Tongue and laryngeal exercises improve tongue strength and vocal function outcomes in a Pink1-/- rat model of early Parkinson disease.

Parkinson disease (PD) causes voice and swallow dysfunction even in early stages of the disease. Treatment of this dysfunction is limited, and the neuropathology underlying this dysfunction is poorly defined. Targeted exercise provides the greatest benefit for offsetting voice and swallow dysfunction, and previous data suggest the hypoglossal nucleus and noradrenergic-locus coeruleus (LC) may be involved in its early pathology. To investigate relationships between targeted exercise and neuropathology of voice and swallow dysfunction, we implemented a combined exercise paradigm that included tongue force and vocalization exercises early in the Pink1-/- rat model. We tested the hypotheses that (1) tongue and vocal exercise improves tongue force and timing behaviors and vocalization outcomes, and (2) exercise increases optical density of serotonin (5-HT) in the hypoglossal nucleus, and tyrosine hydroxylase immunoreactive (Th-ir) cell counts in the LC. At two months of age Pink1-/- rats were randomized to exercise or non-exercise treatment. Age-matched wildtype (WT) control rats were assigned to non-exercise treatment. Tongue force and timing behaviors and ultrasonic vocalizations were measured at baseline (two months) and final (four months) timepoints. Optical density of 5-HT in the hypoglossal nucleus and TH-ir cell counts in the LC were obtained. Pink1-/- rats produced greater tongue forces, faster tongue contraction, and higher-intensity vocalization following exercise. There were no differences in LC TH-ir. The non-exercised Pink1-/- group had reduced density of 5-HT in the hypoglossal nucleus compared to the WT control group. The changes to tongue function and vocalization after targeted exercise suggests exercise intervention may be beneficial in early PD.

Dysphagia in Parkinson Disease: Part I - Pathophysiology and Diagnostic Practices.

Purpose of Review: Dysphagia affects the majority of individuals with Parkinson disease (PD) and is not typically diagnosed until later in disease progression. This review will cover the current understanding of PD pathophysiology, and provides an overview of dysphagia in PD including diagnostic practices, gaps in knowledge, and future directions. Recent Findings: Many non-motor and other motor signs of PD appear in the prodrome prior to the manifestation of hall- mark signs and diagnosis. While dysphagia often presents already in the prodrome, it is not routinely addressed in standard neurology examinations. Summary: Dysphagia in PD can result in compromised efficiency and safety of swallowing, which significantly contributes to malnutrition and dehydration, decrease quality of life, and increase mortality. The heterogeneous clinical presentation of PD complicates diagnostic procedures which often leads to delayed treatment. Research has advanced our knowledge of mechanisms underlying PD, but dysphagia is still largely understudied, especially in the prodromal stage.

Effects of social isolation on 50-kHz ultrasonic vocalizations, affective state, cognition, and neurotransmitter concentrations in the ventral tegmental and locus coeruleus of adult rats.

Vocal communication, cognition, and affective state are key features of sustained health and wellness, and because vocalizations are often socially-motivated, social experience likely plays a role in these behaviors. The monoaminergic systems of the ventral tegmental area (VTA) and the locus coeruleus (LC) are associated with social and reward processing, vocalization production, and neurotransmitter changes in response to environmental stressors. The effect of social isolation on these complex behaviors and the underlying neural mechanisms is relatively unknown. To add to this body of literature, we randomized adult male Long-Evans rats to control (housed with a cagemate) or isolated (housed individually) conditions and assayed ultrasonic vocalizations, cognition (novel object recognition test), anxiety (elevated plus maze) and anhedonia (sucrose preference test) at 2, 4, 6, 8, and 10 months of age. At 10 months, VTA and LC samples were assayed for dopamine, norepinephrine, and serotonin using high performance liquid chromatography. We tested the hypotheses that isolation 1) diminishes vocalizations and cognition, 2) increases anxiety and depression, and 3) increases levels of dopamine, norepinephrine, and serotonin in the VTA and LC. Results showed isolation significantly reduced vocalization tonality (signal-to-noise ratio) and increased maximum frequency. There were no significant findings for cognition, anxiety, or anhedonia. Dopamine and serotonin and their respective metabolites were significantly increased in the VTA in isolated rats. These findings suggest chronic changes to social condition such as isolation affects vocalization production and levels of VTA neurotransmitters.

Biological and Acoustic Sex Differences in Rat Ultrasonic Vocalization.

The rat model is a useful tool for understanding peripheral and central mechanisms of laryngeal biology. Rats produce ultrasonic vocalizations (USVs) that have communicative intent and are altered by experimental conditions such as social environment, stress, diet, drugs, age, and neurological diseases, validating the rat model's utility for studying communication and related deficits. Sex differences are apparent in both the rat larynx and USV acoustics and are differentially affected by experimental conditions. Therefore, the purpose of this review paper is to highlight the known sex differences in rat USV production, acoustics, and laryngeal biology detailed in the literature across the lifespan.

Correction to: Patient Adherence to Dysphagia Recommendations: A Systematic Review.

The original version of this article unfortunately contains mistakes. The second sentence in the section "Results", under the heading "Study Design" was incorrect. It should read as: Two studies [24, 29] used a prospective cohort study design with a JAMA rating of 2. Four studies [17, 25, 27, 34] completed retrospective studies earning a JAMA score of 3. Four studies [26, 28, 30, 33] earned a JAMA quality rating score of 4 and used the following designs: case series [26, 28, 33], and pilot study [30]. In Table 1, "Study Population (n)" and "Design (JAMA quality rating)" values were incorrect for Shinn et al. (2013) [24]. The correct information is given here. HNC (n = 109) Prospective Cohort (2).

Patient Adherence to Dysphagia Recommendations: A Systematic Review.

Patient adherence to treatment recommendations is an important issue for healthcare providers, in a multitude of specialties, and is critical when assessing the efficacy and effectiveness of a particular treatment approach. Patients who have swallowing impairment often require complex and specific interventions requiring altered daily patterns of behavior. Patients with dysphagia who do not follow recommendations or prescribed exercises may not receive maximum benefit of an intervention. Poor adherence also makes it more difficult to evaluate efficacy of a treatment both clinically and in experimental settings. Further, swallow safety can be compromised if certain recommendations are not followed. Our purpose was to systematically review the literature to understand what is known about adherence within the field of dysphagia treatment. We systematically identified 12 studies that tracked and reported patient-specific adherence. In this review, we found that the average adherence rate from these studies ranges between 21.9 and 51.9%. Adherence to prophylactic treatment recommendations for patients with head and neck cancer was the focus in 9/12 studies. The findings of this review identify a large gap in knowledge regarding adherence to dysphagia treatment. Few studies account for adherence within their study designs. When planning dysphagia treatment studies, it is imperative that investigators include information regarding patient adherence to accurately interpret findings. Given the variable adherence rates found in this review, factors influencing patient adherence with dysphagia treatments should be identified to increase adherence in future trials.

Methods for measuring swallowing pressure variability using high-resolution manometry.

Any movement performed repeatedly will be executed with inter-trial variability. Oropharyngeal swallowing is a complex sensorimotor action, and swallow-to-swallow variability can have consequences that impact swallowing safety. Our aim was to determine an appropriate method to measure swallowing pressure waveform variability. An ideal variability metric must be sensitive to known deviations in waveform amplitude, duration, and overall shape, without being biased by waveforms that have both positive and sub-atmospheric pressure profiles. Through systematic analysis of model waveforms, we found a coefficient of variability (CV) parameter on waveforms adjusted such that the overall mean was 0 to be best suited for swallowing pressure variability analysis. We then investigated pharyngeal swallowing pressure variability using high-resolution manometry data from healthy individuals to assess impacts of waveform alignment, pharyngeal region, and number of swallows investigated. The alignment that resulted in the lowest overall swallowing pressure variability was when the superior-most sensor in the upper esophageal sphincter reached half its maximum pressure. Pressures in the tongue base region of the pharynx were least variable and pressures in the hypopharynx region were most variable. Sets of 3 - 10 consecutive swallows had no overall difference in variability, but sets of 2 swallows resulted in significantly less variability than the other dataset sizes. This study identified variability in swallowing pressure waveform shape throughout the pharynx in healthy adults; we discuss implications for swallowing motor control.