The open partial horizontal laryngectomy was underwent in patients with supraglottic or glottic laryngeal carcinoma in T2

The transoral endoscopic laser cordectomy was underwent in patients with supraglottic or glottic laryngeal carcinoma in T1

An open partial horizontal laryngectomy(OPHL) was performed for patients with T2 supraglottic and glottic carcinoma, according to the American Joint Committee on Cancer(AJCC) criteria. Type I OPHL: Entails the resection of the supraglottis, including the pre-epiglottic space and the upper half of the thyroid cartilage. Type II OPHL: Entails the resection of the entire thyroid cartilage, with the inferior limit represented by the upper edge of the cricoid ring. Type III OPHL: Entails the resection of the entire supraglottic, glottic, and part of the subglottic sites, sparing both or at least one functioning crico-arytenoid unit.

The patient, in a sitting position, had to swallow liquid. The tip of a flexible endoscope was positioned beyond the soft palate, and the pharyngeal phase of swallowing was studied, recording videos and images for further analysis. In particular, according to the severity scale, the scores ranged from 1 point (no materials entered the airway) to 8 points (the material penetrated below the vocal cords, but no effort was made to eject the material), representing the severity of risk for penetration

Subglottic pressure was measured while swallowing a thinned solution with and without airflow delivery through the subglottic puncture needle. The unit of subglottic pressure is cmH20.

The EAT-10 questionnaire consists of a 10-item questionnaire with a maximum total score of 40 points. All items are rated on a 5-point scale in which 0 indicates no problem, and 4 indicates a severe problem in swallowing function. An EAT-10 score of over 3 is abnormal and indicates a higher self-perception of the presence of dysphagia.

An early 5-point scoring system (score one corresponding to the early postoperative assessment) was applied to each patient depending on his ability to swallow one to four different textures (liquid, semi-liquid, semi-solid, and solid). A score of 0 is poor (no power to swallow), while a score of 4 is good.

Every participant was asked to phonate a sustained vowel /a/ at a habitual comfortable pitch and intensity for voice pitch, quality assessments, and habitual vocal intensity. The recordings were made in a quiet clinical room. The participant sat in front of a microphone positioned approximately 10cm from the left corner of the mouth. The voice signal coupled with Roland's Audio interface with a sampling rate of 44k-Hz and 16-bit accuracy. The signal was stored in a computer system after collecting sustained vowels. The voice signals were analyzed using speech analysis software. The stable phase of the voice sample was extracted for analysis. The 3,000-msec sample was analyzed for acoustic parameters. The voice acoustic parameters include F0 (fundamental frequency) in Hertz(Hz), percentage of jitter(%), percentage of shimmer(%), Harmonic to noise ratio(HNR), and intensity in decibels(dB).