease increased (p=0.001, p

Olfactory bulb neuroplasticity: A prospective cohort study in patients with chronic rhinosinusitis with nasal polyps

To compare the olfactory bulb volumes (OBVs) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) to healthy individuals, and to assess the changes of the OBVs in patients with CRSwNP before and after the endoscopic sinus surgery (ESS) utilising magnetic resonance imaging (MRI) with specialised software. This is a prospective cohort study. Tanta University hospital (tertiary referral hospital), Egypt. Thirty patients with CRSwNP (Group A) were compared with thirty healthy individuals (Group B) as regards the OBVs. Patients with CRSwNP underwent ESS where the Smell Identification Test-40 (SIT-40) and the OBVs were assessed pre-operatively and at least 6months postoperatively. Assessment of the OBVs was carried out using MRI with specialised software. Assessment of the volumetric changes of the olfactory bulbs in patients with CRSwNP before and after endoscopic sinus surgery utilise magnetic resonance imaging. The OBVs were significantly smaller in Group A (58.94±7.96mm3 and 60.79±8.14mm3 on the right and left sides, respectively) as compared with the Group B (73.46±8.54mm3 and 72.96±9.74mm3 on the right and left sides, respectively). There was also a significant increase in the olfactory bulb volumes as well as improvement of the SIT-40 6months postoperatively in the Group A. The olfactory bulb is characterised by neural plasticity, and its volume may be affected by the peripheral olfactory function.

Alterations of Brain Gray Matter Density and Olfactory Bulb Volume in Patients with Olfactory Loss after Traumatic Brain Injury.

Olfactory loss and traumatic brain injury (TBI) both lead to anatomical brain alterations in humans. Little research has been done on the structural brain changes for TBI patients with olfactory loss. Using voxel-based morphometry, the gray matter (GM) density was examined for 22 TBI patients with hyposmia, 24 TBI patients with anosmia, and 22 age-matched controls. Olfactory bulb (OB) volumes were measured by manual segmentation of acquired T2-weighted coronal slices using a standardized protocol. Brain lesions in the olfactory-relevant areas also were examined for TBI patients. Results showed that patients with anosmia have more frequent lesions in the OB, orbitofrontal cortex (OFC), and the temporal lobe pole, compared with patients with hyposmia. GM density in the primary olfactory area was decreased in both groups of patients. In addition, compared with controls, patients with anosmia showed GM density reduction in several secondary olfactory eloquent regions, including the gyrus rectus, medial OFC, anterior cingulate cortex, insula, and cerebellum. However, patients with hyposmia showed a lesser degree of GM reduction, compared with healthy controls. Smaller OB volumes were found for patients with olfactory loss, compared with controls. TBI patients with anosmia had the smallest OB volumes, which were caused by the lesions for OB. In addition, post-TBI duration was negatively correlated with GM density in the secondary olfactory areas in patients with hyposmia, but was positively correlated with GM density in the frontal and temporal gyrus in patients with anosmia. The GM density and OB volume reduction among TBI patients with olfactory loss was largely dependent on the location and severity of brain lesions in olfactory-relevant regions. Longer post-TBI duration had an impact on brain GM density changes, which indicate a decreased olfactory function in patients with hyposmia and possible compensatory mechanisms in patients with anosmia.

Retro- and orthonasal olfactory function in relation to olfactory bulb volume in patients with hypogonadotrophic hypogonadism.

IntroductionIdiopathic hypogonadotrophic hypogonadism with an olfactory deficit is defined as Kallmann syndrome and is distinct from normosmic idiopathic hypogonadotrophic hypogonadism.ObjectiveBecause olfactory perception not only consists of orthonasally gained impressions but also involves retronasal olfactory function, in this study we decided to comprehensively evaluate both retronasal and orthonasal olfaction in patients with idiopathic hypogonadotrophic hypogonadism.MethodsThis case-control study included 31 controls and 45 idiopathic hypogonadotrophic hypogonadism patients. All participants whose olfactory and taste functions were evaluated with orthonasal olfaction (discrimination, identification and threshold), retronasal olfaction, taste function and olfactory bulb volume measurement. The patients were separated into three groups according to orthonasal olfaction: anosmic idiopathic hypogonadotrophic hypogonadism, hyposmic idiopathic hypogonadotrophic hypogonadism and normosmic idiopathic hypogonadotrophic hypogonadism.ResultsDiscrimination, identification and threshold scores of patients with Kallmann syndrome were significantly lower than controls. Threshold scores of patients with normosmic idiopathic hypogonadotrophic hypogonadism. were significantly lower than those of controls, but discrimination and identification scores were not significantly different. Retronasal olfaction was reduced only in the anosmic idiopathic hypogonadotrophic hypogonadism group compared to controls. Identification of bitter, sweet, sour, and salty tastes was not significantly different when compared between the anosmic, hyposmic, and normosmic idiopathic hypogonadotrophic hypogonadism groups and controls. Olfactory bulb volume was lower bilaterally in all patient groups when compared with controls. The olfactory bulb volume of both sides was found to be significantly correlated with threshold, discrimination and identification scores in idiopathic hypogonadotrophic hypogonadism patients.Conclusion1) There were no significant differences in gustatory function between controls and idiopathic hypogonadotrophic hypogonadism patients; 2) retronasal olfaction was reduced only in anosmic patients but not in orthonasally hyposmic participants, possibly indicating presence of effective compensatory mechanisms; 3) olfactory bulb volumes were highly correlated with olfaction scores in the hypogonadotrophic hypogonadism group. The current results indicate a continuum from anosmia to normosmia in idiopathic hypogonadotrophic hypogonadism patients.

Decreased olfactory bulb volumes in patients with fibromyalgia syndrome.

Among the other symptoms, impaired olfactory function such as odor identification, threshold, and discrimination have been reported in patients with fibromyalgia syndrome (FMS). To investigate olfactory bulb (OB) volumes in FMS, by using magnetic resonance imaging (MRI), and to make reasonable suggestions are the goals of the present study. The study included 62 individuals as the FMS group (n=30) and the control group (n=32). MRI examinations were performed by a 1.5-T scanner and a standard head coil was used for the images. The coronal T2-weighted images were used for to measure OB volumes. Right, left, and total OB volumes were calculated with the aid of these images. The mean age of the FMS group was 44.2±8.3years and the control group was 41.7±3.53years. The mean volume of the right OB was 74.9±12.4mm3 in the FMS group and was 92.6±12.9mm3 in the control group. The mean value of the left OB volume was 74.3±10.8mm3 in the FMS group and 92.8±12.6mm3 in the control group. The mean of the total OB volume was 146.6±20.81mm3 in the FMS group and 186.5±23.5mm3 in the control group. Left, right, and total OB volumes were significantly lower in the FMS group than in the control group (all p<0.05). Female patients with FMS are under the risk of the decreased olfactory bulb volumes. This situation should be kept in mind for proper and reasonable management of this tough syndrome.

Volumetric study of the olfactory bulb in patients with chronic rhinonasal sinusitis using MRI

ObjectiveOlfaction plays an important role in human daily life. The olfactory bulb size is dependent on stimulation. Smell loss is one of the main symptoms in chronic rhinonasal sinusitis. MRI has been indicated to evaluate the size of the olfactory bulb in such patients.The aim of this study was to assess the volumetric changes of the olfactory bulb in patients with sinonasal polyposis before and after treatment using MRI. Patients and methodsFifteen control subjects and 30 patients were included in the study, 24 of them patients underwent endoscopic sinus surgery. Volumetric analysis of their olfactory bulb volume was done using MRI and specialized software. ResultsIt was found that the olfactory bulb volume was significantly smaller in patients (19.98±5.88mm3) when compared to control mean (39.6±13.8mm3) and there was a significant increase in the olfactory bulb volumes in patients who underwent surgery 6months postoperatively (24.79±5.11mm3). ConclusionsMRI with volumetric analysis is a useful tool in assessment of the olfactory bulb volume in patients with olfactory loss and appears to be of help in assessment of the degree of recovery in patients after sinus surgery.

Correlation Between Olfactory Bulb Volume and Chronic Depression: A Magnetic Resonance Imaging Study

ABS TRACT: Correlation between olfactory bulb volume and chronic depression: a magnetic resonance imaging study Objective: Olfactory dysfunction can be seen secondary to various diseases, such as sinonasal disease, infections of the upper respiratory tract, head trauma, and neurodegenerative diseases. A small number of recent studies have focused on olfactory dysfunction in different neuropsychiatric disorders. This study aimed to investigate olfactory bulb (OB) volume in patients with chronic major depression, as diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). In particular, we investigated patients treated with selective serotonin reuptake inhibitors (SSRIs). To the best of our knowledge, this is the first study to investigate this subject. Methods: Participants included 31 outpatients (17 females and 14 males) with chronic major depression recruited from the University School of Medicine and Public Hospital psychiatry outpatient clinic between March 1 and August 31, 2013. Participants were examined using the Beck Depression Inventory (BDI). All patients were receiving treatment with a single SSRI. The BDI was also administered to a control group of 31 healthy volunteers (16 females, 15 males). All participants were recruited over the telephone after the study design was finalized. Additionally, both groups underwent a magnetic resonance imaging (MRI) scan with a 1.5-Tesla MRI system. Volumes of the right and left OBs were determined using MRI scans of the head and a standardised protocol for OB examination. Results: OB volumes were calculated separately for the depressed and the control groups. MRI measurements revealed significantly smaller olfactory bulb volume in patients with chronic major depression as compared to the control group. Furthermore, we detected a negative correlation between BDI score and olfactory bulb volume. Conclusions: Olfactory bulb volumes are notably smaller in patients with chronic major depression treated only with SSRIs (fluoxetine, sertraline, citalopram, escitalopram, paroxetine). To our knowledge, this is the first study to reveal reduced olfactory bulb volume in patients with chronic major depression. This study has demonstrated a negative correlation between OB volume and elevated depression scores.

The olfactory bulb volume in patients with idiopathic Parkinson's disease.

This study addresses the question of whether the neuropathological findings on the olfactory bulb (OB) in idiopathic Parkinson's disease (IPD) correspond to a detectable change in volume of the OB. Additionally, the relationship between OB volume and residual olfactory function, clinical disease characteristics and age are investigated. Fifty-two IPD patients were investigated and compared to 31 healthy age-matched controls. All participants were scanned using a 3 T magnetic resonance imaging MRI scanner including a T2 DRIVE sequence in coronal slices through the OB. The OB volumes were measured via manual segmentation of the OB. Olfactory testing was carried out using the Sniffin' Sticks test battery. The OB volume in the IPD group was 42.1 mm³ (SD ± 11.6) for the right and 41.5 mm³ (SD ± 11.7) for the left OB and showed no difference from the controls. Additionally, there were no significant correlations between OB volume and disease characteristics such as disease duration or Unified Parkinson's Disease Rating Scale motor score. Likewise, patients' residual smell function did not correlate with their OB volume. In contrast, controls indicated a correlation between smell function and OB volume. The study shows that high resolution MRI does not show a detectable volume loss of the OB in PD patients. It is concluded that OB measurement using in vivo high resolution MRI at 3 T is not helpful to identify IPD.

Ipsilateral reduced olfactory bulb volume in patients with unilateral nasal obstruction.

To evaluate the effect of unilateral nasal obstruction (by nasal polyps of different histopathology) on olfactory bulb volume using MRI technique. Cross-sectional study. Tertiary university hospitals, Departments of Otolaryngology and Radiology. Eleven patients with a few months of complete unilateral nasal obstruction of different pathological etiologies were selected. MRI assessment of olfactory bulb volume was performed using planimetric manual contouring. The contralateral olfactory bulb was used as a comparative control for the same patient. Eleven healthy controls constituted the control group. Mean olfactory bulb volume ± SD of obstructed side = 14.3 ± 3.7 mm(3), mean olfactory bulb volume ± SD of nonobstructed side = 43.49 ± 10.7 mm(3). The difference between the 2 sides was significant (P = .003). The difference in olfactory bulb volume between normal subjects and nonobstructed nasal side was statistically nonsignificant (t = .9118, P = .3727), while the difference between normal subjects' olfactory bulb volume and obstructed nasal side olfactory bulb volume in our patients was extremely statistically significant (t = 9.7320, P < .0001). A strong negative correlation was found between duration of obstruction and olfactory bulb volume (R = -0.9761). This study shows that unilateral nasal obstruction may be associated with a lateralized ipsilateral difference of olfactory bulb volume.

Olfactory bulb volume in patients with temporal lobe epilepsy

The study aimed to investigate the volume of the olfactory bulb (OB) in patients with temporal lobe epilepsy (TLE). Specifically, we wanted to see whether the olfactory deficit typically found in TLE patients also exerts a top-down influence on the OB. Twenty patients, and 20 age- and sex-matched healthy controls underwent olfactory testing by means of the Sniffin' Sticks testing device (measurement of odor threshold, and identification abilities). In addition, they underwent an MR scan with 2-mm-thick T2-weighted fast spin-echo images without interslice gap in the coronal plane covering the anterior and middle segments of the base of the skull. Olfactory function was significantly impaired in TLE patients compared to healthy controls both at threshold level and for odor identification (p < 0.001); in addition, OB volumes were smaller than in controls (p = 0.013). The deficit seen at the level of the OB did not correlate with the side of the epileptic focus. Assuming that the olfactory deficit in TLE patients is due to the central nervous epileptic focus it appears that the OB volume is not only subject to changes in the periphery of the olfactory system, but also changes as a consequence to changes at a cortical level.

Olfactory bulb volume in patients with idiopathic normal pressure hydrocephalus

An important pathological feature of idiopathic normal pressure hydrocephalus (iNPH) is a dysfunction of cerebrospinal fluid dynamics. Considering the delicate olfactory structures it appears possible that the olfactory bulb (OB) is compromised by this disease. Reports on the anatomy of the olfactory bulb and smell function in patients with idiopathic normal pressure hydrocephalus are absent in the literature. The main purpose of the present study was to evaluate the olfactory bulb (OB) volume and smell function in iNPH. The study comprised 17 patients with iNPH (seven women and ten men, mean age = 66years); they were compared to a group of 24 healthy people (11 women and 13 men, mean age = 62years). Comprehensive assessment of olfactory function was conducted with the "Sniffin' Sticks" test kit. In an additional pilot study, in a small subgroup of eight patients, measurements were performed before and approximately 7months after surgical treatment of the hydrocephalus. The OB volume in patients with iNPH was significantly smaller compared to healthy controls. In our small postoperative patient population (n = 8), there was no significant change of the OB volume. In conclusion our results suggest that iNPH significantly affects OB volumes.

The Age of Olfactory Bulb Neurons in Humans

Continuous turnover of neurons in the olfactory bulb is implicated in several key aspects of olfaction. There is a dramatic decline postnatally in the number of migratory neuroblasts en route to the olfactory bulb in humans, and it has been unclear to what extent the small number of neuroblasts at later stages contributes new neurons to the olfactory bulb. We have assessed the age of olfactory bulb neurons in humans by measuring the levels of nuclear bomb test-derived (14)C in genomic DNA. We report that (14)C concentrations correspond to the atmospheric levels at the time of birth of the individuals, establishing that there is very limited, if any, postnatal neurogenesis in the human olfactory bulb. This identifies a fundamental difference in the plasticity of the human brain compared to other mammals.