Evaluation of Spontaneous Swallow Frequency in Healthy People and Those With, or at Risk of Developing, Dysphagia: A Review

Abstract

Dysphagia is a common and frequently undetected complication of many neurological disorders and of sarcopoenia in ageing persons. Spontaneous swallowing frequency (SSF) has been mooted as a possible tool to classify dysphagia risk. We conducted a review of the literature to describe SSF in both the healthy population and in disease-specific populations, in order to consider its utility as a screening tool to identify dysphagia. We searched Medline, Embase, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials databases. Metadata were extracted, collated and analysed to give quantitative insight. Three hundred and twelve articles were retrieved, with 19 meeting inclusion and quality criteria. Heterogeneity between studies was high (I2 = 99%). Mean SSF in healthy younger sub-groups was 0.98/min [CI: 0.67; 1.42]. In the Parkinson’s sub-group, mean SSF was 0.59/min [0.40; 0.87]. Mean SSF in healthy older, higher risk and dysphagic populations were similar (0.21/min [0.09; 0.52], 0.26/min [0.10; 0.72] and 0.30/min [0.16; 0.54], respectively). SSF is a novel, non-invasive clinical variable which warrants further exploration as to its potential to identify persons at risk of dysphagia. Larger, well-conducted studies are needed to develop objective, standardised methods for detecting SSF, and develop normative values in healthy populations.

Effects of the GABA(B) agonist baclofen on volitional swallowing in normal subjects

“…In the current protocol, the stimulus for spontaneous swallows was likely to include the sensation of the catheter within the throat, as well as accumulation of saliva. Overall spontaneous swallow rate determined in our study was 1.3/min (95% CI, 0.60–2.07), which is higher compared to studies using other devices 19 . While the spontaneous swallow rate was numerically reduced during baclofen exposure, this difference did not reach significance.…”

“…Overall spontaneous swallow rate determined in our study was 1.3/min (95% CI, 0.60-2.07), which is higher compared to studies using other devices. 19 While the spontaneous swallow rate was numerically reduced during baclofen exposure, this difference did not reach significance. The recording of spontaneous swallows inter-dispersed between repeat bolus challenges and during a relatively short (20 min) study protocol is a likely explanation for the lack of effect seen here.…”

Swallow Detection with Acoustics and Accelerometric-Based Wearable Technology: A Scoping Review

“…Swallowing is a natural yet essential part of our daily life. Human performs spontaneous swallowing (saliva and food/drink) 0.98 times per minute on average [1]. With different definitions and measurement techniques, Lear et al [2] suggested that humans swallow approximately 200 to 1000 times a day, while Rudney et al [3] reported that spontaneous swallows are performed by healthy humans 18 to 400 times per hour.…”

Spontaneous Swallowing Frequency in Post-Stroke Patients with and Without Oropharyngeal Dysphagia: An Observational Study

“…One of the open questions about the study of the SSF is what is the most appropriate method to evaluate it [ 32 ]. Our study not only demonstrates the reproducibility of the previous studies [ 26 , 29 , 30 ], but also the reproducibility by means of another SSF evaluation technique.…”

“…Little is known yet about reflexive swallow mechanisms and the role of spontaneous swallowing frequency in OD. As Bulmer et al [ 32 ] found, there is a negative association of SSF with age, which could be implicated in dysphagia. However, they conclude in their review that although dysphagia has been associated with lower SSF there is still high heterogeneity in SSF data and methodologies used to evaluate it, that it is difficult to assess the cause and effect of SSF on dysphagia and that age and comorbidities are potential confounding factors [ 32 ].…”