The extended posterior glottic opening technique was performed in 10 patients with bilateral vocal cord paralysis by CO2 laser laryngomicrosurgery. The subsequent phonatory function was then examined by the use PS-77 phonatory function test equipment, with the simultaneous measurement of subglottic pressure, during easy phonation preoperatively and again at one month post operation. This extended glottic opening technique consisted of an extended posterior cordectomy and a medial arytenoidectomy or arytenoidectomy. After the operation, the patients were free from dyspnea, and the tracheal fistulae were closed at 3 weeks after the operation. The patients' voices became slightly husky, weak, and the pitch was noticeably lower. The mean pre versus post operative phonatory function values (from pre-mean value to postmean value) revealed a shorter maximum phonation time (from 6.3 to 5.3 sec), a higher air flow rate (from 316 to 429 ml/sec), a decreased subglottic pressure (from 12.7 to 5.9cmH2O), a lower laryngeal resistance (from 93.3 to 34.1 cmH2O), and a lower level of laryngeal efficiency (from 2.09 to 1.53×10-4), respectively. However, the subglottic power remained almost the same (from 5.0 to 4.9 × 106) from pre to post operation. Based on our study, the extended posterior glottic opening technique by CO2 laser laryngomicrosurgery might be sufficient to open the glottis to avoid dyspnea and to maintain voice production in patients with bilateral abductor vocal paralysis.
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