Investigation into intraoral approach for nerve block injection at the mental foramen in the horse
Authors: Eckert R. E., Griffin C. E., Cohen N. D., Marx S.
Journal: Equine Veterinary Education
Summary
# Editorial Summary: Intraoral Mental Foramen Nerve Block in Horses Dental work on standing, sedated horses relies heavily on effective regional anaesthesia, yet the standard transcutaneous approach to the mental foramen often proves poorly tolerated in clinical practice. Eckert and colleagues evaluated an alternative intraoral needle insertion technique using CT imaging in 15 equine cadaver heads and two live horses, systematically testing Tuohy needle placement and contrast medium distribution at varying volumes (3, 6, and 10 mL) with and without digital occlusion of the mental foramen. All injections achieved correct needle placement within the mandibular canal with reliable retrograde flow regardless of occlusion status or volume, though the 10 mL group demonstrated greater flow distance; notably, 79% of specimens receiving 10 mL showed contrast medium reaching the fourth premolar region, suggesting utility for more rostral cheek tooth procedures. The study precisely located the mental foramen at approximately 60–80% of the distance along the interdental space between the lateral corner incisor and second premolar, providing anatomical landmarks for consistent needle positioning. This intraoral approach offers practitioners a patient-friendly alternative to transcutaneous mental nerve block that maintains efficacy for incisive procedures whilst potentially extending anaesthetic coverage to rostral premolar teeth, though further clinical trials are warranted to confirm safety and efficacy in standing horses.
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Practical Takeaways
- •The intraoral approach to mental foramen nerve block offers a potential alternative to transcutaneous injection, which may improve patient tolerance during standing dental procedures
- •This technique could simplify nerve blocks for incisive tooth procedures and may extend coverage to more rostrally located cheek teeth (PM4 region) with 10 mL injection volumes
- •Anatomical consistency of mental foramen location in the interdental space provides reliable landmark for intraoral needle placement without fluoroscopy in clinical practice
Key Findings
- •Intraoral Tuohy needle placement at the mental foramen was successfully achieved in all 15 cadaver heads and 2 live horses using CT verification
- •Retrograde flow of contrast medium into the mandibular canal was accomplished with all injection volumes (3, 6, and 10 mL) regardless of digital occlusion
- •79% of injections with 10 mL contrast medium achieved retrograde flow to PM4 position, suggesting utility for proximal cheek teeth blocks
- •Mental foramen consistently located in distal third of interdental space (60-80% of distance between lateral corner incisor and second premolar)