Bilateral hypoglossal nerve paralysis after irradiation therapy.

Cancericidal doses of irradiation therapy to be the head and neck may be followed by paralysis of cranial nerves due to fibrosis of tissue about the nerves and infiltration of the nerves with fibrous tissue. The hypoglossal nerve is particularly prone to this delayed effect of irradiation therapy and a case is presented here in which there was bilateral hypoglossal paresis appearing three years after therapy.