Características dermatoscópicas de las papilas fungiformes pigmentadas de la lengua / Dermoscopic Features of Pigmented Fungiform Papillae of the Tongue

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[Gustatory loss: causes, consequences and treatment]. / Smaakverlies: oorzaken, gevolgen en behandeling.

The loss of taste is a common symptom and may have serious somatic and psychological consequences. Little attention is paid to the condition in doctors' practices, however, and the topic is also hardly mentioned in scientific publications. It is important to distinguish between isolated gustatory loss and gustatory loss in combination with other neurological symptoms. Isolated gustatory loss can be the result of a laesion of the chorda tympani of the facial nerve caused by otitis media or damage to the taste buds, for example. Treatment is aimed at removing the cause, e.g. medication or chronic otitis media, but the treatment options are often limited. Zinc supplementation in patients with zinc deficiency has not been proven to be effective. Gustatory loss in combination with other neurological symptoms is caused by damage to one or more cranial nerves, to the brain stem or cerebral cortex, and is an indication for referral to a neurologist. Early detection of the loss of taste, good patient counselling, diagnostics and possible treatment may limit the negative consequences of this condition.

Lgr5 Identifies Progenitor Cells Capable of Taste Bud Regeneration after Injury.

Taste buds are composed of a variety of taste receptor cell types that develop from tongue epithelium and are regularly replenished under normal homeostatic conditions as well as after injury. The characteristics of cells that give rise to regenerating taste buds are poorly understood. Recent studies have suggested that Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5) identifies taste bud stem cells that contribute to homeostatic regeneration in adult circumvallate and foliate taste papillae, which are located in the posterior region of the tongue. Taste papillae in the adult anterior region of the tongue do not express Lgr5. Here, we confirm and extend these studies by demonstrating that Lgr5 cells give rise to both anterior and posterior taste buds during development, and are capable of regenerating posterior taste buds after injury induced by glossopharyngeal nerve transection.

Effects of sensory or motor nerve deafferentation on oromotor function in mice.

OBJECTIVE: To investigate the effect of sensory or motor nerve damage to the tongue using a mouse model. STUDY DESIGN: Animal study. SETTING: Research laboratory. SUBJECTS AND METHODS: Adult male and female mice from inbred strains B6 (n = 19) and D2 (n = 25). Following lick training, bilateral lingual-chorda tympani nerve cuts (LX) (n = 6 B6, n = 7 D2), unilateral hypoglossal nerve cuts (HX) (n = 7 B6, n = 9 D2), or sham surgery (n = 6 B6, n = 9 D2) was performed. Mice were lick tested postsurgically with both water and sucrose (4 days total). Following testing, post mortem dissections and microscopic analysis of tongue papillae were performed. RESULTS: In both strains, HX and LX mice demonstrated a significant reduction in volume per lick (VPL) in the surgical groups relative to shams. Neither motor nor sensory nerve transection affected local lick rate. In most LX mice in both strains, taste papillae were reduced compared with HX or sham mice. CONCLUSION: Mice of either strain with either a sensory or a motor nerve injury have a significant loss of VPL during ingestion of either a neutral (water) or preferred (sucrose) stimulus. This reduction in VPL reflects a deficit in licking. Lick rate was not affected by deafferentation. A reduction in fungiform papillae following LX but not HX mice was noted.

Effects of chorda-lingual nerve injury and repair on human taste.

Citric acid detection threshold and magnitude response were measured on the anterior tongue in 10 patients with unilateral chorda-lingual nerve transections before and after repair. Fungiform taste buds were analysed by videomicroscopy. Preliminary data suggests that humans can regenerate fungiform taste buds and recover some taste sensitivity after repair.