Reliable Anatomic Landmarks to Avoid Trochlea Injury during Anterior Skull Base Surgery

Introduction: The biorbitofrontal craniotomy is a versatile and well-recognized approach to anterior midline skull base lesions which involves a bifrontal craniotomy in conjunction with a biorbital or biorbitonasal bar. The trochlea, the cartilaginous pulley, through which the superior oblique muscle loops for its functionality, is located within the superior medial orbit. The trochlea is in very close proximity to the orbital bar osteotomies, typically made just medial to the supraorbital notch for the biorobitofrontal craniotomy. Hence, the trochlea remains at high risk, with diplopia and ocular dysmotility possible complications of this approach.