[Taste disorders and recovery of the taste function after middle ear surgery]

Comparison of anterior and posterior tympanomeatal flap elevations in endoscopic transcanal tympanoplasty

Background: There is not an ideal tympanomeatal flap incision type for transcanal procedures. Aims/Objectives: Comparing the outcomes and feasibility of posteriorly and anteriorly based tympanomeatal flap incisions for anterior perforations in endoscopic transcanal cartilage tympanoplasty. Material and methods: Twenty-six patients who had anterior TM perforation were included. Patients were divided into two groups with randomization. All of the data were prospectively collected. These included demographic data, date of the surgery, mean surgery time, preoperative and postoperative sixth-month pure-tone audiometry (PTA), type of tympanomeatal flap incision and graft healing success. Results: Mean follow up time was 20.69 ± 5.03 months. Graft healing rate was 100% in both groups. There was no major complication in both of groups. Mean air bone gap level improvement of (dB HL) at all frequencies was 7.69 ± 2.83 dB HL in group 1 and 7.98 ± 3.08 dB HL in group 2 respectively. Regarding pre-and postoperative mean air bone gap levels and mean surgery times, there was no significant difference between groups (p>.05). Conclusions and significance: For non-complicated anterior perforations that are less than 50% of TM, endoscopic transcanal cartilage tympanoplasty using anterior tympanomeatal flap elevation procedure was seemed minimally invasive and feasible to perform with successful audiologic and postoperative outcomes.

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.

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.

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.

Endoscopic transcanal stapedotomy: how I do it

Current paper presents a surgical technique and preliminary results of the first eight consecutive fully endoscopic transcanal stapedotomies. All eight procedures were performed under local anesthesia by the same surgeon using rigid endoscopes of 3-mm diameter, 14-cm length, 0° and 30°. A posterior tympanomeatal flap was elevated transmeatally with the 0° endoscope and then transposed anteriorly. Stapes fixation was confirmed, the stapes tendon was cut with curved micro-scissors, and the stapes was separated from the incus in the incudo-stapedial joint. The anterior and posterior stapedial crus were carefully fractured, and the superstructure was removed. The hole in the foot-plate was created with a Skeeter microdrill using a 0.5-mm-diameter diamond burr. A platinum/fluoroplastic piston prosthesis (0.4-mm diameter) was placed into this hole and fitted along the long process of the incus. The tympano-meatal flap was repositioned, and the external auditory canal was filled with Gelfoam(®). The chorda tympani nerve was preserved in all cases. A 4.5-mm prosthesis was used in six cases and a 4.75-mm prosthesis in two. Pure tone audiograms demonstrated improved air- and bone-conduction threshold averages across the three speech frequencies (0.5-1.2 kHz) 6 months after surgery (64 vs. 29.8 dB and 30.6 vs. 25.1 dB, respectively). The average postoperative air-bone gap was within 10 dB in six ears and between 10 and 15 dB in the other two ears. Our preliminary results indicate that transcanal fully endoscopic stapedotomy is a feasible and safe technique for surgical management of hearing loss associated with otosclerosis.

Normative data for a solution-based taste test

The aim of our study was to study gustatory function in a large portion of the general population using liquid tastants, extending previous research. Further, we investigated the test-retest reliability of the test used. Data from 944 healthy subjects were used (498 women and 446 men, mean age 45 years; age range 5-90 years). For lateralized assessment of gustatory function, liquid taste solutions were used with different concentrations of each tastant (sweet 0.03, 0.1, 0.4, 2 g/mL sucrose solution; sour 0.01, 0.05, 0.1, 0.15 mL citric acid; salty 0.025, 0.075, 0.15, 0.36 mL sodium chloride solution; bitter 0.0002, 0.0005, 0.001, 0.01 mL quinine hydrochloride). A drop (approximately 20 µL) of liquid tastant was applied on the right side or on the left side of the anterior/posterior third of the extended tongue. The taste test had a good test-retest reliability r (304) = 0.78 (P < 0.001) for the total score and r (304) = 0.77 (P < 0.001) for the right-sided measures and r (304) = 0.75 (P < 0.001) for the left-sided measures, respectively. Gustatory sensitivity was found to decrease with age; women were more sensitive to gustatory stimuli than men. Irrespective of the sex-related differences, the total score at the 10th percentile was 28 in subjects younger than 15 years, 26.1 for ages from 16 to 35 years, 25 for ages from 36 to 55 years, and 24 for subjects older than 56 years of age. In conclusion, this test is recommended for clinical assessment of the ability to taste. The test provides reliable data, which is easy to handle, inexpensive, timesaving and can be self-made.

Clinical Assessment of Gustatory Function before and after Middle Ear Surgery: A Prospective Study with a Two-Year Follow-up Period

Objectives:

Middle ear surgery can affect gustatory function because of the course of the chorda tympani nerve (CTN) close to the tympanic membrane. The aim of the study was to evaluate the sense of taste before and after middle ear surgery with a test suitable for clinical routine. Moreover, subjective complaints were assessed over a relatively long period of time.

Methods:

Forty-seven patients (26 female, 21 male; mean age, 42 years) were investigated before and 4 days after surgery on both sides of the anterior part of the tongue. Self-assessment of taste function was performed by visual analog scales.

Results:

The mean (±SD) taste scores significantly decreased on the side ipsilateral to the operated ear in patients with major manipulation of the CTN (12.0 ± 4.5 before surgery and 6.9 ± 4.5 after surgery; p < 0.001), whereas no significant changes were measured in patients with minor manipulation of the CTN (12.5 ± 3.1 before surgery and 11.2 ± 3.9 after surgery; p = 0.14). Self-assessed ratings of taste function significantly decreased after surgery in all patients (p < 0.001). Reassessment of subjective taste function after 2 years indicated no persisting complaints.

Conclusions:

Depending on the amount of manipulation of the CTN, taste function is decreased after surgery. However, long-lasting changes of gustatory function seem to be rare.

Changes of oral trigeminal sensitivity in patients after middle ear surgery

OBJECTIVES

The specific aim of this study was to re-investigate the effect of chorda tympani damage on both trigeminal sensitivity and taste ability.

STUDY DESIGN

Prospective study.

METHODS

Capsaicin-impregnated filter paper strips (5 concentrations, 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 seconds. Thresholds were estimated in two ways: 1) thresholds related to sensory perception and 2) intensity-related thresholds. The test was applied to 29 patients who underwent middle ear surgery (mean age, 49 yr; 16 females, 13 males). Results were compared with those of 63 healthy subjects (mean age, 40 yr; 36 females, 29 males). In addition to trigeminal thresholds, measures of gustatory function were also obtained using both the validated "taste strips" test kit and electrogustometry.

RESULTS

For lateralized testing with capsaicin, significant differences were found between preoperative and postoperative thresholds and between the operated and nonoperated side, with thresholds being higher postoperatively on the operated side. The sensation-related thresholds from the operated tongue side exhibited a correlation with the corresponding postoperative electrogustometric thresholds. A higher degree of chorda manipulation was associated with higher postoperative capsaicin thresholds at the operated tongue side.

CONCLUSION

Pain-related sensitivity of the tongue decreases after middle ear surgery, indicating that chorda tympani function also influences intraoral trigeminal sensitivity.

Chorda tympani injury: operative findings and postoperative symptoms

OBJECTIVES

This study aims to assess whether operative findings of chorda tympani nerve (CTN) trauma correlate with postoperative symptoms.

STUDY DESIGN AND SETTING

A prospective study was conducted over 2 years on 140 middle ear operations analyzing taste disturbances. The operations were subdivided into myringoplasty/tympanoplasty (56 cases), mastoidectomy (64 cases), and tympanotomy (20 cases).

RESULTS

Twenty-one (15%) patients reported taste disturbance. Altered taste was most reported (n=15, 71%) with loss of taste reported by 29% (n=6). Symptoms were most observed in the tympanotomy group (45%). Stretching of the CTN was associated with more symptoms than nerve transection. Recovery was complete in 76% (n=16) of the symptomatic cases by 12 months.

CONCLUSION

Patients who undergo middle ear surgery should be thoroughly counseled with respect to CTN injury and symptoms regardless of the type of damage to the nerve.

SIGNIFICANCE

This study highlights the high incidence of postoperative alterations in taste after middle ear surgery, especially in non-diseased ears, and that CTN transection results in fewer symptoms than CTN stretching.

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.

Contact Endoscopic Comparison of Morphology of Human Fungiform Papillae of Healthy Subjects and Patients with Transected Chorda Tympani Nerve

BACKGROUND

The chorda tympani nerve (CTN) carries gustatory fibers from taste buds of fungiform papillae (fPap) of the anterior portion of the tongue. Accordingly, middle ear surgery with transection of the CTN may result in gustatory impairment. With use of contact endoscopy, the present study aimed to compare number and shape of fPap and subepithelial vessel formation in patients after CTN transection with that of healthy controls.

MATERIAL AND METHODS

The number of fPap per square centimeter was obtained in addition to measures of gustatory sensitivity using electrogustometry and intensity ratings of natural taste stimuli. Data from 32 healthy subjects (mean age 40 yr; 16 female, 16 male) were compared with those from 14 patients whose CTN had been cut and partly resected during middle ear surgery because of cholesteatoma (mean age 38 yr; 7 female, 7 male). Middle ear surgery was performed by two of the authors.

RESULTS

In healthy subjects, a higher fPap density was found on the tongue's tip compared with its edge; younger subjects had higher densities than older subjects. No sex-related differences were observed. Patients with transected CTN exhibited a significant decrease of taste function as measured with both natural and electric stimuli. In patients, we found significantly fewer and flatter fPap on the side of the tongue where surgery had been performed in comparison with the contralateral side. In addition, fPap density at the ipsilateral side was significantly lower compared with fPap density on the respective side in healthy controls.

CONCLUSION

As established through contact endoscopy, the number of fPap decreases in relation to deafferentation and also in relation to the subjects' age, both of which are accompanied by a decreased gustatory sensitivity.