Chemosensory dysfunction in primary Sjögren's syndrome: a topical review

Primary Sjögren's syndrome is an autoimmune exocrinopathy related to lymphocytic infiltration of the exocrine glandular epithelia (such as salivary, lacrimal, nasal, and sebaceous glands or vaginal mucosa) with systemic manifestations of an immuno-inflammatory nature, and not associated with any other systemic disease. It is characterized by severe dryness (Sicca syndrome), particularly in mouth and eyes, with potential strong impact on quality of life and could increase the risk of depression in Sjögren's patient. To date, the impairment of taste and olfactory functions related to Sjögren syndrome remains poorly assessed; so is the trigeminal functions which remain sparsely studied in patients with Sjögren disease. However, other factors can also modify chemosensory functions (olfactory or gustatory sensations and trigeminal nerves), in particular the reduction of the masticatory coefficient or halitosis, due to oral saliva flow decrease, and poor dental condition, which are often present in Sjögren patients. Of the 12 articles evaluated after a 22-year literature search of this review, chemosensory disorders (including taste, smell, and trigeminal impairments) are described and evaluated in pSS patients, with mainly poorer performance compared to healthy controls. Diagnostic and therapeutic (including rehabilitation) approaches of chemosensory disorders in pSS are discussed in this review. Clinician should be more attentive to taste as well as olfacto-trigeminal disorders in primary Sjögren's disease, if possible at the earlier stage, in order to take the best care of Sjögren's patients. This review also highlights some lack in knowledge on pSS chemosensory disorders that should provide new research perspectives. Key Points •Chemosensory functions (including taste, smell, and trigeminal functions) are altered in patients with primary Sjögren's syndrome (pSS) due to dryness of the mouth and the nose. •The trigeminal nerve which interacts with olfactory and gustatory nerves contributes to olfactory and taste perception but remains little studied to date. •Chemosensory function should be considered in the daily clinical assessment of patients with pSS. •Chemosensory function treatment is not standardized yet, however symptomatic treatment of Sjögren syndrome-associated dryness transiently would improve taste and smell, and olfactory or gustatory rehabilitation in pSS patients would be useful.