Orbital Apex Syndrome

Excerpt

The orbital apex disorders include superior orbital fissure syndrome, cavernous sinus syndrome, and orbital apex syndrome. Though these disorders have been described separately based on the anatomical site of involvement and clinical features, the evaluation and management of these conditions are almost alike.

Orbital apex syndrome (OAS), also called Jacod syndrome, is a complex neurological disorder characterized by a constellation of signs resulting from multiple cranial nerve involvement. The typical clinical features are attributed to the involvement of the orbital apex by various neoplastic, vascular, infectious, or inflammatory conditions. They primarily involve one of the adjacent structures like the paranasal sinuses or the orbit from which they spread to the orbital apex. Hence, understanding the etiology of the orbital apex syndrome with early recognition and swift treatment may help reduce associated comorbidities.

Anatomy of the Orbital Apex

The orbital apex is an opening connecting the orbit and the cranial cavity. The roof of the orbital apex is contributed by the lesser wing of the sphenoid, the lateral wall by the greater wing of the sphenoid, the medial wall by the ethmoidal sinus, and the floor by the orbital plate of the palatine bone. The bony orbital apex consists of the optic canal superomedially and the orbital apex inferolateral. The contents of the optic canal include the optic nerve, ophthalmic artery, and the postganglionic sympathetic fibers from the carotid plexus.

The intracanalicular part of the optic nerve is present above the orbital apex, passes through the optic canal, and runs to the posteromedial optic chiasm. The middle portion of the superior orbital fissure contains the cranial nerves III, IV, and VI and the ophthalmic division of the trigeminal nerve (V1). The annulus of Zinn is a fibrous chord located superior and medial to the superior orbital fissure. The annulus of Zinn is the common origin of the four rectus muscles and contains the optic nerve and ophthalmic artery in the optic foramen.

Knowledge of the anatomy of the orbital apex and its contents is essential to diagnosing and managing orbital syndromes.