Increasing olfactory bulb volume due to treatment of chronic rhinosinusitis--a longitudinal study (original) (raw)
Related papers
Olfactory bulb volume in the clinical assessment of olfactory dysfunction
The olfactory bulb (OB) plays a central role in the processing of olfactory information. It receives input from sensory neurons located in the olfactory epithelium responding to odours. OB are paired, of oval shape that occupy the most anterior portion of the skull base. In animals, one of the most pronounced effects of olfactory deprivation is the reduction of olfactory bulb size . This is probably due to the decreased activity of OB neurons and also to a negative effect on cholinergic centrifugal systems (3) . In contrast, behaviour such as olfactory training may have a positive impact on neurogenesis, migration and replacement of interneurons in the OB indicating plasticity (4). Moreover, olfactory conditioning during early postnatal period temporally stimulates neurogenesis in the OB in rats, suggesting that stimulation in early life is of importance for the normal development of the OB (5) . There is some evidence that OB volume is related to olfactory dysfunction in humans and OB volume has been correlated to results from psychophysical or electrophysiological testing . On the other hand, relation with olfactory function and OB volume in healthy subjects also suggests that a close relationship exists between structure and function . In this review, we will discuss the actual knowledge regarding OB function, volumetry using magnetic resonance imaging, and the clinical evaluation
The aim of this study was to investigate the olfactory bulb (OB) and sulcus (OS) in a large group of patients who have been well-characterized in terms of olfactory function, with a specific focus on the comparison between patients with olfactory loss due to chronic rhinosinusitis, head trauma, or acute infections. A retrospective study of 378 patients with olfactory loss was performed. Orthonasal olfactory function was assessed with the''Sniffin' Sticks'' test kit, including tests for odor threshold, odor discrimination, and odor identification. Magnetic resonance imaging analyses were focused on OB volume and OS depth. Major results of the present study included the (1) demonstration of a correlation between olfactory function and OB volume across the various pathologies in a very large group of subjects; (2) the three functional tests exhibited a similar degree of correlation with OB volume. (3) The right, but not the left OS correlated with olfactory function; in addition, (4) OS was negatively correlated with age. In contrast to OS, (5) no side differences were found for the OB. Finally, (6) the three different causes of olfactory loss exhibited different patterns of results for the three olfactory tests. The present data suggest that the morphological assessment of the OB volume and OS depth produces useful clinical indicators of olfactory dysfunction.
OBJECTIVE: To investigate whether differences in olfactory function between healthy individuals and patients with olfactory loss could be detected by various diagnostic tests. DESIGN: Psychophysical testing of orthonasal and retronasal olfactory functions, magnetic resonance imaging of olfactory bulb (OB) volume, and chemosensory event-related potential (ERP) measurement performed between January 1, 2005, and October 31, 2005. SETTING: Academic tertiary referral medical center. PATIENTS: Eleven healthy individuals with normal olfactory function (NL) and 11 patients with nasal polyposis (NP), 11 with posttraumatic olfactory loss (PT), and 11 with postinfectious olfactory loss (PI) were included in this study. MAIN OUTCOME MEASURES: Orthonasal and retronasal olfactory test results, magnetic resonance imaging-based OB volume, and ERPs to both olfactory and intranasal trigeminal stimulation. RESULTS: Orthonasal and retronasal testing revealed that NL individuals had higher scores than patients with NP, PT, or PI. Retronasal scores were higher in NP patients compared with PT and PI patients. The OB volumes were higher in NL individuals compared with NP, PT, and PI patients. The OB volumes in PT patients were significantly lower than those from NP and PI patients. Olfactory ERPs were different between NL individuals and NP, PT, and PI patients, and trigeminal ERPs were significantly different when comparing NL individuals with NP patients. For the entire cohort, a significant correlation was found between orthonasal testing and OB volume, between retronasal testing and OB volume, and between both orthonasal and retronasal testing and olfactory ERP amplitudes. Olfactory ERPs were recorded in the 11 NL individuals and in 3 NP, 3 PT, and 4 PI patients, defined as responders. Orthonasal and retronasal test scores, OB volume, and olfactory ERPs were significantly larger in responders compared with nonresponders. CONCLUSIONS: Significant differences in various tests that evaluate olfactory function were detectable in a cohort of NL individuals and NP, PT, and PI patients. This finding suggests that these diagnostic tools provide information in terms of the clinical assessment of olfactory function. Future studies will investigate their combined use in terms of the prognosis of olfactory function in patients with olfactory loss.
Correlation between olfactory bulb volume and olfactory function in children and adolescents
Experimental Brain Research, 2011
The olfactory bulb (OB) is considered to be the most important relay station in odor processing. Involving 125 randomly selected subjects (58 men, 67 women; age range: 19 to 79 years), the present study aimed to investigate a possible correlation between OB volume and specific olfactory functions including odor threshold, odor discrimination, and odor identification. The history of all participants was taken in great detail to exclude possible causes of smell dysfunction. All participants received an otolaryngological investigation including a volumetric scan of the brain (MRI), lateralized olfactory tests and a screen for cognitive impairment. Volumetric measurements of the right and left OB were performed by manual segmentation of the coronal slices through the OB. Significant correlations between OB volumes in relation to olfactory function were observed, independent of the subjects' age. Additionally, OB volumes decreased with age. In agreement with previous research the present study confirmed the correlation between OB volume and specific olfactory functions. Furthermore, the correlation between OB volume and olfactory function was not mediated by the subjects' age. In conclusion, the present data obtained from a relatively large group of subjects forms the basis for age-related normative values of OB volumes.
Editorial: Physiology and pathophysiology of the olfactory system
Frontiers in Neural Circuits
Editorial on the Research Topic Physiology and pathophysiology of the olfactory system One of the intriguing features of the mammalian olfactory system is the integration of newly generated sensory neurons and interneurons in the olfactory bulb throughout our life. The continuous reconstitution of the olfactory neural circuit that arises from the integration could modify the olfactory information processing, and thus impair the olfactory image of objects. Therefore, to maintain the olfactory perception, the olfactory system has developed homeostatic plasticity which works under physiological and even pathophysiological conditions. This Research Topic intends to represent the most recent and exciting results focused on understanding the mammalian olfactory system covering the olfactory epithelium to higher olfactory centers, from molecular mechanisms to olfactory recognition.
Olfactory bulb volume and depth of olfactory sulcus in patients with idiopathic olfactory loss
European Archives of Oto-Rhino-Laryngology, 2010
Olfactory loss is considered as idiopathic (IOL) when no cause can be found, neither on the basis of a standardized history nor a thorough clinical evaluation. Olfactory bulb volume (OB) has been shown to be decreased in patients with olfactory loss due to trauma, infections, or sinonasal disease. However, OB volume has not yet been investigated in IOL patients. Twenty-two patients with IOL were compared with 22 controls in terms of olfactory performance and of OB volume assessed with magnetic resonance imaging (MRI). Psychophysical testing conWrmed that patients had lower scores than controls: P < 0.001 for threshold (T), discrimination (D), identiWcation (I) and global TDI score. Mean right, left and total OB volumes were signiWcantly smaller for IOL patients as compared to controls. Both for IOL and controls, there was a signiWcant correlation between odor thresholds and total OB volume, respectively. In conclusion, patients with IOL have decreased olfactory function and decreased OB volume when compared with controls. This was previously demonstrated for patients with postinfectious or posttraumatic olfactory dysfunction, but not for patients with uneventful conditions possibly damaging their olfactory apparatus.
Reduced olfactory bulb volume in post-traumatic and post-infectious olfactory dysfunction
NeuroReport, 2005
The olfactory bulb is a highly plastic structure the volume of which partly re£ects the degree of a¡erent neural activity. In this study, 22 patients with post-infectious olfactory de¢cit, nine participants with post-traumatic olfactory de¢cit, and 17 healthy controls underwent magnetic resonance volumetry of the olfactory bulb. Patients presented with signi¢cantly smaller olfactory bulb volumes than controls; signi¢cant correlations between olfactory function and bulb volume were observed. Patients with parosmia exhibited smaller olfactory bulb volumes than those without parosmia. Findings indicate that smell de¢cits leading to a reduced sensory input to the olfactory bulb result in structural changes at the level of the bulb. Reduced olfactory bulb volumes may also be considered to be characteristic of parosmia. NeuroReport16:475^478
Olfactory function and olfactory bulb volume in patients with postinfectious olfactory loss
The …, 2006
OBJECTIVE: The study aimed to investigate whether the degree of postinfectious olfactory loss is reflected in volume of the olfactory bulb (OB). STUDY DESIGN: Retrospective study of 26 patients with postinfectious olfactory loss. MATERIALS AND METHODS: Olfactory function was assessed with the "Sniffin' Sticks" test kit, and the magnetic resonance imaging study focused on OB volume and the olfactory sulcus. RESULTS: The study revealed that 1) OB volume varies with regard to olfactory function, 2) OB volume decreases with duration of olfactory loss, and 3) patients with parosmia had smaller OB volumes than patients who did not report such smell distortions, although their overall olfactory function was not significantly different from each other. CONCLUSION: The study emphasizes that OB volume is a gauge of olfactory function.
European Archives of Oto- …, 2009
Studies of the tissues of the human olfactory mucosa have been performed to investigate olfactory dys-function and, more recently, olfactory mucosa has attracted a novel interest of investigators because it can be used as an early marker of neurodegenerative conditions of the brain ...