Ultrasound-guided continuous block of median and ulnar nerves in horses: development of the technique.

The study outlines the development of an ultrasound-guided technique to continuously block the median and ulnar nerves in horses. These nerve blocks can be useful in managing chronic pain conditions in horses, and the study demonstrated success in both technique accuracy and pain reduction in two case studies.

Methods

Researchers conducted the study in three defined phases:

• Phase 1: This consisted of dissection of median and ulnar nerves in the antebrachial region of two cadaver limbs to identify localizing landmarks. They used ultrasound to describe the sonoanatomy in 14 cadaver limbs, following which they inserted catheters into six limbs and carried out computed tomography.
• Phase 2: Ultrasound images of the limbs of 18 healthy horses were used to define an acoustic window and to optimize the approach to the nerves. This was to ensure the most effective and accurate method for the procedure.
• Phase 3: Two case reports were presented of horses with chronic pain. The researchers inserted catheters into the site of pain, guided by ultrasound, followed by continuous infusion of a pain solution. These case studies were used to validate the effectiveness of the methods used in the first phases of the study.

Results

The results of phase one were directly used to guide the process in phase two, leading to 100% technique accuracy. In the clinical test cases presented in phase three, the horses showed a reduction in pain, determined by increased weight bearing on affected limbs and less need for other pain medications. There were no local reactions observed.

Conclusions

The technique developed using ultrasound to guide the continuous blocking of the median and ulnar nerves in horses proved successful, both in accuracy and effectiveness. The horses demonstrated no discomfort or infection signs at the site of catheter insertion. However, the researchers conclude that further studies are necessary to fully validate this technique’s efficacy.