Article
Evaluation of gustatory function after primary middle ear surgery - Implementing a classification of the intraoperative anatomy of the chorda tympani nerve
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Published: | August 8, 2007 |
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Objective: Postoperative gustatory dysfunction is a well-known complication after otosurgical interventions. The aim of this prospective study is to demonstrate a possible correlation of the anatomic course of the chorda tympani nerve (CTN) in the middle ear and the prevalence of postoperative taste disorders.
Study design: Prospective, clinical study.
Setting: Tertiary care, academic medical center.
Material and methods: Preoperatively, gustatory testing with standardised solutions (sweet, sour, salty, bitter) sprayed on the tongue was performed. Intraoperatively, the course of the CTN was classified by 3 topographical criteria: The angle (A), the height (H) and the depth (D) of the nerve`s emergence from the posterior tympanic bone. In cases of postoperative taste dysfunction the patients were followed-up on a regular basis.
Results: 45 patients (24 male, 21 female, mean age: 46.2) were included in the study. The angle of the nerve`s emergence from the tympanic bone was below 30° in 26 cases, between 30° and 60° in 17 cases and within 60° and 90° in 2 cases. The height of emergence was 17 times in the superior, 25 times in the middle and 3 times in the inferior third of the posterior meatal wall. The depth of emergence lay within the plane of the fibrous tympanic anulus in 9 individuals, 20 times medially to this plane without overlapping bone and 16 times medially but covered by a bony spur. The CTN was preserved in 41 procedures, whereas it had to be sacrificed in 4 cases. Postoperatively, gustatory function was not deminished in 89 % of the cases. A significant correlation to the anatomic course of the nerve could not be found.
Conclusion: The results of this study show a very variable intraoperative anatomy of the CTN, every oto-surgeon needs to be aware of. However, the probability of a postoperative gustatory dysfunction seems to depend on the kind of the applied otosurgical procedure, only. Nevertheless, the hereby suggested classification of the nerve`s anatomic course in the lateral tympanon might be useful in similar studies to come.