Needle electromyographic activity of myofascial trigger points and control sites in equine cleidobrachialis muscle–an observational study.

This research article investigates the characteristics of myofascial trigger points in horses, comparing them to normal muscle tissue using electromyographic (EMG) techniques. The study concludes that equine myofascial trigger points exhibit similar signs and electrophysiological properties to those found in human and rabbit skeletal muscle tissues.

Understanding Myofascial Trigger Points

Myofascial trigger points are hypersensitive points found in taut bands of skeletal muscle that cause chronic pain. These trigger points are common in humans and have characteristic signs such as abnormal spontaneous electrical activity, spike activity and local twitch responses. The presence of myofascial trigger points in horses is less studied and their electrophysiological characteristics are not well documented.

Study Design and Methods

• The study involved four horses that showed chronic pain signs and impaired performance. These horses showed symptoms that were consistent with myofascial trigger points in their cleidobrachialis muscle or brachiocephalic muscle.
• The horses were selected for acupuncture treatment. During the acupuncture sessions, EMG activity and twitch responses were recorded at 25 positions at the suspected trigger point and at a nearby control point.

Results and Findings

• The horses demonstrated the key signs associated with myofascial trigger points – spontaneous electrical activity, spike activity, and local twitch responses within taut bands of muscle at the suspected trigger points.
• The frequency of these signs was significantly greater at the trigger points compared to the control sites, providing evidence that these were indeed myofascial trigger points.

Conclusions and Implications

• Like humans and rabbits, horses can also have myofascial trigger points. The study established that these trigger points in horses have similar electrophysiological properties and signs as those documented in human and rabbit skeletal muscle tissue.
• Despite the parallels drawn, the study notes some limitations with its findings particularly in the case of pain patterns. Unlike in human studies, referred pain patterns and the reproduction of pain profiles cannot be determined in animals, which might hinder a comprehensive understanding of myofascial trigger points in the equine population.