Anisocoria

Hello, I am a 33 yo female, overall good health. I have suffered from right sided headaches for over 12 years.  I do not have a family history of migraine, and did not get them when I was younger. I did have 2 car accidents resulting in concussions when I was a teenager, not sure if thats relevant. The headaches are not throbbing in nature, and I do not get nausea or vomting.  Around 7 years ago I noticed my right pupil was larger than the left. I saw a neurologist and had an MRI/MRA which was fine.  I repeated the MRI/MRA in 2006, again it was fine.  My headaches have returned along with the anisocoria. Both pupils respond briskly and properly to light, always have. I still cant help but worry because I have read online that anisocoria can be caused by an aneurysm. Do you think I have reason to worry?

[Michael J Kutryb, MD]

Welll first, it is likely that an aneurysm would show up on MRI/MRA so that should make you see better.  This is an excellent case for a neuro-ophthalmologist.  Generally an aneurysm affecting the pupil would compress fibers of the third cranial nerve causing an enlarged pupil and sometimes a droopy eyelid and sometimes an eye that turns down and out and does not move properly.  Now you have not determined which pupil is the abnormal one.  Sometimes the larger pupil is the abnormal one due to a third nerve palsy or an adies pupil (generally harmless and usually easily diagnosed by the wormlike slow iris movement and hypersensitivity to weak pilocarpine.)  If the abnormal pupil is the smaller one then Horners Syndrome is a possibility and the affected side usually has a slight droop.  There are several possible causes of Horners.  Finally, there are always some rare situations where tumors or strokes can affect pupil size and there are usually definite findings on the MRI.  In the end you need to see a neuro-ophthalmologist - but the normal scans should help you to sleep better at night.

MJK MD