Diseases of the Orbit MCQs

Early vision loss; visual loss is early in orbital apex syndrome as apex has optic canal optic nerve also Orbital apex syndrome (inflammation of the posterior orbit, including the superior orbital fissure through which cranial nerves III, IV, V, and VI and the superior ophthalmic vein traverse, as well as the optic canal involving the ophthalmic artery and optic nerve and characterized by less edema and proptosis but more vision loss than cavernous sinus thrombosis) Reference: Parson 21st edition pg 476

Total ophthalmoplegia: In this condition all extraocular muscles including LPS and intraocular muscles, viz., sphincter pupillae and ciliary muscle are paralysed. It results from combined paralysis of third, fourth and sixth cranial nerves. It is a common feature of orbital apex syndrome and cavernous sinus thrombosis. Reference: A k Khurana, 5th edition, Pg: 333.

Cavernous sinus thrombosis; diplopia occurs because of 6th nerve involvement in cavernous sinus Nasal congestion suggests it might be sinusitis leading to orbital cellulitis and finally to cavernous sinus thrombosis Cavernous sinus thrombosis is usually caused by a bacterial infection that spreads from another area of the face or skull. Many cases are the result of an infection of staphylococcal (staph) bacteria, which can cause: sinusitis Reference: Parson 21st edition pg 482

Common malignant lymphoproliferative lesions in the orbit include non-Hodgkins lymphoma and myeloma and these commonly present with insidious subacute mass effect rather than pain and vision loss, as can be seen with idiopathic orbital inflammation and some epithelial malignancies. Reference: Kanski, 8th Edition, Page no. 13.

Thyroid eye disease may be associated with other autoimmune manifestations such as myasthenia gravis. Both Parinaud's dorsal midbrain syndrome and eczema may cause eyelid retraction, but are not closely related to thyroid eye disease. Myotonic dystrophy causes ptosis and is not closely related to thyroid eye disease. Reference: Kanski 8th edition/82-84

Thyroid-related orbitopathy is an immunologically related inflammatory condition that affects orbital tissues, particularly the extraocular muscles. The most common cause for unilateral orbital proptosis in an adult is thyroid-related orbitopathy. Even though the clinical finding may indicate a unilateral problem, a CT scan or MRI often show bilateral disease. The CT findings consist of fusiform enlargement of the extraocular muscle, commonly the inferior and medial rectus muscles, with sparing of the tendons. Reference: Kanski 8th edition/82-84

The inferior rectus is most commonly involved in thyroid eye disease, followed by the medial rectus and superior rectus. The sequence of muscle involvement - I M SLOw. ( pneumonic ) I - IR M - MR S -SR L - LR O - obliques Reference: Kanski 8th edition/82-84

In children it is orbital cellulitis Reference: Parson 21st edition pg 484