Surgical anatomy of the labyrinthine and subarcuate arteries and clinical implications.

Abstract Objective To study the surgical anatomy of the labyrinthine artery (LA) and the subarcuate artery (SA) their anatomical relationships, and clinical implications as injury of the LA can result in hearing loss. Methods Ten formalin-fixed latex-colored specimens were studied (twenty sides). After a retrosigmoid craniotomy and neurovascular dissection under microscopic magnification, a 4-mm, 0o and 30o endoscopic lenses were used to improve visualization. Results were statistically analyzed. Results The LA was a constant artery that followed the vestibulocochlear nerve into the internal auditory canal. The SA was an inconstant artery that ended in the dura mater around the subarcuate fossa in 35% of cases. The LA originated from the AICA in 89.3% of specimens and from the basilar artery in 10.7%. The SA branched off from the AICA when present. The origin of the LA was inferomedial to the vestibulocochlear nerve in most cases (71.4%) whereas the SA was usually lateral (70%). The distal portion of the LA was inferomedial to the vestibulocochlear nerve in 71.4% of cases. The distal portion of the SA was superolateral to the nerve in all cases (p Conclusion Knowledge of the different trajectory and anatomical relationship of the LA and the SA with the vestibulocochlear nerve is of paramount importance to differentiate them during surgery. The LA is usually inferomedial to the vestibulocochlear nerve at its distal and proximal aspects, whereas the SA usually originates lateral and ends superolateral to the nerve.