Hyposmia in neurodegenerative disorders

Douglas J Lanska MD FAAN MS MSPH (Dr. Lanska of the Great Lakes VA Healthcare System and the University of Wisconsin School of Medicine and Public Health has no relevant financial relationships to disclose.)
Originally released April 21, 2013; last updated February 7, 2017; expires February 7, 2020

Overview

In this article, the author explains the clinical presentation, pathophysiology, diagnostic workup, and management of hyposmia in neurodegenerative disorders. Olfactory deficits involving odor detection, identification, and discrimination are very common early in the course of Parkinson disease and dementia with Lewy bodies. Odor identification is also impaired in patients with REM sleep behavior disorder, a common and very early feature of Lewy body alpha-synucleinopathies. In patients with Parkinson disease or dementia with Lewy bodies, olfactory threshold and odor identification do not improve with levodopa therapy, or with other pharmacologic manipulation of dopaminergic or cholinergic status.

Key points

 

• Olfactory deficits involving odor detection, identification, and discrimination are very common early in the course of Parkinson disease and dementia with Lewy bodies.

 

• Odor identification is also impaired in patients with REM sleep behavior disorder, a common and very early feature of Lewy body alpha-synucleinopathies.

 

• Less commonly, some degree of olfactory loss has also been reported in various other dementing disorders, including Alzheimer disease and frontotemporal dementia.

 

• In patients with Parkinson disease or dementia with Lewy bodies, olfactory threshold and odor identification do not improve with levodopa therapy, or with other pharmacologic manipulation of dopaminergic or cholinergic status.

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