Spectral arc length as a method to quantify pharyngeal high-resolution manometric curve smoothness

Pharyngeal high-resolution manometry (HRM) has emerged over the last decade as a valuable assessment tool for oropharyngeal dysphagia. Data analysis thus far has focused primarily on measures of pressure and duration within key anatomic regions. We apply spectral arc length (SPARC), a dimensionless metric for quantifying smoothness felt to indirectly reflect neuromuscular coordination, as a new method of describing manometric curves. We then use it to distinguish swallows from healthy subjects and those with dysphagia related to stroke.

Previously collected pharyngeal HRM data from eight subjects with history of stroke and eight age- and sex-matched controls were reviewed. Receiver operating characteristic (ROC) analysis was used to optimize SPARC inputs. SPARC was then computed for the velopharynx, tongue base, hypopharynx, and upper esophageal sphincter (UES), and the values were compared between the two subject groups.

Optimized parameter settings yielded an ROC curve with area under the curve (AUC) of 0.953. Mean SPARC values differed between control and stroke subjects for the velopharynx (t = 3.25, p = 0.0058), tongue base (t = 4.77, p = 0.0003), and hypopharynx (t = 2.87, p = 0.0124). Values were similar for the UES (t = 0.43, p = 0.671).

In this preliminary study, SPARC analysis was applied to distinguish control from post-stroke subjects. Considering alternative methods of analyzing pharyngeal HRM data may provide additional insight into the pathophysiology of dysphagia beyond what can be gleaned from measures of pressure and duration alone.