Accurate investigation of swallow function, particularly the pharyngeal stage, remains challenging. Alterations in duration of phases of a swallow may reflect underlying abnormalities. The laryngograph provides quantitative data on conducted impedance changes across the neck. During a swallow, a characteristic and reproducible trace is obtained which we have applied to the assessment of swallowing. METHODS: 67 asymptomatic volunteers with no history of swallowing complaints were recruited. Laryngograph (Lx) measurements were recorded by flat electrodes applied superficially to the neck while swallowing 10ml boluses of water. A glottal electromagnetic micropower sensor (GEMS) was combined to refine identification of start and end points of the swallow. Three time intervals were measured: peak-to-peak, time for whole swallow, and trough-to-trough. Mean values were obtained from 5 swallows per subject. A further 31 subjects with no swallowing complaints underwent concurrent videofluoroscopy and laryngography and images of the passage of a barium bolus were matched with simultaneously acquired Lx data. RESULTS: The Lx trace correlates with videoradiographic defined phases of the swallow: trough before first peak (1), beginning of pharyngeal swallow; first peak (2), vocal fold closure; end of final peak (3), pharyngoesophageal opening.
Measurements of the intervals display normal distributions. Mean times (seconds) are: peak-to-peak, 0.54 (s.d 0.15); mean duration of whole swallow: 1.53 (s.d 0.45); trough-to-trough: 0.44 (s.d 0.12). CONCLUSION: A reference range of durations are provided for the pharyngeal stage of swallowing in a normal population using a non-invasive tool. Lx may contribute to the detection and monitoring of patients with swallowing abnormalities.
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