Walsh & Hoyt: Acquired

When an etiology can be determined, blunt head trauma, usually a direct orbital, frontal, basal, or oblique cranial blow, is the most common cause of isolated, acquired, unilateral and bilateral trochlear nerve palsy in both adults and children. As with other ocular motor nerve palsies, almost any pathologic process can damage the trochlear nerve at any point from its nucleus to its termination in the orbit where it innervates the superior oblique muscle. Lesions of the trochlear nerve nucleus. Lesions of the trochlear nerve fascicle. Lesions of the trochlear nerve in the subarachnoid space. Lesions of the trochlear nerve within the cavernous sinus and superior orbital fissure. Lesions of the trochlear nerve within the orbit. Lesions of the trochlear nerve of uncertain or variable location. Recovery from acquired trochlear nerve palsy.