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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 26  |  Issue : 3  |  Page : 155-158

Effect of middle ear surgery on taste in patients with chronic otitis media


1 Department of Otorhinolaryngology, Yenepoya Medical College, Mangalore, Karnataka, India
2 Department of ENT, Yenepoya Medical College, Mangalore, Karnataka, India

Date of Submission11-Apr-2020
Date of Acceptance03-Jun-2020
Date of Web Publication22-Dec-2020

Correspondence Address:
Dr. K S Gangadhara Somayaji
Department of ENT, Yenepoya Medical College, Mangalore - 575 018, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_58_20

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  Abstract 


Objective: The objective was to identify the gustatory changes in patients with chronic otitis media due to chorda tympani nerve involvement and to identify the gustatory changes with minimal manipulation, stretching, and cutting of the nerve during surgery and its postoperative recovery. Methodology: A total of 100 patients were selected. Clinical assay, with tests based on “taste strips” with different concentrations of salt, sweet, bitter, and sour, was done preoperatively. The taste strips used were sodium chloride for salt, sucrose for sweet, quinine sulfate for bitter, and citric acid for sour. The same was tested postoperatively after 1 week, 1 month, and 6 months. Analysis: Of the total 100 patients, 22 patients had squamosal disease, and the remaining 78 patients had mucosal disease. Fourteen patients were found to have taste changes preoperatively, of whom nine recovered their taste 1 week following surgery. Remaining five patients recovered at 1 month following the surgery. It was also observed that, in all the 25 patients where the nerve was cut, postoperative changes were noted, which recovered completely at the end of 6 months, except in two patients. In patients where the nerve was stretched, patients showed more gustatory alterations when compared with patients where the nerve was minimally manipulated. Conclusion: We conclude from our study that cutting the nerve produced less gustatory alterations, when compared with patients where the nerve was stretched. We also concluded that chronic inflammation of the middle ear itself can cause gustatory alterations, and these changes recovered once the disease was cleared.

Keywords: Chorda tympani, chronic otitis media, gustatory alterations


How to cite this article:
Ravindran V, Shetty D, Somayaji K S. Effect of middle ear surgery on taste in patients with chronic otitis media. Indian J Otol 2020;26:155-8

How to cite this URL:
Ravindran V, Shetty D, Somayaji K S. Effect of middle ear surgery on taste in patients with chronic otitis media. Indian J Otol [serial online] 2020 [cited 2021 Mar 7];26:155-8. Available from: https://www.indianjotol.org/text.asp?2020/26/3/155/304287




  Introduction Top


Several studies have reported that functional impairment of the chorda tympani nerve (CTN) occurs in chronic otitis media (COM).[1] The CTN lies within the middle ear and does not have a bony covering as it passes close to the annulus of the tympanic membrane where theoretically it is susceptible to damage in middle ear diseases and surgery.[2] Functionally, the CTN has two components: preganglionic secretomotor fibers to the submandibular and sublingual salivary glands and fibers carrying taste sensation to the anterior two-thirds of the tongue.[2] Patients with chronic diseases of the middle ear usually have a gradual decrease in the gustatory function.[3]

The CTN is susceptible to injury during middle ear surgery because of transection, stretching, ischemia, thermal injury, and excessive handling. These events may cause dysgeusia, hypogeusia, or even ageusia, which are usually transient complaints in the postoperative period.[4]

Iatrogenic damage to the CTN is a well-recognized complication of middle-ear surgery. Three areas have been recognized where CTN is commonly encountered during middle ear surgery. The most frequently manipulated area is the portion running just behind the annulus in the posterior–superior quadrant. When the tympanomeatal flap is elevated and the bony annulus is removed by drilling or chisel to see the incudostapedial joint, CTN is damaged by touching, traction, or stretching. The second-most frequently manipulated area is the portion anterior to the malleus neck. When calcification is removed with a fine pick or when the anterior tympanic scutum is cut using a chisel, injury to the CTN may occur without being apparent. The third-most frequently touched area is the bifurcation from the descending portion of the facial nerve. As this portion runs through the bony canal, CTN is sometimes injured by drilling the opening of the facial recess during canal wall up procedure or cochlear implant surgery.[5]

Most of the otologists consider hearing improvement as the most important postoperative result; taste disturbance has rarely been focused in middle ear surgeries.[6] Our study was done with the aim of assessing the taste sensation before and after middle-ear surgery.


  Methodology Top


This was a prospective study which was conducted in a tertiary care teaching hospital over a period of 24 months on 100 patients who were diagnosed with COM of either mucosal or squamosal type after obtaining the clearance from the institutional ethics committee. All the patients were above the age of 18 years. Patients who were previously subjected to ear surgeries and a prior history of facial paralysis were excluded from our study.

Patients with active tongue disease and diabetes mellitus were also excluded from the study. Relevant clinical and demographic data including history were obtained from all the patients. A detailed clinical examination was performed. Informed and written consent was obtained from all the patients. The patients were evaluated for the gustatory changes before and after middle-ear surgery. Clinical assay, with tests based on “taste strips” with different concentrations of salt, sweet, bitter, and sour, was done preoperatively. The concentration of the taste strips included salt-sodium chloride (0.25 g/ml, 0.1 g/ml, 0.04 g/ml, and 0.016 g/ml), sweet-sucrose (0.4 g/ml, 0.2 g/ml, 0.1 g/ml, and 0.05 g/ml), bitter-quinine sulfate (0.006 g/ml, 0.0024 g/ml, 0.0009 g/ml, and 0.0004 g/ml), and sour-citric acid (0.3 g/ml, 0.165, 0.09 g/ml, and 0.05 g/ml). The same was tested postoperatively after 1 week, 1 month, and 6 months. The patients were prohibited from taking food or drink, except for water, for 1 h before undergoing the gustatory test. Testing was done using taste testing solutions on the anterior tongue bilaterally. A drop of taste testing solution was applied on the testing site of each tongue. The patients were divided into two groups depending on the degree of manipulation of the CTN, as stated in the surgical report. One group consisted of patients with minor manipulation of the CTN, i.e., touch only, without significant stretching of the nerve. The other consisted of patients experiencing moderate to significant manipulation of the CTN including severed CTN. The patient's gustatory test results and intraoperative findings focusing on the state of the CTN were compared and analyzed.


  Results Top


A total of 100 patients were studied, and 22 patients had squamosal disease, and the remaining 78 patients had mucosal disease [Figure 1].
Figure 1: Type of disease,Blue for Squamosal(Attico antral), Red for Mucosal(Tubo tympanic)

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Squamosal disease

Our study showed that on the assessment of the CTN function before surgery in the squamosal group, it was found that 2 of the 22 patients had changes in the function [Table 1].
Table 1: Chorda assessment before surgery in the squamosal group

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In our study group, on the assessment of the CTN function, 1 week following surgery in the squamosal group, it was found that none of the patients had any changes in the taste function [Table 2]. On the assessment of CTN after 6 months of surgery in the same group, it was found that 2 of the 22 patients had changes in the function.
Table 2: Chorda assessment after 1 week of surgery in the squamosal group

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Mucosal disease group

In our study group, on the assessment of the chorda tympani before surgery in the mucosal disease group, it was found that 66 out of 78 patients had changes in the function [Table 3].
Table 3: Chorda assessment before surgery in mucosal disease group

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In our study group, on the assessment of the CTN 1 week following surgery in the mucosal disease group, it was found that 55 of 78 patients had no changes [Table 4].
Table 4: Chorda assessment after 1 week of surgery in the mucosal disease group

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In our study group, on the assessment of the chorda tympani 1 month following surgery in the mucosal disease group, it was found that 65 of the 78 patients had no changes, which is Statistically significant with P = 0.0001 [Table 5].
Table 5: Chorda tympani nerve assessment after 1 month of surgery in the mucosal disease group

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In our study group, on the assessment of the chorda tympani after 6 months of surgery in the mucosal disease group, it was found that 2 of the 78 patients had changes in the function [Table 6].
Table 6: Chorda assessment after 6 months of surgery in the mucosal disease group

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In our study, 14 patients were found to have taste changes preoperatively, of which nine patients recovered their taste 1 week following surgery, and the remaining five patients recovered at 1 month following the surgery. This was a significant recovery and concluded that chronic inflammation of the middle ear itself can cause gustatory alterations, and these changes recovered once the disease was cleared. It was also observed that in all the 25 patients where the nerve was cut, postoperative changes were noted, which recovered completely at the end of 6 months, except in two patients. In patients where the nerve was stretched, patients showed more gustatory alterations, when compared with patients where the nerve was minimally manipulated. In cases where the nerve was cut, the symptoms were less severe compared to stretching.


  Discussion Top


Patients with otosclerosis complain of postoperative taste disturbance more often than do those with chronic middle ear diseases. One of the reasons proposed was that CTN function in COM was already damaged by chronic inflammation, whereas CTN function remained intact in otosclerosis.[1] The tympanic segment is the segment of chorda tympani as it traverses through the middle ear cavity between the malleus and incus in a posterior to anterior direction and is not visible with current imaging techniques. During ear surgery, the CTN is constantly exposed, and it can be stretched or even cut during the procedure. These events may cause dysgeusia, hypogeusia, or even ageusia, which are most of the times transient complaints during the postoperative period.[5]

In our study, 14 patients were found to have taste changes preoperatively, of which nine patients recovered their taste 1 week following surgery, and the remaining five patients recovered at 1 month following surgery. This was a significant recovery, and we conclude that chronic inflammation of the middle ear itself can cause gustatory alterations, and these changes are expected to recover once the disease is cleared. It was also observed that in all the 25 patients where the nerve was cut, postoperative changes were noted, which recovered completely at the end of 6 months, except in two patients. In patients where the nerve was stretched, patients showed more gustatory alterations, when compared with patients where the nerve was minimally manipulated.

Gopalan et al. conducted a prospective study that looked into the prevalence of CTN injury and related symptoms following varying degrees of trauma to the nerve during three common types of middle ear operation: myringoplasty, tympanotomy, and mastoidectomy. Increased occurrence of the nerve-related symptoms and a prolonged recovery time were observed in the tympanotomy group. Stretching of the nerve produced more symptomatic cases than cutting it in the myringoplasty and mastoidectomy groups.[7] Recovery was complete in 92% of the symptomatic patients by 12 months. These findings are similar to our present study.

Huang et al. conducted a prospective study involving 38 patients with unilateral COM using taste testing solutions to evaluate each patient's taste function. Intraoperative assessments of the CTN were also compared and analyzed. They concluded that middle ear surgery for COM not only treats the ear but also improves gustatory function in the majority of patients. In patients with intraoperative injury to the CTN, postoperative taste decline is only temporary.[8] These findings are similar to our present study.

Rehman et al. conducted a prospective study involving 178 patients who underwent middle-ear cleft surgery that looked into the prevalence of CTN injury and related symptoms following varying degrees of trauma to the nerve during four common types of middle-ear operations and concluded that stretching of the nerve produced more symptomatic cases than thermal injury or drying.[9] In our study, nerve transection produced less severe symptoms compared to stretching.

Mueller et al. investigated 47 patients (26 females, 21 males; mean age, 42 years) before and 4 days after the surgery on both sides of the anterior part of the tongue for taste sensation. Self-assessment of taste function was performed by visual analog scales. The study concluded that depending on the amount of manipulation of the CTN, taste function decreased after the surgery. However, long-lasting changes of gustatory function seem to be rare.[10] These findings are also similar to our present study.

Goyal et al. performed a prospective study on 85 patients having unilateral chronic inflammatory middle ear disease of either squamosal or mucosal type. Gustatory assessment on both sides of the tongue was performed using dry taste strips. They concluded that a patient with chronic inflammatory middle-ear disease already has dysfunctional chorda tympani and is unlikely to notice a change in the taste sensation in the event of cutting of the nerve during the course of an ear surgery.[11] These findings are similar to our present study.


  Conclusion Top


We conclude that cutting of the nerve produced less gustatory alterations in surgeries for COM, when compared with patients where the nerve was stretched. There were no symptoms when the nerve was minimally manipulated. We also conclude that chronic inflammation of the middle ear itself can cause gustatory alterations, and these changes are bound to recover once the disease was cleared. Similarly, surgical procedures done as a treatment for COM can have an effect on taste. However, all are transient and within 6 months, the patients will have no complaints with respect to taste. It is better to advise the patients undergoing middle ear surgery about the risk of transitory taste dysfunction and at the same time, to reassure them about the chances of recovery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Sakagami M, Sone M, Tsuji K, Fukazawa K, Mishiro Y. Rate of recovery of taste function after preservation of chorda tympani nerve in middle ear surgery with special reference to type of disease. Ann Otol Rhinol Laryngol 2003;112:52-6.  Back to cited text no. 1
    
2.
Boileau Grant J. Grant's Atlas of Anatomy. Balti-More: Williams and Wilkins; 1972.  Back to cited text no. 2
    
3.
Saito T, Yamada T, Okamoto M, Narita N. Comparison of regeneration of the chorda tympani nerve and gustatory function recovery after severing the nerve between pediatric and adult patients. Otol Neurotol 2012;33:1567-72.  Back to cited text no. 3
    
4.
Felix F, Tomita S, Pereira Bde B, Cordeiro JR, Carleti G, Barros Fde S, et al. Gustatory alteration evaluation in patients with chronic otitis media. Braz J Otorhinolaryngol 2009;75:550-5.  Back to cited text no. 4
    
5.
Sone M, Sakagami M, Tsuji K, Mishiro Y. Younger patients have a higher rate of recovery of taste function after middle ear surgery. Arch Otolaryngol Head Neck Surg 2001;127:967-9.  Back to cited text no. 5
    
6.
Saito T, Manabe Y, Shibamori Y, Yamagishi T, Igawa H, Tokuriki M, et al. Long-term follow-up results of electrogustometry and subjective taste disorder after middle ear surgery. Laryngoscope 2001;111:2064-70.  Back to cited text no. 6
    
7.
Gopalan P, Kumar M, Gupta D, Phillipps JJ. A study of chorda tympani nerve injury and related symptoms following middle-ear surgery. J Laryngol Otol 2005;119:189-92.  Back to cited text no. 7
    
8.
Huang CC, Lin CD, Wang CY, Chen JH, Shiao YT, Tsai MH. Gustatory changes in patients with chronic otitis media, before and after middle-ear surgery. J Laryngol Otol 2012;126:470-4.  Back to cited text no. 8
    
9.
Rehman A, Hamid S, Sangoo M, Kirmani M, Wani A, Chisti LA. Short term and long term subjective taste disorder after middle ear cleft surgery. Indian J Otol 2013;19:111-3.  Back to cited text no. 9
  [Full text]  
10.
Mueller CA, Khatib S, Naka A, Temmel AF, Hummel T. Clinical assessment of gustatory function before and after middle ear surgery: A prospective study with a two-year follow-up period. Ann Otol Rhinol Laryngol 2008;117:769-73.  Back to cited text no. 10
    
11.
Goyal A, Singh PP, Dash G. Chorda tympani in chronic inflammatory middle ear disease. Otolaryngol Head Neck Surg 2009;140:682-6.  Back to cited text no. 11
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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