Attempts to restore abduction of the paralyzed equine arytenoid cartilage. I. Nerve-muscle pedicle transplants.

The study investigates the use of nerve-muscle pedicle transplants in horses to restore the function of respiratory-associated muscles that control an anatomical structure found in their throat called the arytenoid cartilage. This technique, which has been previously applied in humans and dogs, involves moving a nerve and its associated muscle from one location to another to reactivate a muscle that has lost its original nerve supply.

Surgical technique adaptation

The research aimed to adapt a surgical technique usually performed on humans and dogs for use on horses. The procedure involves transplanting a part of a muscle (in this case, a respiratory muscle) and its nerve supply to a muscle that has lost its nerve supply due to paralysis. This process could potentially restore motion and function to the affected muscle.

Anatomical dissections

• Seven horses underwent anatomical dissections, which revealed two possible donor nerve-pedicle grafts: the omohyoid and sternothyrohyoid muscle. Both of these muscles are controlled by the first and second cervical nerves.

Histochemical evaluations

• The research also includes histochemical evaluations of the targeted muscles in two ponies, showing similar types of muscle fibers in the three muscles: the dorsal cricoarytenoid, omohyoid and sternothyrohyoid.

Electromyographic studies

• Electromyographic (muscle function) studies showed that the muscles chosen for the donor grafts contracted in sync with the horse’s breathing during forced inspiration under general anesthesia.

Surgical application and follow-up

• The technique was then applied in four ponies, using a section of the omohyoid muscle and its second cervical nerve to reinnervate the left dorsal cricoarytenoid muscle, a muscle that controls the arytenoid cartilage in the horse’s airway.
• Post-surgery observations for 30 weeks provided evidence for the effectiveness of the procedure. Although the control group of ponies showed no movement in their arytenoid cartilage and signs of muscle atrophy, the article abstract ends before the results of the treated group are stated.