The effects of therapeutic irradiation on olfactory function were investigated in 20 patients who received radiation therapy because of a malignant tumor of the nose or paranasal sinuses. The standard olfaction test with a T&T olfactometer and an intravenous olfaction test were given before the radiation therapy, during the period of radiation therapy and 1, 3, 6 and 12 months or more later.
Five patients whose olfactory epithelium was outside the radiation field showed no damage to olfactory function. The olfactory function of the other 15 patients whose olfactory epithelium had been exposed to radiation was not obviously changed or damaged at the time of radiation therapy. However, 6 months after irradiation, some patients showed a decline in olfactory function, and after 12 months, 4 of 7 patients showed severe damage to olfactory function.
These results suggest that a therapeutic dose of irradiation will not cause severe damage to the olfactory function during the period of radiation therapy, but could cause delayed olfactory disorders in some patients after a few years. These olfactory disorders might be caused by damage to or degeneration of the olfactory epithelium or olfactory nerve.
