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Neuroplasticity after olfactory training in post-surgical olfactory impaired patients, using functional magnetic resonance imaging. A randomized pilot study
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  • Francisco García-Huidobro,
  • Cristian Montalba,
  • Andres Rosenbaum,
  • David Jofre,
  • Marcelo Andia,
  • Pablo Villanueva,
  • Claudio Callejas,
  • Claudia Gonzalez
Francisco García-Huidobro
Pontificia Universidad Católica de Chile

Corresponding Author:[email protected]

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Cristian Montalba
Pontificia Universidad Catolica de Chile
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Andres Rosenbaum
Pontificia Universidad Catolica de Chile
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David Jofre
Pontificia Universidad Catolica de Chile
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Marcelo Andia
Pontificia Universidad Catolica de Chile
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Pablo Villanueva
Pontificia Universidad Catolica de Chile
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Claudio Callejas
Pontifical Catholic University of Chile
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Claudia Gonzalez
Pontificia Universidad Catolica de Chile
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Abstract

Abstract Objectives: Treatment for olfactory dysfunction is challenging due to limited therapeutic options. Olfactory training has shown improvement in smell identification, discrimination, and threshold for odor detection. The primary objective is to assess the effect of olfactory training in patients with olfactory dysfunction after pituitary surgery, using functional Magnetic Resonance Imaging (fMRI). Design: This study was designed as a two-arm pilot clinical trial. Setting: Chilean tertiary hospital providing endoscopic pituitary surgery and olfactory evaluation and treatment. Participants: We included two cohorts of subjects: healthy subjects, and patients with post-surgical olfactory dysfunction. Healthy patients were recruited voluntarily at the ENT clinic to assess fMRI testing paradigms and as a control group for the olfactory dysfunction group. Main outcome measures: The main outcome measures were functional activation analysis obtained by fMRI. Olfactory test assessment scores were also obtained during each testing session. Results: 119 patients that underwent an endoscopic transsphenoidal approach were contacted and surveyed for olfactory dysfunction. Twelve patients met inclusion criteria, but six of them declined to participate. Six patients were randomized using computer-generated random numbers. The patients in the trained group showed a significant improvement in the olfactory test results after olfactory training compared to the no-training group (P < 0.05). The group that underwent olfactory training showed more areas of activation after training than in baseline analysis (P < 0.05). Conclusion: Patients that underwent olfactory training showed significant improvement in olfactory testing. fMRI results showed more activated areas in the olfactory training group, which could be compatible with neuroplasticity.