Idiopathic Generalized Onset and Idiopathic Focal Onset Epilepsies

by Roy Strowd, MD

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    00:01 So let's walk through each of these.

    00:03 We'll start with childhood absence epilepsy.

    00:06 This is a seizure syndrome that begins anywhere between the 2nd to 12th year of life.

    00:11 It happens in childhood.

    00:14 The primary seizure type are absence seizures.

    00:17 Patients have brief seizures, with multiple occurring a day and they typically involve staring or a behavioral arrest.

    00:26 90% of these can be invoked by hyperventilation.

    00:29 And this is important when we do an EEG two of the provocative factors that are done during that 30 minute EEG are hyperventilation.

    00:38 And we're looking to see if we can induce an absence seizure or a photic stimulation.

    00:43 And we're looking to drive a photo convulsive response.

    00:47 And we're looking for these types of genetic epilepsies.

    00:51 The EEG and childhood absence epilepsy shows 3 hertz spike and wave.

    00:56 That's an interictal EEG finding, and we'll look at it on a subsequent slide.

    01:00 And that's something we can see anytime whether the patient's having a seizure or not.

    01:05 That 3 hertz discharge is generalized throughout the entire scalp electrode.

    01:10 The seizure comes from a deep focus in the thalamus, but we see it out on the surface of the brain at the same time.

    01:17 And that generalized spiking wave discharge is important for making this type of generalized epilepsy diagnosis.

    01:24 Interestingly, this runs in families.

    01:26 We see a 44% of patients have a family history, and 75% concordance between twins.

    01:32 And what that means is we can see other family members who may be affected by this if we're treating one patient.

    01:39 This condition is caused by an abnormality in the T-type calcium channels, and some channelopathy conditions or genetic changes in that channel can predispose patients to this type of epilepsy.

    01:51 This epilepsy gets better over time.

    01:53 And we typically see spontaneous remission within two to six years of the age of onset.

    01:59 We often treat these children. we typically treat the children.

    02:02 The behavioral rest can preclude interaction with school, and work, and home, and play.

    02:09 And so patients are typically treated with medications that address those T-type calcium channels like ethosuximide.

    02:15 But ultimately, many patients are able to come off their seizure drugs and live a normal, healthy life.

    02:23 In contrast, juvenile absence epilepsy begins later in life.

    02:27 We see the onset between 10 and 16 years of age.

    02:30 It has a lot of the similarities. We see absence seizures.

    02:34 These patients can also develop generalized tonic-clonic seizures, which is an important difference.

    02:39 So young children that have absence episodes, we follow over the course of time.

    02:45 Many will resolve spontaneously and meet a diagnosis of childhood absence epilepsy.

    02:51 Others may develop a new generalized tonic-clonic seizure That diagnosis would move from childhood absence to juvenile absence epilepsy.

    03:00 The EEG for juvenile absence epilepsy tends to be a slightly faster 3.5 to 4 hertz generalized spike and wave discharge.

    03:08 Again, it's a generalized discharge for a generalized epilepsy.

    03:11 And that's an interictal finding that we can see on any EEG.

    03:15 And usually this condition is responsive to AEDs, but lifelong treatment may be required, which is an important difference for childhood absence epilepsy, and juvenile absence epilepsy.

    03:27 What is the EEG show in these conditions? This is a normal EEG.

    03:32 When we look at the EEG, we talked about looking from top to bottom.

    03:35 The odd numbers of the left, the even numbers to the right.

    03:39 The first four lines are the left parasagittal chain.

    03:43 The next four lines are the right parasagittal chain.

    03:47 If we move down again, the next four lines to the left temporal chain, and the next four lines to the right temporal chain.

    03:52 And so this gives us coverage of all of the brain.

    03:55 In these childhood and juvenile absence epilepsies, this is what we see.

    04:00 And here we're looking at an absence seizure.

    04:03 You can see in the initial two to three seconds of the tracing, the brain appeared normal.

    04:08 There was an eyeblink right at the beginning, that's a normal finding that we can see.

    04:12 Then all of a sudden, at around the middle of the recording, we see the beginning of a generalized a discharge.

    04:20 A spike in a wave that occurs throughout the brain.

    04:23 In the parasagittal, the temporal change, the left and right side of the brain, and that continues rhythmically throughout the rest of the recording.

    04:31 If we counted the number of spikes and waves that we see in each second, it would be about three to three and a half.

    04:37 And that's consistent with what we see with childhood absence, or in some cases of juvenile absence epilepsy.

    04:43 This is a good example on the EEG of an absence seizure.

    04:47 Clinically, during this event, the patient would be normal leading up to these abnormal ECG findings, and then have a brief staring episode or behavioral arrest, they would stop what they're doing and stare off with their eyes open.

    04:59 And when the event resolves, they would come back to, and immediately come back to typically without a lot of post-event or postictal confusion.

    05:10 The last type of idiopathic generalized epilepsy that we should remember and understand is juvenile myoclonic epilepsy.

    05:18 This typically begins around the age of 12 to 18 years.

    05:22 Patients have three types of seizures.

    05:24 Absence seizures, like we just talked about, which is present in 20%.

    05:29 Myoclonic seizures, which are very brief, single jerks.

    05:33 They're just like those jerks we have when we're going to sleep.

    05:36 But an epileptic patients, they can happen during the daytime, and the nighttime.

    05:40 Sometimes with a nocturnal predominance.

    05:43 And the third seizure type are generalized tonic-clonic seizures.

    05:46 Present in more than 96% of patients, and they can be provoked by sleep deprivation.

    05:52 These patients typically present early with absence seizures, or myoclonic seizures.

    05:56 And then ultimately, during their teenage years, we may see the first onset of a generalized tonic-clonic seizure.

    06:02 And the presence of those three seizures should tip us off to being worried about this diagnosis.

    06:08 The EEG shows a 4 to 6 hertz, generalized polyspike and wave, which is different from the childhood and juvenile absence epilepsies.

    06:17 Those showed a spike, followed by a wave and a spike, followed by a wave.

    06:21 Here we see multiple spikes followed by a wave on the EEG, and we'll look at that in just a few slides.

    06:27 In 30 to 50% of patients, we can see focal discharges even though this is a generalized epilepsy.

    06:33 And patients are photo sensitive.

    06:34 So with repeated photic stimulation that can drive either an EEG discharge or a frank seizure, which is a photo convulsive response.

    06:44 Generally, this is easily controlled.

    06:46 It's well controlled with antiepileptic medications that treat generalized epilepsies.

    06:51 We often think of things like lamotrigine or valproic acid, but lifelong treatment is required in 90% of patients.

    06:59 After patients are treated, if we try and withdraw the medicine, frequently, patients will have breakthrough seizures.

    07:06 So what does the EEG looked like in this condition in juvenile myoclonic epilepsy? Here we can see an interictal finding.

    07:13 This is a generalized discharge.

    07:15 Throughout the entire brain, we see this discharge, it's on the left to the odd numbers, that right the even numbers, the front of the brain, and the back of the brain.

    07:24 And as opposed to the last EEG we looked at, we see a polyspike discharge with many spikes, followed by a wave.

    07:31 And that's characteristic of juvenile myoclonic epilepsy.

    07:34 This polyspike and wave discharge.

    07:37 This is not associated with any clinical abnormality.

    07:40 The brain is normal leading up to this discharge and normal after this discharge.

    07:45 And so, there's really no clinical evidence or outward sign of this discharge.

    07:49 This is an interictal finding.

    07:54 So if those are the idiopathic generalized epilepsies.

    07:58 Let's talk about one really important example of an idiopathic focal epilepsy.

    08:03 And that's benign childhood epilepsy with centrotemporal spikes.

    08:08 The name gives away a lot of the features.

    08:10 It's a benign epilepsy that resolves over time.

    08:12 And there's a characteristic EEG change or finding that is centrotemporal spikes.

    08:18 The onset is between 1 to 16 years.

    08:20 So that age range throughout childhood and the teenage years.

    08:24 Patients have nocturnal seizures.

    08:26 That can present with drooling or hemifacial clonus.

    08:30 Sometimes, their face will draw up or jerk.

    08:34 And sometimes patient can have ipsilateral hand jerking.

    08:37 The centrotemporal spikes are located right in that area of hand, eye, and face movement along the frontal lobe.

    08:46 And that's why we see those characteristic findings at night.

    08:49 The EEG shows centrotemporal spikes that can be activated by sleep.

    08:54 So this is a sleep induced seizure phenomenon.

    08:57 The centrotemporal spikes are present interictally.

    08:59 So we can see them at any time.

    09:02 EEG findings are autosomal dominant it tends to be an autosomal dominant epilepsy so it can run in families, and we can look for those findings on EEG or clinically in family members.

    09:13 And many patients will will present with language problems, either Frank aphasia or some type of dysphasia.

    09:19 And again, this gets back to the problem.

    09:22 Those EEG discharging that epileptic focus is starting around the motor and language area, typically on the left side of the brain.

    09:30 And that can result in language dysfunction.

    09:34 Typically, this will improve over time.

    09:36 It is a benign epilepsy that resolves spontaneously and so usually by the age of 16 years, language is normal and seizures have resolved.

    09:45 And this is a good example of an EEG for a patient with Beck's syndrome, Benign rolandic epilepsy.

    09:51 The rolandic region of the brain is that frontal gyrus where language sits and that's where we see these discharges.

    10:00 They are centrotemporal.

    10:01 So here we see them on the left side.

    10:03 And they're primarily in the temporal chains the chains with the T, as well as in the center of the brain, which you see down in the bottom on some of the blue lines here.

    10:13 And each of those discharges is an interictal discharge.

    10:16 It's an area of irritated brain that can result in seizures, that can drive some of the nocturnal abnormality, but it's not a frank seizure in and of itself.

    10:25 And the patient would be acting normally during this period of time.

    About the Lecture

    The lecture Idiopathic Generalized Onset and Idiopathic Focal Onset Epilepsies by Roy Strowd, MD is from the course Seizures and Epilepsy.

    Included Quiz Questions

    1. Treatment targeting calcium channels
    2. Peak onset at age 2–4
    3. Seizures provoked by hypoventilation
    4. Requirement of lifelong medication
    5. 95% concordance in twins
    1. It can lead to generalized tonic-clonic seizures.
    2. It does not require lifelong treatment.
    3. The onset peaks at 16 years of age.
    4. 3 Hz spike and wave are seen on EEG.
    5. It is refractory to medication.
    1. Photosensitivity is common.
    2. Peak onset at 10 years of age
    3. Increased seizures with hyperventilation
    4. Does not require lifelong medication
    5. 3.5–4 Hz generalized spike and wave EEG
    1. BECTS presents as a language disorder.
    2. 4–6 Hz polyspike seen on EEG
    3. Nocturnal symptoms are rare.
    4. BECTS has no known genetic predisposition.
    5. Peak onset is at 17 years of age.

    Author of lecture Idiopathic Generalized Onset and Idiopathic Focal Onset Epilepsies

     Roy Strowd, MD

    Roy Strowd, MD

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