Perineural Injection of the Ethmoidal Nerve of Horses.
Authors: Caruso Michael, Schumacher Jim, Henry Robert
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Perineural Injection of the Ethmoidal Nerve in Horses The ethmoidal nerve supplies sensory innervation to portions of the equine paranasal sinuses and nasal cavity, making selective blockade potentially valuable during standing sinonasal procedures; however, its precise anatomical location and accessibility for perineural injection had not been systematically evaluated. Using equine cadaver heads, Caruso and colleagues identified consistent bony landmarks in the rostromedial supraorbital fossa and developed a standardised injection technique employing a 20-gauge spinal needle inserted at a specific 110° angle through a defined anatomical window. The technique proved highly accurate across 30 injection sites, with dye deposited immediately adjacent to the nerve in 27 cases (90%) and within 5 mm in the remaining three, demonstrating reproducibility suitable for clinical application. For practitioners performing sinonasal surgery in standing patients, this reliable blockade technique offers the prospect of selective desensitisation of ethmoidal nerve-innervated tissues, potentially improving analgesia and reducing the requirement for systemic analgesics or excessive local infiltration. The straightforward anatomical approach and high success rate suggest this is a practical addition to the standing equine surgery toolkit, particularly where precision regional anesthesia is needed for procedures involving the paranasal sinuses or rostral nasal passages.
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Practical Takeaways
- •Use a 20G spinal needle inserted at 110° angle into the rostromedial supraorbital fossa (just rostral to where zygomatic process emerges) as a reliable technique for ethmoidal nerve blocks in standing horses
- •This block can improve anesthesia coverage for sinonasal surgical procedures, particularly reducing nociception from paranasal sinuses and nasal passages
- •The technique is simple to perform with high accuracy (90%) when anatomical landmarks are properly identified, making it practical for field or clinical settings
Key Findings
- •Perineural injection technique achieved 90% accuracy (27/30 sites) with dye surrounding the ethmoidal nerve or within 5 mm
- •A standardized injection technique using 20-gauge spinal needle at 110° angle to the head axis reliably deposits local anesthetic adjacent to the ethmoidal nerve
- •The ethmoidal nerve innervates portions of ipsilateral paranasal sinuses and nasal cavity amenable to desensitization