Seizure: Classification and Focal vs. Generalized Onset

by Roy Strowd, MD

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    00:01 So if you've determined it's a seizure.

    00:03 Now what? Step 1 is to classify the seizure.

    00:07 What kind of seizure is it? And over the years, there's been many classification systems that are used to categorize seizure.

    00:15 The oldest of these considered 3 seizure types, focal, grand mal and petit mal.

    00:21 And you'll still see these words used to describe seizures.

    00:26 Our prior categorization system classified seizures as simple partial, complex partial or secondarily generalized tonic-clonic seizures.

    00:36 These are all the focal onset seizures or primary generalized seizures.

    00:42 And alternative classification has been localization-related epilepsy, or generalized epilepsy.

    00:50 Our current classification system considers focal onset and generalized onset seizures.

    00:55 The focal onset seizures can be with retained awareness and being motor or non-motor or with altered awareness and be motor or non-motor.

    01:04 And then the third category is focal onset seizures that progressed to tonic-clonic seizures.

    01:10 The generalized onset can be sub classified as motor or non-motor.

    01:15 What you see in this table is regardless of the classification system, there's 2 basic types of seizures.

    01:21 Those that start in a single focus, those are the focal, the grand mal, the simple complex partial, the localization-related epilepsy, and the focal onset seizures.

    01:31 They start out on the surface of the brain and can progress.

    01:35 And those are different from the generalized seizures, which again have been described with many words, petit mal, primary generalized, generalized or generalized onset, all indicating the same thing.

    01:48 So when we think about the current classification system, the International League Against Epilepsy, which is the largest governing body for epilepsy and seizures, considers the following algorithm to evaluate a patient seizure and classify it.

    02:02 Seizures can be focal and onset.

    02:04 Those are seizures that start in and affect one part of the brain.

    02:08 And those focal onset seizures can either be with retained awareness, or with an impaired awareness.

    02:15 Focal onset seizures can be subclassified as being motor and onset, and we see a number of motor symptoms automatisms, atonic, clonic, epileptic spasms, hyperkinetic, myoclonic or tonic seizures.

    02:29 Or non-motor in onset with non-motor automatisms, behavior arrest, cognitive changes, emotional or sensory findings.

    02:38 And all focal onset seizures can secondarily generalize to a secondary generalized tonic-clonic seizure.

    02:45 And this category was previously considered secondary generalized seizures.

    02:52 Seizures can also be generalized and onset.

    02:54 These are seizures that start from a deep focus in the brain and manifest throughout the cortex at the same time.

    03:01 Again, these can be motor and onset or non-motor and onset.

    03:06 And then there's a new category of unknown seizure onset used to describe seizures if doctors are unaware of where in the brain the seizure starts.

    03:15 These unknown onset seizures can also have motor or non-motor subclassification.

    03:20 And this group is important.

    03:22 When we're treating patients with epilepsy, patients who are refractory to medications, we would consider a seizure surgery, which is good for localization-related epilepsy or a focal onset seizure, but we wouldn't consider that for an unknown onset seizure.

    03:37 And then there's the last category of unclassified seizures where there's not enough information available about the person seizure, or an unusual nature of seizure.

    03:47 And this is really used by advanced medical professionals if they are confident that they've truly ruled out a focal onset, generalized onset or unknown onset epilepsy.

    03:58 And when I'm evaluating a patient, I really like the older classification.

    04:02 It helps me to understand how to categorize this patient seizure and approach their management.

    04:08 So I like to consider seizures as being focal and onset and either being simple partial, complex partial or secondarily generalized.

    04:16 The simple partial seizures are those with retained awareness.

    04:20 Those are the auras that patients experience.

    04:22 Complex partial seizures involved alteration of awareness.

    04:25 Patients may lose consciousness or they may just be altered, not able to speak or interact with the world around them.

    04:33 And then secondary generalized tonic-clonic seizures involve convulsions.

    04:37 These start from a focus, we can see it on a scalp EEG and hear it when we're evaluating patients clinically through their aura or ictal onset.

    04:46 Those are different from the generalized onset seizures, and there's 6 generalized seizure types.

    04:51 Absence those are brief small behavioral myoclonic, atonic, tonic, clonic and generalized tonic-clonic seizures

    About the Lecture

    The lecture Seizure: Classification and Focal vs. Generalized Onset by Roy Strowd, MD is from the course Seizures and Epilepsy.

    Included Quiz Questions

    1. Absence
    2. Secondary generalized
    3. Complex
    4. Myoclonic
    5. Atonic
    1. Secondary generalized tonic-clonic seizures
    2. Primary generalized seizures
    3. Grand mal seizures
    4. Absence seizures
    5. Myoclonic seizures

    Author of lecture Seizure: Classification and Focal vs. Generalized Onset

     Roy Strowd, MD

    Roy Strowd, MD

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