Electrogustometric assessment of taste after otologic surgery in children

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.

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.

Olfaction and Gustation in Children With Primary Ciliary Dyskinesia

Objective

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder whereby abnormal cilia cause a wide array of respiratory tract manifestations including chronic rhinosinusitis. The purpose of this study was to determine whether olfaction and gustation are impaired in children with PCD.

Study Design

Cross-sectional study.

Setting

Tertiary pediatric academic hospital.

Methods

Children with confirmed PCD based on having at least 1 of 3 approved diagnostic criteria as per The American Thoracic Society guidelines were recruited from The PCD Clinic in our tertiary care pediatric hospital. Odor identification ability was tested using the Universal Sniff (U-Sniff) test and taste threshold was measured using an electrogustometer. The main outcome of this study is to determine the incidence of olfactory dysfunction in children with PCD and investigate if there is an associated gustatory dysfunction.

Results

Twenty-five children participated (14 male, 11 female), The median age was 10.8 years (range: 4.1-17.9 years). Only 4/25 (16%) complained of olfactory dysfunction prior to testing. None of the patients complained of dysgeusia. However, 48% (12/25) scored less than 7 on the U-Sniff, signifying hyposmia or anosmia. In contrast, scores obtained by electrogustometry were in the normal range. There was no correlation between performance on the U-Sniff and electrogustometry testing.

Conclusion

Olfactory impairment in children with PCD is common but underrecognized by patients. This is not associated with abnormal gustation. Among other, this places children with PCD at an increased risk with respect to smelling a fire or detecting spoiled or poisonous food.

The effect of mucosal dryness on the electrogustometric threshold

Electrogustometry (EGM) is one of the most useful diagnostic tools widely used to evaluate the taste function by measuring the perception threshold to electrogustatory stimuli on the tongue. However, the effects of oral environments on electrogustometric threshold (EGMT) remain to be established despite its simple applicability. Thus, this study aims to determine the effect of mucosal dryness on EGMT in 68 healthy subjects. The experiment was conducted in two different conditions. First, the baseline EGMT was measured when the dryness of the tongue surface was normal. Second, the EGMT was remeasured after the tongue was intentionally desiccated. The current study showed that the mean of the EGMT was significantly increased when the tongue was desiccated, possibly indicating the reduced sensitivity to electrogustatory stimuli. Such an alteration may be related to the disturbed EGM electrical circuit through the dried mucosa with enhanced impedance. Thus, these findings suggested that mucosal dryness should be considered for better evaluation of gustatory function using EGM.

Taste dysfunction in children - a clinical perspective and review of assessment methods

Taste dysfunction has been associated with aging and is therefore thought to be less common in children. However, children can face medical conditions influencing their taste function. Measuring and understanding taste dysfunction in children may foster the development of treatments/interventions mitigating the detrimental effects of taste dysfunction on children's appetite and quality of life. But measuring loss of taste function requires adequate tools. This review was conducted to (1) provide an overview of etiologies (i.e., disease and iatrogenic) associated with taste dysfunction in a pediatric population; (2) to investigate which tools (psychophysical tests and questionnaires) are available to assess taste function in children; and (3) to identify what tools can be and are actually used in clinical practice. It is concluded that only a minority of available tools to assess taste function in children are readily suitable for a pediatric clinical setting. Considering the profound impact of taste dysfunction in the pediatric setting, developing and implementing a standard taste test that is sensitive, simple, and practical to use with children is pertinent.

Gustatory function in persons with cerebral palsy

Gustatory function is closely related to chewing and swallowing; however, there are currently no reports regarding gustatory function in persons with cerebral palsy (CP). The aim of this study was to compare the gustatory function between persons with CP and healthy controls. We investigated sweet, salty, sour and bitter tastes using the whole-mouth method and measured the electrogustometric thresholds in the chorda tympani nerve area. Twelve participants with CP (6 women and 6 men) for whom gustatory testing was possible at our facilities, and 17 age-matched controls (9 women and 8 men) were included. The mean age ± standard deviation was 58.6 ± 8.1 years and 58.5 ± 8.7 years in subjects with CP and controls, respectively. Taste detection and identification were significantly worse in persons with CP compared with the controls. Taste identification was more impaired than taste detection. At the highest concentration, taste identification was impossible 11 times out of 48 (12 persons × 4 kinds of tastes) in persons with CP but such a deficit was not observed in 68 attempts (17 persons × 4 kinds of tastes) involving controls. The electrogustometric thresholds were not significantly different between the groups. Gustatory function associated with chewing and swallowing is worse in persons with CP compared to the controls.

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.

Influences of age, tongue region, and chorda tympani nerve sectioning on signal detection measures of lingual taste sensitivity

Although the ability to taste is critical for ingestion, nutrition, and quality of life, a clear understanding of the influences of age, sex, and chorda tympani (CT) resection on taste function in different regions of the anterior tongue is generally lacking. In this study we employed criterion-free signal detection analysis to assess electric and chemical taste function on multiple tongue regions in normal individuals varying in age and sex and in patients with unilateral CT resections. The subjects were 33 healthy volunteers, ranging from 18 to 87 years of age, and 9 persons, 27 to 77 years of age, with unilateral CT lesions. The influences of age, sex, tongue region, and chorda tympani resections on signal detection sensitivity (d') and response bias (β) measures was assessed in 16 tongue regions to weak electric currents and solutions of sucrose, sodium chloride, and caffeine. Significant age-related decrements in d' were found for sucrose (p=0.012), sodium chloride (p=0.002), caffeine (p=0.006), and electric current (EC) (p=0.0001). Significant posterior to anterior, and medial to lateral, gradients of increasing performance were present for most stimuli. β was larger on the anterior than the posterior tongue for the electrical stimulus in the youngest subjects, whereas the opposite was true for sucrose in the oldest subjects. No sex differences were apparent. d' was depressed ipsilateral to the CT lesion side to varying degrees in all tongue regions, with the weakest influences occurring on the medial and anterior tongue. CT did not meaningfully influence β. This study is the first to employ signal detection analysis to assess the regional sensitivity of the tongue to chemical and electrical stimuli. It clearly demonstrates that tongue regions differ from one another in terms of their age-related sensitivity and their susceptibility to CT lesions.

Regeneration of the nerves in the aerial cavity with an artificial nerve conduit --reconstruction of chorda tympani nerve gaps-

OBJECTIVES/HYPOTHESIS

Due to its anatomical features, the chorda tympani nerve (CTN) is sometimes sacrificed during middle ear surgery, resulting in taste dysfunction. We examined the effect of placing an artificial nerve conduit, a polyglycolic acid (PGA)-collagen tube, across the gap in the section of the resected chorda tympani nerve (CTN) running through the tympanic cavity.

METHODS

The CTN was reconstructed with a PGA-collagen tube in three patients with taste disturbance who underwent CTN resection. To evaluate the effect of the reconstruction procedure on the patients' gustatory function, we measured the patients' electrogustometry (EGM) thresholds. The patients were followed-up for at least two years.

RESULTS

Gustatory function was completely restored in all of the patients after the reconstruction. The patients' EGM thresholds exhibited early improvements within one to two weeks and had returned to their normal ranges within three months. They subsequently remained stable throughout the two-year follow-up period. In a patient who underwent a second surgical procedure, it was found that the PGA-collagen tube used in the first surgical procedure had been absorbed and replaced by new CTN fibers with blood vessels on their surfaces.

CONCLUSION

These results suggest that reconstruction of the CTN with an artificial nerve conduit, a PGA-collagen tube, allows functional and morphological regeneration of the nerve and facilitates the recovery of taste function. PGA-collagen tubes might be useful for repairing CTNs that are resected during middle ear surgery. Further research is required to confirm these preliminary results although this is the first report to describe the successful regeneration of a nerve running through an aerial space.

Taste sensation following cochlear implantation surgery

OBJECTIVES

The chorda tympani nerve (CTN) is at risk of damage during cochlear implantation, especially during posterior tympanotomy. The aim of this study was, therefore, to elicit the risk of taste disorders following cochlear implantation surgery involving a mastoidectomy and a posterior tympanotomy approach.

METHOD

Twenty-six patients underwent a taste test before, 3 days after, and 6 weeks after cochlear implantation surgery. The taste sensations - sweet, sour, salt and bitter - were determined. Patients' self-ratings of taste function were also obtained. In addition, the surgeons provided information concerning the intraoperative status of the CTN.

RESULTS

In total, 19.2% (5 of 26) of the patients had postoperative taste dysfunction, as measured either subjectively or objectively or both. One of these five individuals had taste disturbance as assessed by both subjective and objective measures; in another, it was merely reported subjectively. Three patients were subjectively asymptomatic but the postoperative taste test revealed a dysfunction. Sixteen percent of the patients in whom the CTN was reported to be preserved intraoperatively had a postoperative taste dysfunction. Although the CTN was rerouted in five patients, only two of them (40%) had transient gustatory dysfunction. In two of those patients with postoperative taste dysfunction, the CTN was not intraoperatively exposed (being protected by bone) despite these individuals' experiencing postoperative taste problems. The recovery rate was 100% at 6 weeks after surgery.

CONCLUSION

Our study indicates that cochlear implantation entails only a minimal risk of taste dysfunction and that this is chiefly a transient problem.

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.

Taste evaluation in adolescents and pediatric patients with benign migratory glossitis

OBJECTIVE

Benign migratory glossitis (BMG) is a disease that affects the tongue and is considered an inflammatory disorder well recognized. It is characterized by the appearance of erosive areas on the dorsum and lateral border of the tongue that can be isolated or multiple. The aim of this study was to assess whether the perception of taste to the four basic tastes is altered due to the presence of BMG.

METHODS

Forty individuals of both sexes with a mean age of 12.1 years were divided into two groups (20 BMG patients and 20 healthy controls) and had their taste function assessed in relation to four basic tastes: bitter, sour, sweet, and salty.

RESULTS

All participants in the case group exhibited lesions over the dorsum, edges and tip of the tongue with a possible extension to the surface below. No statistic difference was observed between BMG patients and controls for the taste scores (Mann-Whitney U test: P=0.0955). The percentage of correctly identified taste strips for the highest concentrations was 100% for all tastes. For the lowest concentrations it was 85% for sweet, 50% for sour, 95% for salty, and 95% for bitter. Three patients with BMG and three control subjects showed hypogeusia.

CONCLUSION

This study revealed that BMG is not able to change the perception of taste for salty, sweet, sour and bitter.

Chorda tympani nerve function in children: relationship to otitis media and body mass index

OBJECTIVE/HYPOTHESIS

A relationship between acute otitis media and elevated body mass index has recently been reported. Intriguingly, it was postulated that this relationship may result from altered chorda tympani nerve function impacting taste sensation and eating habits. We sought to test this directly by measuring chorda tympani nerve function in children with and without a previous history of acute otitis media and to determine the relationship to body mass index.

STUDY DESIGN

Retrospective cohort study.

METHODS

Institutional research ethics board approval was obtained. Study participants included 142 children (5-18 years of age) who were recruited from an otolaryngology outpatient clinic at a tertiary academic pediatric hospital between May and August 2009. Children were excluded if they were not able to communicate effectively, younger than age 5, or had developmental disabilities. Body mass index was calculated and the history of previous otologic disease carefully elicited from the caregivers. Electrogustometric threshold, a validated measure of chorda tympani function, was obtained bilaterally in each child. Children were divided into cohorts based on the number of acute otitis media episodes, and electrogustometry thresholds were compared between cohorts.

RESULTS

Electrogustometric thresholds were successfully obtained in all children. There was no significant relationship between chorda tympani nerve function and history of acute otitis media. Similarly, there was no significant association between the history of otitis media and body mass index.

CONCLUSION

This study did not demonstrate any effect of previous acute otitis media history on chorda tympani nerve function. Furthermore, it did not demonstrate a relationship between acute otitis media and elevated body mass index. This is counter-evidence to the previous hypothesis that increasing acute otitis media is responsible for increasing childhood obesity through alteration in chorda tympani nerve function.

Olfactory and gustatory function in healthy adult Chinese subjects

OBJECTIVE: To investigate the effect of age and gender on olfactory and gustatory function and to establish test methodology and normative values in Chinese subjects.

STUDY DESIGN: Cross-sectional study.

SETTING: The center laboratory and the Department of Otolaryngology—Head & Neck Surgery, Beijing Tongren Hospital.

SUBJECTS AND METHODS: The T&T olfactometer, the Sniffin' Sticks olfactory test, olfactory event-related potentials (oERPs), trigeminal event-related potentials (tERPs), and the triple drop method for gustatory testing were used to examine the chemosensation in 90 healthy adults (45 men and 45 women).

RESULTS: Older subjects (age 51–65 years) showed worse olfaction compared with younger subjects (age 18–35 years) when both T&T (younger —1.71 ± 0.41, older —0.92 ± 0.95; P < 0.01) and Sniffin' Sticks (threshold, discrimination, identification score: younger 33.17 ± 2.83, older 30.89 ± 3.35; P < 0.05) testing were performed. Measurement of oERPs revealed that older patients (N1 471 ± 85 ms, P2 676 ± 93 ms) had longer latencies compared with younger ones (N1 368 ± 57 ms, P2 561 ± 74 ms, P < 0.05) of N1/P2 wave. The results of trigeminal nerve-related potential examination showed that N1/P2 latencies were longer and amplitudes were lower in older people (N1 384 ± 98 ms/—5.01 ± 4.00 uv, P2 568 ± 95 ms/6.53 ± 3.62 uv) compared with younger patients (N1 316 ± 31 ms/—7.20 ± 3.43 uv, P2 472 ± 66 ms/8.72 ± 3.09 uv; P < 0.05). Gustation was normal in all subjects, and there was no significant difference between younger and older groups.

CONCLUSION: Age and gender affect olfaction in Chinese adults as measured by standard testing methods used in other human populations. In healthy Chinese subjects, gustation was normal and did not vary with age. Our data provide preliminary normative values for future investigation of chemosensation in the Chinese population.