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Objectives: It is generally thought that the recovery of damaged chorda tympani nerve (CTN) function after middle ear surgery is different in pediatric patients from that in adult patients. The purpose of this study was to investigate the changes and the progress of taste and somatosensory functions of the tongue after middle ear surgery in pediatric patients compared with those of adult patients., Study Design: Prospective study., Methods: Fifty-nine pediatric patients and 106 adult patients underwent middle ear surgery. Taste and somatosensory functions of the anterior tongue, the so-called CTN functions, were assessed using electrogustometry (EGM), a 2-point discriminator, an electrostimulator, and a questionnaire before and 2 weeks and 6 months after surgery., Results: Two weeks after surgery, there was no significant difference in the incidence of dysgeusia and abnormal EGM thresholds between the patient groups. The incidence of tongue numbness was significantly lower in pediatric patients than in adult patients regardless of CTN manipulation. Although the lingual somatosensory thresholds of adult patients were significantly increased, those of pediatric patients were not increased. Six months after surgery, the incidences of dysgeusia and an abnormal EGM threshold were lower in pediatric patients than in adult patients. Tongue numbness disappeared, and the thresholds of lingual somatosensory tests returned to normal in most pediatric patients., Conclusion: Not only taste function but also lingual somatosensory function was damaged after middle ear surgery even in pediatric patients. Pediatric patients complained of tongue numbness less frequently and showed earlier recovery than adult patients., Level of Evidence: 2 Laryngoscope, 130:1016-1022, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives: Patients after middle ear surgery often complain of taste disturbance and a lingual numbness. The purpose of this study was to objectively assess changes in the somatosensation of the tongue and taste function in patients undergoing stapes surgery., Study Design: Prospective study., Methods: Symptoms of taste disturbance and tongue numbness after surgery were investigated before and after surgery in 41 patients (13 males, 28 females; mean age 41.8 years) who underwent stapes surgery. Twenty-eight patients (9 males, 19 females; mean age 43.1 years) underwent sensory and taste function tests before and after surgery. Sensory function of the tongue was measured at the operated side and the nonoperated side using the 2-point discrimination test and an electrostimulator test. Taste function was assessed with electrogustometry (EGM)., Results: The chorda tympani nerve (CTN) was gently touched or stretched in all patients. Postoperative thresholds on the operated side were significantly higher than preoperative thresholds in all tests in the patients who underwent all three kinds of tests. Tongue somatosensory symptoms improved significantly earlier than the taste disturbance postoperatively, and the sensory thresholds returned to the baseline along with recovery of symptoms., Conclusion: These findings suggest that dysfunction of the CTN occurred following surgery even when the CTN was preserved, and that the sensory nerve threshold of the tongue correlated with the symptom of lingual numbness. The CTN may play a role not only in taste function but also in the somatosensory function of the tongue., Level of Evidence: 4. Laryngoscope, 128:701-706, 2018., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: To establish clinical tests for measurement of trigeminal sensitivity on the human tongue and objectively assess changes in oral trigeminal sensitivity and taste ability after chorda tympani nerve (CTN) injury., Study Design: Prospective study., Setting: University hospital., Patients: One-hundred and twenty-six patients with unilateral middle ear diseases who underwent primary middle ear surgery., Main Outcomes and Measures: Trigeminal sensation was measured each operated side as well as nonoperated side both before and 14 days after surgery using 3 kinds of tests: Semmes-Weinstein sensory test (SW test), 2-point discrimination test, and the electrostimulator test. Taste function was assessed with electrogustometry (EGM) similarly., Results: The patients which the CTN was not touched (n = 6) showed no differences between preoperative and postoperative thresholds in any tests. In the patients with sectioned CTN (n=30), postoperative thresholds on the operated side were significantly higher than preoperative thresholds on the electrostimulator test, 2-point discrimination test, and EGM. In the patients with manipulated but not sectioned CTN (n = 90), postoperative thresholds were significantly higher than preoperative thresholds on the electrostimulator test and EGM. The patients with manipulated but not sectioned CTN and abnormal EGM postoperative thresholds (n = 48) showed that postoperative thresholds were significantly higher than preoperative thresholds in all tests., Conclusion: These findings suggest that the electrostimulator test was most useful to objectively assess small changes of trigeminal sensation among the 3 tests. The finding that trigeminal sensitivity of the tongue deteriorated on the operated side after CTN injury suggests that CTN function affected both taste sensation and trigeminal sensation of the tongue.

Objective: To investigate prospectively the clinical manifestations and the functional recovery of taste after section of chorda tympani nerve (CTN) during middle ear surgery, the subjective and objective study on the patients was performed., Methods: Thirty-five patients underwent surgery with unilateral (n=32) or bilateral (n=3) section of CTN between January 2000 and April 2002. The patients were asked about taste symptoms before surgery and 2 weeks and 2 years after surgery. The CTN function was also measured with electrogustometry (EGM) at the same time points., Results: In unilateral section of CTN, 19/32 (59.4%) complained of taste disorder and 11/32 (34.4%) tongue numbness. Most of these taste symptoms disappeared within 2 years although the EGM threshold did not recover. 16/17 patients (94.1%) who used to cook everyday had little difficulty in flavoring dishes. In bilateral section of CTN, the patients had no problem of taste at 2 years after surgery, either., Conclusion: These findings help explain the potential complications to the patients before surgery, although the number of cases was small in this series.

Objective: It is generally said that taste function deteriorates naturally with age. Taste function after middle ear surgery in elderly patients has not been clarified., Material and Methods: The taste function of the chorda tympani nerve on the normal and diseased sides was examined before and after middle ear surgery using electrogustometry in 79 patients aged>60 years, and the findings were compared with those in 228 young and middle-aged patients., Results: The threshold of electrogustometry on the normal side increased significantly with increasing age (p<0.0001). The rate of thresholds that were off the scale was highest in the>70 years age group. The preoperative threshold on the diseased side increased significantly with increasing age in patients with chronic otitis media (p=0.0029) and cholesteatoma (p<0.0001). In patients with chronic otitis media, the postoperative threshold of the>60 years age group tended to be higher than that of the<60 years age group., Conclusions: These findings suggest that the taste function of the chorda tympani nerve deteriorated on the diseased side as much as on the normal side in elderly patients. Therefore, in most cases, we do not have to pay as much attention to the chorda tymapani nerve when performing surgery in elderly patients compared to young and middle-aged patients.

To study the recovery of function of the chorda tympani nerve, we examined by electrogustometry 79 patients (83 ears) with both preoperative normal function of the nerve and operative preservation of the nerve, every 2 days during hospitalization and at 6 months after surgery. For symptoms such as tongue numbness and taste disturbance, patients with noninflammmatory (NI) diseases (13/20 or 65.0%) showed a significantly higher rate of symptoms than did patients with chronic otitis media (COM; 13/35 or 37.1%) at 2 weeks after surgery (p = .032). The patients with NI diseases (5/20 or 25.0%) tended to show a higher rate of symptoms than did the COM patients (2/35 or 5.7%) or cholesteatoma patients (2/28 or 7.1%) at 6 months after surgery. The rate of recovery of the EGM threshold to normal at 2 weeks after surgery was significantly lower in NI disease patients (6/20 or 30.0%) than in COM patients (23/ 35 or 62.9%) or cholesteatoma patients (19/28 or 67.9%; p = .015 and .008, respectively). Thus, the patients with NI diseases had postoperative symptoms and elevation of EGM threshold more frequently than did the patients with inflammatory diseases.