Epilepsy
Episode #9 of the course Introduction to clinical neuropsychology by Alicia Nortje
Welcome to Lesson 9, where we will learn about epilepsy. In today’s lesson, I’ll introduce you to some of the key terms that are used to describe epilepsy, as well as the different types of epilepsy syndromes. Diagnosing epilepsy is a bit different for a neuropsychologist because we’re not able to test for this condition using tests like reading or memory. Instead, a neurologist will assist with the assessment of this patient by administering an EEG. Part of the difficulty with diagnosing epilepsy is that the patient needs to be assessed soon after seizure took place because the EEG will measure the unusual brain waves that are associated with the seizure.
Definition of Epilepsy
Epilepsy is quite a common condition, with a prevalence rate of about 1.2%. It is considered a neurological disorder that is characterized by recurrent seizures. Seizures are experiences where our senses don’t work properly anymore; these episodes are typically sudden and stop suddenly.
Suffering one seizure does not mean that you have epilepsy. In fact, most people will experience one seizure throughout this lifetime. Instead, to satisfy the diagnosis, the seizures must re-occur or occur frequently.
There are numerous reasons why someone may suffer from epilepsy (i.e., recurrent seizures). For example, some of these reasons might be:
• brain damage (e.g., an accident that damaged part of your brain)
• an illness (e.g., an infection on the brain or a tumor)
• substance abuse
Not all the reasons for epilepsy are noxious; for example, flashing lights can also induce a seizure. In some cases, the cause of epilepsy might be unknown (i.e., it is idiopathic). For these reasons, we do not refer to epilepsy as a disease, instead, it’s a group of symptoms.
Epilepsy is also a syndrome that is not limited to human beings; other animals can also experience epilepsy. In fact, my dog Smartie used to suffer from idiopathic epilepsy and suffered from seizures.
Types of Seizures
Not all seizures are the same. There are two primary types of seizures: Generalised, and Partial Seizures. The distinction between these two types of seizures is based on how they present clinically (i;.e., what the patient is doing during the seizure) as well as the EEG findings. An EEG is an electroencephalogram, which is a way of measuring brain activity and brain waves.
Generalized seizures. Generalized seizures are common and occur in approximately 30% of patients with epilepsy. Typically these seizures are accompanied by muscular contractions. These types of seizures can be:
• tonic (where the muscles stiffen)
• clonic (whether the muscles twitch)
• tonic-clonic (where the muscles stiffen, and then after a while, spasm)
In tonic-clonic seizures, the person might also lose consciousness. Tonic-clonic seizures used to be grand mal seizures.
Another variation of generalized seizures is absent seizures (aka petit mal). Absent seizures are very common among children, and are characterized by a blank stare, after which they “come back”.
Regardless of the subtype of seizures, all generalized seizures start from deep, white matter structures in the brain. These types of seizures are not limited to only one brain region.
Furthermore, patients with generalized seizures do not experience an aura, which is the experience of sensory disturbance before the start of all seizures. Auras are also sometimes experienced by people who suffer from migraines. Additionally, these types of seizures are not accompanied by movements of one limb (for example).
Partial seizures. Partial seizures can be classified further in simple-partial epilepsy, or complex-partial epilepsy. In both types of epilepsy, the seizure begins in one part of the brain. Based on the sensory and motor experiences of the patient during the seizure, we can determine where the seizure originated. For example, if the patient experiences visual disturbances, then we know that the occipital lobe might be involved. The difference between the two types is that patients lose consciousness in complex-partial epilepsy.
Patients who experience partial seizures might also experience:
• auras (sensory distortions)
• psychomotor behaviors (automatic movements like blinking)
• emotions accompanying the seizure, like fear
Conclusion
In today’s lesson, we covered epilepsy. We learned about two types of epilepsy: generalized and partial epilepsy, as well as the different types of seizures. Remember: epilepsy can often be a symptom of another condition, so it’s important to assess the patient holistically.
Tomorrow is our final lesson, and we’ll learn about a few more unusual syndromes.
Until then,
Alicia
Recommended book
How the Mind Works by Steven Pinker
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