Paragangliomas of the head and neck are tumors which are believed to function as chemosensory reflex receptors that respond to changes in their chemical environment. They may occur in the carotid body, on the vagus nerve, along the jugular vein, in the middle ear, in the orbit, in the larynx and nasopharynx. The incidence of multiple paragangliomas is about 3% of all the patients with this tumor and 26% of the patients with positive family history.