alternating anisocoria

Hi there wondering if you can help, about 4 years ago i suddenly developed anisocoria in left eye after a recent fall where i really jolted my spine and neck it was eventually diagnosed as a horner's syndrome after cocaine eye drop test and i was sent for firstly a cta scan of carotid and vertebral arteries which was fine although by time i was sent for scan symptoms seemmed to be improving.I was also sent for further brain mri 2 months later as iwas continuing to have dizzy spells and visual jumps as well but it came back completely normal.Soon after this a really weird thing happened the pupil that had been the small(horner's) pupil suddenly became the lager pupil and the normal pupil became the smaller one especially in dark and it stayed this way until recently where it has reversed again and now it is back the way it was 3 years ago.I am baffled at this alternating anisocoria and possibly alternating horners and so are my doctors as i also had complete upper ct body scan  which was completely clear apart for swollen lymph nodes and an eventually axillary biopsy which proved negative,i am going back to gp again  but can anybody shed any light on this,thanks paolo

[Michael J Kutryb, MD]

Very interesting case - and very difficult to diagnose the cause.  It sounds like you have undergone and extensive workup and I don't have much to add.  Thankfully, you don't appear to have a tumor or aneurysm or carotid dissection so that is a major blessing.  I would concentrate on that good news for now.  I've dealt with a few very mysterious cases of Horner's Syndrome and sometimes never find the cause.  Thank God, no serious problems found at this point.

MJK MD

[Michael J Kutryb, MD]

Also, anisocoria is tougher to pin down sometimes than you might think.  I would be sure you had an experienced neuro-ophthalmologist diagnose which pupil is abnormal before you assume which  one is.  If well trained they can pick up subtle differences that a neurologist wouldn't notice.  So being contrarian - perhaps the abnormal pupil didn't change - just fooled untrained examiners possibly?

MJK MD

[paolo2142]

Hi there thanks Dr Kutryb, i was wondering if you could tell help me further i was under the impression that an aneurysm would cause one of the pupils to enlarge/dilate and not react/contract well to light wheras my pupils both react briskly to light and also enlarge and contract normally except the smaller pupil does not dilate as quickly or as much in dark,thanks paolo.

[Michael J Kutryb, MD]

Yes, that's right if it pressed on the 3rd cranial nerve.  I just threw it in there as another pathology that could affect pupils - they can occur in other locations also with other symptoms and other effects on pupils.  Just  one of many possible causes of pupillary abnormalities.

MJK MD