ORIGINAL ARTICLE
Gustatory Function After Tonsillectomy
Christian A. Mueller, MD; Saher Khatib; Basile N. Landis, MD; Andreas F. P. Temmel, MD; Thomas Hummel, MD
Design: Prospective study.
assessment of gustatory function was performed by visual analogue scales. Thirty-two patients were retested
64 to 173 days after TE. Thirty-three patients could not
be retested after TE but were interviewed by telephone.
Setting: University hospital.
Results: Self-assessed taste function significantly de-
Patients: Sixty-five patients (42 females, 23 males; mean
age, 28 years).
creased (P=.001). Yet, none of the subjects reported taste
dysfunction. Tonsillectomy had no major effect on taste
test scores (P ⬎.27).
Main Outcome Measures: Taste function was inves-
Conclusion: Persisting taste dysfunction seems to be rare
tigated before TE with 4 concentrations each of sweet,
sour, salty, and bitter quality, respectively, on both sides
of the anterior and posterior areas of the tongue. Self-
after TE.
Objective: To assess taste function before and after
tonsillectomy (TE).
T
Author Affiliations:
Department of
Otorhinolaryngology, Medical
University of Vienna, Vienna,
Austria (Drs Mueller and
Temmel and Mr Khatib);
Rhinology-Olfactory Unit,
Department of
Otorhinolaryngology, University
Hospital of Geneva, Geneva,
Switzerland (Dr Landis); and
Smell and Taste Clinic,
Department of
Otorhinolaryngology, University
of Dresden Medical School,
Dresden, Germany
(Dr Hummel).
Arch Otolaryngol Head Neck Surg. 2007;133(7):668-671
OGETHER WITH OLFACTION
and oral trigeminal sensitivity, the sense of taste contributes considerably to flavor perception during eating
and drinking and thus plays a major role
in the enjoyment of foods and beverages.1
Other important physiological properties
of gustation include the regulation of salt
and energy intake and the detection of potential toxins during mastication. Consequently, damage to the gustatory system
might lead to considerable dietary changes.2
The sense of taste depends on 3 cranial
nerves (VII, IX, and X) innervating both
sides of the oral, lingual, and pharyngeal mucosa (for a detailed anatomical review, see
Witt et al3). It is a rather robust system that
shows little deterioration of suprathreshold sensitivity during aging.4,5 Nevertheless, disease and/or medication might contribute to a clinically relevant loss of taste
sensitivity. Other possible causes of taste
dysfunction include iatrogenic damage (eg,
damage to the chorda tympani during
middle ear surgery, tonsillectomy [TE], dental or oral surgery), or radiation to the head
and neck that involves major parts of the
salivary glands.6,7
Tonsillectomy is the most frequently
performed otolaryngologic operation.8 The
occurrence of taste disorders after TE has
been reported in the literature mainly in
case reports.9-11 Only a few attempts have
been made to investigate the occurrence of
taste disorders after TE,12 with some of the
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668
published reports based on nonvalidated or
relatively crude testing devices.13,14 Consequently, to our knowledge, the actual frequency of damage to the gustatory system
after TE has not been elucidated. However, this information would be useful, especially in light of an increasing number of
medicolegal claims involving such damage. In particular, patients who rely on their
sense of taste (eg, cooks, food specialists,
sensory experts) need to be provided with
more detailed information regarding the potential risk of damage to the gustatory system during TE.
To obtain data on the frequency of gustatory loss after TE, we investigated the
sense of taste before and after TE using a
well-validated test of gustatory function.
METHODS
The investigation was conducted at the Department of Otorhinolaryngology at the Medical University of Vienna, Vienna, Austria, according to
the guidelines of the Declaration of Helsinki on
biomedical research involving human subjects.
Sixty-five patients (42 females and 23 males) were
included (mean [SD] age, 28.0 [9.1] years; range,
15-68 years). Written consent was obtained from
all patients after information about the purpose
and method of the investigation had been provided. After their medical history was taken, the
patients rated their acuity of smell and taste using
visual analog scales (VAS); patients with diseases affecting gustatory sensitivity (eg, xerostomia, depression, diabetes mellitus, or renal failure) were not eligible for the study.6 The scores
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ranged from 0 (no sense of smell and taste) to 100 (excellent sense
of smell and taste). A full otorhinolaryngologic examination was
performed in all patients to rule out diseases of the middle ear
and the oral cavity that might affect taste sensitivity.6 Gustatory
testing (see the following subsection) was performed in all patients the day before TE. Patients were asked not to eat or drink
anything except water 1 hour prior to testing, not to smoke, and
not to brush their teeth. The TE was performed under general
anesthesia using a McIvor retractor (Medical Development and
Engineering, Frittlingen, Germany) (fixing the tongue with a plate
in the midline) and bipolar electric coagulation to stop bleeding.
The operations were performed by multiple surgeons, including
those who were experienced and those beginning their training.
However, the surgical technique was similar in all patients.
Tonsillectomy was performed to treat chronic tonsillitis in all
patients.
Gustatory testing after TE was performed in 32 patients (20
females and 12 males) (mean [SD] age, 27.1 [7.8] years; range,
15-44 years) 105.0 (28.5) days (range, 64-173 days) after the operation. (Values are given as mean [SD] throughout the text.)
Again, taste sensitivity was rated using VAS. Moreover, patients
were asked to report any changes in taste sensitivity immediately after the operation and at the time of retesting. The time point
of postoperative taste testing was chosen to rule out alterations
caused by wound healing or pain after surgery. Thirty-three patients (22 women and 11 men) aged 28.8 (10.4) years (range, 18-68
years) who could not be tested psychophysically after the operation were interviewed by telephone to find out if any loss or changes
in gustatory function had occurred. Moreover, patients rated gustatory function on a scale ranging from 0 (no taste) to 10 (excellent taste). Twelve of 77 initially tested patients could not be
reached for postoperative assessment of gustatory function and
were excluded from the data analysis.
GUSTATORY TESTING
The assessment of taste function was performed by a wellvalidated test of gustatory function using taste strips made of
filter paper that had been dried after impregnation with taste
solutions.15 The taste strips were presented in a pseudorandomized sequence starting with the lowest concentrations. Sixteen taste strips (4 concentrations each of sweet, sour, salty,
and bitter quality) 8 cm in length and with an impregnated area
of 2 cm2 were presented at the tongue’s posterior area (innervated by the glossopharyngeal nerve) and the anterior area (innervated by the chorda tympani nerve) on both sides, resulting in a maximum taste strip score of 16 for each of the 4 tested
sites. None of the subjects had an insuppressible gag reflex during testing of posterior tongue sites. The tested portions of the
tongue are indicated in Figure 1.
STATISTICAL ANALYSIS
Results were submitted to analysis of variance for repeated measures, using the within-subject factors “before TE” and “after
TE.” Age was used as a covariate, and sex was used as a betweensubject factor. In addition, t tests for paired samples were used
to compare results of the anterior vs posterior areas of the tongue
and for ratings of gustatory sensitivity. We used SPSS statistical software (version 12.0 for Windows; SPSS Inc, Chicago, Illinois) for analyses. The ␣ level was set at .05.
RESULTS
Taste strip results of all tested sites of the tongue before
and after TE are presented in the Table. Ratings of smell
Figure 1. Schematic drawing of tongue areas where taste testing was
performed. Sixteen taste strips (impregnated with 4 concentrations each
of sweet, sour, salty, and bitter quality) made of filter paper with an area of
2 cm2 were presented at the tongue’s posterior area (at a distance of
approximately 1 cm from the circumvallate papillae) and the anterior area
(at a distance of approximately 1.5 cm from the tip).
Table. Results From Taste Testing a
Tongue Area
Posterior tongue
Right
Left
Total
Anterior tongue
Right
Left
Total
Before TE
After TE
11.9 (3.2)
11.8 (3.2)
23.7 (6.0)
12.5 (3.3)
12.3 (2.9)
24.8 (5.9)
13.4 (2.7)
13.7 (2.6)
27.1 (4.9)
13.7 (2.5)
14.1 (1.8)
27.8 (4.1)
Abbreviation: TE, tonsillectomy.
a Using the taste strips of those 32 patients who were tested before and
after TE, separately for the anterior and posterior portions of the tongue.
Data are given as mean (SD). See “Methods” section, “Gustatory Testing”
subsection.
function showed normal results in all patients for the VAS
(62.0 [20.7]).
Results indicated that there was a difference between
taste scores obtained in the back vs the front areas of the
tongue (t64 =5.56, P =.001). However, TE had no major
effect on taste scores as indicated by nonsignificant ef-
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A
B
C
100
32
32
75
Taste Score
Rating, %
24
Taste Score
24
16
50
16
25
8
8
8
Before
After
Before
Before
After
After
Figure 2. Change of individual taste scores and ratings in relation to tonsillectomy. No systematic changes were found for taste scores obtained in the front (A) or back
(B) of the tongue, although ratings exhibited an overall decrease (C). In general, taste scores obtained in the back vs the front of the tongue were lower.
fects of the factors “before TE” and “after TE” (P ⬎.27).
In addition, neither sex nor age had a significant effect
on taste scores (P⬎ .18). In contrast to the results from
measured gustatory sensitivity, ratings indicated a decrease of gustatory function after TE (VAS before TE, 62.3
[18.3]; after TE, 51.1 [14.5]) (t31 =3.77, P=.001). The results are graphically presented in Figure 2.
The VAS ratings before TE in the patients who were
not tested after surgery yielded scores indicating gustatory function in the reference range: 65.0 (19.8). Selfrating of gustatory function after TE by the 11-point scale
yielded scores of 7 to 10 (9.0 [0.9]), again showing normal gustatory function.
None of the patients reported persisting gustatory dysfunctions at the time of retesting or requestioning. However, 15 of the 65 patients (23%) remembered the presence of dysgeusia shortly after the operation.
COMMENT
The major findings of the present study were that (1) psychophysical taste testing showed no change in gustatory function after TE in either the anterior or posterior
areas of the tongue, although (2) subjective taste perception assessed by means of VAS was lower after TE.
However, none of the patients reported persisting taste
loss after TE.
Most authors10,11 hypothesize that taste dysfunction
after TE is caused by surgical injury of the lingual branch
of the glossopharyngeal nerve (LBGN), which carries the
gustatory fibers from the rear third of the tongue. In a
number of subjects, this nerve seemed to adhere to the
inferior pole of the tonsil. According to an anatomical
study by Ohtsuka et al16 of 83 human cadavers, in only
23% was the palatine tonsil continuously separated from
the LBGN by the pharyngeal constrictor muscles. In 55%
the muscle layer was partially lacking, and in 22% a large
space between the pharyngeal constrictor muscles could
be demonstrated. In the latter cases, the LBGN adhered
to the tonsillar tissue, separated only by loose connective tissue that was 1 to 2 mm thick. According to that
study,16 approximately 20% of the patients could be expected to exhibit decreased gustatory function on the back
of the tongue. However, the present data indicate that
TE does not result in a lasting functional damage of the
LBGN in a large percentage of patients. Obviously, the
presence of the LBGN in proximity to the field of operation does not necessarily mean that it will be damaged
during surgery.
The results of the present study show that permanent taste disturbances after TE constitute a rare adverse effect of the surgery. None of the patients reported
persisting changes or loss of gustatory function at a mean
time point of approximately 100 days after TE. Congruently objective results of taste testing with taste strips revealed no statistically significant differences of regional
gustatory sensitivity before and after TE.
Results of self-assessment of gustatory function
using VAS showed a slight but statistically significant
decrease (P = .001) at the time of retesting after TE,
although measured gustatory sensitivity remained
unchanged, and, most important, the subjects did not
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report persisting taste loss. This raises the question of
whether taste ratings also depend on attentional factors.
Thus, it may be hypothesized that the patients’ ratings
of taste function were influenced by the presence of
postoperative pain, oral discomfort, or wound healing
during the first days and weeks after TE. This may be
supported by the fact that 15 patients reported dysgeusia immediately after TE, which resolved within days
and weeks. However, temporal hypogeusia might also
have been caused by the lingual pressure exerted by the
gag during surgery.
A number of case reports and a few systematic investigations of patients experiencing taste disorders after TE
have been published.9-12,14 Uzun et al9 described a patient who experienced impairment of sweet taste on the
left side of the posterior tongue persisting at 10 months
after TE. Goins and Pitovski10 described a patient who
had undergone unilateral right TE and experienced loss
of taste function in the right posterior area as well as phantom taste on the left side. Electrogustometric testing revealed a detection threshold out of the range of the capacity of the electrogustometer on the posterior right side
of the tongue. Moreover, no taste solution of sweet, sour,
salty, or bitter quality could be detected at this site with
spatial taste testing at 6 months after TE. The taste loss
was attributed to injury of the LBGN owing to considerable tissue removal at the inferior pole of the right tonsil. Similarly, Collet et al11 attributed 1 patient’s taste concerns after TE to damage to the LBGN of the left side.
The electrogustometric threshold of the left posterior side
was reported to be 50% higher than on the right side.
Moreover, a bitter solution was not perceived at this site
by the patient. The taste concerns still remained at retesting 18 months after TE.
Only a few systematic studies have investigated gustatory function after TE. In accordance with the present
results, an investigation by Arnhold-Schneider and
Bernemann14 detected no loss of gustatory function in
150 patients during repeated testing 7 days after TE.
However, the method of taste testing was not reported
in detail, and no taste score results were presented for
the tested sites of the tongue. In an investigation conducted by Tomofuji et al,12 3 of 35 patients reported
taste disturbances a few days after TE. In only 1 patient
could abnormal electrogustometric thresholds be obtained, and these returned to reference range 11 days after TE. Subjective taste sensitivity remained diminished
for 25 days. Taste function of all 3 patients recovered
within 1.5 months.
How often are patients found to have taste loss after
TE in clinical routine? In a retrospective analysis of 3583
outpatients of a specialized taste disorder clinic over a
15-year period, only 11 patients could be identified as
having taste disorders after TE.17 In 3 patients, gustatory loss was attributed to disturbance of the LBGN,
whereas the other causes included adverse effects of drugs,
zinc deficits, or remained unknown. Compared with the
present prospective data, these data indicate the rare occurrence of taste disorders after TE.
In conclusion, owing to the close anatomical relationship of the LBGN to the tonsillar bed, damage or tearing
and stretching of this nerve seems to be possible, result-
ing in taste disorders. However, based on the present results, taste loss after TE seems to be a rare complication.
Submitted for Publication: August 31, 2006; final revision received February 21, 2007; accepted March 15, 2007.
Correspondence: Christian A. Mueller, MD, Department of Otorhinolaryngology, Medical University
Vienna, AKH Vienna, Waehringer Guertel 18-20, 1090
Vienna, Austria ([email protected]).
Author Contributions: Drs Mueller, Landis, and Temmel
and Mr Khatib had full access to all the data in the study
and take responsibility for the integrity of the data and
the accuracy of the data analysis. Study concept and design: Mueller, Temmel, and Hummel. Acquisition of data:
Khatib. Analysis and interpretation of data: Mueller, Landis,
and Hummel. Drafting of the manuscript: Mueller and
Hummel. Critical revision of the manuscript for important intellectual content: Khatib, Landis, Temmel, and
Hummel. Statistical analysis: Landis and Hummel. Obtained funding: Mueller. Administrative, technical, and material support: Mueller, Khatib, and Temmel. Study supervision: Mueller, Temmel, and Hummel.
Financial Disclosure: None reported.
Funding/Support:This study was supported by a grant from
the Medizinisch-Wissenschaftlicher Fonds des Bürgermeisters der Bundeshauptstadt Wien (Dr Mueller).
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