This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
Most isolated trochlear nerve palsies are due to 
Select and explain. 
A. Idiopathic, B. Closed head injuries, C. Aneurysmal rupture, D. Diabetes mellitus
B: Closed head injuries
Answer: B: Closed head injuries 
Explanation: The most common cause of congenital trochlear nerve palsies is congenital cranial dysinnervation syndrome, followed by an abnormal superior oblique tendon. The most common cause of acquired isolatedfouh nerve palsy, after idiopathic, is head trauma. ... Fouh nerve palsymay become manifest after cataract surgery Ref ganong's review of medical physiology 25e 542