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Gunder N, Dörig P, Witt M, Welge-Lüssen A, Menzel S, Hummel T. Future therapeutic strategies for olfactory disorders: electrical stimulation, stem cell therapy, and transplantation of olfactory epithelium-an overview. HNO 2023; 71:35-43. [PMID: 36734997 PMCID: PMC9897160 DOI: 10.1007/s00106-022-01249-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2022] [Indexed: 02/04/2023]
Abstract
Olfactory disorders may be temporary or permanent and can have various causes. Currently, many COVID-19 patients report a reduced or complete loss of olfactory function. A wide range of treatment options have been investigated in the past, such as olfactory training, acupuncture, medical therapy, transcranial magnetic stimulation, or surgical excision of olfactory epithelium, e.g., in severe qualitative smell disorders. The development of a bioelectric nose, e.g., in connection with direct electrical stimulation or transplantation of olfactory epithelium or stem cells, represent treatment options of the future. The basis of these developments and the state of knowledge is discussed in the following work.
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Affiliation(s)
- N Gunder
- Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Carl Gustav Carus an der Technischen Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
| | - P Dörig
- Universitäts-HNO Klinik Basel, Basel, Switzerland
| | - M Witt
- Institut für Anatomie, Universitätsmedizin Rostock, Rostock, Germany
| | | | - S Menzel
- Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Carl Gustav Carus an der Technischen Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany
| | - T Hummel
- Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Carl Gustav Carus an der Technischen Universität Dresden, Fetscherstr. 74, 01307, Dresden, Germany
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Hummel T, Power Guerra N, Gunder N, Hähner A, Menzel S. Olfactory Function and Olfactory Disorders. Laryngorhinootologie 2023; 102:S67-S92. [PMID: 37130532 PMCID: PMC10184680 DOI: 10.1055/a-1957-3267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.
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Affiliation(s)
- T Hummel
- Interdisziplinäres Zentrum Riechen und Schmecken, HNO Klinik, TU Dresden
| | - N Power Guerra
- Rudolf-Zenker-Institut für Experimentelle Chirurgie, Medizinische Universität Rostock, Rostock
| | - N Gunder
- Universitäts-HNO Klinik Dresden, Dresden
| | - A Hähner
- Interdisziplinäres Zentrum Riechen und Schmecken, HNO Klinik, TU Dresden
| | - S Menzel
- Interdisziplinäres Zentrum Riechen und Schmecken, HNO Klinik, TU Dresden
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Park JW, Wang X, Xu RH. Revealing the mystery of persistent smell loss in Long COVID patients. Int J Biol Sci 2022; 18:4795-4808. [PMID: 35874953 PMCID: PMC9305264 DOI: 10.7150/ijbs.73485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/09/2022] [Indexed: 11/05/2022] Open
Abstract
COVID-19 is hopefully approaching its end in many countries as herd immunity develops and weaker strains of SARS-CoV-2 dominate. However, a new concern occurs over the long-term effects of COVID-19, collectively called "Long COVID", as some symptoms of the nervous system last even after patients recover from COVID-19. This review focuses on studies of anosmia, i.e., impairment of smell, which is the most common sensory defect during the disease course and is caused by olfactory dysfunctions. It remains mysterious how the olfactory functions are affected since the virus can't invade olfactory receptor neurons. We describe several leading hypotheses about the mystery in hope to provide insights into the pathophysiology and treatment strategies for anosmia.
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Affiliation(s)
- Jung Woo Park
- Center of Reproduction, Development & Aging, and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Taipa, Macau, China.,Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, Taipa, Macau, China
| | - Xiaoyan Wang
- Center of Reproduction, Development & Aging, and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Taipa, Macau, China.,Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, Taipa, Macau, China
| | - Ren-He Xu
- Center of Reproduction, Development & Aging, and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Taipa, Macau, China.,Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, Taipa, Macau, China
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Olfactory and gustatory disorders in COVID-19. ALLERGO JOURNAL INTERNATIONAL 2022; 31:243-250. [PMID: 35755859 PMCID: PMC9208356 DOI: 10.1007/s40629-022-00216-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/28/2022] [Indexed: 12/05/2022]
Abstract
Loss of olfaction is one of the symptoms most commonly reported by patients with coronavirus disease 2019 (COVID-19). Although the spontaneous recovery rate is high, recent studies have shown that up to 7% of patients remain anosmic for more than 12 months after the onset of infection, leaving millions of people worldwide suffering from severe olfactory impairment. Olfactory training remains the first recommended treatment. With the continued lack of approved drug treatments, new therapeutic options are being explored. This article reviews the current state of science on COVID-19-related olfactory disorders, focusing on epidemiology, pathophysiology, cure rates, currently available treatment options, and research on new treatments.
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Abstract
PURPOSE OF REVIEW This article reviews the literature on COVID-19 related anosmia, focusing on the epidemiology, pathophysiology recovery rates, current available treatment options, and research regarding novel treatments. RECENT FINDINGS Loss of sense of smell is one of the most prevalent symptoms reported by patients after COVID-19 infection. Even though there is a high self-reported recovery rate, recent studies have demonstrated that up to 7% of the patients remain anosmic more than 12 months after onset, leaving millions worldwide with severe olfactory dysfunction. Olfactory training remains the first line recommended treatment. Given the paucity of effective medical treatments options researchers are exploring novel therapeutic options. SUMMARY Olfactory dysfunction remains a significant and persistent legacy of the COVID-19 pandemic, but heightened awareness may stimulate research that leads to the development of much-needed treatment options.
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Affiliation(s)
- Katerina Karamali
- Department of Otorhinolaryngology, Guy's and St Thomas NHS Foundation Trust
| | - Michael Elliott
- Department of Otorhinolaryngology, Guy's and St Thomas NHS Foundation Trust
| | - Claire Hopkins
- Guy's and St Thomas’ NHS Foundation Trust, London, United Kingdom
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Klimek L, Hagemann J, Döge J, Koll L, Cuevas M, Klimek F, Hummel T. Störungen des Riech- und Schmeckvermögens bei COVID-19. ALLERGO JOURNAL 2022; 31:35-43. [PMCID: PMC9618349 DOI: 10.1007/s15007-022-5602-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Der Verlust des Riechvermögens ist eines der Symptome, die von Patienten mit COVID-19 mit am häufigsten angegeben werden. Obwohl die Spontanheilungsrate hoch ist, haben neuere Studien gezeigt, dass bis zu 7 % der Patienten mehr als zwölf Monate nach Beginn der Infektion anosmisch bleiben, sodass weltweit Millionen von Menschen unter schweren Riechstörungen leiden. Riechtraining ist nach wie vor die erste empfohlene Behandlungsform. Angesichts weiterhin fehlender zugelassener medikamentöser Behandlungsmöglichkeiten werden neue therapeutische Optionen erforscht. Dieser Artikel gibt einen Überblick über den aktuellen Stand der Wissenschaft zu COVID-19-bedingten Riechstörungen, wobei der Schwerpunkt auf der Epidemiologie, der Pathophysiologie, den Heilungsraten, den derzeit verfügbaren Behandlungsmöglichkeiten und der Forschung zu neuen Behandlungsmethoden liegt. Zitierweise: Klimek L, Hagemann J, Döge J, Freudelsperger L, Cuevas M, Klimek F, Hummel T. Olfactory and gustatory disorders in COVID-19. Allergo J Int 2022;31:243-50 https://doi.org/10.1007/s40629-022-00216-7
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Affiliation(s)
- Ludger Klimek
- FA für Dermatologie u. Allergologie, Zentrum f. Rhinologie und Allergologie, An den Quellen 10, 65183 Wiesbaden, Germany
| | - Jan Hagemann
- Klinik f. Hals-Nasen-Ohrenheilkunde, Universitätsmedizin Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Julia Döge
- Klinik f. Hals-Nasen-Ohrenheilkunde, Universitätsmedizin Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Laura Koll
- Hals-, Nasen-, Ohrenklinik und Poliklinik, Universitätsmedizin Mainz, Mainz, Germany
| | - Mandy Cuevas
- Klinik u. Poliklinik für Hals- Nasen- und Ohrenheilkunde, Univ.-Klinikum Carl Gustav Carus, Fetscherstr. 74, 01307 Dresden, Germany
| | - Felix Klimek
- Zentrum für Rhinologie und Allergologie Wiesbaden, An den Quellen 10, 65183 Wiesbaden, Germany
| | - Thomas Hummel
- Klinik und Poliklinik für HNO-Heilkunde, Universitätsklinikum Carl Gustav Carus, Dresden, Germany
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Dörig P, Gunder N, Witt M, Welge-Lüssen A, Hummel T. [Future therapeutic strategies for olfactory disorders: electrical stimulation, stem cell therapy, and transplantation of olfactory epithelium-an overview]. HNO 2021; 69:623-632. [PMID: 33988723 PMCID: PMC8120256 DOI: 10.1007/s00106-021-01060-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2021] [Indexed: 11/08/2022]
Abstract
Passagere oder permanente Riechstörungen können verschiedene Ursachen haben. Ganz aktuell berichtet eine Vielzahl von Patienten im Rahmen von COVID-19-Infektionen über ein fehlendes oder vermindertes Riechvermögen. In der Vergangenheit wurden vielfältige Therapieoptionen untersucht, diese variieren vom Riechtraining über Akupunktur und medikamentöse Therapien bis hin zur transkraniellen Magnetstimulation oder, z. B. bei ausgeprägten qualitativen Riechstörungen, der chirurgischen Resektion der Riechschleimhaut. Die Entwicklung einer bioelektrischen Nase, z. B. in Verbindung mit direkter elektrischer Stimulation des Bulbus olfactorius, oder die Transplantation von Riechschleimhaut oder von Stammzellen stellen Behandlungsmöglichkeiten der Zukunft dar. Die Grundlagen für diese Entwicklungen sowie der Stand des Wissens werden in der vorliegenden Arbeit erläutert.
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Affiliation(s)
- P Dörig
- Universitäts-HNO Klinik Basel, Petersgraben 4, 4031, Basel, Schweiz.
| | - N Gunder
- Universitäts-HNO Klinik Dresden, Dresden, Deutschland
| | - M Witt
- Institut für Anatomie, Universitätsmedizin Rostock, Rostock, Deutschland
| | - A Welge-Lüssen
- Universitäts-HNO Klinik Basel, Petersgraben 4, 4031, Basel, Schweiz
| | - T Hummel
- Universitäts-HNO Klinik Dresden, Dresden, Deutschland
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Commensal microbiota affects ischemic stroke outcome by regulating intestinal γδ T cells. Nat Med 2016; 22:516-23. [PMID: 27019327 PMCID: PMC4860105 DOI: 10.1038/nm.4068] [Citation(s) in RCA: 693] [Impact Index Per Article: 86.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/17/2016] [Indexed: 12/12/2022]
Abstract
Commensal gut bacteria impact the host immune system and can influence disease processes in several organs, including the brain. However, it remains unclear whether the microbiota has an impact on the outcome of acute brain injury. Here we show that antibiotic-induced alterations in the intestinal flora reduce ischemic brain injury in mice, an effect transmissible by fecal transplants. Intestinal dysbiosis alters immune homeostasis in the small intestine, leading to an increase in regulatory T cells and a reduction in interleukin (IL)-17-positive γδ T cells through altered dendritic cell activity. Dysbiosis suppresses trafficking of effector T cells from the gut to the leptomeninges after stroke. Additionally, IL-10 and IL-17 are required for the neuroprotection afforded by intestinal dysbiosis. The findings reveal a previously unrecognized gut-brain axis and an impact of the intestinal flora and meningeal IL-17(+) γδ T cells on ischemic injury.
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Posttraumatic olfactory dysfunction. Auris Nasus Larynx 2015; 43:137-43. [PMID: 26441369 DOI: 10.1016/j.anl.2015.08.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 07/30/2015] [Accepted: 08/26/2015] [Indexed: 11/20/2022]
Abstract
Impairment of smell may occur following injury to any portion of the olfactory tract, from nasal cavity to brain. A thorough understanding of the anatomy and pathophysiology combined with comprehensively obtained history, physical exam, olfactory testing, and neuroimaging may help to identify the mechanism of dysfunction and suggest possible treatments. Although most olfactory deficits are neuronal mediated and therefore currently unable to be corrected, promising technology may provide novel treatment options for those most affected. Until that day, patient counseling with compensatory strategies and reassurance is essential for the maintenance of safety and QoL in this unique and challenging patient population.
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Abstract
Decreased sense of smell can lead to significant impairment of quality of life, including taste disturbance and loss of pleasure from eating with resulting changes in weight, and difficulty in avoiding health risks such as spoiled food or leaking natural gas. Recent epidemiological reports have shown that despite fairly low self-reported prevalence of these disorders in large population studies, when validated smell identification or threshold tests are used they reveal quite a high prevalence of hyposmia and anosmia in certain groups, especially the elderly. Several different pathophysiological processes, such as head trauma, aging, autoimmunity, and toxic exposures, can contribute to smell impairment, with distinct implications concerning prognosis and possible treatment. Otolaryngologists are most likely to see this symptom in patients with chronic rhinosinusitis, and this now appears to be caused more by the mucosal inflammation than by physical airway obstruction.
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Affiliation(s)
- Alan Gaines
- Department of Medicine, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA.
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Current world literature. Curr Opin Otolaryngol Head Neck Surg 2011; 19:58-65. [PMID: 21233627 DOI: 10.1097/moo.0b013e32834344aa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Olfactory epithelial transplantation: possible mechanism for restoration of smell. Curr Opin Otolaryngol Head Neck Surg 2011; 19:54-7. [PMID: 21102335 DOI: 10.1097/moo.0b013e328341e242] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW To discuss the unique properties of the olfactory epithelium and the potential use of olfactory epithelial grafts to restore olfactory function. RECENT FINDINGS Sensory neurons in the olfactory epithelium undergo continuous regeneration, grow new axons, and reestablish connections with the olfactory bulb throughout life. When transplanted into different regions of the brain, olfactory epithelial graft cells retain their morphological and regenerative properties. Olfactory cells within the grafts grow axons that enter into the surrounding brain tissue. Recent studies have shown that the olfactory epithelium can be grafted directly to the olfactory bulb. SUMMARY The olfactory epithelium has a remarkable capacity to continuously generate new sensory neurons and survives grafting into different regions of the brain. A review of the literature and the future use of olfactory grafts as a potential method to restore olfactory function is discussed.
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