Question

The patient came with unilateral Proptosis and bilateral Abducent nerve palsy. This could be from

• A. Cavernous sinus
• B. Orbital cellulitis
• C. Orbital pseudotumor
• D. Orbital lymphoma

Answer 1

The Correct Option is A

The scenario presented involves a patient with unilateral proptosis and bilateral abducent nerve palsy. To deduce the correct cause, we must consider the anatomical and pathological relationships involved.

1. Anatomy and Symptoms: The abducent nerve (Cranial Nerve VI) innervates the lateral rectus muscle, which is responsible for lateral eye movement. If this nerve is impaired on one or both sides, it results in the inability to move the eye laterally, manifesting as abducent nerve palsy. Proptosis, or the protrusion of the eye, suggests an issue within the orbit or surrounding structures.

2. Evaluating the Options:

• Cavernous sinus: This large collection of thin-walled veins sits at the base of the skull, near the pituitary gland. It encompasses the internal carotid artery and several cranial nerves, including the abducent nerve. Lesions or issues in this area (e.g., thrombosis, infection, or tumor) frequently affect these structures, causing symptoms such as unilateral proptosis and bilateral abducent nerve palsy.
• Orbital cellulitis: Typically causes unilateral proptosis due to inflammation but would not usually cause bilateral abducent nerve palsy unless there was widespread infection causing intracranial complications.
• Orbital pseudotumor: This inflammatory condition causes unilateral proptosis, but typically doesn't affect cranial nerves bilaterally as seen in this patient.
• Orbital lymphoma: This can cause unilateral proptosis due to space-occupying lesions but is less likely to cause bilateral nerve issues unless there is extensive intracranial involvement, which is atypical in initial presentations.

3. Conclusion: Given that the involvement is bilateral for the abducent nerve palsy and the presence of unilateral proptosis, the cavernous sinus is the most likely site affected, as it accommodates the structures involved in these specific symptoms.