A 70-year-old male patient reports sudden onset vertical diplopia. What questions would you ask during the history and symptoms and which are the mostly likely muscles to be affected?

An adage in medicine is that 70% of diagnoses can be made from (good) history and symptom taking alone. In the case outlined in this question there are three important elements: ‘A 70-year-old patient reports sudden onset vertical diplopia.’ The first, the patient is an older person; the second the visual problem is acute; third the diplopia is vertical. The third element tells us that one or more of the extraocular muscles with a vertical action is involved.

A question to ask would be: In which direction of gaze is the image separation the greatest? This will put two muscles in the frame as possible culprits. For example, if the patient reports that greatest image separation occurs looking down and to his right, that puts the left superior oblique and right inferior rectus in the frame. A quick alternating cover test in that direction of gaze will reveal the affected muscle and the affected nerve.

If the patient reports that the greatest separation is when looking up and to the left that puts the right inferior oblique and the left superior rectus in the frame.

Again, a quick alternating cover test in that position of gaze will reveal the affected muscle and nerve. In this case whether it is the right or left third cranial nerve. In my experience, even if the cranial nerve involved innervates more than one muscle, there will be one muscle that under acts to a greater extent than the others.

The acute element tells us that the cause is a sinister one. The age of the patient tells us that this could be an eye problem with an underlying cardiovascular cause. A question on any recent head trauma will, if denied, rule out a superior oblique and fourth cranial nerve problem. Questions about current general health and medication would be useful. Third nerve palsies are the most common reason for vertical diplopia in this age group.