Computed tomographic geometrical analysis of surgical treatments for equine recurrent laryngeal neuropathy.

The research investigates the 3D geometry of a horse’s larynx experiencing laryngeal hemiplegia and four different surgical interventions using CT scans. The study aims to establish the relationship between airflow geometries and impedance for each surgical procedure.

Research Methodology:

In the study, the researchers performed various procedures and experiments:

• The research included 10 cadaveric horse larynxes as their test sample.
• Using CT scans, the researchers replicated the conditions of inhalation during exercise for each of the five scenarios: laryngeal hemiplegia; left laryngoplasty with ventriculocordectomy; left laryngoplasty with ipsilateral ventriculocordectomy and arytenoid corniculectomy; corniculectomy; and partial arytenoidectomy.
• They measured laryngeal impedance and selected cross-sectional areas along each larynx for each test.
• Finally, the measured areas and constriction characteristics were analyzed in connection with impedance using a multilevel, mixed-effects model.

Research Findings:

The findings from the conducted experiment were as follows:

• The study found that factors such as incident angle, entrance coefficient, outlet coefficient, friction coefficient, orifice thickness, and the surgical procedure had a significant association with upper airway impedance based on a bivariable model.
• In the multivariate model, it showed a significant influence of incident angle, entrance coefficient, and surgical procedure on impedance. Meanwhile, the orifice thickness became nonsignificant.

Research Conclusion:

The study concluded the following:

• Laryngeal impedance was found to be significantly associated with the entrance configuration for each surgical procedure.
• It suggested that even though the equine upper airway has complex geometry, it still adheres to fluid dynamic principles that apply to constrictions within pipe flow.
• The underlying flow characteristics might explain the clinical outcomes observed in some patients and lead to areas of improvement in the treatment of obstructive upper airway disease in horses.