BackgroundVideofluoroscopic swallow study (VFSS) is the gold standard for diagnosis of dysphagia in veterinary medicine but lacks standardized protocols that emulate physiologic feeding practices. Age impacts swallow function in humans but has not been evaluated by VFSS in dogs.Hypothesis/ObjectivesTo develop a protocol with custom kennels designed to allow free‐feeding of 3 optimized formulations of contrast media and diets that address limitations of current VFSS protocols. We hypothesized that dogs evaluated by a free‐feeding VFSS protocol would show differences in objective swallow metrics based on age.AnimalsHealthy juvenile, adult, and geriatric dogs (n = 24).MethodsProspective, experimental study. Custom kennels were developed to maintain natural feeding behaviors during VFSS. Three food consistencies (thin liquid, pureed food, and dry kibble) were formulated with either iohexol or barium to maximize palatability and voluntary prehension. Dogs were evaluated by 16 swallow metrics and compared across age groups.ResultsDevelopment of a standardized VFSS protocol resulted in successful collection of swallow data in healthy dogs. No significant differences in swallow metrics were observed among age groups. Substantial variability was observed in healthy dogs when evaluated under these physiologic conditions. Features typically attributed to pathologic states, such as gastric reflux, were seen in healthy dogs.Conclusions and Clinical ImportanceDevelopment of a VFSS protocol that reflects natural feeding practices may allow emulation of physiology resulting in clinical signs of dysphagia. Age did not result in significant changes in swallow metrics, but additional studies are needed, particularly in light of substantial normal variation.
We have established a new LAR protocol that permits quantification of novel LAR metrics that are translatable between mice and humans. Using this protocol, we showed that VF adduction is impaired in primary aging mice, whereas VF abduction is impaired in ALS-affected mice. These preliminary findings highlight the enhanced diagnostic potential of LAR testing.
IMPORTANCE Essential vocal tremor (EVT) is a neurologic voice disorder characterized by periodic fluctuations in pitch and loudness that can hinder intelligibility. Defining the normative range of vocal tremor frequency may assist in diagnosis and provide insight into disease mechanisms. OBJECTIVE To characterize the normative voice tremor frequency in EVT (in hertz). DESIGN, SETTING, AND PARTICIPANTS Cross-sectional observational study of 160 patients with EVT. The setting was a tertiary voice center. Participants were identified from a database of consecutive patients diagnosed as having laryngeal movement disorders between January 1, 1990, and April 1, 2017. MAIN OUTCOMES AND MEASURES The following 3 methods measured the frequency of tremor experienced by patients with EVT: perceptual method, computerized peak detection method, and laryngeal electromyography method. Within-person and population-level tremor frequencies were compared across modalities to assess measurement reliability and consistency and to characterize the normal distribution of tremor frequencies in this population. RESULTS Among 160 participants (median age, 70 years; interquartile range [IQR], 64-77 years; 90.6% female [n = 145]), the median frequency of EVT was consistently between 4 and 5 Hz across all 3 methods (perceptual, 4.8 Hz [IQR, 4.4-5.5 Hz]; computerized peak detection, 4.6 Hz [IQR, 4.2-5.0 Hz]; and laryngeal electromyography, 4.3 Hz [IQR, 3.8-5.0 Hz]). The mean in-person differences between each measurement method were not clinically meaningful (range, 0.1-0.5 Hz). Including all interquartile ranges across measurement modalities, the normative tremor frequency range for EVT was 3.8 to 5.5 Hz. CONCLUSIONS AND RELEVANCE To our knowledge, this is the largest study to date to characterize the normal frequency of tremor in patients with EVT. The normative frequency of EVT (range, 3.8-5.5 Hz) falls within a much narrower range than previously reported. Those whose frequency is outside this range may still have EVT but should be carefully evaluated for potential other causes of vocal tremor. Defining characteristics of EVT may aid appropriate diagnosis and improve understanding of this disease.
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