Symptomatic Epilepsies

by Roy Strowd, MD

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    00:01 Now, let's move to some of the important symptomatic epilepsies.

    00:04 Symptomatic epilepsy or secondary epilepsies.

    00:07 It's epilepsy secondary to some type of problem.

    00:11 And there are a few really important conditions that you should know.

    00:15 The first is West syndrome.

    00:16 This is a combination of epilepsy in someone in a patient who has other neurodevelopmental abnormalities.

    00:24 The classic triad is infantile spasms, hyparrhythmia on the EEG, and psychomotor delay on clinical exam.

    00:32 So what is West syndrome? What do we see? The peak onset is early in life.

    00:37 Within the first 4 to 7 months, patients begin to develop seizures.

    00:41 That characteristic seizure is an epileptic spasm.

    00:45 We also call that an infantile spasm.

    00:47 And those cluster during sleep transitions.

    00:50 So typically, when a patient is waking up, we can see a number of seizures, or sometimes when a patient is going to sleep.

    00:56 Epileptic spasms have a very characteristic clinical appearance.

    01:00 The patient's arms extend out.

    01:03 Their head often can go down, and then the arms and head go back to the normal posture.

    01:08 And that brief episode is a seizure, with the arms extended head down, and then slowly returning back to normal posture.

    01:15 And seeing that in a child should raise suspicion for a possible epileptic phenomenon, which would be confirmed by EEG.

    01:22 In addition, the EEG also shows an important interictal abnormality.

    01:26 And abnormality that's there at all times.

    01:29 And this is called hypsarrhythmia, which we'll look at on a subsequent slide.

    01:33 We see both the hypsarrhythmia interictally, and an electrodecrement ictally.

    01:40 So that clinical epileptic spasm is associated with a spike.

    01:43 And then as the spasm is resolving, we see a decrement where the EEG resolves down and is suppressed for a short period of time.

    01:51 And that discharge tips us off that we may be dealing with West syndrome or infantile spasms.

    01:57 This is a secondary epilepsy.

    01:59 It's caused by some type of problem and there are numerous etiologies, or insults that can lead to this.

    02:06 Perinatal hypoxic-ischemic injury, brain malformations, tuberous sclerosis, Down syndrome, and other metabolic disorders are inherited and genetic metabolic disorders, all can result in the presentation of West syndrome.

    02:20 So many different underlying pathologies or problems with the brain can present with a common epileptic syndrome.

    02:27 The prognosis depends on the underlying etiology, upwards of 75 or more percent of patients will be severely delayed with neurodevelopmental abnormalities and dysfunction.

    02:40 What is the EEG look like in West syndrome? Well, here again, we're looking at a normal EEG from front to back and left to right, odd numbers indicate the left side of the brain, and even numbers the right side of the brain.

    02:53 When we look at an EEG for someone who has an infantile spasm, this is what we tend to see.

    02:58 You can see on the left side of the tracing, we see a chaotic rhythm.

    03:03 There is no organization.

    03:04 It looks dramatically different from the normal EEG, which has some characteristic waves in the back part of the brain that's called an alpha rhythm, and otherwise, is a low amplitude and irregular tracing.

    03:17 This is irregular and chaotic. It's also disorganized.

    03:20 We can't pick out individual lines or individual waves.

    03:24 And in the middle of this tracing, we see that all that disorganization calms into a smooth line that comes back down to the baseline and that is called an electrodecrement.

    03:37 And in some cases can be associated with an infantile spasm or seizure.

    03:42 This disorganized and chaotic pattern is characteristic of a hypsarrhythmia.

    03:47 Again, we see chaos, irregularity, and disorganization of the EEG.

    03:51 And this is an interictal pattern that occurs without any clinical seizure activity.

    03:58 The second very important symptomatic generalized epilepsy is Lennox-Gastaut syndrome.

    04:03 There are a lot of similar features to West syndrome to Lennox-Gastaut, but some important differences.

    04:09 The first is its age of onset.

    04:11 West syndrome begins very early.

    04:14 A perinatal or early injury to the brain or neurodevelopment results in early onset West syndrome.

    04:22 Lennox-Gastaut patients tend to present a little bit later, in the first 2 to 8 years of life.

    04:28 We see multiple seizure types: tonic, atonic, absence or a typical absences is a myoclonic seizures.

    04:36 All of these are generalized onset seizures, and most patients have multiple seizure types.

    04:42 The EEG shows a 1.5 to 2.5 hertz, polyspike and wave discharge, which we call a slow spike and wave discharge.

    04:51 What that looks like is not as important as the name slow spiking wave discharge.

    04:56 And that's characteristic of a diagnosis of Lennox-Gastaut syndrome.

    05:00 There are multiple etiologies, multiple underlying insults that can contribute to the development of Lennox-Gastaut.

    05:07 Two-thirds of patients are symptomatic, and 1/3 have a history of infantile spasms.

    05:12 Early in life that then develops into full blown Lennox-Gastaut syndrome.

    05:17 Patients frequently have medically refractory seizures for their lifetime, and severe developmental delay.

    05:23 Some being nonverbal and fully dependent on others for complete care.

    05:28 In Lennox-Gastaut as well as West syndrome underscores the way that we make a diagnosis of a symptomatic epilepsy.

    05:35 And the things we're looking at clinically and in vignettes with these patients.

    05:38 Were characterizing the seizures And with Lennox-Gastaut, 30% of patients have infantile spasms, and will progress on to Lennox-Gastaut syndrome.

    05:47 That seizure type is important in making this epilepsy diagnosis.

    05:51 We're also evaluating the neurologic status of the patient.

    05:54 And 80% of patients with Lennox-Gastaut will have cognitive dysfunction, the second key pillar of this triad.

    06:02 And the last we're incorporating EEG findings.

    06:05 And with Lennox-Gastaut, we see that slow spike and wave activity.

    06:08 And that triad of infantile spasms, cognitive dysfunction or neurodevelopmental delay, and slow spike and wave is what establishes this diagnosis of Lennox-Gastaut syndrome.

    06:19 There are specific medications that are approved to treat Lennox-Gastaut vaigabatrin is one of those as well as others.

    06:26 And we can use this information to prognosticate for patients and Lennox-Gastaut is associated with long-term difficult to treat epilepsy and significant neurodevelopmental delay.

    06:38 This is an example of an EEG for a patient with Lennox-Gastaut.

    06:42 We see it's quite different from that hypsarrhythmia pattern for West syndrome.

    06:46 We see spike and wave. And this is very slow.

    06:49 The hertz is about 1.5 to 2.5 hertz.

    06:52 That's how many bumps, spikes, and waves you see each second of this tracing.

    06:57 And this slow spike and wave activity, which we see generalized throughout the entire brain is characteristic of Lennox-Gestaut.

    07:06 And last, let's finish by talking about temporal lobe epilepsy.

    07:09 This is one of the most common forms of symptomatic focal onset epilepsy.

    07:14 It's one of those epilepsies we see in adults and a diagnosis that sometimes we make in adults.

    07:20 The onset can be between 10 and 20 years.

    07:23 That we can see patients that present even after the age of 20 with their first time seizure.

    07:29 This is the most common form of focal onset or partial epilepsy.

    07:34 Patients have that typical description of a focal onset epilepsy coming from the temporal lobe.

    07:39 The aura often begins with déjà vu, or a rising nausea, or other temporal lobe localization symptoms.

    07:48 This progresses to alteration and awareness.

    07:51 During that altered awareness patients may have automatisms, motor automatisms, like lip smacking or chewing, or other automatisms in their behavior.

    08:01 And this ultimately will progress to generalize convulsions and postictal confusion.

    08:06 The EEG shows temporal lobe spikes interictally or sharp waves interictally, and we can see a seizures arising out of the temporal lobe, ictally.

    08:16 And the treatment begins with antiepileptic medications.

    08:20 Typically, we start with one medication and titrate to the maximum dose.

    08:24 If the patient fails, we would consider a second medication.

    08:28 In this syndrome is important for understanding the definition of medically refractory epilepsy.

    08:34 Treatment refractory epilepsy, or medically refractory epilepsy is a patient with epilepsy who has failed two medications at maximum doses.

    08:43 And in those patients they should be considered for a surgical evaluation.

    08:47 One of the reasons to consider that is temporal lobe epilepsy.

    08:50 This can be highly amenable to temporal lobe resection.

    08:54 Removing that epileptic nidus Some patients will be able to reduce their medicines and others may be able to come off of all antiepileptic medications as a result of that surgery.

    09:05 Importantly, seizure surgery must happen early before one epileptic focus co ops another.

    09:11 and a patient develops multi-focal epilepsy that would not be amenable to surgery.

    09:16 And that's why we think about this at the time of failing two medications at maximum doses or medically refractory epilepsy.

    09:26 Here we see the characteristic imaging of a patient with temporal lobe epilepsy.

    09:30 This is associated with scarring of the temporal lobe, which we call mesial temporal sclerosis.

    09:37 We're looking at a coronal picture at T2 looking back through a patient's eyes.

    09:42 And again, the patient is flipped as we look at this image.

    09:46 The left temporal lobe is over on the right side of the screen and the right temporal lobe is on the left side of the screen.

    09:54 The green arrow is pointing to the temporal lobe.

    09:57 We can see it's smaller than the right side.

    09:59 The left hippocampus is smaller.

    10:02 It's a little bit brighter and scarred compared to the right side.

    10:05 And this is a good example of mesial temporal sclerosis, which is a cause of temporal lobe epilepsy.

    10:12 This underscores that the symptomatic epilepsies have a cause we need to go looking for them.

    10:17 And a high resolution MRI is important for looking at temporal lobe sclerosis, a cortical dysplasia, or some other underlying nidus and cause of the patient's epilepsy.

    10:28 Surgically, we would target this and by removing that scar, we're removing the nidus for epilepsy and can cure the patient's seizures.

    About the Lecture

    The lecture Symptomatic Epilepsies by Roy Strowd, MD is from the course Seizures and Epilepsy.

    Included Quiz Questions

    1. Lennox-Gastaut syndrome is classified as symptomatic.
    2. BECTS is classified as symptomatic.
    3. West syndrome is classified as idiopathic.
    4. Juvenile myotonic epilepsy is classified as symptomatic.
    5. Juvenile absence epilepsy is classified as symptomatic.
    1. EEG shows interictal hypsarrhythmia.
    2. Peaks at 8 years of age.
    3. West syndrome is associated with normal psychomotor development.
    4. No specific seizure characteristics are seen.
    5. EEG shows ictal slow spike and wave.
    1. Cognitive dysfunction in most patients
    2. Very responsive to medication
    3. EEG shows ictal electrodecrement
    4. Causes focal seizures
    5. Peaks at < 1 year of age
    1. Presence of aura with nausea or déjà vu
    2. Onset in early childhood.
    3. EEG shows hypsarrhythmia.
    4. Surgery is not a therapeutic option.
    5. Temporal lobe epilepsy usually resolves without treatment.

    Author of lecture Symptomatic Epilepsies

     Roy Strowd, MD

    Roy Strowd, MD

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