[Disorders of the sense of smell and taste].

Disorders of olfaction and taste are infrequent, but a complete loss of smell or taste reduces the quality of life significantly. The sensitivity of human olfaction is remarkable, even for specific stimuli: Just a few molecules are enough to induce the correct identification of sterilised and ultraheated milk. Olfaction and taste are called 'chemical senses' because in both cases the adequate stimulus consists of molecules that bind to receptors of the sensory cells. The perceptions of smell and taste are often combined. Taste differentiates only four qualities: sweet, sour, salty, and bitter. The typical flavor of food or drink is detected by olfaction. Disturbances of olfaction can be due to respiratory disorders such as nasal polyps, a deviation of the nasal septum or chronic sinusitis. Such conditions can reduce airflow through the olfactory cleft at the roof of the nasal cavity. They can be corrected by modern endoscopic surgery of the nose. Epithelial disorders involving the sensory cells are most often caused by viral infections (influenza-anosmia) or toxic destruction of the sensory epithelium (solvents or gases). Epithelial disorders can be cured only rarely by any treatment. Corticosteroids, zinc, and vitamin A are tried frequently. Neural disorders occur after frontobasal trauma and during neurological diseases such as Parkinson's or Alzheimer's disease. Disorders of olfaction can be an early sign of such neurological diseases and sophisticated examination of this sense can contribute to their early diagnosis. However, no specific treatments have yet been identified. Disorders of taste can be due to toxic, chemical or inflammatory damage to the sensory cells of the tongue.(ABSTRACT TRUNCATED AT 250 WORDS)