Olfactory function and dysfunction

Abstract

Olfaction is phylogenetically the oldest sense, but receives scant attention in contrast to other special senses. Smell is often taken for granted, but it is central to our everyday life and helps to protect us from harmful substances, contributes to the livelihood of many professions as well as to the nutritional status and general quality of life. Olfactory disorders are common, yet remain the least understood. This paper gives an overview of the anatomy, physiology, and management of olfactory disorders with particular emphasis on current clinical measurements of olfactory dysfunction. Literature from relevant textbooks and selected journal articles has been reviewed in this article. Olfactory disorders can be classified as conductive, sensory, and neural. Localization of olfactory centers in the brain by electroencephalography has been described recently. However, quantitative evaluation by threshold measurements and qualitative testing with identification test formats continues to be the most popular type of olfactory test in use. While treatment of olfactory disorders remains disappointing, conductive disorders are amenable to treatment. Full understanding of the olfactory organ and its pathways is essential for the development of any reliable means of testing its function and managing dysfunction. With recent developments in olfactory mapping of the brain, it won't be long before a more robust test for olfaction akin to visual acuity and auditory thresholds is developed.