Unusual complication of tonsillectomy: taste disturbance and the lingual branch of the glossopharyngeal nerve

Taste disturbance is an unusual complication of tonsillectomy of which there are very few reports in the literature. The possible causes of this rare complication are: (1) direct or indirect damage to the glossopharyngeal nerve or its lingual branch (LBGN), (2) lack of dietary zinc, and (3) habitual drug intake. We report a 41-year-old man, who complained of taste disturbance following tonsillectomy that was performed for chronic tonsillitis and unilateral (left) tonsillar hypertrophy. During surgery, hypertrophic tonsils were found to be sited deeply into the tonsillar bed, especially at the lower pole of the left tonsil. Pathologic examination following tonsillectomy revealed a keratinous cyst and chronic infection at the left tonsil, and lymphoid hyperplasia and chronic infection at the right tonsil. Although his complaint had been getting better, qualitative examination of his taste function revealed bilateral impairment of the sense of sweet taste on the base of his tongue two months after the surgery, and a taste disturbance of sweet taste on the left side persisted the 10th month after the surgery. His serum zinc value was normal, and he did not take any drug that could affect his sense of taste. Depending on the literature data, possible indirect damage to the LBGN was suspected as the cause of the taste disturbance. This symptom may be reversible within two years after tonsillectomy, but it can also be irreversible. Therefore, tonsillectomy should be performed with minimal trauma to the tonsillar bed, especially when there is an additional pathology extending into the lower pole, and such a patient should be informed of the risk of post-operative taste disturbance after tonsillectomy as being one of the rare complications of this surgery.     

Taste Disturbance in Two Patients after Dental Anesthesia by Inferior Alveolar Nerve Block

We report two cases of temporary taste disturbance after inferior alveolar nerve block. The first patient to present with this rare complication of anesthesia for dental surgery was a 41-year-old woman. She lost the sense of taste on the left side of her tongue after local anesthesia for treatment of a left mandibular molar and first visited our outpatient clinic complaining of taste disorder 3 months later. Electrogustometry (EGM) and filter paper disk (FPD) testing revealed a taste disturbance in the innervation area of the left chorda tympani nerve and atrophy of the fungiform papillae on the left side of the tongue was observed. Eleven months after the dental treatment, the fungiform papillae and the results of EGM were normal. The second patient, a 22-year-old woman, received local anesthetic for extraction of a right mandibular molar and subsequently developed loss of taste on the right side of the tongue. When she visited our outpatient clinic 3 months later, atrophy of the fungiform papillae on the right side was observed. Her gustatory sense began to improve 4 months after the dental surgery and was normal at 13 months. From these findings we conclude that taste disturbance on the same side as the inferior alveolar nerve block in each case was due to direct injury to the chorda tympani and lingual nerves during administration of the local anesthetic. The results of EGM and FPD testing were diagnostic: atrophy of the fungiform papillae on the same side and disappearance of taste on the same side in the intravenous taste test provided complementary diagnostic information. The outcome was satisfactory in both cases.     

Taste disturbance in two patients after dental anesthesia by inferior alveolar nerve block

We report two cases of temporary taste disturbance after inferior alveolar nerve block. The first patient to present with this rare complication of anesthesia for dental surgery was a 41-year-old woman. She lost the sense of taste on the left side of her tongue after local anesthesia for treatment of a left mandibular molar and first visited our outpatient clinic complaining of taste disorder 3 months later. Electrogustometry (EGM) and filter paper disk (FPD) testing revealed a taste disturbance in the innervation area of the left chorda tympani nerve and atrophy of the fungiform papillae on the left side of the tongue was observed. Eleven months after the dental treatment, the fungiform papillae and the results of EGM were normal. The second patient, a 22-year-old woman, received local anesthetic for extraction of a right mandibular molar and subsequently developed loss of taste on the right side of the tongue. When she visited our outpatient clinic 3 months later, atrophy of the fungiform papillae on the right side was observed. Her gustatory sense began to improve 4 months after the dental surgery and was normal at 13 months. From these findings we conclude that taste disturbance on the same side as the inferior alveolar nerve block in each case was due to direct injury to the chorda tympani and lingual nerves during administration of the local anesthetic. The results of EGM and FPD testing were diagnostic: atrophy of the fungiform papillae on the same side and disappearance of taste on the same side in the intravenous taste test provided complementary diagnostic information. The outcome was satisfactory in both cases.     

Younger patients have a higher rate of recovery of taste function after middle ear surgery

BACKGROUND: Although the chorda tympani nerve (CTN) is frequently damaged during tympanoplasty, little attention has been given to the patients' symptoms and taste function. OBJECTIVE: To investigate patients' symptoms and the functional recovery of taste after surgery using electrogustometry (EGM). DESIGN: Prospective study. PATIENTS: Analysis of 163 ears of 156 patients who underwent middle ear surgery from April 1997 through December 1999. There were 18 ears with noninflammatory diseases, 80 with chronic otitis media, and 65 with cholesteatoma. The patients' taste functions were examined 2 days before surgery and 2 weeks and 6 months after surgery. MAIN OUTCOME MEASURES: The taste disturbance before and after middle ear surgery and the relationship between age and the recovery rate of CTN function. RESULTS: Two weeks after surgery, the mean EGM threshold was elevated in all groups regardless of preservation or section of the CTN. Numbness in the tongue and taste disturbance were more frequently found in patients with preservation of CTN than in those with section of the CTN (P =.008 and P =.001, respectively). In patients with preservation of the CTN, 6 months after surgery, the recovery rate of EGM threshold was 83% in those aged 20 years or younger (P =.008 compared with the 2 older groups), 53% in the those aged 21 to 40 years, and 44% in those aged 41 to 60 years. CONCLUSION: Age is an important factor for recovery of taste function after middle ear surgery, which is useful information when explaining complications to patients.     

Clinical study of flavor disturbance

OBJECTIVE: We have observed that, in cases of smell loss, patients often complain of taste loss as well even though they actually have normal gustatory acuity according to gustatory tests; we have defined such symptoms as "flavor disturbance". The clinical features of flavor disturbance are reported in this paper. MATERIAL AND METHODS: A total of 297 patients (99 males, 198 females; mean age 55.5 years) were treated for olfactory disturbance at the hospital of Hyogo College of Medicine between July 1995 and August 2001. Sixty-six out of 297 patients (22.5%) also experienced taste disturbance, and 49 of these 66 cases were evaluated by means of smell and taste tests. These 49 patients who complained of taste and smell loss were classified into two groups according to the results of their smell and taste tests. Patients who only complained of olfactory disturbance were also reviewed. RESULTS: There was no relationship between the severity of olfactory disturbance and the degree of flavor disturbance. The incidence of flavor disturbance was high in patients with sudden olfactory disturbance after upper respiratory tract infection or head trauma and low in those with slowly progressive olfactory disturbance. The symptoms of flavor disturbance improved regardless of whether smell was improved or not. CONCLUSIONS: The patients with flavor disturbance tended to misrecognize that they had taste loss because of sudden smell loss, and there were more of these cases than we expected. When patients with smell and taste loss are treated, flavor disturbance should also be considered.     

Taste function after section of chorda tympani nerve in middle ear surgery

ObjectiveTo 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.MethodsThirty-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.ResultsIn 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.ConclusionThese findings help explain the potential complications to the patients before surgery, although the number of cases was small in this series.     

治疗阻塞性睡眠呼吸暂停低通气综合征的咽成形术对嗅觉和味觉的影响

目的:观察治疗阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的咽成形术对嗅、味觉的影响。方法:总结2005年4月~12月行咽成形术的39例患者中有嗅、味觉改变的主诉情况。结果:4例诉术后味觉改变,其中1例诉同时有嗅觉改变。例1嗅觉减退,酸和咸感觉丧失,2个月后部分恢复,对甜感觉过敏;例24种味觉均减退;例3对酸的感觉过度敏感;例4感痰中有酸和苦的感觉,属味幻觉。味觉改变的发生率达10%。结论:嗅觉和味觉的改变可能是咽成形术的并发症,影响患者的生活质量,必须给予重视,术前应向患者交代清楚,以免引起不必要的医疗纠纷。术中尽可能避免损伤味觉功能,如果发生嗅、味觉损伤,术后需给予处理。     

Posttonsillectomy taste distortion: a significant complication

OBJECTIVE/HYPOTHESIS: Tonsillectomy is among the most commonly performed procedures. As with any surgery, head and neck surgeons must be aware of possible complications and their potential affects. At our smell and taste center, we have been referred several patients in a 6-month period with the complaint of taste distortion after tonsillectomy. We report in this article a patient that complains of taste distortion after a right tonsillectomy for unilateral tonsillar hypertrophy. STUDY DESIGN: A prospective study documenting taste distortion after tonsillectomy using clinical, subjective, and objective evaluation. METHODS: The clinical course of a patient with taste distortion after a tonsillectomy is described. The gustatory function was investigated by conducting electrogustometry and spatial taste testing. Threshold measurements were determined at three left- and three right-side tongue regions: 1) the tongue tip region (innervated by the chorda tympani branch of the facial nerve), 2) the lateral margin of the tongue (anterior to the foliate papillae), and 3) the posterior tongue region (innervated by the lingual branch of the glossopharyngeal nerve). RESULTS: After a complete clinical evaluation and taste testing, it was found that the patient suffered an injury to the right lingual branch of the glossopharyngeal nerve. The close anatomic relationship between the palatine tonsil and lingual branch of the glossopharyngeal nerve makes the nerve vulnerable during tonsillectomy. This injury has caused the patient to suffer ageusia to the right posterior one third of the tongue, compensated by a contralateral phantogeusia (phantom taste) with clinical dysgeusia. The phantogeusia was abolished by application of anesthetic to the area where the phantom was perceived. We propose that the phantogeusia is the result of release-of-inhibition in the contralateral glossopharyngeal nerve. CONCLUSION: Taste distortion (including, phantogeusia and dysgeusia) after tonsillectomy is rarely reported as a complication but has a significant impact on quality of life. This article examines the taste distortion presence as a complication after tonsillectomy to make head and neck surgeons aware of this serious complication and the pathophysiology of taste distortion.     

Taste disorders after tonsillectomy: a long-term follow-up

In a former study, taste disturbances after tonsillectomy seemed to be more frequent than expected. Eight percent of patients reported subjective taste disorders 6 months after tonsillectomy. Fifteen patients from the initial trial, who reported taste disorders after tonsillectomy, were contacted again for this long-term follow-up. A telephone interview using the same questionnaire addressing the current self-estimate of taste function was performed. At 32 ± 10 months following surgery, two (0.9%) patients still reported suffering from taste disturbance. This long-term follow-up study shows that dysgeusia following tonsillectomy occurs in approximately 1% of patients. These data should be considered when patients are informed about complications after tonsillectomy.     

Treatment outcome in patients with taste disturbance

The importance of taste has been recently evaluated from the standpoint of quality of life, but few reports exist on the clinical status of taste disturbance. We classified taste disturbance by cause and studied the effect of treatment and recovery duration. Subjects were 321 patients with taste disturbance, i.e., 131 men and 190 women (mean age: 59.9 years). Electrogustometry (EGM) and filter paper disks (FPD) were used to assess taste function in all subjects. We also asked them all about the degree of symptoms using visual analog scale (VAS). Statistical analysis was done using the unpaired t-test, with p<0.05 considered significant. Patients were treated with zinc sulfate, ferrotherapy, herbal medicine, and minor tranquilizers. Causes of taste disturbance were classified into idiopathic, post-common-cold, drug-induced, psychogenic, constitutional, and iron deficiency. Idiopathic taste disturbance was the commonest cause (125 cases, 38.9%), followed by drug-induced (62 cases, 19.3%), and post common cold (38 cases, 11.8%). Drug induced and psychogenic taste disturbance have increased. Recovery from symptoms was 79/103 (76.7%) in idiopathic taste disturbance, 24/33 (72.7%) in post-common-cold, and 14/17 (82.4%) in iron deficiency. Recovery took 22.2 weeks. Recovery was 32/50 cases (62.4%) in drug induced, taking 48 weeks. For all causes, EGM and FPD results were not associated with the degree of symptoms. Both tests tended to show delayed improvement compared to symptoms. Cases taking more than 6 months from symptom onset to medical examination showed significantly lower improvement and longer recovery time than those taking 6 months on less (p = 0.04).     

Tongue paresthesia and dysgeusia following operative microlaryngoscopy

OBJECTIVES: This study was performed to assess the overall incidence and duration of alterations in tongue sensation and taste after operative microlaryngoscopy, and the relation of these symptoms to operative time. METHODS: We performed a retrospective review of information regarding tongue symptoms in patients who completed standard post-microlaryngoscopy follow-up at 1 week, 1 month, and 3 months. RESULTS: One hundred patients (54 male and 46 female; mean age, 46 years; age range, 14 to 83 years) met the inclusion criteria. Eighteen patients had positive findings at 1 week: 15 complained of paresthesia and 3 of dysgeusia. The symptoms decreased over time without treatment (4% of patients at 1 month and 1% of patients at 3 months). Only 1 case of dysgeusia persisted past 3 months. Gender was found to be a significant independent risk factor for the development of symptoms (odds ratio, 5.63; 95% confidence interval, 1.36 to 31.29; p = .013). Patients whose operations lasted longer than 1 hour were almost 4 times more likely to develop tongue-related symptoms than those with an operative time less than 30 minutes, although these findings did not achieve statistical significance (odds ratio, 3.91; 95% confidence interval, 0.62 to 30.95; p = .182). CONCLUSIONS: Alterations in tongue sensation and taste, most likely due to lingual nerve injury, are common after microlaryngoscopy, especially in female patients. They also tend to be associated with longer operative times. Although transient in nearly every case, lingual paresthesia and dysgeusia should form part of the preoperative discussion with the patient.     

Course of Recovery from Taste Receptor Disturbance

The course of recovery from taste receptor disturbance was studied in 119 patients with moderate-to-severe taste receptor disturbance that was cured or improved with zinc therapy. Taste receptor disturbance was idiopathic in 45 patients, drug-induced in 38 and due to zinc deficiency in 36. Recovery of taste, evaluated by filter paper disk testing and electrogustometry, followed 1 of 3 patterns: (i) in 54 (45.4%) of the 119 cases, taste improved simultaneously in the anterior (innervated by the chorda tympani nerve) and posterior (innervated by the glossopharyngeal nerve) portions of the tongue; (ii) in 53 (44.5%) of the cases, taste improved in the posterior portion first; and (iii) in 12 (10.1%) of the cases, taste improved in the anterior portion first. Zinc therapy was more effective in patients with the "posterior" pattern of recovery, and these patients also recovered the ability to sense sweet and bitter tastes earlier than other tastes. These results indicate that recovery of taste begins on the posterior portion of the tongue, which has an abundance of taste buds. The results of electrogustometry were not helpful in assessing recovery from taste disturbance, but testing for taste using the filter paper disk method on the posterior portion of the tongue was useful for identifying the onset of recovery.     

Course of recovery from taste receptor disturbance

The course of recovery from taste receptor disturbance was studied in 119 patients with moderate-to-severe taste receptor disturbance that was cured or improved with zinc therapy. Taste receptor disturbance was idiopathic in 45 patients, drug-induced in 38 and due to zinc deficiency in 36. Recovery of taste, evaluated by filter paper disk testing and electrogustometry, followed 1 of 3 patterns: (i) in 54 (45.4%) of the 119 cases, taste improved simultaneously in the anterior (innervated by the chorda tympani nerve) and posterior (innervated by the glossopharyngeal nerve) portions of the tongue; (ii) in 53 (44.5%) of the cases, taste improved in the posterior portion first; and (iii) in 12 (10.1%) of the cases, taste improved in the anterior portion first. Zinc therapy was more effective in patients with the "posterior" pattern of recovery, and these patients also recovered the ability to sense sweet and bitter tastes earlier than other tastes. These results indicate that recovery of taste begins on the posterior portion of the tongue, which has an abundance of taste buds. The results of electrogustometry were not helpful in assessing recovery from taste disturbance, but testing for taste using the filter paper disk method on the posterior portion of the tongue was useful for identifying the onset of recovery.     

Taste disorder involving Hunter's glossitis following total gastrectomy

We treated five patients with Hunter's glossitis following total gastrectomy. The major complaints of the patients were taste disorder and abnormal glossal sensation. In all five cases, the patient's tongue was red and smooth, and laboratory testing showed the presence of macrocytic anemia and decreased serum concentration of vitamin B12 (cyanocobalamin). Gustometry was carried out in four cases and the results documented the presence of taste disorder. All five patients were treated by administration of vitamin B12, which led to improvements in the appearance of the tongue, the patients' subjective complaints and the results of taste testing. When patients present with a red, smooth tongue, Hunter's glossitis (which can easily be improved by administration of vitamin B12) should be considered in the differential diagnosis.     

Taste Disorder Involving Hunter's Glossitis Following Total Gastrectomy

We treated five patients with Hunter's glossitis following total gastrectomy. The major complaints of the patients were taste disorder and abnormal glossal sensation. In all five cases, the patient's tongue was red and smooth, and laboratory testing showed the presence of macrocytic anemia and decreased serum concentration of vitamin B12 (cyanocobalamin). Gustometry was carried out in four cases and the results documented the presence of taste disorder. All five patients were treated by administration of vitamin B12, which led to improvements in the appearance of the tongue, the patients' subjective complaints and the results of taste testing. When patients present with a red, smooth tongue, Hunter's glossitis (which can easily be improved by administration of vitamin B12) should be considered in the differential diagnosis.     

Clinical Use of Electrogustometry: Strengths and Limitations

Electrogustometry (EGM) has a number of strengths and a few limitations in clinical use. The strengths of EGM are: (i) the range of measurements can be kept constant; (ii) quantitative control of the intensity of the stimulation is possible; (iii) only a short period of time is required for testing; (iv) it is possible to detect even slight taste disorders for which the patient has no subjective symptoms; (v) it is useful for topognosis of lesions of taste pathways and for determining prognosis; and (vi) it is the only quantitative method for diagnosing disorders of the glosssopharyngeal nerve. The limitations of EGM are: (i) it is not useful for determining or diagnosing some of the symptoms often complained of by patients with taste disorder, namely dissociated taste disorder, heterogeusia and spontaneous dysgeusia; and (ii) it is not useful for following the progress of taste disorder. The many strengths and few limitations of EGM make it the first choice among taste examinations. This paper describes the clinical use of EGM as well as discussing other taste examinations used in our taste clinic and, in particular, the advantages and disadvantages of filter paper disk testing with taste solutions.     

Anatomy of the Tonsillar Bed: Topographical Relationship Between the Palatine Tonsil and the Lingual Branch of the Glossopharyngeal Nerve

Taste disturbance may result from injury to the lingual branch of the glossopharyngeal nerve (LBGN) during tonsillectomy. Because an understanding of the anatomy of this nerve is required in order to avoid injuring it, a gross, histologic anatomic study was undertaken of the topographical relationship between the LBGN and the muscle layer of the palatine tonsillar bed. Evaluation of 107 sides of 83 Japanese adult cadavers (aged 27-88 years) confirmed that the muscular composition and lamination of the tonsillar bed do not change with age or pathological conditions such as inflammation. In about a quarter (23.4%) of cases, the LBGN traveled inferior to the styloglossus muscle and lateral to the superior constrictor pharyngeal muscle over its whole course to the base of the tongue, so that the palatine tonsil was clearly separated from the LBGN. In 55.1% of cases, however, the muscle lining of the tonsillar bed was discontinuous and thin muscle bundles, derived from the stylopharyngeus, palatopharyngeus or superior constrictor pharyngeal muscle, partially covered the tonsillar capsule externally. Moreover, in 21.5% of cases the LBGN was firmly adherent to the tonsillar capsule, due to the complete absence of muscles lining the tonsillar bed. In these cases, and also probably in a similar percentage of patients undergoing tonsillectomy, taste disturbance may occur on removal of the hypertrophic tonsillar capsule. Therefore, minimal disturbance of the tonsillar bed is recommended in all cases of tonsillectomy.     

Clinical use of electrogustometry: strengths and limitations

Electrogustometry (EGM) has a number of strengths and a few limitations in clinical use. The strengths of EGM are: (i) the range of measurements can be kept constant; (ii) quantitative control of the intensity of the stimulation is possible; (iii) only a short period of time is required for testing; (iv) it is possible to detect even slight taste disorders for which the patient has no subjective symptoms; (v) it is useful for topognosis of lesions of taste pathways and for determining prognosis; and (vi) it is the only quantitative method for diagnosing disorders of the glosssopharyngeal nerve. The limitations of EGM are: (i) it is not useful for determining or diagnosing some of the symptoms often complained of by patients with taste disorder, namely dissociated taste disorder, heterogeusia and spontaneous dysgeusia; and (ii) it is not useful for following the progress of taste disorder. The many strengths and few limitations of EGM make it the first choice among taste examinations. This paper describes the clinical use of EGM as well as discussing other taste examinations used in our taste clinic and, in particular, the advantages and disadvantages of filter paper disk testing with taste solutions.