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Adobamen and Iribhogbe, J Otol Rhinol 2013, 2:3
http://dx.doi.org/10.4172/2324-8785.1000127
Journal of
Otology & Rhinology
Research Article
Post-Tonsillectomy Taste
Disorders- Review of Literature
Hanna Temporale1*, Krzysztof Zub1, Tomasz Zatoński1 and
Tomasz Kręcicki1
Abstract
On the basis of the available literature this review shows the
characteristics, possible causes, pathophysiology and treatment
of persistent taste disorders, occurring as a complication after
tonsillectomy. Attention was drawn to the underestimation of the
incidence of these complications and the need to inform patients
assigned to tonsillectomy about the possibility of a deficit or
distortion of taste after surgery.
Keywords
Tonsillectomy; Complications; Taste disorders; Dysgeusia
Introduction
As one of the most important senses, correct perception of taste
determines proper physical and mental functioning. Some claim that
both taste and smell are responsible, to a large extent, for the food
selection, affect human nutritional status, and their dysfunction can
lead to diseases such as depression [1,2].
The Sense of Taste and its Perception
There are four basic types of taste: sweet, salty, bitter, sour and
extra-fifth taste umami (the taste of glutamate). Receptors of taste the taste buds are mainly located on the tongue, soft palate, epiglottis,
upper 1/3 of esophagus, as well as on the lips, cheeks, and they are
scattered in the oral mucosa [3]. The taste stimulus is transformed
into a nerve impulse and it is carried from the chemoreceptors of
taste buds afferently by three cranial nerves: the branch of facial nerve
(VII) - special sensory fibers of chorda tympani, conducting sense of
taste from the anterior 2/3 of the tongue, the glosso-pharyngeal nerve
(IX) - from the base of the tongue and the vagus nerve (X) - from
the soft palate, hypopharynx and epiglottis [4]. Next the impulse is
transmitted to the solitary tract, then to the thalamus, neurons project
to the insular cortex, the posterior limb of the internal capsule, and
the operculum (primary gustatory areas).
The Role of the Glosso-Pharyngeal Nerve
The glosso-pharyngeal nerve is a mixed nerve: the bigger part
consists of sensory fibers that innervate the throat (including tonsils),
middle ear and tongue, the smaller part is formed by motor fibers for
the throat muscles, tongue, palate and secretory (parasympathetic)
to the parotid gland. Terminal branches from the nerve sensory
innervate the 1/3 of the tongue.
*Corresponding author: Hanna Temporale, Borowska 213, 50-556 Wrocław,
Poland, Tel: +48 606 831 562; E-mail: [email protected]
Received: May 14, 2013 Accepted: August 05, 2013 Published: August 15,
2013
International Publisher of Science,
Technology and Medicine
a SciTechnol journal
Taste Malfunction (Dysgeusia)
An impairment or dysfunction of the sense of taste (dysgeusia)
is the result of damage to the gustatory pathway that may occur
at each stage. Thus epithelial, neural, and central dysgeusia can be
distinguished. These disorders, depending on their nature, can be
divided into quantitative (ageusia, hypogeusia, hypergeusia) and
qualitative (parageusia, pseudogeusia, cacogeusia, phantogeusia).
Impaired perception of all tastes is called total dysgeusia and of
some selected tastes – partial dysgeusia. According to Janczewski,
the most common cause of reduced sense of taste is rhinitis and
other diseases with nasal blockage or coexisting smell disorders [4].
Other causes might be inflammation of the oral mucosa (e.g. after
radiotherapy), systemic diseases (diabetic neuropathy, renal failure,
hepatic cirrhosis), hormonal disorder (pregnancy, hypothyreoisis,
adrenal insufficiency), deficiency of micronutrients (zinc, copper),
avitaminosis (deficiency of vitamin A, C, and B), chronic nicotinism,
alcoholism, central nervous system diseases (tumors, vascular diseases,
trauma, meningitis), some mental illnesses (schizophrenia), longterm use of some medicines (e.g. captopril, metformin, imipramine,
chemotherapeutics), or congenital taste buds malformation [4]. The
sense of taste is impaired in the elderly. Head and neck surgeries (like
ear, pharyngeal and laryngeal surgery) and tonsillectomy among
them, might also affect the sense of taste.
Post-Tonsillectomy Dysgeusia
Tonsillectomy is one of the oldest and most frequently
performed surgical procedures in otolaryngology. Although
surgical techniques have improved over the years, complications
still happen. Patients mostly suffer from pain or dysphagia. Lifethreatening complications like haemorrhage occur in 2-4% of the
patients [5]. Before tonsillectomy each patient must be informed
about the risk of taste impairment. Transient post-tonsillectomy taste
dysgeusia (PTD) is a common complaint. Long-lasting PTD is less
frequent but has significant consequences on patients’ quality of life.
Transient taste perception changes seem to be relatively frequent
after tonsillectomy [6-8]. They are mostly manifested by a metallic
or bitter taste and generally maintain from 4 days to 2 weeks after
the procedure. Persistent dysgeusia may last for 2 years or longer and
retreat spontaneously [1,6,7]. The cause of this complication remains
unknown, although there are several theories, which try to explain its
occurrence.
Nerves Injury
Indirect and direct intrasurgical injury of the lingual or tonsillar
branch of the glossopharyngeal nerve as well as pressure on the
lingual nerve (along with chorda tympani nerve) caused by tongue
retractor during tonsillectomy may lead to taste disturbance [1,2].
The close anatomic relationship between the palatine tonsil and
the lingual branch of the glossopharyngeal nerve makes the nerve
vulnerable during tonsillectomy. Clamping tonsillar branches of the
lingual or facial arteries to control hemorrhage at the inferior tonsillar
pole as well as using electrocautery can injure the nerve [9].
All articles published in Journal of Otology & Rhinology are the property of SciTechnol, and is protected by copyright laws.
Copyright © 2013, SciTechnol, All Rights Reserved.
Citation: Temporale H, Zub K, Zatoński T, Kręcicki T (2013) Post-Tonsillectomy Taste Disorders- Review of Literature. J Otol Rhinol 2:3.
doi:http://dx.doi.org/10.4172/2324-8785.1000127
In 2004 Goins and Pitovski reported a case study of a patient with
post-tonsillectomy taste disturbance. Using electrogustometry the
lingual branch of the glossopharyngeal nerve (LBGN) was recognised.
The patient suffered from ageusia of the posterior one-third of the
tongue, which was compensated contralaterally with phantogeusia
manifested by metallic or bitter taste. The report suggests that
phantogeusia (taste perception despite the absence of the stimulus)
might result from the release-of-inhibition in the contralateral
glossopharyngeal nerve [10].
Inadvertent extension of lingual nerve and its compression
during tonsillectomy may be prevented by ensuring that the tongue
retractor is not fasten too tightly in the mouth, especially in cases
where the mouth opening is naturally limited [1,9]. Collet et al. notes
that also LBGN may be damaged in the mechanism of stretching
and compression by depression of the tongue [11]. Patients, who are
suspected of taste disorders caused by compression of the tongue,
usually complain of hypogeusia and also of glossodynia of the tip of
the tongue. In such cases, the prognosis is considered to be successful
because there is no permanent damage of the nerve [12]. On the
other hand, the researchers did not find that the occurrence of taste
disorders after tonsillectomy was affected by the length of surgery,
including the length of the use of tongue retractor [6].
Neuritis or cicatrisation during postoperative infection is
considered to be another possible cause of the LBGN dysfunction
[12].
Scinska et al. take into consideration the injury of the soft palate
innervation: the tonsillar branch from the glossopharyngeal nerve,
the palatine nerve (a branch from the maxillary nerve) or the petrosal
nerve (a branch from the facial nerve) as a possible cause of dysgeusia
after tonsillectomy [2]. The above observations seem to be supported
by cases of taste disorders in patients with the obstructive sleep apnea
syndrome (OSAS) after Uvulopaltopharyngoplasty (UPPP) [13].
The Role of Zinc in Dysgeusia
Some authors also claim that dietary zinc deficiency plays a role
in the development of PTD [1,7]. It is estimated that 25% of taste
and smell disorders is caused by zinc deficiency. This deficiency may
lead to parakeratosis of taste buds as well as impaired function of a
zinc-dependent enzyme gustin that is responsible for taste perception
in the taste buds. It is assumed that, apart from low-level zinc diet,
malnutrition due to postoperative pain and malabsorption, tissue
injury during surgical treatment may lead to release of interleukin-1
(IL-1) and serum-tissue zinc redistribution [3]. Surgery also increases
demand for zinc due to its participation in blood clotting and wound
healing. Another mechanism of zinc deficiency in post tonsillectomy
cases is the use of zinc-chelating medications, such as analgesics and
antibiotics administered peri and postoperatively. This situation
happens especially if the patient has also been undergoing long-term
treatment with a zinc-chelating drug (eg. antihypertensives) before
surgery [12].
Serum zinc-level test is cheap and easy to perform. However,
taking into account that over 90% of zinc in the human body is located
intracellularly, the results may not be indicative of the deficiency.
Zinc sulfate is used in idiopathic dysgeusia treatment. As no
confirmed side effects of oral zinc supplementation have been
reported such treatment is recommended in all long-lasting posttonsillectomy dysgeusia. Windfuhr et al. report a case of a female
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patient with a 4-year PTD who recovered within 2 months after
an oral intake of zinc sulphate [7]. However, Stathas et al. did not
confirm zinc, copper and ferrum disorder in serum in patients with
post-tonsillectomy dysgeusia [1].
Other Investigations on Post-Tonsillectomy Dysgeusia
Drugs interactions are listed as one of taste dysfunction causes
[1,12]. Some claim that pathogenesis of those disorders can be
explained by the zinc chelate due to the post-operative drug treatment
(pain killers, antibiotics), whilst non-chelate zinc is responsible for
proper taste perception [2,12,14]. According to the literature, the use
of local anesthesia and adrenaline are mentioned as one of the factors
that lead to post-tonsillectomy dysgeusia [10,12,14].
A type of chosen surgical method has not been found to
have any influence on the occurrence of taste impairment
[1,6]. Stathas et al. compared the occurrence of taste disorders,
according to two methods of tonsillectomy: the first one:
using scissors and raspatory with electrocautery for coagulation, the
second one: pressure-assisted tissue- welding technology, and found
no statistically significant difference [1].
Other researchers studied the role of possible factors that might
lead to irregulation of taste after tonsillectomy such as post-operative
pain, intubation complications, operative time, hemostasis technique,
wound healing. No significant correlation was observed [6]. PTD
probably occurs even after uneventful tonsillectomy [6].
Several reports have pointed out the possibility of linking the
occurrence of taste disorders to depression. A somatic disease and
surgery increase the overall risk of depression. Dysgeusia might cause
anorexia, weight loss, malnutrition, fatigue and as a result stress
and depressed mood. The reports draw attention to the fact that
post-tonsillectomy taste dysfunction with symptoms of depression
may reflect genuine depression, not a postoperative complication.
Therefore, in difficult cases, psychiatric consultation is desirable to
explain the disorders [2].
Diagnostics and Evaluation of Taste Disorders
Several methods are used in the qualitative and quantitative
evaluation as well as in the subjective and objective assessment of
dysgeusia. Electrogustometry and specific gustometry are exerted to
measure the taste perception threshold. Intensive studies conducted
lately are aimed at improving the methods of evaluation of gustatory
evoked potentials (GEPs) and gustatory evoked magnetic fields
(GEMfs) [15,16].
Glossopharyngeal nerve damage can be diagnosed by a thermal
stimulation test. It can explore the thermal and taste sensitivity of
the glossopharyngeal nerve. Cruz and Green induced a bitter or sour
sensation by applying a thermode to the region of the posterior third
of the tongue at a temperature of 15°C for 5 to 10 seconds, whereas
at 35°C there was no sensation (n=24) [17]. If the glossopharyngeal
nerve is damaged, the taste and thermal sensations caused by cold
disappear. The induction of a taste sensation by a thermal stimulation
resulted, according to Cruz and Green [17], from the fact that the
neurons sensitive to cold present in the circumvallate papillae
encode according to sodium and hydrogen ion channels, which are
involved in the response to an acid stimulus. In clinical practice,
the sensation of cold set off by the application of cold water with a
cotton-tipped applicator to the foliate papillae confirms the integrity
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Citation: Temporale H, Zub K, Zatoński T, Kręcicki T (2013) Post-Tonsillectomy Taste Disorders- Review of Literature. J Otol Rhinol 2:3.
doi:http://dx.doi.org/10.4172/2324-8785.1000127
of the glossopharyngeal nerve, and an absence or a diminution in the
perception of cold is noted in the case of a lesion [18]. This test is
relatively easy to carry out and is not expensive.
Dysgeusia diagnostics also involves serum zinc-level test as well
as an accurate medical interview, including drug usage.
Post-Tonsillectomy Taste Disorder Treatment
Prognosis in dysgeusia after tonsillectomy is optimistic. In most
cases disturbances retreat spontaneously, however, they may not
retreat completely. Complete recovery of the sense of taste depends
on natural healing, the regenerative capacity of the peripheral nerve
fibers and gustatory pathway [10]. In transient taste malfunction it is
recommended to use zinc sulfate, e.g. zinc gluconate in a dose of 140
mg daily [16]. It is essential to monitor further course of the disorders
and recovery.
However some researchers underline that meticulous, saving
dissection of tonsils and limited use of electrocautery may limit
damage to the throat muscles and consequently reduce the risk of
destruction of the surrounding structures, including branches of the
nerves responsible for the reception of taste sensations [9].
Careful fixation of tongue retractor is also emphasized.
Conclusion
Post-tonsillectomy dysgeusia is still underestimated and only
little attention is given to it in clinical practise. The available literature
mentions nerves injury- mainly LBGN as a possible cause of taste
disturbances. Other causes mentioned might be zinc deficiency and
drug interactions. Typically, short-term dysgeusia does not require
treatment. There are case reports with the usage of zinc sulfate as
an effective therapy of persistent taste disturbances, occurring as
a complication of tonsillectomy. The aim of this publication is to
emphasize the problem of dysgeusia after tonsillectomy and the
need of informing patients about the possible risk of dysgeusia. It is
essential to take any required steps in order to prevent taste disorder
and, in case it does occur, to perform the appropriate diagnostic
procedures and monitor the treatment.
References
1. Stathas T, Mallis A, Naxakis S, Mastronikolis NS, Gkiogkis G, et al. (2010)
Taste function evaluation after tonsillectomy: a prospective study of 60
patients. Eur Arch Otorhinolaryngol 267: 1403-1407.
2. Scinska A, Jodkowska A, Korkosz A, Kukwa W, Sienkiewicz-Jarosz H (2008)
Post-tonsillectomy dysgeusia with weight loss: possible involvement of soft
palate. J Laryngol Otol 122: e5.
3. Konopka W, Dobosz P, Kochanowicz J (2003) Zaburzenia smaku w
otolaryngologii. Otolaryngol 2: 145-149.
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7. Windfuhr JP, Cao Van H, Landis BN (2010) Recovery from long-lasting posttonsillectomy dysgeusia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
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9. Leong SC, Karkos PD, Papouliakos SM, Apostolidou MT (2007) Unusual
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14.Fukasawa T, Orii T, Tanaka M, Suzuki N, Kanzaki Y (2008) Relation between
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(Tokyo) 56: 1177-1180.
15.Bollinger E (1950) Geschmacksstorungen nach Tonsillektomie. Diss. Zurich
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16.Dzaman K (2011) Zaburzenia smaku – trudnosci diagnostyczne i
terapeutyczne. Terapia 11-12: 56-61.
17.Cruz A, Green BG (2000) Thermal stimulation of taste. Nature 403: 889-892.
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Author Affiliation
Top
Department of Otolaryngology Head and Neck Surgery, Wrocław Medical
University, Poland
1
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