[Effects of transcutaneous silicon injection for aspiration caused by unilateral vocal cord paralysis]

The purpose of this study was to determine the effects of transcutaneous silicon injection on swallowing function in unilateral vocal cord paralysis with aspiration. The preoperative and postoperative swallowing function were evaluated by means of videofluoroscopy and pharyngeal manometry in eight patients who received injection of silicon into the laryngeal vestibule, ventricle and vocal cord. Data analysis compared 1) types of aspiration and pharyngeal clearance, 2) timing of laryngeal closure (complete closure between arytenoid and epiglottic base) that was correlated with the onset of cricopharyngeal (CP) opening as time zero, and 3) swallowing pressure in the pyriform sinus on the side of the paralyzed vocal cord. In seven of the 8 patients, a favorable clinical response was achieved and aspiration and/or penetration were not observed on the fluoroscopic images after the silicon injection. Timing of laryngeal closure could be quantified in six patients, and mean values of the times preceding the onset of CP opening were significantly earlier on the postoperative examinations than preoperative examinations. Pharyngeal clearance on the affected vocal cord side was improved in six of the 8 patients, and swallowing pressure in the pyriform sinus was significantly elevated in four patients following surgery. These results suggested that silicon injection therapy produced earlier laryngeal closure during the swallow and improvement of pharyngeal clearance on the affected side after the swallow, so that aspiration and/or penetration with vocal cord paralysis might be prevented.