Brain volume changes in hyposmic patients before and after olfactory training

Gellrich, Janine; Han, Pengfei; Manesse, C.; Betz, Amelie; Junghanns, Anne; Raue, Claudia; Schriever, Valentin A.; Hummel, Thomas

doi:10.1002/lary.27045

Cited by 59 publications

(75 citation statements)

References 46 publications

(115 reference statements)

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“…It is important to point out that the improvements in olfactory ability with training did not reflect changes in the OBs for either patient group . Our nonsignificant changes to OB volumes are at odds with studies showing increases in olfactory patients undergoing medical treatment, spontaneous recovery, and studies in healthy subjects .…”

Section: Discussioncontrasting

confidence: 57%

“…in the OBs for either patient group. 30,34 Our nonsignificant changes to OB volumes are at odds with studies showing increases in olfactory patients undergoing medical treatment, 29,31 spontaneous recovery, 57 and studies in healthy subjects. 58 The current findings seem to suggest that improvements induced through training in olfactoryimpaired individuals may be, at least in part, a top-down effect through plasticity of the central nervous system and increased attention.…”

Section: Training Effects On Obmentioning

confidence: 77%

“…The OB volumes of healthy individuals are larger compared to posttraumatic patients . Structural and fMRI have been successful at revealing dysfunction in olfactory perception and predicting increased olfactory functionality with rehabilitation practices such as olfactory training . To our knowledge, this study is the first to measure functional changes in hyposmic patients after olfactory training.…”

Section: Introductionmentioning

confidence: 93%

“…1,9,29 Structural and fMRI have been successful at revealing dysfunction in olfactory perception 29 and predicting increased olfactory functionality with rehabilitation practices such as olfactory training. [30][31][32][33][34] To our knowledge, this study is the first to measure functional changes in hyposmic patients after olfactory training. We hypothesize an increased identification ability after olfactory training among patients suffering olfactory loss after head trauma, with increased activation in related semantic processing areas.…”

Section: Introductionmentioning

confidence: 94%

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Effectiveness of olfactory training on different severities of posttraumatic loss of smell

et al. 2019

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Objective/Hypothesis A common, lasting condition from traumatic brain injury is impairment to smell. In patients with olfactory impairment, recent meta‐analyses have demonstrated that olfactory training consistently improves higher‐order functions, such as odor identification. The focus of this work was to assess effects of olfactory training (OT) in posttraumatic olfactory loss patients through several metrics including psychophysical, olfactory bulb (OB) volume, and functional magnetic resonance imaging. Study Design Prospective cohort study. Methods Sniffin’ Sticks were used to classify two patient groups (anosmic [N = 23] and hyposmic [N = 14]) and measure changes after OT. Additionally patients were asked the intensity, valence, and uncued identification of odors presented (coffee and peach) within the magnetic resonance imaging scanner before and after olfactory training. Olfactory training was performed twice daily with a four‐odor training set for 24 weeks, and sets were replaced halfway through the entire training session (~12 weeks). Results Patients had an increase in test scores (threshold and identification) and in‐scanner intensity ratings and identification. Anosmic patients showed improved olfactory thresholds to 2‐phenylethanol, increased intensity ratings, and activation in the right superior frontal gyrus (SFG) to odors after OT. Hyposmic patients were able to identify odors better after training. This behavior was mirrored with increased, ipsilateral activations in semantic processing areas such as Broca's area, left angular gyrus, and left SFG. Conclusions Taken together, along with neither patient group showing changes in OB volumes, OT improves olfactory performance in patients with posttraumatic olfactory loss and seems to be driven, at least in part, by top‐down processes (central) rather than bottom‐up (peripheral). Levels of Evidence 2Laryngoscope, 129:1737–1743, 2019

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Section: Discussioncontrasting

confidence: 57%

Section: Training Effects On Obmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 94%

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Effectiveness of olfactory training on different severities of posttraumatic loss of smell

et al. 2019

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“…MCID was defined as a .5.5 or .6 increase in TDI scores by the individual study authors. In 2006, Gudziol et al 33 demonstrated that an increase of 5.5 points in TDI composite scores corresponded to more than 60% of patients reporting subjective olfactory improvement; 4 studies use this value as 18 Prospective cohort study 39 COT 8 mo Gellrich et al (2018) 26 Prospective case-control study 61 COT 3 mo Hummel et al (2009) 16 Prospective cohort study 24 COT 3 mo Hummel et al (2017) 27 Retrospective cohort study 170 COT 3 mo Kollndorfer et al (2015) 17 Prospective cohort study 10 COT alone vs COT and vitamin A 3 mo Konstantinidis et al (2013) 28 Prospective cohort study 81 COT 4 mo Konstantinidis et al (2016) 19 Prospective cohort study 111 Short-term COT vs long-term COT 4 mo, 14 mo Oleszkiewicz et al (2018) 29 Prospective 20 Prospective cohort study 125 Combination 1 OT vs combination 2 OT 6 mo Saatci et al (2020) 31 Prospective cohort study 60 Olfactory training ball vs COT 3 mo…”

Section: Study Characteristicsmentioning

confidence: 99%

Olfactory Training for Postviral Olfactory Dysfunction: Systematic Review and Meta‐analysis

Kattar¹,

Triet

Unis

et al. 2020

Otolaryngol.--head neck surg.

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Objective Olfactory dysfunction is a common problem that is most frequently attributed to upper respiratory infection. Postviral olfactory dysfunction (PVOD) can be prolonged and clinically challenging to treat. Olfactory training (OT) has demonstrated potential benefit for patients with nonspecific olfactory dysfunction. We sought to evaluate the efficacy of OT specifically for PVOD by pooled analysis of the existing evidence. Data Sources PubMed, Embase, and Web of Science. Review Methods Following PRISMA guidelines, PubMed, Embase, and Web of Science databases were queried and abstracts screened independently by 2 investigators. We included studies evaluating the efficacy of OT for PVOD and excluded studies evaluating pharmacologic interventions or olfactory loss from other causes. Results Of the initial 1981 abstracts reviewed, 16 full-text articles were included. Sniffin’ Sticks olfactory testing results were reported in 15 (93%) studies as threshold (T), discrimination (D), and identification (I) subscores and TDI total scores. All studies reported clinically significant results after OT, defined as a score improvement of TDI >5.5. Four studies were included in the meta-analysis, in which pooled estimates revealed that patients with PVOD who received OT had a 2.77 (95% confidence interval, 1.67-4.58) higher odds of achieving a clinically important difference in TDI scores compared to controls. Conclusion Meta-analysis of existing data demonstrates clinically significant improvements in PVOD associated with OT. Variability exists among OT protocols and may benefit from further optimization. Existing data supports the use of OT for the treatment of existing and newly emerging cases of PVOD.

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Evaluation of the Incidence of Other Cranial Neuropathies in Patients With Postviral Olfactory Loss

Jitaroon

Wangworawut

et al. 2020

JAMA Otolaryngol Head Neck Surg

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IMPORTANCE Postviral olfactory loss is a common cause of olfactory impairment, affecting both quality of life as well as overall patient mortality. It is currently unclear why some patients are able to recover fully after a loss while others experience permanent deficit. There is a lack of research on the possible association between postviral olfactory loss and other cranial neuropathies.OBJECTIVE To evaluate the incidence of other cranial nerve deficits in patients with postviral olfactory loss and determine if there is an association with neurologic injury in this group. This study also sought to determine if other known risk factors were associated with postviral olfactory loss. DESIGN, SETTING, AND PARTICIPANTSA case-control study was conducted at a tertiary care rhinology clinic from January 2015 to January 2018 to review the incidence of cranial neuropathies in 2 groups of patients, those with postviral olfactory loss and those with chronic rhinosinusitis without olfactory loss used as a control group.

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Brain volume changes in hyposmic patients before and after olfactory training

Abstract: 3b. Laryngoscope, 128:1531-1536, 2018.

Cited by 59 publications

References 46 publications

Effectiveness of olfactory training on different severities of posttraumatic loss of smell

Effectiveness of olfactory training on different severities of posttraumatic loss of smell

Olfactory Training for Postviral Olfactory Dysfunction: Systematic Review and Meta‐analysis

Evaluation of the Incidence of Other Cranial Neuropathies in Patients With Postviral Olfactory Loss

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