Standing left recurrent laryngeal neurectomy for prospective evaluation of laryngeal hemiplegia evaluated by a high-speed treadmill test.

This research explores the effects of left recurrent laryngeal neurectomy (LRLn) on horse’s upper respiratory tract function using high-speed treadmill tests (HST). The study successfully performed LRLn on standing horses, and found that it alters respiratory function in a specific way that the researchers were able to measure using HSTs.

Objectives

• The central aim of the research was to describe the procedure of left recurrent laryngeal neurectomy (LRLn) performed on standing horses and evaluate its effect on their upper respiratory tract functionality using a high-speed treadmill test (HST).
• The authors hypothesized that unilateral LRLn could result in a specific type of collapse of the arytenoid cartilage – a structure in the horse’s larynx – and that this could be tested using HSTs.

Methods

• The study was conducted on six Thoroughbred horses. Initially, the horses underwent a baseline HST until they became exhausted.
• Various measurements were made including airflow, pharyngeal and tracheal pressures, and an endoscopic examination of the upper respiratory tract.
• Two specific calculations, the trans-laryngeal impedance (TLI) and the left-to-right quotient angle ratio (LRQ), were calculated after the testing.
• The following day after the baseline test, standing LRLn was performed, and within 4 days, another HST was conducted.

Results

• The researchers managed to perform LRLn without any complications, which resulted in complete paralysis and discernible collapse of the arytenoid cartilage.
• The results also showed that an increase in treadmill speed lead to an increase in TLI (P < .001) and a reduction in LRQ (P < .001), respectively. The neurectomy led to similar outcomes.

Conclusions

• The conclusion drawn from the study is that standing LRLn induces laryngeal hemiplegia, a specific condition that can be assessed using a HST shortly after the surgical procedure.
• The study suggests that standing LRLn could be used in future evaluations of surgical interventions for laryngeal hemiplegia.