Diagnostic sensitivity of subjective and quantitative laryngeal ultrasonography for recurrent laryngeal neuropathy in horses.

This research article explores the efficiency of subjective and quantitative laryngeal ultrasonography in detecting Recurrent laryngeal neuropathy (RLN), a leading cause of laryngeal hemiplegia in horses, responsible for muscular atrophy and impaired respiratory function. The study, involving 154 horses, validates the use of ultrasonography to determine RLN and its impact on a horse’s performance.

Research Context

• The research focuses on Recurrent laryngeal neuropathy (RLN), an ailment which causes neurogenic atrophy of the intrinsic laryngeal muscles in horses, most notably the cricoarytenoideus lateralis muscle. This disease usually leads to temporary or permanent paralysis of the vocal fold and arytenoid cartilage, severely compromising respiratory function and hence the performance of the horses.

Research Methods

• The study uses subjective and quantitative laryngeal ultrasonography, a non-invasive imaging technique, to detect RLN. The technique visualizes the physical and functional state of the horses’ larynx. Ultrasonographic parameters recorded include cricoarytenoideus lateralis echogenicity (subjective and quantitative), thickness of the same muscle, vocal fold movement, and arytenoid cartilage movement.
• The recorded ultrasonographic parameters are then contrasted with laryngeal grades determined through a standard resting and exercising upper airway endoscopy.

Key Findings

• The study uncovers that increased left cricoarytenoideus lateralis echogenicity, as observed through subjective ultrasonography, had a high sensitivity (94.59%) and specificity (94.54%) for detecting RLN when compared with results from the reference standard exercising laryngeal endoscopy.
• The quantitative values of left cricoarytenoideus lateralis echogenicity varied across resting laryngeal grades from I to IV. This implies that the level of RLN can affect the muscular architecture in a way observable through ultrasonography.

Interpretation and Implications

• The research substantiates previous findings about the value of subjective and quantitative laryngeal ultrasonography as RLN diagnostic tools. Such non-invasive techniques are crucial for the early detection and management of RLN, especially given the crippling impacts of the disease on a horse’s athletic performance.
• Furthermore, high sensitivity and specificity percentages signify the strong potential of ultrasonography in correctly diagnosing and ruling out RLN among horses. This validates the process as a critical diagnostic tool for veterinarians to evaluate horses presenting with performance issues suspected to have arisen from upper airway disease like RLN.