Ep 134: A 72-Year-Old Man with New-Onset Seizures
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This is Katarina Heidhausen, Executive Editor of Harrison's Principles of Internal Medicine. Harrison's Pod Class is brought to you by McGraw-Hills Access Medicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. Hi, everyone. Welcome back to Harrison's Pod Class. We're your co-hosts. I'm Dr. Kathy Handy. And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. Welcome to Episode 134, A 72-Year-Old Man with Seizures.

Kathy, today's patient is a 72-year-old man who was brought to the emergency department by ambulance after apparently having a seizure at home. He's currently somnolent and when aroused is disoriented. His vital signs are notable for an irregular heart rate of 90 to 100 with a blood pressure of 160 over 90, normal respirations, and normal oxygen saturation. He cannot cooperate with a full neurologic examination but appears to have a left hemiparesis.

His wife reports that while watching a football game, he fell out of the couch and developed a seizure involving his entire body. She does not know how long the seizure lasted, but it was finished by the time the emergency medical system arrived. He has a past medical history only notable for hypertension, and his only medication is amlodipine. All right, so today let's start talking about seizures. There are some new developments in this area that we should discuss before we get to our patient here.

Okay, well, let's start with definitions. What's the difference between seizure and epilepsy? Are they the same thing? No, and that's an important distinction. A seizure, which comes from the Latin word cesare, I think that's how you pronounce it, which means to take possession of, is a transient occurrence of signs or symptoms due to abnormal, excessive, or synchronous neuronal activity in the brain.

Depending on the distribution of discharges, this abnormal brain activity can have various manifestations, and that ranges from dramatic convulsive activity to experiential phenomenon not readily discernible by an observer. Approximately 5 to 10 percent of the population will have at least one seizure, with the highest incidence occurring in early childhood and late adulthood. Okay, so seizures are pretty common. What about epilepsy?

Epilepsy describes a condition in which a person has a risk of recurrent seizures due to a chronic underlying process. This definition implies that a person with a single seizure or recurrent seizures due to correctable or avoidable circumstances does not necessarily have epilepsy.

That being said, a single seizure associated with clinical or EEG features pertaining high risk of recurrence may establish the diagnosis of epilepsy. Furthermore, epilepsy is not a single disease entity. It refers to a clinical phenomenon. There are many forms and causes. In contrast to seizure, the prevalence of epilepsy is much lower at less than 3%.

Great. Any additional background we should know before we get to the questions about this patient or about the topic? Yes, one last thing. There has been some change in the terminology describing seizure syndromes. A fundamental principle is that seizures may be either focal or generalized.

We no longer use the term partial seizures. Focal seizures are often associated with structural abnormalities of the brain. In contrast, generalized seizures may result from cellular, biochemical, or structural abnormalities that have a more widespread distribution.

We also no longer use the term simple focal seizures or complex focal seizures. Instead, the new classification emphasizes the effect on awareness, so that's either intact or impaired, and the nature of the onset, such as motor or non-motor. Focal seizures can also evolve into generalized seizures.

In the past, this was referred to as focal seizures with secondary generalization, but the new system relies on descriptions of the type of generalized seizures that evolve from the focal seizure. Generalized seizures can be motor or non-motor.

Okay, so the terminology, I guess, is trying to get more specific in terms of the descriptions. And it sounds like our patient had a generalized tonic-clonic seizure from the spouse's description. Yeah, and these are the most common form of seizures, accounting for about 10% overall. And now he's likely in a postictal state, which can last minutes or even up to hours. Okay, so that gets us to the question. And the question is going to ask, in this patient, which of the following is the most likely etiology of his seizure?

Option A is amylodipine. Option B is an embolic stroke. Option C is hypoglycemia. Option D is a subdural hemorrhage. And option E is a thrombotic stroke.

Interesting. Okay, first I'm going to rule out option A, amlodipine. There are a large number of commonly used medications that are associated with seizures. Some of those would include antimicrobials, analgesics, psychotropic medications. To my knowledge, the calcium channel blockers are not implicated. Also recall that withdrawal from alcohol, recreational drugs, and some sedatives can also cause seizures. Okay, well what about the others then?

Well, all of the others are definitely associated with seizures. Any kind of head trauma, including a subdural hemorrhage, can lead to a tonic-clonic seizure. Head trauma is a common cause of epilepsy in adolescents and young adults. Also, a variety of metabolic insults, such as uremia or liver failure, can result in seizures. Hypoglycemia is definitely a cause, but I'm going to rule that out because EMS should have checked that on their initial screen, and patients with any suspicion of hypoglycemia are given glucose.

Okay, well that leaves us with an embolic or thrombotic stroke. That seems more likely given it's hemiparesis anyway. Yes, the causes of seizures in older adults such as our patient include cerebral vascular disease, trauma, and I've already mentioned subdural hematoma, CNS tumors, metabolic disorders, and degenerative diseases. Cerebral vascular disease may account for about 50% of new cases of epilepsy in patients over 65.

A seizure occurring at the time of the stroke is more likely due to an embolic rather than hemorrhagic or thrombotic stroke. Chronic seizures typically appear months to years after the initial event and are associated with all forms of stroke. So this man was at risk of thrombotic or hemorrhagic stroke due to his hypertension.

Yes, but I'm worried that he may have had recent asymptomatic intermittent atrial fibrillation that was picked up on initial exam with the irregular heart rate. Given that, plus his presentation, I'm going to say that the best answer is B, an embolic stroke. But if this were an exam, I'd also have to be open to option E, a thrombotic stroke. In either event, he needs an immediate CT scan. Okay, he's not seizing now, but do you want to say something about his treatment?

It's a huge area that we don't have time for in this episode, but let me say that ongoing seizures are best initially treated with intravenous benzodiazepines. Anti-seizure drug therapy should be started in any patient with recurrent seizures of unknown etiology or a known cause that cannot be reversed.

Whether to initiate therapy in a patient with a single seizure is controversial. Patients with a single seizure due to an identified lesion, such as a CNS tumor or infection, a structural defect or trauma, in which there's strong evidence that the lesion is contributing to epilepsy, should be treated. Lamotrigine and valproic acid are common first-line therapies, but the choice of medication is best discussed with a specialist.

Okay, well, let's finish there for now. We may revisit this sometime in the future. Today's teaching points are that seizures should be characterized initially as either focal or generalized. In older adults, the most common causes of new seizures are tumors, head or CNS trauma, metabolic disorders, degenerative disorders, or stroke. Within strokes, embolic strokes are a more common cause of seizures than thrombotic strokes.

If you liked this episode, you can find this question and others like it on Harrison Self-Review, and you can read more about this in the chapter on seizures and epilepsy. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on Access Medicine. If you enjoyed this episode, please leave us a review so we can reach more listeners just like you. Thanks so much for listening.