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

Complications of Surgery: Recognition and Management

The middle ear and mastoid spaces contain delicate and functionally important structures. Safe cholesteatoma surgery requires mastery of otologic anatomy as well as thorough preoperative investigation. Cholesteatoma can damage otologic structures on its own; however, there is also an opportunity for an iatrogenic complication given the distortion of anatomy by the disease process. This article explores complications that can occur during cholesteatoma surgery, guidance on how to avoid intraoperative complications, and treatment of such complications.

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.

Taste Changes after Atresioplasty in Patients with Congenital Aural Atresia

OBJECTIVE

We evaluated chorda tympani nerve (CTN) and postoperative taste dysfunction according to anomaly severity and intraoperative CTN status.

STUDY DESIGN

Prospective observational study.

SETTING

Tertiary referral center, Samsung medical center hospital.

PATIENTS

Thirty-one patients who underwent atresioplasty by a single surgeon in a tertiary referral center were enrolled.

INTERVENTIONS

Therapeutic surgery.

MAIN OUTCOME MEASURES

Preoperative Schuknecht type and Jahrsdoerfer score and intraoperative CTN status were recorded, and a postoperative questionnaire was administered to evaluate taste function.

RESULTS

A significant difference was found among intact, cut, and unidentified groups in terms of Schuknecht type ( p = 0.000) and Jahrsdoerfer score (9.28 ± 1.11, 8.80 ± 0.83, 8.10 ± 0.93, p = 0.028). CTN was observed in Schuknecht type B, and not in type C ( p = 0.000), and was more likely to be observed as Jahrsdoerfer score increased ( p = 0.012). Taste disturbance tended to last longer in adult patients than in children. A significant difference was observed in the incidence of taste change between cut and intact CTN groups ( p = 0.018).

CONCLUSION

CTN was not identified during surgery in patients with Schuknecht type C anomalies, and there was no change in taste after surgery. Meanwhile, CTN was observed in all patients with Schuknecht type B anomalies, and CTN injury occurred in 41.67%. Therefore, CTN presence can be predicted by severity of anomaly, and patients with type B anomalies should be informed of the risk of CTN injury before surgery.

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.

The impact of injury of the chorda tympani nerve during primary stapes surgery or cochlear implantation on taste function, quality of life and food preferences: A study protocol for a double-blind prospective prognostic association study

BACKGROUND

The chorda tympani nerve (CTN) is a mixed nerve, which carries sensory and parasympathetic fibres. The sensory component supplies the taste sensation of the anterior two-thirds of the ipsilateral side of the tongue. During middle ear surgery the CTN is exposed and frequently stretched or sacrificed, because it lacks a bony covering as it passes through the middle ear. Injury may cause hypogeusia, ageusia or altered taste sensation of the ipsilateral side of the tongue. To date, there is no consensus regarding which type of CTN injury (sacrificing or stretching), during middle ear surgery, leads to the least burden for the patient.

METHODS

A double-blind prospective prognostic association study was designed in a single medical centre in the Netherlands to determine the effect of CTN injury on postoperative taste disturbance and quality of life. 154 patients, who will undergo primary stapes surgery or cochlear implantation will be included. The taste sensation, food preferences and quality of life of these patients will be evaluated preoperatively and at one week, six weeks and six months postoperatively using the Taste Strip Test, Electrogustometry, supplementary questionnaire on taste disturbance, Macronutrient and Taste Preference Ranking Task, Appetite, Hunger and Sensory Perception questionnaire and Questionnaire of Olfactory Disorders to assess the association of these outcomes with CTN injury. Evaluation of olfactory function will only take place preoperatively and at one week postoperatively using the Sniffin' Sticks. The patient and outcome assessor are blinded to the presence or absence of CTN injury.

DISCUSSION

This study is the first to validate and quantify the effect of chorda tympani nerve injury on taste function. The findings of this study may lead to evidence-based proof of the effect of chorda tympani injury on taste function with consequences for surgical strategies.

TRIAL REGISTRATION

Netherlands Trial Register NL9791. Registered on 10 October 2021.

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.

Immune responses in the injured olfactory and gustatory systems: a role in olfactory receptor neuron and taste bud regeneration?

Sensory cells that specialize in transducing olfactory and gustatory stimuli are renewed throughout life and can regenerate after injury unlike their counterparts in the mammalian retina and auditory epithelium. This uncommon capacity for regeneration offers an opportunity to understand mechanisms that promote the recovery of sensory function after taste and smell loss. Immune responses appear to influence degeneration and later regeneration of olfactory sensory neurons and taste receptor cells. Here we review surgical, chemical, and inflammatory injury models and evidence that immune responses promote or deter chemosensory cell regeneration. Macrophage and neutrophil responses to chemosensory receptor injury have been the most widely studied without consensus on their net effects on regeneration. We discuss possible technical and biological reasons for the discrepancy, such as the difference between peripheral and central structures, and suggest directions for progress in understanding immune regulation of chemosensory regeneration. Our mechanistic understanding of immune-chemosensory cell interactions must be expanded before therapies can be developed for recovering the sensation of taste and smell after head injury from traumatic nerve damage and infection. Chemosensory loss leads to decreased quality of life, depression, nutritional challenges, and exposure to environmental dangers highlighting the need for further studies in this area.

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.

Subtotal Petrosectomy With Preservation of Chorda Tympani for Petrous Bone Cholesteatoma: Case Report

A petrous bone cholesteatoma (PBC) is a rare epidermoid cyst of the petrous portion of the temporal bone. The main treatment is subtotal petrosectomy (SP), which generally involves sacrificing the chorda tympani. We report a case of extensive supralabyrinthine PBC in an elderly patient undergoing hemodialysis that was treated by SP with anatomical preservation of the chorda tympani. To the best of our knowledge, preservation of the chorda tympani during SP has not been previously reported. For maintenance of postoperative taste and appetite, preservation of the chorda tympani is a meaningful maneuver whenever possible.

Comparison of gustatory function between mucosal and squamous disease: a randomised controlled study

OBJECTIVE

The aim of this study was to evaluate and compare the gustatory function between patients with chronic mucosal and squamous diseases before and after the surgery.

METHOD

A total of 33 patients with mucosal diseases and 34 patients with squamous diseases were evaluated for gustatory function both in the pre-operative and post-operative periods. The taste scores were compared between the two groups.

RESULTS

The gustatory scores in the mucosal disease group were significantly better than the scores in the squamous disease group (p < 0.05). There was no significant correlation detected between the age of the patients or duration of the disease with the taste scores in any of the study groups.

CONCLUSION

The improvement in gustatory score was better in the chronic mucosal disease group than the squamous disease group. There was no significant correlation found between the age of the patients or duration of disease and the taste score in any of the study groups.

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.

Gustatory function in chronic otitis media (mucosal type) before and after tympanoplasty

Chronic inflammation in the middle ear may result in functional impairment of the chorda tympani nerve, which carries taste from the anterior two-thirds of the tongue. This may lead to impaired taste sensation. Timely intervention and adequate disease clearance may help the chorda tympani nerve to recover. Gustatory function of 107 patients who underwent Tympanoplasty for Chronic otitis media (mucosal type) was evaluated in a cohort of Indian patients. To compare the preoperative and postoperative gustatory function in these patients taste scores were documented preoperatively, and at 6 weeks and 3 months postoperatively, in an effort to document taste function improvement after disease clearance. The taste scores thus obtained were recorded and analyzed. A significant improvement in taste threshold postoperatively in comparison to the preoperative taste scores (p = 0.001) was found. It was observed that age of the patient and duration of illness have a significant impact on the recovery of taste function. Our study suggests that taste perception improves over a period of time after successful tympanoplasty in patients with chronic otitis media (mucosal type).

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.

A high-fat diet is associated with otitis media with effusion

OBJECTIVE

An association between obesity and otitis media with effusion (OME) has been previously reported. The aim of this study was to evaluate the association between dietary intake and OME when adjusting obesity.

METHODS

We analyzed the differences in dietary intake between children with/without OME who were 4 through 13 years of age using data from a large population-based survey - the Korea National Health and Nutrition Examination Survey - from 2008 through 2012. Data from 4359 participants were analyzed using simple and multiple logistic regression analyses with complex sampling.

RESULTS

The BMI category, the proportion of total calorie intake, protein intake, water intake, and Na intake (intake/recommendation), and the distribution of carbohydrate intake were not associated with OME. The distribution of fat intake was associated with OME (each 10% increase of fat calories/total calories: unadjusted odds ratio [OR]=1.331, 95% confidence interval [CI]=1.016-1.744, P=0.038; age- and sex-adjusted OR=1.359, 95% CI=1.028-1.797, P=0.031; adjusted for age, sex and other factors OR=1.392, 95% CI=1.054-1.839, P=0.020). Based on BMI subgroup analysis, the distribution of fat intake was associated with OME in the healthy weight group (each 10% increase of fat calories/total calories: unadjusted OR=1.393, 95% CI=1.017-1.909, P=0.039; adjusted OR=1.470, 95% CI=1.051-2.055, P=0.024) but not in the obese group.

CONCLUSIONS

A high-fat diet was associated with OME and may represent a confounding factor between obesity and OME.

Taste and olfaction in middle ear surgery

OBJECTIVE

The aim of this study was to assess pre- and postoperative taste ability in patients undergoing middle ear surgery for otosclerosis or chronic otitis media. Olfactory function was also evaluated to rule out taste deficits due to concomitant nasal pathology.

METHODS

All patients underwent ear, nose, and throat examination, otomicroscopy, nasal endoscopy, anterior rhinomanometry, taste testing, and olfactory testing. Patients were evaluated at 1 to 5 days preoperatively (T0), and at 1 (T1), 6 (T6), and 12 (T12) months postoperatively.

RESULTS

Both groups of patients experienced worsening of the mean taste threshold postoperatively. This phenomenon was more serious in poststapedotomy patients. Follow-up showed progressive improvement in both groups. All values of olfactory testing were within the normal range for otosclerosis patients. Patients with chronic otitis media showed variable postoperative findings.

CONCLUSION

Chorda tympani function can be negatively affected by middle ear surgery. Deficits may be more marked in stapedotomy patients than in those undergoing tympanoplasty. Postoperative recovery of taste is satisfactory, although with different timelines for the 2 types of pathology.

Surgery of the ear and the lateral skull base: pitfalls and complications

Surgery of the ear and the lateral skull base is a fascinating, yet challenging field in otorhinolaryngology. A thorough knowledge of the associated complications and pitfalls is indispensable for the surgeon, not only to provide the best possible care to his patients, but also to further improve his surgical skills. Following a summary about general aspects in pre-, intra-and postoperative care of patients with disorders of the ear/lateral skull base, this article covers the most common pitfalls and complications in stapes surgery, cochlear implantation and surgery of vestibular schwannomas and jugulotympanal paragangliomas. Based on these exemplary procedures, basic "dos and don'ts" of skull base surgery are explained, which the reader can easily transfer to other disorders. Special emphasis is laid on functional aspects, such as hearing, balance and facial nerve function. Furthermore, the topics of infection, bleeding, skull base defects, quality of life and indication for revision surgery are discussed. An open communication about complications and pitfalls in ear/lateral skull base surgery among surgeons is a prerequisite for the further advancement of this fascinating field in ENT surgery. This article is meant to be a contribution to this process.

Aging profoundly delays functional recovery from gustatory nerve injury

The peripheral taste system remains plastic during adulthood. Sectioning the chorda tympani (CT) nerve, which sends sensory information from the anterior tongue to the central nervous system, causes degeneration of distal fibers and target taste buds. However, taste function is restored after about 40 days in young adult rodents. We tested whether aging impacts the reappearance of neural responses after unilateral CT nerve injury. Taste bud regeneration was minimal at day 50-65 after denervation, and most aged animals died before functional recovery could be assessed. A subset (n=3/5) of old rats exhibited normal CT responses at day 85 postsectioning, suggesting the potential for efficient recovery. The aged taste system is fairly resilient to sensory receptor loss and major functional changes in normal aging. However, injury to the taste system reveals a surprising vulnerability in old rodents. The gustatory system provides an excellent model to study mechanisms underlying delayed recovery from peripheral nerve injury. Strategies to accelerate recovery and restore normal function will be of interest, as the elderly population continues to grow.

From Conception to Application of a Tele-Operated Assistance Robot for Middle Ear Surgery

The authors’ goal was to design and evaluate a robot dedicated to middle ear surgery. Specifications for dimensions, forces, and kinematics were collected, based on the otosclerosis procedure. The robot structure has a compact geometry with 3 linear and 3 rotatory motors. It is remotely piloted via a robot–surgeon interface under operative microscope. Ability to reach anatomical targets, to perform stapedectomy, and to place prosthesis in a model of stapedotomy was evaluated by 6 surgeons. Multiple anatomical targets in the middle ear could be successfully reached without damaging surrounding structures. The robot could be used under operative microscope with minimal visual field impairment or jointly with a 4-mm endoscope through the external auditory canal to perform stapedectomy in temporal bone specimens. Prosthesis could be inserted in the stapedotomy model. The assistance robot is the first prototype with 6 degrees of freedom, a kinematic structure, and dimensions optimized for tele-operated middle ear surgery.

Taste disturbance after mastoid surgery: immediate and long-term effects of chorda tympani nerve sacrifice

Objective:

To determine the immediate and long-term taste effects of chorda tympani nerve sacrifice in patients undergoing open cavity mastoidectomy.

Design, setting and participants:

A retrospective, questionnaire survey of patients receiving follow up and aural toilet following open cavity mastoidectomy, over a four-month period. The questionnaire assessed taste disturbance, both immediately post-operative and current. Available surgical records were reviewed for chorda tympani references.

Results:

Of 57 patients, six had undergone surgery to both ears. Of those who could recall (37/57), 24.3 per cent were aware of taste disturbance immediately after surgery, while 8.7 per cent reported current disturbance (median post-operative interval, 28.5 years; range, one month to 67 years). No bilateral surgery patients were aware of taste disturbance.

Conclusion:

Mastoidectomy consent procedure emphasises the risk of hearing loss and facial nerve injury, yet in open cavity surgery chorda tympani division is almost inevitable. Reassuringly, most post-operative taste disturbance resolves, and most patients are not aware of long-term disturbance. However, a small percentage suffer ongoing taste disturbance; this could be significant for professional chefs and wine-tasters. The risk of taste disturbance should be addressed in the consent procedure.

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.

Evaluation of electrogustometry and the filter paper disc method for taste assessment

CONCLUSION

The results indicate that electrogustometry and the filter paper disc method are reliable methods to measure taste with a high degree of reproducibility.

OBJECTIVES

To thoroughly evaluate the reliability of electrogustometry and the filter paper disc method for taste assessments.

METHODS

Thirty-nine healthy test persons without any history of chronic middle ear disease, aged between 27 and 62 years, were recruited. In all, 772 electrogustometry and 30 filter paper disc assessments were made. A nerve decay test was performed, with measures taken before and after eating sweet, sour, bitter, salt, a mild or spicy meal, after smoking, and after taking Swedish tobacco snuff ('snus'), as well as before and after local anesthesia of the tongue. Measurements were performed on 5 consecutive days and repeatedly during 1 day. The correlation between electrogustometry and the filter paper disc method was also studied.

RESULTS

The results indicate that electrogustometry and the filter paper disc method are reliable methods to measure taste with a high degree of reproducibility. The only actions causing significant changes in the electrogustometry readings were eating a bitter substance and having local anesthesia of the tongue. The correlation between the methods was statistically significant except for the bitter flavor, where the correlation was just below the level of significance.

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.

Relationship between pediatric obesity and otitis media with effusion

Although eustachian tube dysfunction and bacterial infection have been shown to cause otitis media with effusion (OME), other etiologies are possible. One of the most common medical conditions in children is obesity, which can have effects throughout the body. Little is known, however, about the relationship between obesity and OME. Obesity may result in altered cytokine expression, gastroesophageal reflux disease, or fat accumulation, all of which may contribute to OME. Conversely, OME may induce taste changes through middle ear cavity inflammation, thus contributing to obesity. A similar pattern of taste change has been shown in patients with gustatory nerve anesthesia. Further research on the relationship between obesity and OME may help to determine the exact etiology of OME and contribute to our knowledge about the causes of obesity.

Electrogustometric assessment of taste after otologic surgery in children

OBJECTIVES/HYPOTHESIS

Long term taste dysfunction after otologic surgery has never been characterized in children. The aim of this study is to determine the rates of gustatory dysfunction in normal and postotologic surgery in children.

STUDY DESIGN

Cross-sectional study.

METHODS

One hundred sixty children visiting a tertiary pediatric otolaryngology clinic, 4 to 18 years of age, were recruited. Surgical groups included patients who had undergone tympanoplasty, combined approach mastoidectomy, modified radical mastoidectomy, and unilateral and bilateral cochlear implantation. They were then tested using a Rion TR-06 electrogustometer (Sensonics, Inc., Haddon Heights, NJ) using a standardized protocol to assess chorda tympani nerve function. An abnormal gustometry result was defined as any recording of > or =16 dB or a difference of 6 dB between ears.

RESULTS

The control group had a 9% (5/61) abnormal electrogustometric threshold rate. Rates of dysfunction after surgery were: tympanoplasty (27%, 4/15), combined approach mastoidectomy (30%, 11/29), modified radical mastoidectomy (50%, 4/8). Unilateral cochlear implantation yielded a 26% (7/27) per ear risk of dysfunction, whereas bilateral cochlear implantation had a 5% (2/40) per ear risk.

CONCLUSIONS

There is a 9% baseline level of electrogustometric abnormality in the pediatric population, which suggests a subclinical level of gustatory dysfunction. Normal electrogustometry was found in 50% of children after modified radical mastoidectomy, suggesting a degree of neural regenerative capacity. Finally, cochlear implantation, using newer surgical techniques (in the bilateral cochlear implant group) has a low risk for causing gustatory dysfunction, reducing concerns over the safety profile of bilateral cochlear implantation.

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.

Incorporating the Endoscope into Middle Ear Surgery

We conducted a study to evaluate the use of a pediatric rigid otoendoscope for determining the extent of middle ear disease and for assessing ossicular integrity and mobility during tympanoplasty. Our study population was made up of 132 patients who were undergoing surgery for the treatment of chronic suppurative otitis media; of this group, 41 patients underwent otoendoscopy and 91 underwent scutum lowering for purposes of visualization. In the otoendoscopy group, the ossicles were successfully visualized and their mobility assessed in 34 patients; the remaining 7 patients subsequently underwent scutum lowering. A 30° endoscope allowed for complete visualization of the middle ear in almost all of the 34 cases. The mean duration of surgery for the 34 patients in the otoendoscopy group was 62.85 minutes (± 15.57), which was significantly shorter than the duration of surgery (71.23 ± 15.65 mitt) for the 98 patients who underwent scutum lowering (p < 0.005). A total of 50 patients required less than 60 minutes of surgical time—26 of 34 (76.5%) in the endoscopy group and 24 of 98 (24.5%) in the scutum-lowering group. Statistical analysis revealed that the possibility of completing a procedure in less than 60 minutes was 73.65% (± 12.56%) when endoscopy was used and 58.62% (± 12.60%) when scutum lowering was used—again, a statistically significant difference (p < 0.005). We conclude that incorporation of an angled otoendoscope into middle ear surgery is a worthwhile alternative to scutum lowering.

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.

Gustatory function in chronic inflammatory middle ear diseases

HYPOTHESIS

Changes of gustatory function after ear surgery have been studied extensively. However, little is known on the influence of repeated/chronic inflammation within the middle ear on taste.

STUDY DESIGN

Prospective study.

MATERIALS AND METHODS

Forty-six patients suffering from either cholesteatoma (n = 25) or chronic otitis media mesotympanalis (n = 21) received quantitative gustatory tests. None of these patients had been operated on before these investigations.

RESULTS

Side by side comparison showed a significantly lower taste function on the anterior two thirds of the tongue ipsilateral to the site of inflammation, regardless of the diagnosis. Further analyses exhibited a trend toward greater impairment in relation to the severity of the inflammatory process.

CONCLUSION

These data are proof that taste function changes in relation to chronic middle ear diseases. It further shows that many of these alterations go unnoticed by the patients.

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 elderly patients with unilateral middle ear disease

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.

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.

Electrogustometry: strengths, weaknesses, and clinical evidence of stimulus boundaries

Electrogustometry is well established as a clinical tool for the estimation of taste detection thresholds. Nevertheless, the user is sometimes unaware of the impact of superficially minor procedural and psychophysical factors upon the reliability and comparability of threshold estimates. The inherent strengths and limitations of the procedure are outlined, and aspects of the control and specification of the stimulus that moderate threshold measures are discussed. In addition, threshold estimates from two individuals with severe unilateral taste loss are used to illustrate the level at which anodal dc current may elicit common, rather than taste, sensation. Where chorda tympani section is complete and historical (older than 7-14 days), very high stimulus levels, conservatively over 5 micro A/mm2 (100 micro A linear current with a 5-mm diameter electrode), are required to activate trigeminal responses.

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

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.

Expression of activating transcription factor 3 and growth-associated protein 43 in the rat geniculate ganglion neurons after chorda tympani injury

The purpose of this study was to evaluate the degree of damage in the geniculate ganglion and its target organ as a result of chorda tympani (CT) injury. We performed unilateral transection of the rat CT and examined expression of the activating transcription factor 3 (ATF3), a neuronal injury marker, and the growth-associated protein 43 (GAP-43), a regeneration-associated molecule. The mean proportion of ATF3-immunoreactive (ir) neurons in the geniculate ganglion was approximately 32% at 3 days after CT injury, but these neurons were never detected in the naive ganglion. Using in situ hybridization, the mean percentage of GAP-43 mRNA-labeled neurons (signal : noise ratio > or = 10) was observed to have increased significantly to approximately 60% for 1-7 days after CT injury, while that in the naive ganglion was < 15%. The results of morphological studies using scanning electron microscopy and immunohistochemistry indicated that atrophic change and reduction of protein gene-product 9.5-ir fibers in the denervated papillae, mainly in the intragemmal region, were observed after CT injury. Increase in GAP-43 mRNA, suggesting CT axonal regeneration, may have a role in recovery from taste disorders. However, this regenerative process may be involved in abnormal activity in the axotomized neurons or the adjacent intact neurons and so one must not disregard the existence of injured geniculate ganglions when considering the treatment of diseases that cause CT injury.