Electrogustometry: Normative data for stimulus duration, tongue site and age decline.

OBJECTIVES: Our primary goal was to evaluate the effect of stimulus duration on electrogustometry (EGM) thresholds. Additionally, we sought to evaluate any sex-related influences and compare the above results to those of taste strips. DESIGN: Electrogustometry thresholds of various stimulus durations (0.5, 1.0, 1.5 and 2.0 seconds) were measured in 212 non-smokers (age range: 10-80 years, divided into eight age-groups) without self-reported gustatory impairment. Furthermore, taste strips chemogustometry measurements in 132 participants were performed. SETTING: Tertiary referral medical centre. PARTICIPANTS: 212 non-smokers, divided into eight age-groups participated in the study. MAIN OUTCOME MEASURES: Electrogustometry thresholds and taste strips, duration of EGM stimuli. RESULTS: Electrogustometry thresholds increased progressively with age and with stimulus duration from 0.5 to 2 seconds. This pattern was consistent in all six anatomic areas, irrespective of sex. In contrast, when using chemogustometry, no age- or sex-related differences were observed. CONCLUSIONS: Electrogustometry-threshold values increase progressively with age and with stimulus duration. Therefore, we recommend documenting stimulus duration in the future EGM recordings as it may significantly affect EGM amplitude threshold values.

Bilateral taste disorders in patients with Ramsay Hunt syndrome and Bell palsy.

OBJECTIVE: Ramsay Hunt syndrome (RHS) and Bell palsy (BP) are typically known as facial nerve motor syndromes and are primarily unilateral. The aim of this study was to challenge this assertion, because both conditions are also known to be associated with viruses that typically affect several nerves. METHODS: Ten participants with RHS, 12 with BP, all clinically unilateral, and 12 healthy controls were prospectively enrolled. Electrogustometric thresholds were measured bilaterally in the areas of the chorda tympani, the glossopharyngeal, and the major petrosal nerve. Also bilaterally, the taste function was tested using chemogustometry with different tastant concentrations. Again bilaterally, the morphology of the mucosa and the vessels of the anterior fungiform papillae were examined by contact endoscopy. Statistically, RHS and BP participants were compared with the healthy controls, and the paretic sides of RHS and BP were compared pairwise with their mobile sides. RESULTS: Electrogustometrically, perception was reduced bilaterally in RHS (10-19dB, p < 0.001) and BP (3-5dB, p = 0.011-0.030) in all 3 innervation areas. Chemogustometrically, it was also reduced bilaterally in RHS (20-70%) and BP (8-50%). Papillary atrophies were increased 100% in RHS (p = 0.001) and BP (p < 0.001). They were more increased on the paretic side in RHS (30%, p = 0.078) and BP (83%, p < 0.001). INTERPRETATION: In these 2 clinically unilateral conditions, the gustatory perception and morphology are bilaterally affected, more in RHS and more on the paretic side. BP, known as an isolated motor condition, appears to be a cranial polyneuritis. A bilateral examination and therapeutic gustatory monitoring might follow these observations in evidence-based practice. Ann Neurol 2018;83:807-815.

Electrogustometry Thresholds, Tongue Tip Vascularization, Density, and Form of the Fungiform Papillae Following Smoking Cessation.

The objective of this study was to evaluate differences in gustatory function and in shape, density, and vascularization of the fungiform papillae (fPap) of smokers' tongue before and after smoking cessation. In 24 smokers (19 males, 5 females; median age: 54.6 ± 2.9 years) electrogustometry (EGM) thresholds at the chorda tympani area, at the soft palate area and at the area of the vallate papillae were recorded bilaterally. Morphology and density of the fungiform papillae (fPap) and blood vessels' density and morphology at the tip of the tongue were examined using contact endoscopy (CE). Follow-up exams (EGM and CE) were performed on average 3.2 months after smoking cessation. Findings were compared between the 2 conditions as well as to those of a group of 24 non-smokers (median age: 55.2 ± 3.4 years; 19 males, 5 females). After smoking cessation, EGM thresholds decreased significantly (P = 0.02 or P = 0.03 depending on the tested area) but nonetheless still were quite different from those of non-smokers (P = 0.05 or 0.04 depending on the site of EGM measurement). Under CE the fPap density was higher after quitting smoking (P = 0.05) and the shape and vascularization of fPap also exhibited a trend to improvement (P = 0.05) after smoking cessation. Chronic exposure to cigarette smoke infers long lasting, although to a large extent reversible, alterations in morphology of taste buds in fungiform papillae, but rather irreversible EGM-related functional gustatory compromise, suggesting a profound physiologic effect on human peripheral taste organs.

Changes in electrogustometry thresholds, tongue tip vascularization, density and form of the fungiform papillae in smokers.

The objective of this study was to evaluate differences in gustatory function in smokers of both sexes and identify any differences in the shape, density and vascularisation of the fungiform papillae (fPap) of smokers' tongue. Additional aim was to investigate any relation between the age, pack years and differences in shape, density, vascularization of fPap and sex. In 166 smokers (81 males, 85 females, age range 20-80 years), divided in age groups, electrogustometry (EGM) thresholds at the chorda tympani area, at the soft palate area and at the area of the vallate papillae were recorded bilaterally. Morphology and density of the fPap and blood vessels' density and morphology at the tip of the tongue were examined using contact endoscopy (CE). EGM thresholds of all smoking subjects tended to increase compared to the non-smoking participants. Morphology, vascularization and density of fPap were found to be worse in smokers than in non-smokers. Interestingly, some participants, despite having increased number of pack years, tended to have almost similar EGM thresholds with non-smoking subjects of the same age group. Smoking tends to affect density, morphology and vascularization of the fPap. There is a correlation between the duration of smoking (pack years) and the afore-mentioned parameters. The use of τ-Kendall criterion provided useful information about the different correlation between the EGM thresholds and vascularization, the EGM thresholds and morphology of fPap and EGM thresholds and density of fPap. The majority of smokers had elevated EGM thresholds compared to non-smokers. Smoking is an important factor which can lead to decreased taste acuity. The combination of methods, such as EGM and CE, can provide useful information about the morphology and function of taste buds. Of interest, women are less affected than men, irrespective of the age group.

Memantine's action against aminoglycoside-induced ototoxicity.

The objectives of this study were (1) to assess the protective role of NMDA antagonists against the ototoxic effects of aminoglycosides, (2) to provide any possible evidence between ototoxicity due to aminoglycosides and excitotoxicity. An animal experiment was conducted. Twenty-eight, 3-month-old female New Zealand rabbits, weighing 1,000-1,500 g, were studied prospectively for 28 days after intramuscular administration of amikacin (15 mg/kg/day divided into two equal doses) for 14 days. Twenty-one rabbits were categorized into three equal treatment groups and seven animals received no medication and served as the control group. The animals of A, B and C groups were injected, intramuscularly, with amikacin 15 mg/kg/day, divided into two equal doses every day for 14 days. Animals of group A received in parallel memantine (per os) and those of group B received p.o. the same volume of placebo solution. The rabbits of the third group (group C) received on the 15th day and every 2 days for the next 2 weeks, until the day 28, memantine of the same quantity as the members of group A. Differences in DPOAE amplitudes, and therefore in cochlear activity, between group A and group B were revealed. DPOAE amplitudes of group B were further reduced compared to the respective amplitudes in rabbits of group A. No improvement was observed in DPOAE measurements performed after the discontinuation of injections. The findings in group C should be examined separately. The measurements showed apparent reversal ototoxic effects in four of the animals. The development of aminoglycoside otoprotective strategies is a primary goal in ototoxicity research. The administration of NMDA antagonists has been shown to prevent, at least to some extent, toxic damage to hair cells in guinea pigs, treated with aminoglycoside antibiotics.

Age-related changes in electrogustometry thresholds, tongue tip vascularization, density, and form of the fungiform papillae in humans.

The aim of the study was to investigate age-related changes in electrogustometry (EGM) thresholds, in morphology and density of the fungiform papillae (fPap) and in vessels' shape and density at the tip of the human tongue.In 156 nonsmokers (74 males, 82 females; age range: 10-80 years), divided in age groups, EGM thresholds at the chorda tympani area, at the soft palate area, and at the area of the vallate papillae were recorded bilaterally. Morphology and density of the fPap and blood vessels' density and morphology at the tip of the tongue were examined using contact endoscopy (CE). EGM thresholds at the chorda tympani area were significantly higher in both men and women ←60 years of age than in younger individuals. At the soft-palatine area, EGM thresholds were significantly higher in men aged 20-29 years and ←60 years compared with men of other age groups. In women older than 50 years, thresholds at all 3 areas were significantly higher than in the younger age groups. No significant differences in EGM thresholds between the two sexes at all locations tested were detected. The density of fPap decreased significantly in men aged >50 years and in women aged >60 years compared with younger individuals. Vascular density decreased significantly and vascular morphology worsened at the tip of the tongue in subjects older than 60 years of age compared with younger subjects. The study showed statistically significant differences in EGM thresholds between the right and the left side of the tongue and between the two sexes. Aging is associated with a progressive increase in EGM thresholds. Density of fPap plays an important role for taste acuity in females aged >60 years and males aged ←50 years. Morphology of fPap and vessels' density and morphology at the tip of the tongue, as tested by CE, emerge as factors influencing taste function in subjects of both sexes aged >60 years.

Ototoxicity caused by once- and twice-daily administration of amikacin in rabbits.

OBJECTIVE: The cochleotoxic effects of aminoglycosides, such as amikacin, are well-established. The aim of the present study was to investigate the possible differences in cochleotoxic effects between once-daily administration (ODA) and twice-daily administration (TDA) of amikacin simulating pediatric dosing. METHODS: Twenty-one rabbits were used. Seven animals received intramuscularly amikacin once daily (ODA-group) and seven received the drug twice daily (TDA-group), for a total time period of 2 weeks. All the animals were subjected to Distortion Product Otoacoustic Emissions (DPOAEs) every 3 days since beginning of the experiment. The rest 7 animals did not receive any medication and served as controls (Control group). Two measurements (7 and 14 days) were obtained following the cease of drug administration. RESULTS: Reduced cochlear activity (as depicted in the respective reduced DPOAE-amplitudes) compared to the pre-treatment state was found in both ODA- and TDA-groups. Cochlear activity was reduced at a wider range of frequencies (from 593 to 4031Hz in TDA-group and from 593 to 1093Hz in ODA-group) and to a higher degree in group B than in group A. Cochlear activity was reduced earlier in ODA-group than in TDA-group. No differences to the pre-treatment state were observed in the control group. CONCLUSIONS: The above findings suggest that less frequent administration in higher dose of amikacin is associated with minimal cochleotoxicity.