Olfaction and anosmia in rhinosinusitis

Abstract

Olfactory disorders can cause serious consequences from the inability to detect many olfactory warning signals (eg, smoke, spoiled food, and gas leaks) and can significantly impact nutritional status, eating satisfaction, and many other issues related to quality of life. More than 200,000 people a year seek treatment for impaired olfactory ability, and available evidence suggests this figure is a significant underestimate of those affected. Rhinitis and rhinosinusitis are the primary etiologies for olfactory loss or distortion among patients presenting to chemosensory clinics, and they are among the most common chronic medical conditions in the United States, affecting an estimated 33 million people. Both allergic and nonallergic rhinitis/rhinosinusitis can result in diminished, distorted, or absent olfactory ability. Current therapies are only partially or transiently effective in reversing olfactory loss. The underlying mechanisms by which rhinitis/rhinosinusitis impact olfactory ability are likely to be multifactorial and might include altered air flow and odor deposition, changes in mucus composition, and effects of inflammatory mediators on receptor cell differentiation, maturation, or function.

An Odor is Not Worth a Thousand Words: From Multidimensional Odors to Unidimensional Odor Objects

“…They send one dendrite-like process to the olfactory epithelium, and the other axon-like process joins the olfactory nerve bundle (cranial nerve I) to cross through the cribriform plate and synapse at specialized neuropoil termed "glomeruli" on the surface of the ipsilateral olfactory bulb (Figure 1). The epithelium is obviously a key structure in olfaction, and damage to the human epithelium can lead to anosmia (a complete loss of smell) (Dalton 2004, Doty & Mishra 2001). …”

Environmental Toxicants-Induced Immune Responses in the Olfactory Mucosa

“…Environmental agents entering the nasal cavity may become allergens, causing inflammation in the olfactory mucosa (OM) (olfactory inflammation), and leading to allergic rhinitis and infectious sinusitis (1). The symptoms are usually associated with hyposmia or anosmia (2, 3). Olfactory loss in rhinitis/sinusitis is attributable primarily to blockade of airflow to the olfactory sensory neurons (OSNs) that receive odorous molecules, but damage to the OM is also considered as a possible cause (2, 4–6).…”

Hidden consequences of olfactory dysfunction: a patient report series

“…The three most common causes are sinonasal disease, upper respiratory infection, and head trauma (Figure 1). Sinonasal diseases like nasal polyps or chronic inflammation of the nasal passages and/or paranasal sinuses (rhinitis, sinusitis, rhinosinusitis) are the most common cause of olfactory dysfunction (Figure 1) [for an overview see [30-32]]. Chronic inflammation in the nose and sinuses is the most common chronic medical condition in the United States of America [33-35] and more than half of the affected individuals have olfactory symptoms [36].…”