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This review collected the literature on the disorders of visual, taste and smell senses caused by zinc deficiency. Human and experimental studies on the zinc-deficient taste and smell disorders were almost own experiences.
Clinical taste testing in humans is far from being routinely performed in ear, nose and throat (ENT) clinics. Consequently, most reports on posttraumatic and postoperative taste disorders are case reports and mainly consist of qualitative (e.g. dysgeusia, metallic taste) taste changes after either head injury or ENT surgery. Since quantitative taste deficiencies (ageusia, hypogeusia) often go unnoticed by the patients, the real incidence of ageusia and hypogeusia after head trauma and various surgical procedures remains largely unknown. This lack of reliable clinical data is partly due to the lack of easy, reproducible and rapid clinical taste testing devices. The present chapter tries to resume the current knowledge on postoperative and posttraumatic taste disorders. Despite the sparse literature, the chapter focuses on those ENT surgical procedures where at least some prospective and systematic studies on gustatory dysfunction exist. Accordingly, taste disorders after middle ear surgery, tonsillectomy and dental interventions are largely discussed.
There are some patients, though few in number, who complain of taste disturbance after tonsillectomy. Actual measurement of the distance between the lingual branch of the glossopharyngeal nerve, which controls taste in the posterior portion of the tongue, and the lower pole of the palatine tonsil, using a cadaver, showed the distance to be only 2-4 mm, thereby suggesting the danger of direct or indirect disturbance of this nerve by tonsillectomy. Among the 3,583 outpatients complaining of taste disturbance whom we have treated at our taste disorder clinic in the last 15 years, 11 (0.31%) were found to be suffering from taste disorder triggered by tonsillectomy. Among these 11 causes, the causes of taste disturbance have been identified in 8 cases. In three cases, the taste disturbance was caused by direct or indirect damage to the lingual branch of the glossopharyngeal nerve, whereas in another two cases, the disturbance was attributable to medication following tonsillectomy. In the remaining three cases, the diagnosis was a taste disturbance initiated by tonsillectomy but actually caused by a lack of dietary zinc. It is therefore important that patients be informed of the risk of post-operative taste disorder following tonsillectomy, at the time informed consent for tonsillectomy is obtained. It is equally important to measure the taste threshold values for each taste nerve and the serum zinc value as part of the pre-operational examination, and to ask the patients what drugs, if any, they take habitually.
OBJECTIVES: Contact endoscopy is a technique used to obtain detailed images of living epithelium in the fields of gynecology, rhinology and laryngology. Video microscopy is useful for observation of the surface of tongue papillae. In the present study, we attempted to apply the contact endoscopy technique together with video microscopy to observe tongue papillae, and to study the correlation between the condition of fungiform papillae and taste function. METHODS: Ten subjects (3 men, 7 women) were divided into two groups based on the results of a taste examination by electrogustometry. We compared the shape and blood vessels of the papillae between normal taste and taste disorder groups. RESULTS: In the normal taste group, round shaped papillae and clear blood vessels were observed with both microscopy and contact endoscopy. In the taste disorder group, flat and irregular papillae were observed with microscopy. Blood vessel flow of the papillae was observed to be poor with contact endoscopy. CONCLUSION: These findings suggested that the images of microscopy and contact endoscopy were related to taste function, and both techniques were useful for evaluating taste function.
Knowledge of human central taste pathways is largely based on textbook (anatomical dissections) and animal (electrophysiology in vivo) data. It is only recently that further functional insight into human central gustatory pathways has been achieved. Magnetic resonance imaging studies, especially selective imaging of vascular, tumoral, or inflammatory lesions in humans has made this possible. However, some questions remain, particularly regarding the exact crossing site of human gustatory afferences. We present a patient with a pontine stroke after a vertebral artery thrombosis. The patient had infarctions in areas supplied by the anterior inferior cerebellar artery and showed vertical diplopia, right sided deafness, right facial palsy, and transient hemiageusia. A review of the sparse literature of central taste disorders and food preference changes after strokes with a focus on hemiageusia cases is provided. This case offers new evidence suggesting that the central gustatory pathway in humans runs ipsilaterally within the pons and crosses at a higher, probably midbrain level. In patients with central lesions, little attention has been given to taste disorders. They may often go unnoticed by the physician and/or the patient. Central lesions involving taste pathways seem to generate perceptions of quantitative taste disorders (hemiageusia or hypogeusia), in contrast to peripheral gustatory lesions that are hardly recognised as quantitative but sometimes as qualitative (dysgeusia) taste disorders by patients.
To study taste in type I (insulin-dependent) diabetes mellitus, 57 consecutive diabetic outpatients (mean +/- SE duration of diabetes 11.4 +/- 0.4 yr) and 38 control subjects were screened for taste disorders with electrogustometry and chemical gustometry. Both groups were comparable for all subject characteristics except body mass index, which was higher in the diabetic group (P less than .05). A taste impairment was found in the diabetic group relative to the control group with electrogustometry (mean threshold 184.3 +/- 15.8 vs. 58.7 +/- 9.2 microA; P less than .001) and chemical gustometry (mean score 13.2 +/- 0.7 vs. 17.1 +/- 0.8; P less than .001). Hypogeusia was found among 73% of the diabetic patients versus 16% of the control subjects (P less than .001). The four primary tastes were involved in taste impairment. With multivariate analysis, taste disorders were related to diabetic status and tobacco and alcohol consumption. In the diabetic group, taste impairment was significantly associated with complications and duration of disease. With multivariate analysis, peripheral neuropathy had the strongest association with taste disorders. These results suggest that taste is impaired during the course of type I diabetes mellitus and that taste impairment could be a complication of the disease. A mechanism of the neuropathic type could be involved.
BACKGROUND: Besides anamnestic data and taste test, the clarification of epithelial taste disorders makes macroscopic evaluation of the surface of the tongue necessary. METHODS: In this article the contact endoscopy is evaluated for examination of the tongue epithelium and for quantification of the fungiforme papillae. These results are related to the results of the spatial taste test (1. chemical taste test with sodium chloride in 2 different suprathreshold concentrations and sucrose in also 2 different suprathreshold concentrations; 2. electrogustometry with a bipolar electrode). PATIENTS: In a prospective study we performed contact endoscopy in 16 healthy volunteers from ages 7 to 68 years. The subjects were divided into 2 age groups (< or = 45 years and > 45 years) and 2 papillae density groups. In 34 patients with either taste disorders of unknown cause or in patients with macroscopic changes at the tongue surface, the spatial and whole mouth taste tests and contact endoscopy were used to clarify the cause of the complaints. RESULTS: Density and shape of the fungiform papillae as well as the shape of the subepithelial vessels of the papillae vary among the investigated human subjects in the different age groups. No correlation between intensity ratings, papillae density und age was found after stimulation with 40 % sucrose at the tongue tip in the younger age group. Stimulation of the tongue edge with 15 % sodium chloride, however, showed a relationship between the two different density groups and the different age groups. CONCLUSIONS: The contact endoscopy allows the evaluation of the epithelium in the oral cavity. It is a nondestructive method and is additionally easy to handle, but the evaluation of the observed epithelia needs interdisciplinary co-operation with pathologists. No relevant informations are supplied in diagnostics of taste disorders.
Although many conditions and medications have been associated with chemosensory disturbances, data from major chemosensory clinical research centers support three major disorders as being causative: nasal and paranasal sinus disease (21%), post-upper respiratory tract viral infection (19%), and head trauma (14%). Despite extensive evaluation, 22% of patients do not demonstrate identifiable causation.
Separate taste examinations of each area of gustatory innervation are necessary in clinical practice in treating patients with taste disorders. We have developed our own electrogustometer with a dB scale and qualitative and quantitative clinical gustometry using filter-paper discs (the filter-paper disc method). this paper reports on our main basic studies in this field and new insights and experience gained in connection with the two gustometry procedures. Reference is made to the gustatory pathway, innervation area on the tongue and the soft palate, the argument against the localization theory of taste, the correlation between electrogustometry and the filter-paper disc method, differential diagnosis of taste disorders using both methods and the effective use of these methods in clinical practice. The effective use of both methods of measurements is important to give the physician assurance and confidence in the diagnosis and treatment of taste disorders.
Taste threshold detection and recognition were determined on 46 dyspeptic patients and on 42 blind controls. Among the dyspeptic patients 60% suffered from different taste disorders. Among the blind controls the frequency of taste disorder was 41%. Among the dyspeptic patients heterogeusia and dysgeusia dominated, threefold compared to the control blind persons. A mild hypergeusia appeared among the patients in 21%, among the blind in 8%. There was an enhanced hypergeusia in the group of blind persons (16%), but this was found in the group of dyspeptic patients in only 4%. It is suggested that the hypergeusia may also be a compensatory function, a consequence of the loss of seeing. There was an inverse ratio between the taste acuity and taste preference. The taste threshold to the preferred taste in both groups was higher, therefore more food was needed to stimulate the taste nerves.
Saliva is the principal fluid component of the external environment of the taste receptor cells and, as such, could play a role in taste sensitivity. Its main role includes transport of taste substances to and protection of the taste receptor. In the initial process of taste perception, saliva acts as a solvent for taste substances; salivary water dissolves taste substances, and the latter diffuse to the taste receptor sites. During this process, some salivary constituents chemically interact with taste substances. For example, salivary buffers (e.g., bicarbonate ions) decrease the concentration of free hydrogen ions (sour taste), and there are some salivary proteins which may bind with bitter taste substances. Another effect of saliva on taste transduction is that some salivary constituents can continuously stimulate the taste receptor, resulting in an alteration of taste sensitivity. For example, the taste detection threshold for NaCl is slightly above the salivary sodium concentrations with which the taste receptor is continuously stimulated. In contrast, saliva protects the taste receptor from damage brought about by dryness and bacterial infection, and from disuse atrophy via a decrease in transport of taste stimuli to the receptor sites. This is a long-term effect of saliva that may be related to taste disorders. These various effects of saliva on the taste perception differ depending on the anatomical relationship between the taste buds and oral openings of the ducts of the salivary glands. Many taste buds are localized in the trenches of the foliate and circumvallate papillae, where the lingual minor salivary glands (von Ebner's glands) secrete saliva. Taste buds situated at the surface of the anterior part of the tongue and soft palate are bathed with the mixed saliva secreted mainly by the three major salivary glands.
UNLABELLED: Acoustic neuromas must be removed surgically, otherwise serious complications may occur. Removal of an acoustic neuroma most often leads to disorders of balance, hearing, and sometimes facial motor function. Many earlier studies have approached the hearing and facial motor function. However, the facial nerve also comprises sensory and secretory fibers which, when injured, may produce minor disorders affecting patient's quality of life. The purpose of this work was to evaluate the quality of life, secretory and taste disorders after acoustic neuroma surgery. PATIENTS AND METHOD: Among patients operated on between May 1985 and May 1996, we selected only those who presented a normal facial function 3 months after surgery. We thus selected 93 patients and sent them a questionnaire in December 1997. We received 74 answers. RESULTS: The period between the operation and the dispatch of the questionnaire was on an average 5.5 years (range 19 months-12 years 9 months). Impairment of quality of life was frequent (59% of cases), and changing way of life less so (30%). 74% of the patients described balance disorders. One-quarter of the patients indicated they experienced disorders of facial mobility. Only 3 patients had no disorder. CONCLUSION: Secretory and taste disorders are frequent after neuroma surgery. Despite their mildness, patients should be advised accordingly because of possible impact on quality of life. This study also points out the lack of precision in the estimation of facial mobility. A better evaluation of patient complaints would be useful.
BACKGROUND: Taste loss is a major cause of morbidity in patients undergoing head and neck irradiation. METHODS: In a prospective study, 51 patients undergoing radical head and neck irradiation at the Tokyo University Hospital were assessed for taste loss. Taste ability was measured by the taste threshold for the four basic tastes (sweet, sour, salt, and bitter qualities) plus another taste of "umami" quality using a filter-paper-disc method in patients before, during, and after radiotherapy (RT). RESULTS: All tastes declined on the fifth week after the start of RT and improved on the 11th week. Anatomic pathologic analyses in rats revealed that taste buds diminished completely on the sixth day after irradiation of 15 Gy in a single fraction, and the appearance of taste buds returned almost to the preirradiation state on the 28th day. CONCLUSIONS: The main cause of taste disorder resulting from RT was believed to be a disappearance of taste buds and not damage to the taste nerves.
Electrogustometry (EGM) has a number of strengths and a few limitations in clinical use. The strengths of EGM are: (i) the range of measurements can be kept constant; (ii) quantitative control of the intensity of the stimulation is possible; (iii) only a short period of time is required for testing; (iv) it is possible to detect even slight taste disorders for which the patient has no subjective symptoms; (v) it is useful for topognosis of lesions of taste pathways and for determining prognosis; and (vi) it is the only quantitative method for diagnosing disorders of the glosssopharyngeal nerve. The limitations of EGM are: (i) it is not useful for determining or diagnosing some of the symptoms often complained of by patients with taste disorder, namely dissociated taste disorder, heterogeusia and spontaneous dysgeusia; and (ii) it is not useful for following the progress of taste disorder. The many strengths and few limitations of EGM make it the first choice among taste examinations. This paper describes the clinical use of EGM as well as discussing other taste examinations used in our taste clinic and, in particular, the advantages and disadvantages of filter paper disk testing with taste solutions.
PURPOSE: Taste loss is a major cause of morbidity in patients undergoing head-and-neck irradiation. The relationship between the time course and the degree of taste disorder was studied in both acute and late phases. METHODS AND MATERIALS: Taste ability was measured by the taste threshold for the four basic tastes using a filter paper disc method in patients before, during, and after radiotherapy. The subjects were divided into two groups. In Group A, the radiation fields included most of the tongue (n = 100), and in Group B the radiation fields did not include the tip of the tongue (n = 18). RESULTS: In Group A, there was a significant impairment of the threshold of all four basic tastes at 3 weeks after starting radiotherapy (RT), and this impairment remained at 8 weeks (p < 0.05). This was not seen in Group B. In Group A, there was no significant difference in the patterns of taste sensitivity change between the high-dose (>20 Gy) and low-dose (< or =20 Gy) groups. In the late phase, recovery of taste loss was seen in both groups since 4 months after completing RT. CONCLUSIONS: Unless the anterior part of the tongue was irradiated, taste loss was not observed during RT. When the anterior part of the tongue was irradiated, a difference by radiation dose was not observed in the taste loss pattern. Additionally, radiation-induced taste dysfunction appears to be a temporal effect.
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This report presents a rare complication after tonsillectomy--a postoperative noticed impairment of the sense of taste. Due to its course in the parapharyngeal space the glossopharyngeal nerve can be damaged during the operation.