Rate of recovery of taste function after preservation of chorda tympani nerve in middle ear surgery with special reference to type of disease

Taste disturbance following cochlear implantation: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to estimate the rate of taste disturbance following cochlear implantation.

METHODS

The review was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies psychophysically measured taste. DerSimonian and Laird random-effects models were used. An overall mean from studies reporting a single mean of taste strip performance was calculated using inverse variance method for pooling.

RESULTS

Of 380 studies identified, 9 were included across which 55 cases of postoperative taste disturbance were reported in 498 patients. Taste was tested at variable timepoints, from <1 week to ≥6 months postoperatively. The overall rate of postoperative taste disturbance was 13.5% (95% CI, 7.6-20.7%) with high heterogeneity between studies (I2 = 62%).

DISCUSSION

13.5% might indicate a higher prevalence of taste disturbance following cochlear implantation compared to the general population. However, the confidence we can assign to our calculated rate is limited by significant heterogeneity and potential publication bias. Studies reporting mean taste strip scores generally found reduced taste function on the side of the tongue ipsilateral to implantation, but this reduction wasn't statistically significant.

CONCLUSION

Further research, employing more robust and standardised methodologies, is necessary to accurately ascertain the rate and nature of taste disturbance following cochlear implantation.

Effect of Chronic Suppurative Otitis Media on Gustatory Function of chorda Tympani Nerve : A Prospective Study

Introduction the ability to taste is among the life's finest pleasures and perception of taste can be altered by various disorders or therapeutic regimens as colds or dental procedures. Head trauma patients, patients on certain drugs such as phenylbutanone, carbamazepine and baclofen and patients with inflammatory diseases of the middle ear frequently complain about alterations in their ability to taste. So, assessment of gustatory sensitivity is the prerequisite for the correct diagnosis of taste dysfunction which uses taste strips impregnated with taste stimulants. Material and method in this prospective study, 40 patients were enrolled after assessment of history, general and local examination of ear and finally assessment of gustatory function was done according to Muller technique using taste strips. Results in present study out of 40 patients, 16 (40%) patients had COM squamous, 24 patients (60%) had COM mucosal. In the ipsilateral diseased ear (both COM squamous & mucosal) the mean taste score for various taste sensation was 11.65 ± 2.59. In the contralateral normal ear, the mean taste score was 15.42 ± 0.78. The difference between the two was found to be statistically significant (p < 0.0001). Conclusion a significant difference was obtained in taste scores between diseased (ipsilateral) and normal (contralateral) ears both overall and also when subtypes were compared. Thus, the present prospective study indicates that COM squamous as well as mucosal can induce taste dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03703-7.

Chorda tympani injury during endoscopic versus microscopic stapes surgery: a randomized controlled clinical trial

OBJECTIVES

The aim of this study was to compare the incidence of chorda tympani nerve (CTN) injury between endoscopic and microscopic stapes surgery.

METHODS

This randomized controlled clinical trial included 88 patients who were randomly divided into two groups: endoscopic stapedotomy group (n = 44) and microscopic stapedotomy group (n = 44). The incidence of chorda tympani nerve (CTN) injury after surgery was determined by both subjective taste testing and chemical taste tests, before and after surgery. The results were compared between the two groups.

RESULTS

The total number of patients who were identified as having CTN affection (based on the chemical testing) was 16 out of 88 (18.2%). The incidence was significantly lower in the endoscopic group (n = 2) than the microscopic group (n = 14) (p = 0.019).

CONCLUSION

Altered taste as a result of iatrogenic CTN injury can affect the patients' quality of life. Endoscopic ear surgery offers better visualization, less need for extensive manipulation of the chorda tympani, and consequently decreased incidence of CTN injury.

Taste Alteration in External Auditory Canal Cholesteatoma: Indicator of Impending N VII Affection

INTRODUCTION

External auditory canal cholesteatoma (EACC) is a rare disease, with an estimated incidence of approximately 1:1,000 adult and 1.6:1,000 pediatric otologic patients. Systematic studies of chronic ear disease and taste alteration prior to surgery are rare; in fact, there are no such studies for EACCs. Therefore, we describe chorda tympani nerve (CTN) dysfunction and the related clinical consequences in EACC patients.

METHODS/STUDY DESIGN

Between 1992 and 2021, we retrospectively analyzed the symptoms, signs, and radiological and intraoperative descriptions of CTN involvement in 73 patients. Liquid taste tests and, since 2009, Taste StripsTM as well as an olfactory screening test (Smell DiskettesTM) have been performed for all symptomatic patients and, when feasible, all other EACC patients.

LEVEL OF EVIDENCE: 4

RESULTS

Ten of 73 patients complained subjectively of dysfunction, and 8 showed abnormal taste test results. Four patients complained of olfactory dysfunction (3 cases with pathological taste tests). Gustatory dysfunction was most frequent in radiogenic EACC cases (n = 4), followed by postoperative EACC (n = 3). Two postoperative patients were asymptomatic despite abnormal test results. Rarely, patients with idiopathic (n = 2) and posttraumatic (n = 1) EACC showed acute taste dysfunction that was confirmed in each with abnormal test results.

DISCUSSION/CONCLUSION

CTN dysfunction often developed asymptomatically in chronic ears, except for idiopathic and posttraumatic EACCs under previous healthy middle ear conditions. Taste disturbance is not a cardinal symptom of EACC, but objective testing suggests that up to one out of 10 EACC patients with advanced disease may experience regional gustatory dysfunction prior to surgery. Especially in context of a new and acute presentation, regional taste dysfunction may alert the clinician of potential progressive EACC invasion and danger to the facial nerve.

Subjective and Objective Taste Change After Stapes Surgery Systematic Review and Meta-Analysis

INTRODUCTION

Iatrogenic injury to the chorda tympani (CT) is a well recognized, although potentially underestimated, consequence of stapes surgery. This study aims to review the currently available literature to determine the incidence and prognosis of taste disturbances in these patients.

DATA SOURCES

PubMed, Embase, and Cochrane Library databases.

METHODS

Databases were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Search terms included (chorda tympani OR gustatory OR taste OR chemosensory OR dysgeusia OR nervus intermedius) AND (ear surgery OR middle ear OR stapes OR stapedectomy OR stapedotomy). Patients with prospective data collection including preoperative data were further divided by methodology into "objective" and "subjective" assessments of taste dysfunction. A systematic review was performed for all included studies, with meta-analysis using a random-effects model was used for those with comparable methodology and patient populations.

RESULTS

Initial search yielded 2,959 articles that were screened according to inclusion and exclusion criteria. Once duplicates were removed, seven studies were identified, representing 173 patients with subjective testing (all seven studies) and 146 with objective testing (five studies). Eighty of 173 patients (46.2%) noted a disturbance in taste at early follow-up, whereas as 26 of 173 (15.0%) noted long-term problems. Objective methodology and result reporting were heterogenous and not amenable to pooled meta-analysis for all studies included.

CONCLUSION

Changes in taste occur relatively frequently after stapedectomy. Surgeons should continue to counsel prospective patients as to the risks of both short- and long-term taste disturbances.

Change in chorda tympani nerve function after two-stage tympanoplasty for cholesteatoma

Objectives

Chorda tympani nerve (CTN) function may be damaged more by two-stage than by one-stage surgery for middle ear cholesteatoma. However, few studies have reported the relationship between two-stage cholesteatoma surgery and CTN function. This study aimed to investigate CTN function after two-stage surgery for cholesteatoma.

Methods

In this prospective study, 35 patients underwent two-stage canal wall up tympanoplasty (CWUT). Perioperative CTN function was assessed using questionnaires and electrogustometry (EGM). Participants were categorized into minor, major, and section groups, based on the degree of CTN manipulation during surgery.

Results

In the first-stage surgery, posterior tympanotomy with an intact canal wall reduced the degree of CTN manipulation. The incidence of taste disorder after the first-stage surgery was 71.4%. Postoperative taste disorder and the EGM threshold improved early in the minor manipulation group. In the second-stage surgery, no new CTN damage occurred, even if this surgery involved removal of residual cholesteatoma. The incidence of taste disorder after second-stage surgery was less than that after first-stage surgery, independent of CTN preservation. However, the recovery rate of the EGM threshold after second-stage surgery was significantly lower in the section group than in those with CTN preservation.

Conclusion

CTN function, including symptoms and EGM threshold, can be preserved during two-stage cholesteatoma surgery if care is taken to preserve the CTN in both the first- and second-stage surgeries. A two-stage CWUT, ensuring an intact bony annulus, may be effective to facilitate CTN preservation.

Level of Evidence

2b.

Changes of taste perception after stapes surgery: a prospective cohort study

PURPOSE

Taste perception is often affected after stapes surgery despite effort to preserve chorda tympani nerve. The aim was to examine changes of particular taste qualities and their recovery after operation of otosclerosis.

MATERIALS AND METHODS

Taste function was prospectively investigated with a questionnaire and a taste strip test (TST) preoperatively, 3-5 days and 1 year after stapes surgery with the preservation of CTN.

RESULTS

In the early postoperative examination, 34/42 patients had a lower TST score, 7/42 decrease of taste in the questionnaire. One year after surgery, 11/42 patients had a lower TST score, 1/42 patients decrease of taste in the questionnaire. The most pronounced decrease in the TST score was in sweet (- 1.76 points, p < 0.001), followed by bitter (- 1.71 points, p < 0.001), salty (- 1.64 points, p < 0.001) and sour taste (- 1.33 points, p < 0.001). The sour taste had a significant lower alteration compared to others. Men had significantly pronounced alteration in salty taste compared to women. The complete recovery was proved in bitter taste. Better recovery in bitter taste was observed in patients younger than 45 years of age.

CONCLUSIONS

Gustatory changes after stapes surgery are mostly transient with different impairment and recovery rate for particular taste qualities. A sour taste seems to be relatively resistant to damage. The best recovery rate is in a bitter taste, especially in younger patients.

Taste Dysfunction after Tonsillectomy: A Meta-analysis

OBJECTIVES

We aimed to provide information on the effects of tonsillectomy, in particular, its effects on taste dysfunction; also known as dysgeusia, and provide direction for future research in this area.

METHODS

We independently searched five databases (PubMed, SCOPUS, Embase, the Web of Science, and the Cochrane database) for related studies published as recently as December 2019. From the included studies, we reviewed the findings on tonsillectomy and taste disturbance through the use of a questionnaire, chemogustometry, and electrogustometry. We analyzed other conditions that were measured in these studies that included; postoperative pain intensity and other morbidities (eg, postoperative bleeding, hemostasis, tongue numbness and zinc, copper, and iron hemoglobin levels measured).

RESULTS

Postoperative taste disturbance based on questionnaire (VAS) scores at 14 days (SMD = -0.31 [-0.50, -0.12], P value = .0012) tended to decrease significantly in the post-tonsillectomy group compared to the pre-tonsillectomy group. Patients showed significantly decreased taste sensation after tonsillectomy than in the preoperative test. Postoperative electrogusmetry at 7 days (SMD = 0.60 [0.27, 0.94], P = .0004) tended to increase significantly in the post-tonsillectomy group compared to the pre-tonsillectomy group.

CONCLUSION

Tonsillectomy is a commonly performed surgery, and taste disturbance occurs frequently as a post operative effect. Taste dysfunction is important to patients with regard to their quality of life and the overall effects of taste on their day-to-day life. This study can be a useful meta-analysis of dysgeusia in tonsillectomy.

Feasibility of preservation of chorda tympani nerve during noninflammatory ear surgery: A systematic review

OBJECTIVE

The objective of our systematic review is to investigate the postoperative gustatory function of the chorda tympani nerve following noninflammatory ear surgery for which the chorda tympani is at risk for iatrogenic injury (stretching, handling, or sacrificing).

DATA SOURCES

PubMed and EMBASE.

REVIEW METHODS

A PubMed and EMBASE databases search was conducted on November 15, 2016. Study inclusion criteria included: 1) ear surgery performed for noninflammatory ear diseases, and 2) gustatory function of the chorda tympani reported as an outcome. The quality of eligible studies was assessed using the risk of bias assessment tool for nonrandomized studies. Study characteristics and outcome data of the included studies were extracted.

RESULTS

In total 1,094 articles were retrieved. Fourteen studies encompassing 1,062 operated ears were included after quality assessment. Stapedectomy was the most frequent surgical procedure performed in 398 ears. The follow-up time varied between 6 weeks and 99 months. Patients with a preserved chorda tympani were less symptomatic (24% was symptomatic) compared to patients with a stretched (53% was symptomatic) or sacrificed chorda tympani (47% was symptomatic). The recovery rate varied from 61% to 79%. The results of the electrogustometry and strip test showed a discrepancy with the subjective complaints of the patients.

CONCLUSION

Patients with a stretched chorda tympani were slightly more symptomatic compared to patients with a sacrificed chorda tympani. Therefore, in cases for which the chorda tympani greatly hinders a proper view of the surgical field, sacrificing the nerve could be considered to maximize surgical performance and have a satisfactory postoperative result. Laryngoscope, 1904-1913, 2018.

Change of somatosensory function of the tongue caused by chorda tympani nerve disorder after stapes surgery

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.

Taste disturbance after stapes surgery: an evaluation of frequency, severity, duration, and quality-of-life

CONCLUSION

The incidence of taste disturbance after stapes surgery is high (61.9%), whereas the majority (94.8%) recovers within 1 year. More severe surgical nerve trauma caused more disturbance, implying that the nerve should be handled carefully during surgery.

OBJECTIVES

Patients operated on for otosclerosis seem more often to complain about post-operative taste disturbance than those operated on for chronic otitis media, although the chorda tympani nerve more seldom becomes maltreated in stapedotomy. These observations seem paradoxical. It is unclear to what extent a post-operative taste disturbance affects the quality-of-life. This study aims to shed light on the occurrence of post-operative taste disturbances, on possible prognostic factors, and to what extent post-operative taste disturbance impairs the quality-of-life.

METHODS

One hundred and thirty-four adults undergoing primary stapedotomy were included. Questionnaires on taste disturbance and quality-of-life (SF-36) were answered before and after surgery, until 1 year post-operatively.

RESULTS

Eighty-three (61.9%) study persons reported post-operative taste disturbance. Seven (5.2%) reported persisting disturbance at 1 year. Surgically more traumatized chorda tympani nerves correlated with more severe taste disturbance post-operatively than less traumatized. Taste disturbance at 1 year post-operatively correlate with a decrease of the physical function domain in the SF-36.

Effects of Cochlear Implantation on Gustatory Function

Objectives:

Because of the anatomic position of the chorda tympani in the tympanic cavity, the nerve is at risk during cochlear implantation. The aim of this study was to assess changes in taste sensitivity and in self-ratings of gustatory function after surgery.

Methods:

Twenty-four patients (mean age, 54 years) who underwent cochlear implantation were investigated. Taste function was tested with a validated test for regional quantitative assessment of sweet, sour, salty, and bitter tastes on each side of the tongue before and 4 days after surgery.

Results:

The mean taste score was 10.0 (SD, 4.0) before and 8.0 (SD, 4.1) after surgery on the side of the tongue ipsilateral to the operated ear (p = .004). However, only 1 patient reported subjective taste loss due to surgery. Taste testing of the side of the tongue contralateral to the operated ear yielded a score of 10.0 (SD, 4.1) before and 10.9 (SD, 4.5) after surgery (p = .037). Self-ratings of gustatory function did not change significantly as a consequence of the procedure.

Conclusions:

Our results indicate that cochlear implantation is a relatively safe procedure regarding taste function. Preoperative testing of gustatory function is recommended, at least in those patients who already have undergone operation on the contralateral ear.

The chorda tympani degenerates during chronic otitis media: an electron microscopy study

CONCLUSION

Chorda tympani nerve specimens from ears with chronic inflammatory middle ear disease exhibit structural signs of degeneration. These correlate well with taste disturbance. Simultaneously, they exhibit signs of regeneration, which may explain the ability for taste recovery.

OBJECTIVES

The chorda tympani, the major taste nerve, runs uncovered through the middle ear cavity. This situation exposes it to various forms of middle ear pathology. A difference has been noticed regarding taste symptoms pre- and postoperatively between inflammatory and non-inflammatory diseases. The present study aimed to investigate ultrastructural changes of chorda tympani in different forms of inflammatory middle ear disease, such as chronic suppurative otitis media and cholesteatoma, as compared with normal.

METHODS

Five chorda tympani specimens were collected from healthy middle ears of patients subjected to surgery for acoustic neuroma, to be used as normal controls, and five from middle ears with chronic otitis media or cholesteatoma, where the nerve could not be saved during the operation. Light and electron microscopy were performed.

RESULTS

For all five nerves from diseased ears, microscopy showed a higher percentage of axon and myelin sheath degeneration than in the normal controls. Furthermore, three of the five also exhibited sprouting.

Gustatory changes in patients with chronic otitis media, before and after middle-ear surgery

Objective:

We investigated gustatory changes in patients with chronic otitis media, before and after middle-ear surgery.

Methods:

This prospective study included 38 patients with unilateral chronic otitis media. We used taste testing solutions to evaluate each patient's taste function. Intra-operative assessments of the chorda tympani nerve were also compared and analysed.

Results:

Patients with chronic otitis media had significantly worse ipsilateral perception of sour, bitter and salty tastes. In patients with good intra-operative preservation of the chorda tympani nerve, there was significant improvement in gustatory function one month post-operatively, compared with the pre-operative baseline. In patients who sustained intra-operative chorda tympani nerve injury, one month post-operative gustatory function was the same as the pre-operative baseline.

Conclusion:

Middle-ear surgery for chronic otitis media not only treats the ear but also improves gustatory function in the majority of patients. In patients with intra-operative injury to the chorda tympani nerve, post-operative taste decline is only temporary.

Taste function after stapes surgery

OBJECTIVE

A manipulation of chorda tympani nerve (CTN) is frequently necessary during the surgical therapy of stapedial ankylosis. The aim of this study was to re-assess the taste function before and after stapes surgery in patients with unilateral stapes ankylosis.

METHODS

Eighteen patients (14 female and 4 male) with unilateral stapedial ankylosis were included. Taste and olfactory function were measured preoperatively, 3 days and 3 months after surgery by questionnaire, chemical taste test, electrogustometry, and Sniffin'Sticks. The patients who reported deterioration in taste and revealed pathological taste test results were re-investigated 8-12 months after surgery. Postoperatively 11 patients were treated intravenously for 3 days for inner ear protection with 1g of cortisone. The gustatory and olfactory results were compared with age and sex specific normative data.

RESULTS

A significant transient decrease of gustatory measurement values was found on the ipsilateral two thirds of the anterior tongue. 12 out of 17 patients whose CTN was slightly manipulated during stapes surgery reported tongue sensations, such as numbness or gustatory blindness of the ipsilateral tongue side. The measures of chemical taste test significantly decrease in lateralized taste test on the ipsilateral side and in whole mouth testing. There was no significant increase of the EGM measures at the ipslateral tongue. In 11 of 12 patients with symptoms, complaints recovered within one year after surgery completely. The factor "cortisone" did not have a significant effect on the taste test results after surgery.

CONCLUSION

In conclusion, even after minor CTN manipulation the rate of postoperative taste disorders or tongue symptoms after stapes surgery is high. The symptoms appear to be transient. Therefore CTN should be preserved in stapes surgery after mild trauma of the CTN. Transient taste alteration should be mentioned prior to stapes surgery.

Iatrogenic injury of the chorda tympani: a systematic review

Objective:

To review the currently available literature on iatrogenic injury of the adult chorda tympani.

Design:

Systematic literature review.

Method

Five electronic databases and one search engine were used to access available English language literature on the chorda tympani, focusing on iatrogenic injury.

Results:

The chorda tympani is most often injured during middle-ear surgery, after which at least 15–22 per cent of patients experience symptoms, mostly changes in taste and dryness of the mouth. Numerous factors influence whether injury to the chorda tympani causes symptoms, including the extent of injury, type of surgery, age of the patient, anatomical variables and subjective adaptation. Although most patients experience gradual symptomatic recovery, complaints can be persistent and troublesome.

Conclusion:

Care should be taken to preserve the chorda tympani during middle-ear surgery, and to warn patients pre-operatively about this potential complication. This is particularly important if surgery is bilateral.

Chorda tympani nerve analysis with electron microscopy in chronic suppurative otitis media

CONCLUSION

Chronic suppurative otitis media causes some disturbance to the chorda tympani nerve (CTN), which may affect the facial nerve. It is not possible to perform a biopsy of the main truncus of the facial nerve, therefore studies of the CTN might show possible pathologic or physiologic changes of the facial nerve in the future.

OBJECTIVES

The specific aim of this study was to investigate the effects of chronic suppurative otitis media on the CTN.

METHODS

The tympanic segments of CTNs were collected for ultrastructural investigations in patients with chronic suppurative otitis media who underwent canal wall-down tympanoplasty. The study population comprised 10 patients, 7 males, 3 females; the age range was 16-66 years, and the mean age was 38. Qualitative and semiquantitative evaluations were performed on the specimens of CTN by electron microscopy.

RESULTS

Our histopathologic examinations showed that there were changes of varying severity in all the CTNs such as scarcity of unmyelinated nerve fibers, Schwann cell nucleus condensation, scarcity of Schwann cell cytoplasm, adaxonal vacuolation and edema, myelin sheath disintegration, shrunken electron-dense axoplasm, increased collagen fibers, adaxonal circular lamellar complex, interstitial edema, and vacuolation of Schwann cell cytoplasm.

Cutting the chorda tympani: not just a matter of taste

Introduction:

Chorda tympani injury as a complication of middle-ear surgery has been extensively studied with regard to its effects upon taste. However, the chorda tympani also carries parasympathetic fibres to the salivary glands of the oral cavity. To date, little has been reported about the effect of chorda tympani section upon salivary function.

Setting:

Tertiary care centre.

Material and methods:

We report a case series of three patients with bilateral chorda tympani lesions. Chorda tympani function was assessed using ‘taste strips’ and unstimulated sialometry. A careful history of oral symptoms was taken.

Results:

All patients showed transient or permanent bilateral ageusia of the anterior two-thirds of the tongue, and a decreased resting salivary flow rate. In addition, all patients suffered from transient or persistent, distressing xerostomia.

Conclusion:

Taste disorders may occur after middle-ear surgery but they are mostly transient, even when the chorda tympani nerves are sectioned bilaterally. In contrast, bilateral chorda tympani lesions may lead to severe, persistent and distressing xerostomia. Based on this neglected aspect of chorda tympani function, we emphasise the importance of preserving the chorda tympani whenever possible.

Change of the human taste bud volume over time

OBJECTIVE

The specific aim of this study is to measure the taste volume in healthy human subjects over a 2.5-month period and to demonstrate morphological changes of the peripheral taste organs.

MATERIAL AND METHODS

Eighteen human taste buds in four fungiform papillae (fPap) were examined over a 10-week period. The fungiform papillae investigated were selected based on the form of the papillae or the arrangement of surface taste pores. Measurements were performed over 10 consecutive weeks, with five scans in a day once a week. The following parameters were measured: height and diameter of the taste bud, diameter of the fungiform papilla and diameter of the taste pore.

RESULTS

The findings of this exploratory study indicated that (1) taste bud volumes changed over a 10-week period, (2) the interval between two volume maxima within the 10-week period was 3-5 weeks, and (3) the diameter of the fPap did not correlate with the volume of a single taste bud or with the volume of all taste buds in the fPap within the 10-week period.

CONCLUSIONS

This exploratory in vivo study revealed changes in taste bud volumes in healthy humans with age-related gustatory sensitivity. These findings need to be considered when studying the effect of denervation of fungiform papillae in vivo using confocal microscopy.

Gustatory Alteration Evaluation in Patients with Chronic Otitis Media

Many studies have shown the consequent gustatory alteration caused by ear surgeries. However, few have reported this alteration in patients with chronic otitis media (COM), prior to surgical treatment.

Aim

to identify gustatory alterations due to chorda tympani nerve involvement in patients with COM without prior surgery.

Methods

Clinical essay, with tests based on “taste strips” with different concentrations of salt, sweet, bitter, and sour, was performed in 45 patients with unilateral cholesteatomatous or suppurated COM not previously submitted to otological surgery, using the disease-free ear on the contralateral side as control. The score ranged between 0 and 16.

Results

A total of 25 patients presented cholesteatoma and 20 had non-cholesteatomatous disease. The mean score was 6.65 for the affected side and 9.93 for the half of the tongue on the side of the healthy ear (p<0.001). No patients had complained of gustatory alterations before the examination. Among the 24 patients with unilateral hypogeusia, eight cases of unilateral ageusia were found on the affected side. There was an association between cholesteatoma (p=0.055), disease duration (p=0.07) and worsening in gustatory sensitivity.

Conclusion

Patients with COM can have gustatory alterations, even in the absence of complaints.

Taste disturbance after stapes surgery--clinical and experimental study

CONCLUSION

Most of the clinical cases experienced taste disturbance after stapes surgery, and in a few cases this disturbance persisted for a long time. The animal experiment suggested the role of geniculate ganglion (GG) cells in nerve generation.

OBJECTIVES

To clinically examine taste disorder and its recovery after stapes surgery and experimentally demonstrate a role of GG.

PATIENTS AND METHODS

Taste function after preservation of chorda tympani nerve (CTN) in stapes surgery was prospectively investigated with a questionnaire and electrogustometry (EGM). Further, expression of neurotrophic factors in GG after injury of CTN was examined by in situ hybridization histochemistry (ISSH) and RT-PCR.

RESULTS

Among the cases, 15/18 (83.3%) were associated with taste disturbance and 6/18 (33.3%) were associated with tongue numbness 2 weeks after surgery; however, the symptoms ceased in 14/18 cases (77.8%). Two weeks after surgery, the EGM threshold was found to be elevated in 15/18 cases (83.3%), while in 10/18 cases (55.6%), it did not decrease until 1 year after surgery. Expression of ISSH and amplified bands of BDNF and GFR increased at 7 and 14 days after nerve injury in ipsilateral GGs and also increased at 7 days on the contralateral side.

Chorda tympani nerve function after middle ear surgery

OBJECTIVE

To assess chorda tympani nerve function before and after different types of middle ear surgery. The hypothesis was that in cases with cholesteatoma, iatrogenic injury to the nerve results in less postoperative taste disturbance than those undergoing myringoplasty or stapedectomy.

STUDY DESIGN

Prospective questionnaire study.

SETTING

ENT Department of a district general hospital in England.

PATIENTS

Adult patients undergoing middle ear surgery in which there would be elevation of the anulus.

MAIN OUTCOME MEASURE

Patients' change in taste sensation after surgery with follow-up to demonstrate subsequent recovery.

RESULTS

A significantly higher incidence of taste disturbance follows myringoplasty and stapedectomy than for procedures in which the initial diagnosis was cholesteatoma, regardless of the extent of injury sustained by the nerve. The most common complaint after chorda tympani nerve injury is of a metallic taste sensation.

CONCLUSION

Despite the small patient cohort, the results support the hypothesis that iatrogenic chorda tympani nerve injury in surgery for cholesteatoma results in less postoperative taste disturbance than that for otosclerosis. This may be because the disease process of cholesteatoma renders the nerve hypofunctional. The situation after myringoplasty is less clear. A larger study may help validate these findings.

Does the chorda tympani nerve confer general sensation from the tongue?

OBJECTIVE

Patients often complain of numbness of the tongue after otologic procedures; this symptom may occur with or without taste alterations. The purpose of this study was to objectively assess possible changes in the general sensation of the tongue in patients undergoing middle ear surgery.

STUDY DESIGN AND SETTING

Thirty-three individuals were included in this prospective controlled clinical study conducted at a tertiary referral center. Fifteen patients underwent middle ear surgery and 18 volunteers served as a control group. Subjects underwent objective tests to assess general sensation of the tongue before and twice after surgery.

RESULTS

Forty-seven percent of the patients complained of numbness or tingling of the tongue shortly after surgery. In these patients, a significant reduction in sensitivities to light touch and 2-point discrimination on the operated side were noted at that time (P < 0.01; P < 0.009 respectively). Values returned to baseline on subsequent evaluations. No sensitivity change was noted for the contralateral hemi-tongue.

CONCLUSION

Objective changes in the general sensory function of the tongue correlated with post-operative clinical symptoms experienced by patients. The results of this study support the notion that the chorda tympani nerve confers general sensation from the tongue.

EBM RATING

A-1b.

Taste disturbance after tonsillectomy and laryngomicrosurgery

OBJECTIVE

To investigate the incidence of taste disturbance after tonsillectomy and laryngomicrosurgery.

STUDY DESIGN

A prospective study.

METHODS

Thirty-five consecutive patients underwent tonsillectomy with electric coagulator at Kanebo Memorial Hospital from September 2002 to May 2004. Another 35 consecutive patients underwent laryngomicrosurgery in a routine way during the same period. Both procedures were performed by two experienced doctors. The postoperative taste function was evaluated with questionnaire, electrogustometry (EGM), and serum levels of Zn, Cu and Fe.

RESULTS

After tonsillectomy, 3/35 patients (8.6%) complained of taste disturbance, due to the pressure on the tongue in two, and Zn deficiency after lack of intake in one. All three patients recovered taste within 1.5 months. None of our patients had taste disturbance due to surgical insult of the lingual branch of the glossopharyngeal nerve. After laryngomicrosurgery, only one patient (2.9%) complained of taste disturbance with elevation of the EGM threshold that resulted from the pressure on the tongue. In addition, abnormal sensation in the tongue occurred in 9 cases (25.7%) after tonsillectomy and in 2 cases (5.7%) after laryngomicrosurgery, and feeling of thirst occurred in 12 cases (34.3%) and in 8 cases (22.9%), respectively.

CONCLUSION

Taste disturbance occurs in few cases when experienced surgeons perform tonsillectomy or laryngomicrosurgery. However, it is recommended to inform the patients of the potential postoperative complications such as taste disturbance and abnormal sensation of the tongue.

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

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.

Dysgeusia related to urinary obstruction from benign prostatic disease: a case control and qualitative study

Anecdotal reports suggest that dysgeusia may be related to a variety of systemic factors, including bladder outflow obstruction. This is a hospital-based case-controlled study involving 111 patients who were admitted to urological wards for transurethral resection of the prostate for benign prostatic disease with age- and sex-matched control of 137 subjects. We used a semi-structured questionnaire by a trained interviewer at admission (preoperative), at the postoperative period and at follow-up between 4-6 months (median 5 months). Analysis used unpaired t-test and chi(2) test. The incidence of dysgeusia was 22% in the study group and 13% in the control group (P=N.S.). However, strikingly, the dysgeusia in the study group was relieved promptly by relief of urinary obstruction in 100% of cases and did not return within the follow-up period. The mechanism of the dysgeusia associated with dysuria in benign prostatic disease is unknown, but we suggest that the dysgeusia could be from the stress of dysuria or due to a release of an unknown chemical from the urinary tract or an overflow of neural impulse from pontine/cortical micturition centres to the taste centres. An association between dysgeusia and dysuria has not been described before.

Observation of tongue papillae by video microscopy and contact endoscopy to investigate their correlation with taste function

OBJECTIVES

Contact endoscopy is a technique used to obtain detailed images of living epithelium in the fields of gynecology, rhinology and laryngology. Video microscopy is useful for observation of the surface of tongue papillae. In the present study, we attempted to apply the contact endoscopy technique together with video microscopy to observe tongue papillae, and to study the correlation between the condition of fungiform papillae and taste function.

METHODS

Ten subjects (3 men, 7 women) were divided into two groups based on the results of a taste examination by electrogustometry. We compared the shape and blood vessels of the papillae between normal taste and taste disorder groups.

RESULTS

In the normal taste group, round shaped papillae and clear blood vessels were observed with both microscopy and contact endoscopy. In the taste disorder group, flat and irregular papillae were observed with microscopy. Blood vessel flow of the papillae was observed to be poor with contact endoscopy.

CONCLUSION

These findings suggested that the images of microscopy and contact endoscopy were related to taste function, and both techniques were useful for evaluating taste function.

Taste function in Sjögren’s syndrome patients with special reference to clinical tests

OBJECTIVE

We analyzed the correlation between taste functions and clinical features in patients with Sjögren's syndrome (SS).

METHODS

Sixty-three patients were divided into two groups: group A consisting of patients with primary or secondary SS of the European classification, and group B consisting of non-SS complaining of dry eye and mouth.

RESULTS

Eighteen percent of the group A patients and 11% of the group B patients complained of taste disorders. Electrogustometric examination detected taste disorders in 27% of the group A patients and 38% of the group B patients, while the filter paper disc method showed taste disorders in 30% of group A and 40% of group B. In group A, unstimulated and stimulated salivary flows were correlated with the ability to discriminate taste analyzed by the filter paper disc method, but not with the taste electrogustometric threshold. Serum zinc concentration was not significantly correlated with taste disorders in either group.

CONCLUSION

Our findings showed that SS patients presented taste disorders less frequently than previously reported, and we speculated that taste disorder found in SS patients were due to the salivary flow deficiency that might prevent substances from reaching the taste buds.