I have received many questions from friends, family, and over e-mail in the last day about the nature and implications of John Roberts’ seizure. Of course, I don’t have any more specific medical information than is available in the general media. But I can give general information about seizures that will help put Roberts’ situation into perspective.

A seizure is an event – an episode of abnormal electrical activity in the brain. Seizures come in many flavors, largely depending upon what part of the brain the abnormal electrical activity is in. Partial seizures only involve part of the brain, while generalized seizures involve the entire brain. Partial seizures may (which are called “complex”) or may not (“simple”) impair consciousness, and they also may or may not secondarily generalize.

The media reports indicate that Roberts fell to the ground as a consequence of his seizure, was shaking and foaming at the mouth. This sounds like a generalized seizure. It is not possible from this information to tell if the seizure was primarily generalized or started out as a partial seizure and then later generalized.

Epilepsy is the tendency to have recurrent unprovoked seizures. Roberts had his first seizure in 1993. Yesterday’s seizure was his second – 2 seizures buys the diagnosis of epilepsy. You will note that I qualified my definition as “unprovoked” seizures. This is because anyone can have a seizure, if the brain is stressed sufficiently. Sleep deprivation, certain drugs, alcohol use or withdrawal, high fever, oxygen deprivation, low blood sugar and other metabolic derangements can all trigger seizures even in those without epilepsy.

What causes someone to have a seizure? Well, the list of specific causes is long, and it does depend on the kind of seizure. Primary generalized seizures, those that start all over the brain at once, are caused by some defect in brain function or by the entire brain being subjected to an unfriendly environment (like the things I listed above).

Partial seizures start in one part of the brain and therefore can be caused by a focal defect in the brain. These types of seizures are more concerning because they can be caused by tumors, strokes, and bleeds in the brain. They can also be caused by scar tissue in the brain left behind by prior trauma or infection. However, often they are “idiopathic” which means no specific cause can be found. Sometimes a piece of the brain is just wired badly and is producing abnormal electrical activity that occasionally sparks a seizure.

Reports indicate that Roberts had a “neurological evaluation” that did not reveal anything concerning. This is deliberately vague, probably just to protect Chief Justice Roberts’ privacy. A typical evaluation would include an MRI scan of the brain to look for any focal abnormality, an EEG (electroencephalogram) to look for abnormal electrical activity, and blood work to look for any metabolic abnormality that can lower seizure threshold. So I would presume that this workup was negative.

Reports are calling Roberts’ condition as “benign idiopathic epilepsy.” The term “benign,” while arguably accurate, is not generally used in reference to epilepsy and I suspect it was added to soften the sound of the diagnosis. The term “idiopathic,” as I stated, is a fancy way of saying we don’t know what is causing it. Interestingly, there is a special nomenclature for epilepsy and the term idiopathic actually refers to epilepsy that is caused by a genetic predisposition. This is usually determined by having a family history of seizures. For seizures that have absolutely no known cause the term “cryptogenic” is used instead. So in the news reports the term idiopathic was used in its traditional definition, but not the one used in epilepsy. (This is a minor point of no real significance.)

It is odd that Roberts had two seizures 14 years apart. This is not unheard of, just not very common. He went 14 years without treatment and without any further seizures, then had another seizure. It is possible that he was sleep deprived or there was some other factor that lowered his seizure threshold, and generally his risk of seizures is low. This means that he likely has a very mild form of epilepsy, meaning that his threshold for having seizures is moderately lower than the general population.

As noted in the news reports, after two seizures the risk of having a third seizure is 60%. This is generally considered high enough to treat with anti-epileptic medication, but such decisions have to be individualized. While 60% of people go on to have a third seizure, 40% do not. Roberts and his doctor may decide that having one seizure every 14 years is better than taking a daily medication to prevent them. Epilepsy medication, while generally safe and effective, does suppress brain activity and can cause some sedation or a sluggishness of thought processes. This is not a good side effect for patients in an intellectually high functioning job – and I think Chief Justice of the Supreme Court qualifies.

Given the negative workup (assuming the public is being given all the information) and the fact that Roberts is generally healthy and has gone 14 years between seizures it is my professional guess that he will likely not take medication, and he will do just fine. I do not anticipate this interfering with his job as Chief Justice. There is a small chance that something has changed in Roberts brain and for some reason he will start to have more frequent seizures. In this case he will need treatment. He may be lucky and get away with a low dose of one of the more benign antiseizure medications – this is even likely, assuming he needs medication at all. But there is a small chance that in order to control his seizures he will require enough medication to cause significant side effects.

It is likely, however, that Roberts will not be significantly hampered by his condition.