Comparison of two approaches to performing an inferior alveolar nerve block in the horse.

This research paper compares two methods for performing the inferior alveolar nerve block in horses and evaluates the accuracy of used topographical landmarks. It concludes that both methods are equivalently accurate, and the identified landmarks for the mandibular foramen’s location are precisely accurate.

Research Methods

The researchers used the following methods:

• An experimental cadaver model was used which comprised of eleven horse heads. They were positioned to mimic a standing sedated horse.
• Approximation of the position of the mandibular foramen was carried out on these model horse heads.
• Two different techniques of inferior alveolar nerve block were performed. The vertical approach was carried out first, and red dye was used to mark the attempted location. Then, the angled approach was performed where a blue ink was used instead.
• After the approaches were performed, the model heads were dissected to reveal the exact location of the dye, and thus the accuracy of each approach. Hits and misses with each technique were recorded on both sides of the head.
• Measurements of the distance between the dye (which would represent the block injection) and the nerve were noted.
• Straight lateral radiographs were taken of the sectioned heads for further evaluation of the topographical landmarks utilized for the nerve block.

Results

The results of the research can be summarized as follows:

• Each method was performed 22 times (once on each side of the 11 cadaver heads). The angled approach hit the target 16 times (73%) while the vertical method was successful in 59% of attempts (13 hits).
• No significant difference in accuracy was found between the two methods; the P value was found to be 0.34.
• Through the radiographs, it was observed that the topographical landmarks used to approximate the mandibular foramen were accurate, therefore providing a reliable method for locating this position.

Conclusions

At the end of the research, a few conclusions were made:

• Both the angled and vertical approach are essentially equivalent in accuracy with no significant difference found between them.
• The topographical landmarks that have been traditionally used to locate the approximate position of the mandibular foramen are accurate.
• The currently recommended doses of local anaesthetic may be excessive, which suggests a need for further review in this aspect.