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De Luca R, Bonanno M, Rifici C, Quartarone A, Calabrò RS. Post-traumatic olfactory dysfunction: a scoping review of assessment and rehabilitation approaches. Front Neurol 2023; 14:1193406. [PMID: 37521284 PMCID: PMC10374209 DOI: 10.3389/fneur.2023.1193406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
Post-traumatic Olfactory Dysfunction (PTOD) consists of a complete or partial loss of olfactory function that may occur after a traumatic brain injury (TBI). PTOD may be linked to some neuropsychiatric features, such as social, cognitive and executive dysfunction, as well as behavioral symptoms, especially when TBI involves the orbito-frontal cortex. The diagnosis of PTOD is based on medical history and clinical data and it is supported by psychometric tests (i.e., subjective tools) as well as electrophysiological and neuroimaging measures (i.e., objective methods). The assessment methods allow monitoring the changes in olfactory function over time and help to establish the right therapeutic and rehabilitative approach. In this context, the use of the olfactory training (OT), which is a non-pharmacological and non-invasive treatment option, could promote olfactory function through top-down (central) and bottom-up (peripheral) processes. To better manage patients with TBI, PTOD should be detected early and properly treated using the various therapeutic rehabilitative possibilities, both conventional and advanced, also taking into consideration the emerging neuromodulation approach.
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Patel ZM, Holbrook EH, Turner JH, Adappa ND, Albers MW, Altundag A, Appenzeller S, Costanzo RM, Croy I, Davis GE, Dehgani-Mobaraki P, Doty RL, Duffy VB, Goldstein BJ, Gudis DA, Haehner A, Higgins TS, Hopkins C, Huart C, Hummel T, Jitaroon K, Kern RC, Khanwalkar AR, Kobayashi M, Kondo K, Lane AP, Lechner M, Leopold DA, Levy JM, Marmura MJ, Mclelland L, Miwa T, Moberg PJ, Mueller CA, Nigwekar SU, O'Brien EK, Paunescu TG, Pellegrino R, Philpott C, Pinto JM, Reiter ER, Roalf DR, Rowan NR, Schlosser RJ, Schwob J, Seiden AM, Smith TL, Soler ZM, Sowerby L, Tan BK, Thamboo A, Wrobel B, Yan CH. International consensus statement on allergy and rhinology: Olfaction. Int Forum Allergy Rhinol 2022; 12:327-680. [PMID: 35373533 DOI: 10.1002/alr.22929] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/01/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O). METHODS Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus. RESULTS The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies. CONCLUSION This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.
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Affiliation(s)
- Zara M Patel
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Eric H Holbrook
- Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA
| | - Justin H Turner
- Otolaryngology, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - Nithin D Adappa
- Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Mark W Albers
- Neurology, Harvard Medical School, Boston, Massachusetts, USA
| | - Aytug Altundag
- Otolaryngology, Biruni University School of Medicine, İstanbul, Turkey
| | - Simone Appenzeller
- Rheumatology, School of Medical Sciences, University of Campinas, São Paulo, Brazil
| | - Richard M Costanzo
- Physiology and Biophysics and Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Ilona Croy
- Psychology and Psychosomatic Medicine, TU Dresden, Dresden, Germany
| | - Greg E Davis
- Otolaryngology, Proliance Surgeons, Seattle and Puyallup, Washington, USA
| | - Puya Dehgani-Mobaraki
- Associazione Naso Sano, Umbria Regional Registry of Volunteer Activities, Corciano, Italy
| | - Richard L Doty
- Smell and Taste Center, Otolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Valerie B Duffy
- Allied Health Sciences, University of Connecticut, Storrs, Connecticut, USA
| | | | - David A Gudis
- Otolaryngology, Columbia University Irving Medical Center, New York, USA
| | - Antje Haehner
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | - Thomas S Higgins
- Otolaryngology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Claire Hopkins
- Otolaryngology, Guy's and St. Thomas' Hospitals, London Bridge Hospital, London, UK
| | - Caroline Huart
- Otorhinolaryngology, Cliniques universitaires Saint-Luc, Institute of Neuroscience, Université catholgique de Louvain, Brussels, Belgium
| | - Thomas Hummel
- Smell and Taste, Otolaryngology, TU Dresden, Dresden, Germany
| | | | - Robert C Kern
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Ashoke R Khanwalkar
- Otolaryngology, Stanford University School of Medicine, Stanford, California, USA
| | - Masayoshi Kobayashi
- Otorhinolaryngology-Head and Neck Surgery, Mie University Graduate School of Medicine, Mie, Japan
| | - Kenji Kondo
- Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Andrew P Lane
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Matt Lechner
- Otolaryngology, Barts Health and University College London, London, UK
| | - Donald A Leopold
- Otolaryngology, University of Vermont Medical Center, Burlington, Vermont, USA
| | - Joshua M Levy
- Otolaryngology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Michael J Marmura
- Neurology Thomas Jefferson University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Lisha Mclelland
- Otolaryngology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Takaki Miwa
- Otolaryngology, Kanazawa Medical University, Ishikawa, Japan
| | - Paul J Moberg
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Sagar U Nigwekar
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Erin K O'Brien
- Otolaryngology, Mayo Clinic Rochester, Rochester, Minnesota, USA
| | - Teodor G Paunescu
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Carl Philpott
- Otolaryngology, University of East Anglia, Norwich, UK
| | - Jayant M Pinto
- Otolaryngology, University of Chicago, Chicago, Illinois, USA
| | - Evan R Reiter
- Otolaryngology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - David R Roalf
- Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nicholas R Rowan
- Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rodney J Schlosser
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - James Schwob
- Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Allen M Seiden
- Otolaryngology, University of Cincinnati School of Medicine, Cincinnati, Ohio, USA
| | - Timothy L Smith
- Otolaryngology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Zachary M Soler
- Otolaryngology, Medical University of South Carolina, Mt Pleasant, South Carolina, USA
| | - Leigh Sowerby
- Otolaryngology, University of Western Ontario, London, Ontario, Canada
| | - Bruce K Tan
- Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Andrew Thamboo
- Otolaryngology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bozena Wrobel
- Otolaryngology, Keck School of Medicine, USC, Los Angeles, California, USA
| | - Carol H Yan
- Otolaryngology, School of Medicine, UCSD, La Jolla, California, USA
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3
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Saltagi AK, Saltagi MZ, Nag AK, Wu AW, Higgins TS, Knisely A, Ting JY, Illing EA. Diagnosis of Anosmia and Hyposmia: A Systematic Review. ALLERGY & RHINOLOGY 2021; 12:21526567211026568. [PMID: 34285823 PMCID: PMC8264728 DOI: 10.1177/21526567211026568] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/16/2021] [Accepted: 06/02/2021] [Indexed: 11/16/2022]
Abstract
Background Anosmia and hyposmia have many etiologies, including trauma, chronic sinusitis, neoplasms, and respiratory viral infections such as rhinovirus and SARS-CoV-2. We aimed to systematically review the literature on the diagnostic evaluation of anosmia/hyposmia. Methods PubMed, EMBASE, and Cochrane databases were searched for articles published since January 1990 using terms combined with Medical Subject Headings (MeSH). We included articles evaluating diagnostic modalities for anosmia, written in the English language, used original data, and had two or more patients. Results A total of 2065 unique titles were returned upon the initial search. Of these, 226 abstracts were examined, yielding 27 full-text articles meeting inclusion criteria (Level of evidence ranging from 1 to 4; most level 2). The studies included a total of 13,577 patients. The most utilized diagnostic tools were orthonasal smell tests (such as the Sniffin’ Sticks and the UPSIT, along with validated abridged smell tests). Though various imaging modalities (including MRI and CT) were frequently mentioned in the workup of olfactory dysfunction, routine imaging was not used to primarily diagnose smell loss. Conclusion The literature includes several studies on validity and reliability for various smell tests in diagnosing anosmia. Along with a thorough history and physical, validated orthonasal smell tests should be part of the workup of the patient with suspected olfactory dysfunction. The most widely studied modality was MRI, but criteria for the timing and sequence of imaging modalities was heterogenous.
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Affiliation(s)
- Abdul K Saltagi
- Indiana University School of Medicine, Indianapolis, Indiana
| | - Mohamad Z Saltagi
- Indiana University School of Medicine, Indianapolis, Indiana.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, Indiana
| | - Amit K Nag
- Indiana University School of Medicine, Indianapolis, Indiana
| | - Arthur W Wu
- Division of Otolaryngology, Head and Neck Surgery, Cedars-Sinai Division of Otolaryngology, Los Angeles, California
| | - Thomas S Higgins
- Department of Otolaryngology-Head and Neck Surgery, University of Louisville, Louisville, Kentucky.,Kentuckiana Ear, Nose & Throat
| | - Anna Knisely
- Otolaryngology, Swedish Medical Center, Seattle, WA
| | - Jonathan Y Ting
- Indiana University School of Medicine, Indianapolis, Indiana.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, Indiana
| | - Elisa A Illing
- Indiana University School of Medicine, Indianapolis, Indiana.,Department of Otolaryngology-Head and Neck Surgery, Indiana University Health, Indianapolis, Indiana
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4
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A new perspective on imaging of olfactory dysfunction: Does size matter? Eur J Radiol 2020; 132:109290. [PMID: 33035920 DOI: 10.1016/j.ejrad.2020.109290] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/20/2020] [Accepted: 09/11/2020] [Indexed: 01/21/2023]
Abstract
PURPOSE This study assesses the diagnostic utility of olfactory nerve and bulb morphologies in addition to volumetric analysis in classification of different olfactory dysfunction etiologies. METHODS 106 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. RESULTS Volumetric 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. CONCLUSION In 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.
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Shiga H, Wakabayashi H, Washiyama K, Noguchi T, Hiromasa T, Miyazono S, Kumai M, Ogawa K, Taki J, Kinuya S, Miwa T. Thallium-201 Imaging in Intact Olfactory Sensory Neurons with Reduced Pre-Synaptic Inhibition In Vivo. Mol Neurobiol 2020; 57:4989-4999. [PMID: 32820461 PMCID: PMC7541386 DOI: 10.1007/s12035-020-02078-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/14/2020] [Indexed: 11/30/2022]
Abstract
In this study, we determined whether the 201Tl (thallium-201)-based olfactory imaging is affected if olfactory sensory neurons received reduced pre-synaptic inhibition signals from dopaminergic interneurons in the olfactory bulb in vivo. The thallium-201 migration rate to the olfactory bulb and the number of action potentials of olfactory sensory neurons were assessed 3 h following left side nasal administration of rotenone, a mitochondrial respiratory chain complex I inhibitor that decreases the number of dopaminergic interneurons without damaging the olfactory sensory neurons in the olfactory bulb, in mice (6–7 animals per group). The migration rate of thallium-201 to the olfactory bulb was significantly increased following intranasal administration of thallium-201 and rotenone (10 μg rotenone, p = 0.0012; 20 μg rotenone, p = 0.0012), compared with that in control mice. The number of action potentials was significantly reduced in the olfactory sensory neurons in the rotenone treated side of 20 μg rotenone-treated mice, compared with that in control mice (p = 0.0029). The migration rate of thallium-201 to the olfactory bulb assessed with SPECT-CT was significantly increased in rats 24 h after the left intranasal administration of thallium-201 and 100 μg rotenone, compared with that in control rats (p = 0.008, 5 rats per group). Our results suggest that thallium-201 migration to the olfactory bulb is increased in intact olfactory sensory neurons with reduced pre-synaptic inhibition from dopaminergic interneurons in olfactory bulb glomeruli.
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Affiliation(s)
- Hideaki Shiga
- Department of Otorhinolaryngology, Kanazawa Medical University, Uchinadamachi, Kahokugun, Ishikawa, 920-0293, Japan.
| | - Hiroshi Wakabayashi
- Department of Nuclear Medicine, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, 920-8640, Japan
| | - Kohshin Washiyama
- Advanced Clinical Research Center, Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, 960-1295, Japan
| | - Tomohiro Noguchi
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, 078-8510, Japan
| | - Tomo Hiromasa
- Department of Nuclear Medicine, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, 920-8640, Japan
| | - Sadaharu Miyazono
- Department of Sensory Physiology, Asahikawa Medical University, Asahikawa, 078-8510, Japan
| | - Masami Kumai
- Department of Otorhinolaryngology, Kanazawa Medical University, Uchinadamachi, Kahokugun, Ishikawa, 920-0293, Japan
| | - Kazuma Ogawa
- Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Ishikawa, 920-1192, Japan
| | - Junichi Taki
- Department of Nuclear Medicine, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, 920-8640, Japan
| | - Seigo Kinuya
- Department of Nuclear Medicine, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, 920-8640, Japan
| | - Takaki Miwa
- Department of Otorhinolaryngology, Kanazawa Medical University, Uchinadamachi, Kahokugun, Ishikawa, 920-0293, Japan
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Veronesi MC, Alhamami M, Miedema SB, Yun Y, Ruiz-Cardozo M, Vannier MW. Imaging of intranasal drug delivery to the brain. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2020; 10:1-31. [PMID: 32211216 PMCID: PMC7076302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 02/07/2020] [Indexed: 06/10/2023]
Abstract
Intranasal (IN) delivery is a rapidly developing area for therapies with great potential for the treatment of central nervous system (CNS) diseases. Moreover, in vivo imaging is becoming an important part of therapy assessment, both clinically in humans and translationally in animals. IN drug delivery is an alternative to systemic administration that uses the direct anatomic pathway between the olfactory/trigeminal neuroepithelium of the nasal mucosa and the brain. Several drugs have already been approved for IN application, while others are undergoing development and testing. To better understand which imaging modalities are being used to assess IN delivery of therapeutics, we performed a literature search with the key words "Intranasal delivery" and "Imaging" and summarized these findings in the current review. While this review does not attempt to be fully comprehensive, we intend for the examples provided to allow a well-rounded picture of the imaging tools available to assess IN delivery, with an emphasis on the nose-to-brain delivery route. Examples of in vivo imaging, for both humans and animals, include magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), gamma scintigraphy and computed tomography (CT). Additionally, some in vivo optical imaging modalities, including bioluminescence and fluorescence, have been used more in experimental testing in animals. In this review, we introduce each imaging modality, how it is being utilized and outline its strengths and weaknesses, specifically in the context of IN delivery of therapeutics to the brain.
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Affiliation(s)
- Michael C Veronesi
- Department of Radiology & Imaging Sciences, Indiana University School of MedicineUSA
| | - Mosa Alhamami
- Department of Radiology & Imaging Sciences, Indiana University School of MedicineUSA
| | - Shelby B Miedema
- Department of Radiology & Imaging Sciences, Indiana University School of MedicineUSA
- Department of Biomedical Engineering, Indiana University-Purdue University IndianapolisUSA
| | - Yeonhee Yun
- Department of Radiology & Imaging Sciences, Indiana University School of MedicineUSA
| | - Miguel Ruiz-Cardozo
- Clinical Research Institute, Universidad Nacional de Colombia School of MedicineUSA
| | - Michael W Vannier
- Department of Radiology, University of Chicago School of MedicineUSA
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Takahashi Y, Shindo S, Kanbayashi T, Takeshima M, Imanishi A, Mishima K. Examination of the influence of cedar fragrance on cognitive function and behavioral and psychological symptoms of dementia in Alzheimer type dementia. Neuropsychopharmacol Rep 2020; 40:10-15. [PMID: 32037737 PMCID: PMC7292212 DOI: 10.1002/npr2.12096] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 12/16/2019] [Accepted: 12/30/2019] [Indexed: 11/11/2022] Open
Abstract
We examined whether symptoms of dementia are improved by olfactory nerve stimulation in Alzheimer type dementia patients. First, a stick-type olfactory identification ability test was performed in patients with Alzheimer type dementia, to select patients without olfactory dysfunctions. Then, these patients were randomly assigned into the intervention (n = 19) and the control groups (n = 17). To evaluate the effects of olfactory nerve stimulation, we exposed the intervention group to a disinfecting ethanol with added aroma extracts from ceder and the control group to the ethanol without the added aroma extracts. Each group underwent the intervention for 8 weeks, cognitive and behavioral functions were evaluated before and after treatments using the Neuropsychiatric Inventory (NPI), the Japanese version of Zarit Caregiver Burden interview (J-ZBI), and the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). A significant improvement was observed in the NPI score and J-ZBI in the intervention group compared to the control group at 4 and 8 weeks. On the other hand, there was no significant difference in the score of ADAS-cog. Exposure to cedar fragrance improved behavioral and psychological symptoms of dementia (BPSD) in Alzheimer type dementia and may reduce the burden of nursing care. In addition to its effectiveness, the procedure is simple and minimally invasive and would be a valuable non-pharmaceutical treatment.
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Affiliation(s)
- Yuya Takahashi
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
| | - Sho Shindo
- Akita Research Institute of Food and Brewing, Akita, Japan
| | - Takashi Kanbayashi
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan.,International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Masahiro Takeshima
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
| | - Aya Imanishi
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
| | - Kazuo Mishima
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan.,International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
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Functional Olfactory Nerve Regeneration Demonstrated by Thallium-201 Olfacto-Scintigraphy in Patients with Traumatic Anosmia: A Case Report. Case Rep Otolaryngol 2019; 2019:1069741. [PMID: 31827962 PMCID: PMC6881771 DOI: 10.1155/2019/1069741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 10/30/2019] [Indexed: 11/18/2022] Open
Abstract
Head trauma is one of the most common etiologies of olfactory dysfunction. It is difficult to use either the olfactory function test or magnetic resonance imaging to directly assess the course of damage to olfactory nerves. Thallium-201 (201Tl) olfacto-scintigraphy has been shown to be an able means for objectively assessing the olfactory nerve transport function. It is expected to be used to evaluate olfactory nerve regeneration after damage to the olfactory nerves. However, no such result has been reported. We present a patient who lost his olfactory function after experiencing head trauma. When his olfactory function remained anosmic, a 201Tl olfacto-scintigraphy showed no migration of 201Tl from the nasal mucosa to the olfactory bulb. After treatment with medicines and olfactory training, his olfactory function improved. A second 201Tl olfacto-scintigraphy showed an increased migration of 201Tl from the nasal mucosa to the olfactory bulb.
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9
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Shiga H, Okuda K, Taki J, Watanabe N, Tonami H, Kinuya S, Miwa T. Nasal thallium-201 uptake in patients with parosmia with and without hyposmia after upper respiratory tract infection. Int Forum Allergy Rhinol 2019; 9:1252-1256. [PMID: 31356735 PMCID: PMC6899886 DOI: 10.1002/alr.22395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/30/2019] [Accepted: 07/04/2019] [Indexed: 11/11/2022]
Abstract
BACKGROUND In this study, we aimed to determine whether nasal thallium-201 uptake of the olfactory cleft and olfactory bulb (OB) differs between patients with parosmia with and without hyposmia after upper respiratory tract infection (URTI). METHODS Twenty patients with parosmia after URTI were enrolled in this study (15 women and 5 men, 28 to 76 years old). Nasally administered thallium-201 migration to the OB, nasal thallium-201 uptake ratio in the olfactory cleft, and OB volume were determined in 10 patients with normal T&T olfactometry (Daiichi Yakuhin Sangyo, Tokyo, Japan) odor recognition thresholds (≤2.0) who still complained of parosmia (parosmia group), and 10 patients with T&T odor recognition thresholds >2.0 (parosmia and hyposmia group). RESULTS The nasal thallium-201 uptake ratio in the olfactory cleft was significantly higher in the parosmia group than in the parosmia and hyposmia group (p = 0.0015). Thallium-201 migration to the OB was not significantly different between the 2 groups (p = 0.31). The OB volume was significantly larger in the parosmia group than that in the parosmia and hyposmia group (p = 0.029); however, the mean OB volume in both the groups was lower than the normal threshold value in healthy individuals. CONCLUSION Our results signify the recovery of the olfactory epithelium; however, the olfactory neural projections to the OB and regeneration of OB were not complete in patients with parosmia with normal T&T recognition thresholds after URTI.
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Affiliation(s)
- Hideaki Shiga
- Department of Otorhinolaryngology, Kanazawa Medical University, Ishikawa, Japan
| | - Koichi Okuda
- Department of Physics, Kanazawa Medical University, Ishikawa, Japan
| | - Junichi Taki
- Department of Nuclear Medicine, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan
| | - Naoto Watanabe
- Department of Diagnostic and Therapeutic Radiology, Kanazawa Medical University, Ishikawa, Japan
| | - Hisao Tonami
- Department of Diagnostic and Therapeutic Radiology, Kanazawa Medical University, Ishikawa, Japan
| | - Seigo Kinuya
- Department of Nuclear Medicine, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan
| | - Takaki Miwa
- Department of Otorhinolaryngology, Kanazawa Medical University, Ishikawa, Japan
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10
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Huart C, Rombaux P, Hummel T. Neural plasticity in developing and adult olfactory pathways – focus on the human olfactory bulb. J Bioenerg Biomembr 2019; 51:77-87. [DOI: 10.1007/s10863-018-9780-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/23/2018] [Indexed: 01/18/2023]
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11
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Werner S, Nies E. Olfactory dysfunction revisited: a reappraisal of work-related olfactory dysfunction caused by chemicals. J Occup Med Toxicol 2018. [PMID: 30202422 DOI: 10.1186/s12995‐018‐0209‐6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Occupational exposure to numerous individual chemicals has been associated with olfactory dysfunction, mainly in individual case descriptions. Comprehensive epidemiological investigations into the olfactotoxic effect of working substances show that the human sense of smell may be impaired by exposure to metal compounds involving cadmium, chromium and nickel, and to formaldehyde. This conclusion is supported by the results of animal experiments. The level of evidence for a relationship between olfactory dysfunction and workplace exposure to other substances is relatively weak.
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Affiliation(s)
- Sabine Werner
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
| | - Eberhard Nies
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
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Werner S, Nies E. Olfactory dysfunction revisited: a reappraisal of work-related olfactory dysfunction caused by chemicals. J Occup Med Toxicol 2018; 13:28. [PMID: 30202422 PMCID: PMC6124006 DOI: 10.1186/s12995-018-0209-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/30/2018] [Indexed: 11/10/2022] Open
Abstract
Occupational exposure to numerous individual chemicals has been associated with olfactory dysfunction, mainly in individual case descriptions. Comprehensive epidemiological investigations into the olfactotoxic effect of working substances show that the human sense of smell may be impaired by exposure to metal compounds involving cadmium, chromium and nickel, and to formaldehyde. This conclusion is supported by the results of animal experiments. The level of evidence for a relationship between olfactory dysfunction and workplace exposure to other substances is relatively weak.
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Affiliation(s)
- Sabine Werner
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
| | - Eberhard Nies
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
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13
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Ponto LLB, Walsh S, Huang J, Mundt C, Thede-Reynolds K, Leonard Watkins G, Sunderland J, Acevedo M, Donovan M. Pharmacoimaging of Blood-Brain Barrier Permeable (FDG) and Impermeable (FLT) Substrates After Intranasal (IN) Administration. AAPS JOURNAL 2017; 20:15. [PMID: 29218424 DOI: 10.1208/s12248-017-0157-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/21/2017] [Indexed: 01/07/2023]
Abstract
To illustrate the use of imaging to quantify the transfer of materials from the nasal cavity to other anatomical compartments, specifically, transfer to the brain using the thymidine analogue, [18F]fluorothymidine (FLT), and the glucose analogue, [18F]fluorodeoxyglucose (FDG). Anesthetized rats were administered FLT or FDG by intranasal instillation (IN) or tail-vein injection (IV). PET/CT imaging was performed for up to 60 min. Volumes-of-interest (VOIs) for the olfactory bulb (OB) and the remaining brain were created on the CT and transferred to the co-registered dynamic PET. Time-activity curves (TACs) were generated and compared. The disposition patterns were successfully visualized and quantified and differences in brain distribution patterns were observed. For FDG, the concentration was substantially higher in the OB than the brain only after IN administration. For FLT, the concentration was higher in the OB than the brain after both IN and IV and higher after IN than after IV administration at all times, whereas the concentration in the brain was higher after IN than after IV administration at early times only. Approximately 50 and 9% of the IN FDG and FLT doses, respectively, remained in the nasal cavity at 20 min post-administration. The initial phase of clearance was similar for both agents (t1/2 = 2.53 and 3.36 min) but the slow clearance phase was more rapid for FLT than FDG (t1/2 = 32.1 and 85.2 min, respectively). Pharmacoimaging techniques employing PET/CT can be successfully implemented to quantitatively investigate and compare the disposition of radiolabeled agents administered by a variety of routes.
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Affiliation(s)
- Laura L Boles Ponto
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA. .,PET Imaging Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA.
| | - Susan Walsh
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Jiangeng Huang
- College of Pharmacy, Division of Pharmaceutics and Translational Therapeutics, Iowa City, Iowa, USA.,Department of Pharmaceutics, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Christine Mundt
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,PET Imaging Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
| | - Katherine Thede-Reynolds
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,PET Imaging Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
| | - G Leonard Watkins
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,PET Imaging Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
| | - John Sunderland
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,PET Imaging Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
| | - Michael Acevedo
- Department of Radiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Maureen Donovan
- College of Pharmacy, Division of Pharmaceutics and Translational Therapeutics, Iowa City, Iowa, USA
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14
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Prognostic value of olfactory nerve damage measured with thallium-based olfactory imaging in patients with idiopathic olfactory dysfunction. Sci Rep 2017; 7:3581. [PMID: 28620194 PMCID: PMC5472561 DOI: 10.1038/s41598-017-03894-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/05/2017] [Indexed: 11/08/2022] Open
Abstract
Idiopathic olfactory disorder is resistant to treatment, and the recovery time is long. This study investigated the prognostic value of the migration of nasally administered thallium-201 to the olfactory bulb (thallium migration to the OB), a measure of olfactory nerve damage, in patients with idiopathic olfactory disorders. Twenty-four patients with idiopathic olfactory disorders were enrolled in the study (7 women and 17 men; aged 23-73 years). We retrospectively analyzed potential prognostic markers in subjects who underwent thallium-based olfactory imaging with the nasal administration of thallium-201 before conventional treatment with the Japanese herbal medicine tokishakuyakusan and compared those data with the prognosis. Log-rank tests were performed to assess the relationship between thallium migration to the OB (<4.6% [low] vs. ≥4.6% [high]; data dichotomized at the optimal cutoff value) and the duration until recovery of the odor recognition threshold determined by a standard olfactory function test (T&T olfactometry) after the treatment. Upon statistical analysis, we found that high thallium migration to the OB was significantly correlated with better prognosis in patients. Our results suggest that patients with intact olfactory nerve fibers could be selected using thallium-based imaging for the long-term follow-up of olfactory dysfunction.
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15
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Patel VA, Zacharia TT, Goldenberg D, McGinn JD. End-organ radiographic manifestations of cranial neuropathies: A concise review. Clin Imaging 2017; 44:5-11. [PMID: 28364580 DOI: 10.1016/j.clinimag.2017.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/02/2017] [Accepted: 03/22/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cranial neuropathies are a spectrum of disorders associated with dysfunction of one or more of the twelve cranial nerves and the subsequent anatomic structures they innervate. OBJECTIVE The purpose of this article is to review radiographic imaging findings of end-organ aberrations secondary to cranial neuropathies. METHOD All articles related to cranial neuropathies were retrieved through the PubMed MEDLINE NCBI database from January 1, 1991 to August 31, 2014. These manuscripts were analyzed for their relation to cranial nerve end-organ disease pathogenesis and radiographic imaging. RESULTS The present review reveals detectable end-organ changes on CT and/or MRI for the following cranial nerves: olfactory nerve, optic nerve, oculomotor nerve, trochlear nerve, trigeminal nerve, abducens nerve, facial nerve, vestibulocochlear nerve, glossopharyngeal nerve, vagus nerve, accessory nerve, and hypoglossal nerve. CONCLUSION Radiographic imaging can assist in the detailed evaluation of end-organ involvement, often revealing a corresponding cranial nerve injury with high sensitivity and diagnostic accuracy. A thorough understanding of the distal manifestations of cranial nerve disease can optimize early pathologic detection as well as dictate further clinical management.
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Affiliation(s)
- Vijay A Patel
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - Thomas T Zacharia
- Department of Radiology, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - David Goldenberg
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
| | - Johnathan D McGinn
- Department of Surgery, Division of Otolaryngology - Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA.
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16
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Tsutsumi S, Ono H, Yasumoto Y. Visualization of the olfactory nerve using constructive interference in steady state magnetic resonance imaging. Surg Radiol Anat 2016; 39:315-321. [PMID: 27506829 DOI: 10.1007/s00276-016-1731-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/04/2016] [Indexed: 11/28/2022]
Abstract
PURPOSE The olfactory nerve (OlfN) is a small neural structure with inconsistent visualization on neuroimages. The aim of this study was to delineate the intracranial course of the OlfN using constructive interference in steady state magnetic resonance (MR) imaging. METHODS A total of 168 patients were enrolled in this study. Following initial examinations with conventional MR sequences, constructive interference in steady-state sequence (CISS) was performed in coronal and axial sections. RESULTS On coronal sections, the OlfN was entirely visualized in 90 % of patients on the right and 92 % on the left, coursing along the olfactory sulcus. Complete visualization of the OlfN occurred in 100 % of patients on serial axial images. The OlfN was classified into four portions based on the topographical differences and surrounding structures. The olfactory fossa exhibited considerable variability at the midlevel of the olfactory bulb on coronal images. Characteristic appearance of the OlfN with respect to age range or gender was not observed. CONCLUSIONS The OlfN follows a highly consistent course along the olfactory sulcus. Thin-sliced, CISS sequences are useful for consistent visualization of the OlfN.
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Affiliation(s)
- Satoshi Tsutsumi
- Department of Neurological Surgery, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba, 279-0021, Japan.
| | - Hideo Ono
- Division of Radiological Technology, Medical Satellite Yaesu Clinic, Tokyo, Japan
| | - Yukimasa Yasumoto
- Department of Neurological Surgery, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba, 279-0021, Japan
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Proskynitopoulos PJ, Stippler M, Kasper EM. Post-traumatic anosmia in patients with mild traumatic brain injury (mTBI): A systematic and illustrated review. Surg Neurol Int 2016; 7:S263-75. [PMID: 27213113 PMCID: PMC4866055 DOI: 10.4103/2152-7806.181981] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/01/2016] [Indexed: 11/23/2022] Open
Abstract
Background: Olfactory dysfunction (OD) is a disorder associated with traumatic brain injury (TBI), which is prevalent in up to 20% of patients suffering from TBI. Nevertheless, most studies focusing on the relationship between OD and TBIs do not differentiate between the different types of TBI (mild, medium, and severe). In this paper, we conducted a comprehensive and systematic review of the existing literature for the association between mild TBI (mTBI) and OD in order to examine their relationship, focusing on its neurosurgical management and the radiographic characteristics. Methods: The MEDLINE database was systematically reviewed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. We found 66 articles, of which 10 fulfilled our criteria. Results: All except two studies reported a significant association between trauma severity and olfaction. Two studies found a negative correlation between TBI severity and olfactory bulb volume with one reporting an r value of −0.62). Three studies reported an association between the observation of radiographic intracranial hemorrhage or skull base fractures and the history of TBI. Conclusion: According to our search results, we conclude that OD is a prevalent but underdiagnosed problem in mTBI. Because OD is associated with a significant decrease in quality of life, we think that neurosurgical teams need to asses olfactory function in mTBI patients when they report to clinics. To illustrate this scenario, we include two distinct cases of patients with anosmia after mTBI in this review. Finally, we suggest a treatment algorithm for patients with mTBI so that a possible OD can be diagnosed and treated as early as possible.
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Affiliation(s)
| | - Martina Stippler
- Department of Neurosurgery, Beth Israel Deaconess Medical Center, Boston, USA
| | - Ekkehard M Kasper
- Department of Neurosurgery, Beth Israel Deaconess Medical Center, Boston, USA
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Shiga H, Nagaoka M, Washiyama K, Yamamoto J, Yamada K, Noda T, Harita M, Amano R, Miwa T. Reduced nasal transport of insulin-like growth factor-1 to the mouse cerebrum with olfactory bulb resection. Chem Senses 2014; 39:595-9. [PMID: 25056729 DOI: 10.1093/chemse/bju032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Although the olfactory nerve is involved in nasal transport of insulin-like growth factor-1 (IGF-1) to the brain, to our knowledge there have been no direct assessments of the effects of olfactory nerve damage on this transport. To determine whether olfactory bulb resection resulted in reduced transport of nasally administered human recombinant IGF-1 (hIGF-1) to the cerebrum, we measured the uptake of nasally administered iodine-125 hIGF-1 ((125)I-hIGF-1) in the cerebrum as a percentage of that in the blood in male ICR mice subjected to left olfactory bulb resection (model mice) and in sham-operated male ICR mice (control mice). Phosphorylated extracellular signal-regulated kinase (ERK) 1/2 (Thr202/Tyr204)/(Thr185/Tyr187) as a percentage of total ERK 1/2 in the left cerebrum was also assessed by using enzyme-linked immunosorbent assay after nasal administration of hIGF-1. Uptake of nasally administered (125)I-hIGF-1 in the cerebrum as a percentage of that in the blood was significantly lower in the model group than in the control group 30min after nasal administration of hIGF-1. Unilateral olfactory bulb resection prevented nasally administered hIGF-1 from increasing the phosphorylation of ERK 1/2 in the mouse cerebrum in vivo. These findings suggest that olfactory bulb damage reduces nasal transport of hIGF-1 to the brain in vivo.
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Affiliation(s)
- Hideaki Shiga
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
| | - Mikiya Nagaoka
- Department of Quantum Medical Technology, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan
| | - Kohshin Washiyama
- Department of Quantum Medical Technology, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan
| | - Junpei Yamamoto
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
| | - Kentaro Yamada
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
| | - Takuya Noda
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
| | - Masayuki Harita
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
| | - Ryohei Amano
- Department of Quantum Medical Technology, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan
| | - Takaki Miwa
- Department of Otorhinolaryngology, Kanazawa Medical University, 1-1 Daigaku, Uchinadamachi, Kahokugun, Ishikawa 920-0293, Japan and
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Plasticity of the human olfactory system: the olfactory bulb. Molecules 2013; 18:11586-600. [PMID: 24048289 PMCID: PMC6269828 DOI: 10.3390/molecules180911586] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 09/03/2013] [Accepted: 09/11/2013] [Indexed: 01/18/2023] Open
Abstract
In the last years, an increasing interest has been paid to the olfactory system, particularly to its abilities of plasticity and its potential continuous neurogenesis throughout adult life. Although mechanisms underlying adult neurogenesis have been largely investigated in animals, to some degree they remain unclear in humans. Based on human research findings, the present review will focus on the olfactory bulb as an evidence of the astonishing plasticity of the human olfactory system.
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