This has gone around the science blogs already, but as a practicing neurologist I thought I should weigh in. Moving Meet seems to have started the rumor, and Neurotopia has also added to the speculation.  Some people have just noticed that presidential candidate John McCain has left ptosis – which is a slight drooping of his left eyelid. From this they speculate that he may have had a stroke, or worse a brain tumor.

Orac has already done a fine job of dissecting this claim, pointing out that there are many causes of ptosis, most of which are benign. The one correction I would make (which is not his fault as he lifted it from a reliable resource) is that forehead Botox (the location of treatments used for cosmetic purposes) does not cause eyelid ptosis. It may cause brow ptosis (drooping of the brow, which is not what McCain has) but not lid ptosis. Injections of the eyelids themselves for things like blepharospasm (involuntary blinking) can cause lid ptosis. It would take ridiculously poor technique to cause lid ptosis from a forehead injection.

First, I think it is very irresponsible for non-specialists to speculate in public about the significance of a physical finding they don’t understand. It seems that the purpose is to generate rumors disguised as speculation.

Further, the medical information in the speculation was quite poor. Isolated ptosis would be an extremely uncommon presentation of a stroke or tumor, other signs would almost certainly be present. Ptosis is most often physiological – meaning normal for that person. This type of ptosis can also come and go, so it may be more noticable at some times than at others.

I see patients with ptosis all the time. It is ususally benign. The first thing I do is ask if it is old, and if possible look at old pictures to see. If the ptosis has been present for a long time we don’t worry about it. If it is new, then we rely upon other exam findings to determine the location of the problem and the cause.

Some have speculated that McCain also has subtle left facial droop. I don’t think he has, and Orac pointed out that his prior surgery can explain the subtle asymmetry. This is a good example of the perils of speculating based upon some information, but lacking expertise. A stroke causing facial weakness would not cause lid ptosis. It may cause drooping of the lower eyelid – but not the upper eyelid. There are two locations where a stroke can cause lid ptosis – the brainstem and the sympathetics along the carotid artery. In the case of a third cranial nerve involvement causing ptosis, there would also be problems with eye movements and pupil size. If the ptosis were due to a lesion in the carotic artery (which in turn caused a stroke), where the sympathetic fibers to the eyelid travel, then that could occur with a stroke on the same side – but then the weakness would be on the opposite side, which he does not have. The same would apply to a tumor or any cause.

Is the ptosis old? I have looked through many pictures of McCain, including many good closeups of his face, an they all show left sided ptosis to varying degrees. This is an old finding, and therefore of no signficance. People just did not notice it before. I am trained to notice even subtle ptosis, and often I will find it in patients who were not even aware of it themselves. Also, the ptosis appears to be more prominent in some pictures than in others, so it varies and was probably just more noticeable than usual that day.

The probable political motivation for the speculation asside, what this episode shows is that expertise matters. Having most of the information, but not all, and not having the experience to put it into a meaningful context, often means coming to a wrong or misleading conclusion, and having unwarranted confidence in that error.