Gustatory disturbances occur in patients with head and neck cancer who undergo radiotherapy not directed to the oral cavity.

INTRODUCTION: Even the most modern radiation techniques still result in some degree of toxicity to adjacent normal tissues. Consequently, the radiotherapy treatment in head and neck neoplasms potentially leads to gustatory dysfunction even in cases when the treatment area is outside or adjacent to the oral cavity. In this study we quantitatively and qualitatively assessed gustatory function in patients with head and neck cancers who underwent radiotherapy inside and outside of the oral cavity. METHODS: Fifty-six patients with head and neck cancer responded to a specific questionnaire and had their gustatory function tested before, immediately after, and at 3 and 6 months following radiotherapy treatment. The irradiation field did not include the oral cavity in 29 patients and included it in 27 patients. RESULTS: All patients suffered a severe loss of taste immediately after radiotherapy. The identification of sweet and bitter tastes decreased in both groups, but the sour decrement was exclusive to those who had the oral cavity irradiated. Fourteen percent of patients complained of qualitative changes of taste, namely taste distortions. No impact of xerostomia on the taste measures was apparent. CONCLUSION: We found that patients with head and neck neoplasms submitted to radiotherapy have disturbed taste even when irradiation does not include the oral cavity. This deficit is worse immediately after the end of radiotherapy. Our findings do not support the hypothesis that decreased salivary flow is the major cause for radiation-induced changes in taste function.

Sweet and bitter taste in the brain of awake behaving animals.

Taste is responsible for evaluating the nutritious content of food, guiding essential appetitive behaviours, preventing the ingestion of toxic substances, and helping to ensure the maintenance of a healthy diet. Sweet and bitter are two of the most salient sensory percepts for humans and other animals; sweet taste allows the identification of energy-rich nutrients whereas bitter warns against the intake of potentially noxious chemicals. In mammals, information from taste receptor cells in the tongue is transmitted through multiple neural stations to the primary gustatory cortex in the brain. Recent imaging studies have shown that sweet and bitter are represented in the primary gustatory cortex by neurons organized in a spatial map, with each taste quality encoded by distinct cortical fields. Here we demonstrate that by manipulating the brain fields representing sweet and bitter taste we directly control an animal's internal representation, sensory perception, and behavioural actions. These results substantiate the segregation of taste qualities in the cortex, expose the innate nature of appetitive and aversive taste responses, and illustrate the ability of gustatory cortex to recapitulate complex behaviours in the absence of sensory input.

Taste dysfunction and eating behaviors in survivors of head and neck cancer treatment.

Radiation, chemotherapy, and surgery result in eating problems for patients with head and neck cancer. Eating is essential to physical and social functioning. Strategies for head and neck cancer survivors to cope with eating and taste impairments are reported in this study.

A meta-analysis of the relationship among impaired taste and treatment, treatment type, and tumor site in head and neck cancer treatment survivors

PROBLEM IDENTIFICATION: To understand how taste impairment caused by head and neck cancer treatment changes over time or varies with treatment site or type. LITERATURE SEARCH: Ovid MEDLINE® database was searched for reports of health-related quality of life (HRQOL) in head and neck cancer treatment survivors (HNCTS), which included taste function in a HRQOL instrument from 1946-2013. Eligible studies compared taste scores from baseline to post-treatment, using two treatment types or two cancer sites. DATA EVALUATION: 247 reports were identified; 19 were suitable for meta-analysis. DATA ANALYSIS: A series of dichotomous meta-analyses were conducted using comprehensive meta-analysis software .PRESENTATION OF FINDINGS: Taste scores were statistically significantly worse after treatment; the summary effect for the standard measure difference between pretreatment and post-treatment taste scores was 0.353 (p < 0.001). Patients treated with radiation therapy (RT) reported statistically significant worse taste function post-treatment than those who received no RT; the summary effect for the standard mean differences in taste scores was 0.77 (p = 0.001). Differences in tumor site were not significant. IMPLICATIONS FOR NURSING: Taste dysfunction is a long-term complication for HNCTS, and nurses should screen survivors for this sensory dysfunction.

Single bright light exposure decreases sweet taste threshold in healthy volunteers.

INTRODUCTION: Bright light exposure can alter circulating serotonin levels, and alteration of available serotonin by acute selective serotonin reuptake inhibition significantly lowers sweet but not salt taste recognition thresholds. We tested the hypothesis that bright light exposure would increase sweet but not salt taste sensitivity in healthy adults. METHODS: Fourteen healthy volunteers were exposed to bright (10,000 lux) and dim (<20 lux) light for 30 min each, in counterbalanced order. Measures of taste perception (salt and sweet) and mood were determined at baseline, and before and after each light exposure period. RESULTS: Recognition thresholds for sucrose were significantly lower after bright but not dim light exposure. Thresholds for salt were unaffected by either condition. There were no significant changes in taste acuity, intensity or pleasantness for both the taste modalities and on visual analogue scales (VASs) for mood, anxiety, sleepiness and alertness, under either light condition. CONCLUSION: Brief bright light exposure reduces sweet but not salt taste recognition thresholds in healthy humans.

Behavioral changes in adult rats after prenatal exposures to complex, weak magnetic fields.

More than 100 adult male and female albino Wistar rats that had been exposed during their entire prenatal development to one of two patterns of magnetic fields and one of four intensities (reference: 5 to 20 nT; low: 30 to 50 nT; medium: 90 to 580 nT; high: 590 nT to 1.2 microT) were tested for their capacity for two forms of classical conditioning. The rats exposed for 10 sec every 50 sec to a field composed of successive 200 msec sequences of several different patterns known to produce physiological effects exhibited significantly more intense conditioned fear and taste aversion than those exposed continuously to a single frequency-modulated pattern. The behavioral differences, relative to the reference group ("controls"), were greatest for rats exposed to the 30 to 50 nT or 90 to 580 nT (low to medium intensities) for both patterns of fields. These results suggest that prenatal exposure to physiologically-patterned magnetic fields within a specific "window" of intensities that overlap with values found in many human habitats may produce long-term changes in behaviors.

Nasopharyngeal carcinoma: current management, future directions and dental implications.

Nasopharyngeal carcinoma (NPC) is a distinct cancer of the head and neck. Approximately 70% of patients with NPC present with locally advanced disease. Phase III clinical trials support combined chemotherapy and radiotherapy for the initial treatment of these patients. Current treatment approaches for metastatic disease are variable. Oral complications of therapy for NPC are very common. In order to support cancer therapy the dental provider must be aware of the diagnosis, prognosis and approach to treatment. Dental care requires that radiation fields be understood as well as the permanent changes that occur with high dose radiation therapy. Radiation causes changes in bone and soft tissue that may result in acute and chronic oral complications. The most common acute complications are mucositis, infection, xerostomia and taste changes. Mucositis is of increased severity and duration when chemotherapy is combined with radiation therapy. Chronic complications are due to late effects of radiation therapy including hyposalivation, infection, taste change, dysphagia and trismus. Treatment innovations with molecularly targeted therapies and immunotherapy are being assessed to improve treatment outcomes in NPC and will impact oral complications and oral care.