In recent otolaryngological fields, there is an increasing numbers of tympanoplasty with the advancement of otology, surgical oto-microscope and micro-surgical instruments. With this operation, there is increasing chances of injuries to chorda tympani, which passed through the middle ear cavity.
Research on gustatory function is shadowed by the interest of hearing gain and lack of subjective feelings.
With gustatory function tests, we can localize the topographical site of facial nerve paralysis and also it is clinically interest to observe the changes of taste produced by the middle ear surgery with preserved or injured chorda tympani.
For gustatory functional examinations, there have been an objective salivary secretion reflex test and a subjective method with four fundamental test materials and since Krarup (1958) introduced an electrogustometric apparatus, it has become popular to measure the accurate quantitative taste threshold by an electrogustometer.
Authors have studied about gustatory functions with four fundamental taste solutions and electrogustometer in normal control and the middle ear operated groups and following results were obtained;
1. The threshold of taste with electrogustometer was lowest at apex (45. 9 μA), mid at middle (60. 9 uA) and highest at base of the tongue (74. 3,μA).
2. The side difference of threshold between right and left was not significant and showed only 2. 4 aA in average.
3. The threshold of taste increased with age.
4. On unilateral chorda tympanectomy cases, there was almost no subjective loss of taste but the thrashold of taste for electrogustometry was markedly increased (117. 9 ,μA) and also the result of solution test showed negative in 8 of 9 cases.
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