Management of the Zenker diverticulum: multicenter retrospective comparative study of open surgery and rigid endoscopy versus flexible endoscopy.

BACKGROUND AND STUDY AIM: Zenker's diverticulum is a rare disease that affects quality of life due to dysphagia and regurgitation. This condition can be treated by various surgical or endoscopic methods. PATIENTS AND METHOD: Patients treated for Zenker's diverticulum in three centers in the south of France between 2014 and 2019 were included. The primary objective was clinical efficacy. Secondary objectives were technical success, morbidities, recurrences, and need for a new procedure. RESULTS: One hundred forty-four patients with a total of one hundred sixty-five procedures performed were included. A significant difference was found between the different groups in terms of clinical success (97% for open surgery versus 79% for rigid endoscopy versus 90% for flexible endoscopy, p = 0.009). Technical failure occurred more frequently in the rigid endoscopy group than in the flexible endoscopy and surgical groups (p = 0.014). Median procedure duration, median time to resumption of feeding, and hospital discharge were statistically shorter for endoscopies than for open surgery. On the other hand, more recurrences occurred in patients treated by endoscopy than those treated by surgery, and more reinterventions were required. CONCLUSION: Flexible endoscopy appears to be as effective and safe as open surgery in the treatment of Zenker's diverticulum. Endoscopy allows a shorter hospital stay at the expense of a higher risk of recurrence of symptoms. It could be used as an alternative to open surgery for the treatment of Zenker's diverticulum, especially in frail patients.

Using the relaxation oscillations principle for simple phonation modeling.

Well-known multimass models of vocal folds are useful to describe main behavior observed in human voicing but their principle of functioning, based on harmonic oscillation, may appear complex. This work is designed to show that a simple one-mass model ruled by laws of relaxation oscillation can also depict main behavior of glottis dynamic. Theory of relaxation oscillation is detailed. A relaxation oscillation model is assessed through a numerical simulation using conventional values for tissue characteristics and subglottal pressure. As expected, raising the mass decreases the fundamental frequency and increases the amplitude of vocal fold vibration: for a mass ranging from 0.01 to 0.4 g, F0 decreased from 297.5 to 42.5 Hz and vibrational amplitude increased from 1.26 to 3.25 mm (for stiffness k=10Nm(-1), damping r=0.015 N s m(-1), and subglottal pressure=1 kPa). Stiffness value has the opposite effect. The subglottal pressure controls the fundamental frequency with a rate ranging from 20 to 50 Hz/kPa. The vibrational amplitude is also controlled linearly by subglottal pressure from 0.22 to 0.26 mm/kPa. The range of phonation threshold pressure (PTP) is close to the values currently proposed, that is, 0.1 to 1 kPa and varies with the fundamental frequency. The relaxation oscillator is a simple and useful tool for modeling vocal fold vibration.