A variation of the infraorbital nerve: its potential clinical consequence especially in the treatment of trigeminal neuralgia: case report.

Objective: We report the case of a seemingly rare variation of a branch of the trigeminal nerve. This unusual finding is of practical importance to the neurosurgeon because ablation of this nerve(s) in such a case would require modification of technique. The existence of a bifurcated infraorbital nerve is also relevant for application of local anesthesia to portions of the face innervated by the maxillary nerve.

Clinical Presentation: During cadaveric dissection of the face of a male specimen, 2 branches of the infraorbital nerve were identified emanating onto the face. The 2 branches entered separate osseous canals within the orbit to emerge via 2 infraorbital foramina.

Intervention: The unusual variation of the trigeminal nerve branch in the reported case necessitates a change in the way in which the nerve is blocked clinically. A common practice involves blocking the infraorbital nerve as it emerges from the infraorbital foramen. The needle is aimed superiorly, posteriorly, and slightly laterally; however, to provide adequate anesthesia to both branches of the infraorbital nerve, as reported here, a needle can be inserted between the zygomatic arch and the notch of the mandible in the pterygopalatine fossa. After the needle contacts the lateral pterygoid plate, it is withdrawn slightly and angled both superiorly and anteriorly to pass into the pterygopalatine fossa.

Conclusion: Although apparently uncommon, such derangement of the infraorbital nerve should be kept in mind by surgeons during surgical procedures in the region for treatment of various disorders including trigeminal neuralgia.