Post-tonsillectomy dysgeusia with weight loss: possible involvement of soft palate

Suppression of sweet taste-related responses by plant-derived bioactive compounds and eating. Part I: A systematic review in humans

The taste of food plays a crucial role in determining what and how much we eat. Thus, interventions that temporarily block sweet taste receptors offer a promising approach to addressing unhealthy behaviours associated with sugary foods. However, the relationship between reduced sweet taste response and food consumption remains unclear, with contradictory findings. Certain studies suggest that a diminished perception of sweetness leads to a sense of fullness and results in reduced food intake, while others suggest the opposite effect. To shed some light, our systematic review looked into the relationship between diminished sweet taste response and food consumption by examining the effects of bioactive compounds that experimentally inhibit sweetness in healthy individuals. This review was registered in the International Prospective Register of Systematic Reviews and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Scottish Intercollegiate Guidelines Network, and covered original papers included in Web of Science, PubMed, Scopus, Food Science Source and Food Science and technology abstracts. We identified 33 peer-reviewed English-language studies that fit the topic and met the inclusion criteria. The current literature predominantly focuses on the immediate impact of oral gymnemic acids, failing to provide preliminary evidence in support of the specific threshold hypothesis, above which food consumption decreases and below which the opposite effect occurs. Additionally, there was inconsistency in the findings regarding the short-term desire to eat following sweetness inhibition. Considering the downstream effects on energy intake and their clinical applications, further research is needed to clarify both the acute within-session effects (i.e., not wanting any more now) and the longer-term effects (i.e., deciding not to start eating) linked to oral sweet-taste-suppressing compounds.

Adaptive and maladaptive neural compensatory consequences of sensory deprivation-From a phantom percept perspective

It is suggested that the brain undergoes plastic changes in order to adapt to changing environmental needs. Sensory deprivation results in decreased input to the brain leading to adaptive or maladaptive changes. Although several theories hypothesize the mechanism of these adaptive and maladaptive changes, the course of action taken by the brain heavily depends on the age of incidence of damage. The growing body of literature on the topic proposes that maladaptive changes in the brain are instrumental in creating phantom percepts, defined as the perception of a sensory experience in the absence of a physical stimulus. The current article reviews the mechanisms of adaptive and maladaptive plasticity in the brain in congenital, early, and late-onset sensory deprivation in conjunction with the phantom percepts in the different sensory domains. We propose that the mechanisms of adaptive and maladaptive plasticity fall under a universal construct of updating hierarchical Bayesian prediction errors. This theory of the Bayesian brain hypothesizes that the brain constantly compares its internal milieu with changing environmental cues and either adjusts its predictions or discards the change, depending on the novelty or salience of the external stimulus. We propose that adaptive plasticity reflects both successful bottom-up compensation and top-down updating of the model while maladaptive plasticity reflects failure in one or both mechanisms, resulting in a constant prediction-error. Finally, we hypothesize that phantom percepts are generated by the brain as a solution to this prediction error and are thus a manifestation of unsuccessful adaptation to sensory deprivation.

Structural equation modeling of associations among taste-related risk factors, taste functioning, and adiposity

OBJECTIVE

Variation in taste perception and exposure to risk factors of taste alterations have been independently linked with elevated adiposity. Using a laboratory database, taste-adiposity associations were modeled and examined for whether taste functioning mediates the association between taste-related risk factors and adiposity.

METHODS

Healthy women (n = 407, 35.5 ± 16.9 y) self-reported histories of risk factors of altered taste functioning (tonsillectomy, multiple ear infections, head trauma) and were assessed for taste functioning (tongue-tip and whole-mouth intensities of quinine and salt) and density of taste papillae. Twenty-four percent had elevated waist circumferences; thirty-nine percent had overweight or obesity. Using structural equation modeling, direct and indirect associations between taste-related risk factors, taste functioning, and adiposity were tested.

RESULTS

In models with good fit, elevated central adiposity was explained directly by history of risk factors (tonsillectomy, multiple ear infections) and directly by lower taste functioning (lower tongue-tip taste function, lower papillae density). Risk factors of taste alterations were significantly associated with lower taste functioning, with taste mediating the association between head trauma and reduced adiposity.

CONCLUSIONS

This large laboratory-based study supports associations between taste-related risk factors, taste functioning, and adiposity. These findings need to be confirmed with other population-based studies, including the National Health and Nutrition Examination Survey 2013-2014 taste data.

Transoral Surgical Anatomy and Clinical Considerations of Lateral Oropharyngeal Wall, Parapharyngeal Space, and Tongue Base

Objective

With the emergence of transoral robotic approaches, head and neck surgeons are faced with an unfamiliar inside-out head and neck anatomy. This study was performed to describe key anatomic landmarks and surgical considerations of transoral robotic resection of the lateral oropharyngeal wall, the parapharyngeal space, and the base of the tongue.

Study Design

Descriptive transoral anatomic study.

Setting

Academic anatomy laboratory and tertiary academic hospital.

Subjects and Methods

Transoral dissections of the lateral pharyngeal wall, base of tongue, and parapharyngeal space were performed in 5 vascular silicone-injected cadavers to illustrate anatomic landmarks from the inside-out perspective. Lateral neck dissections were also performed to better appreciate the anatomic structures and to be more familiar with intraoperative anatomy.

Results

The neurovascular and muscular structures located in parapharyngeal space, lateral oropharyngeal wall, and base of tongue were described. Surgical significance of key anatomic landmarks was emphasized with high-quality illustrations.

Conclusion

A thorough understanding of transoral anatomy is crucial to perform transoral robotic surgery safely and efficiently. To understand inside-out anatomy of base of tongue, lateral oropharyngeal wall, and parapharyngeal space, cadaveric dissection is highly beneficial and may help to shorten the learning curve for transoral robotic dissections.

Bilateral glossopharyngeal nerve palsy following tonsillectomy: a very rare and difficult complication of a common procedure

Objectives:

Tonsillectomy is one of the most commonly performed otolaryngological procedures. Bilateral palsy of the glossopharyngeal nerve is an exceedingly rare complication that can result in significant morbidity. This case report aimed to raise awareness of this complication and outline management strategies.

Case report:

A 31-year-old woman who underwent routine tonsillectomy presented with progressive numbness of the palate, dysgeusia, xerostomia, paraesthesia of the tongue and the feeling of something in her throat within 2 weeks of surgery. She reported the post-operative onset of snoring. Examination revealed a symmetrically low, ‘dropped’ soft palate. Over time, her symptoms have lessened, but dysgeusia and snoring remain.

Conclusion:

The position of the glossopharyngeal nerve in the tonsillar bed makes it prone to injury during tonsillectomy, especially if ‘hot’ methods are used. Bilateral injury can result in significant morbidity that can be difficult to treat. Patients should be warned about this risk and care should be taken to minimise it.

Taste damage (otitis media, tonsillectomy and head and neck cancer), oral sensations and BMI

Otitis media and tonsillectomy are associated with enhanced palatability of energy dense foods and with weight gain. Otitis media can damage the chorda tympani nerve (CN VII); tonsillectomy and head and neck radiation treatment can damage the glossopharyngeal nerve (CN IX). Both of these nerves function prominently in taste sensation. The present study utilizes these sources of damage to study central interactions among the nerves that mediate oral sensations. Mild damage restricted to one of these nerves can actually intensify sensations evoked from undamaged nerves (i.e., whole-mouth taste, oral tactile sensations evoked by fats and irritants). These intensifications may result from disruption of central inhibitory taste circuits, as taste damage appears to disinhibit other oral sensory nerves. In addition, mild damage restricted to one taste nerve can intensify odors perceived from foods in the mouth during chewing and swallowing (i.e., retronasal olfaction); this may be a secondary consequence of the intensification of whole-mouth taste. Damage to both nerves leads to widespread oral sensory loss. At present, the link between sensory alterations and weight gain has not been established for adults (e.g., does increased fat preference occur in individuals with oral sensory intensifications, those with losses, or both?). Finally, pain in non-oral locations is also related to taste loss. When participants rated "the most intense pain of any kind they had ever experienced," those with the greatest taste loss gave the highest ratings. These effects suggest that taste loss significantly influences long-term health outcomes.

Taste function evaluation after tonsillectomy: a prospective study of 60 patients

Tonsillectomy is regarded as a safe procedure, with post-operative taste disturbances rarely reported. The aim of this study was to access taste function after tonsillectomy in a series of 60 patients. Sixty patients (age range 14-40 years; mean 24.4 years; median 21 years; STD 7.7 years), 24 males and 36 females, underwent bilateral tonsillectomy at the University Hospital of Patras, Greece. All patients were diagnosed with recurrent tonsillitis and randomly assigned to two groups. The first group consisted of 27 patients, who underwent tonsillectomy using scissors and raspatory with electrocautery for coagulation. The remaining 33 patients underwent tonsillectomy using pressure-assisted tissue-welding technology. Chemogustometry was used to evaluate the patients' taste function on the first postoperative day and succeedingly, 15 days and 1 month postoperatively. Three different quantities of tastant were used in each test. Taste recognition in posterior tongue regions proved to be more affected compared with anterior tongue regions in the first postoperative day. Bitter and sour tastes were more affected than those of sweet and salty. Succeeding tests yielded near normal results for all patients except two, with one patient achieving normal taste function 1 month postoperatively and the other still facing taste disorders 1 month after tonsillectomy. The results indicate that Tonsillectomy entails a temporary reduction in taste function. This finding should be attributed to direct or indirect intraoperative damage of the glossopharyngeal nerve or unintentional extension of the lingual nerve by application of the tongue retractor. No significant difference was noted between the two operative techniques evaluated in our study. In most cases taste function returns to preoperative levels within 2 weeks postoperatively. Post-tonsillectomy taste disturbances are uncommon, and patients should be informed of this possibility.