Orbital syndromes.

The orbit is a complex anatomical structure with unique properties not observed in other regions of the body. Composed of seven bones, the orbit is filled by the eye, optic nerve, lacrimal gland, extraocular muscles, peripheral motor and sensory nerves, fat, arteries, and veins. All these structures are intimately related to one another within an intricate framework of connective tissue. A variety of traumatic, vascular, inflammatory, infectious, and neoplastic processes can affect the orbit and its structures. Aside from the many primary orbital diseases, systemic disorders and pathological processes from neighboring structures (eye, ocular adnexa, oral cavity, paranasal sinuses, and intracranial cavity) can involve the orbit. A careful history and complete physical examination, with special attention to the orbit and ocular adnexa, are required to identify subtle orbital abnormalities that otherwise could be overlooked or mistakenly contributed to a nonorbital process. This article reviews the pertinent orbital anatomy, discusses the clinical evaluation and manifestations of orbital syndromes, and highlights several important orbital syndromes germane to the neurologist, including thyroid-associated orbitopathy, nonspecific orbital inflammation (also known as inflammatory orbital pseudotumor), perineural orbital invasion of cutaneous squamous cell carcinoma, rhino-orbital-cerebral mucormycosis, and carotid-cavernous sinus fistula.