Transconjunctival approach to the ethmoidal nerve in the cat: a cadaveric study.

Transconjunctival ethmoidal nerve block achieved 91% target success in feline cadavers.

This cadaveric study describes a novel transconjunctival approach to the ethmoidal nerve in cats, which could facilitate regional anesthesia for ophthalmic procedures. The researchers used 13 feline cadavers to develop and evaluate an injection technique employing an arc-bent 24-gauge needle directed toward the ethmoidal foramen. CT imaging and anatomical dissection initially mapped the ethmoidal nerve course in two cadavers. Methylene blue or radiologic contrast was injected into the peribulbar region, with success assessed by nerve staining and contrast distribution patterns. The technique successfully reached the target ethmoidal nerve in 91% of cases, with comparable results between the two marker substances. Secondary outcomes revealed optic nerve staining in 55% and intraconal migration in 36% of injections, though no intracranial extension or ocular damage occurred. The findings suggest the transconjunctival approach is anatomically feasible in cats, though the relatively high rates of optic nerve involvement warrant further investigation into clinical safety and efficacy before potential application in living animals.

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