Early division of the abducens nerve's prefissural segment: Report of the rarely described variant

The abducens nerve palsy may be associated with various disease processes, as nerve damage may occur at any point of its transit from the pons to the lateral rectus muscle. Our case report presents a rarely described variant of the abducens nerve's cavernous segment and an outline of the potential developmental background of the finding. Early division of the abducens nerve's prefissural segment was found during the cavernous sinus dissection. The nerve was divided into the superior (of 0.68 mm diameter) and inferior (of 0.54 mm diameter) divisions before reaching the superior orbital fissure just after crossing the internal carotid artery. Both divisions entered the orbit separately through the superior orbital fissure. The innervation of the lateral rectus muscle was typical. Early division of the abducens nerve can be defined as the presence of two separate nerve trunks in the anterior cavernous sinus, superior orbital fissure, and orbit. Anatomical variations of the abducens nerve should be kept in mind during diagnostic and surgical procedures.