The value of scintigraphy in the evaluation of oropharyngeal dysphagia

Healthy adults can swallow boluses of 20 ml water in a single swallow. Individuals with impaired swallowing, however, may be unable to do so, instead requiring two or more swallows; this phenomenon is called "piecemeal deglutition". The term "dysphagia limit" refers to the volume at which piecemeal deglutition occurs. The aim of our study was to investigate the potential value of scintigraphic evaluation of piecemeal deglutition and dysphagia limit in patients with dysphagia, based on correlation with the results of submental electromyography (SM-EMG) and laryngeal sensor monitoring (LS). The study population comprised 24 patients with dysphagia secondary to neurological disorders and ten normal adults, who formed a control group. In the scintigraphic evaluation, subjects underwent four separate dynamic studies using 5, 10, 15 and 20 ml of water containing 0.5 mCi technetium-99m labelled sulphur colloid, and time-activity curves (TACs) were created for each study. Static thoracic images were also recorded in order to detect airway aspiration Observation of two or more peaks on TACs within the 10-s acquisition period was considered a sign of piecemeal deglutition. If piecemeal deglutition occurred at or below 20 ml, this volume was regarded as the dysphagia limit. Piecemeal deglutition was not found in any normal subjects; by contrast, it was observed in 14 of the 24 (58%) patients on scintigraphy and in 17 (71%) patients on EMG and LS. In three patients, signs of the airway aspiration were observed on static thoracic images. Scintigraphic and electrophysiological findings were in agreement in 19 patients (79%), and the correlation between scintigraphy and the electrophysiological methods for the evaluation of dysphagia was statistically significant (r=0.57, P=0.003). The novel finding of this study is the demonstration of piecemeal deglutition and dysphagia limit on scintigraphic studies in patients with neurogenic dysphagia. Based on this finding we consider that scintigraphic evaluations of piecemeal deglutition and dysphagia limit could be of value especially in centres which do not have electrophysiological test facilities. The technique should be added to the list of standard scintigraphic methods for the evaluation of patients with oropharyngeal dysphagia.