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Epilepsy and Seizures: Overview

Epilepsy and Seizures: Overview

Epilepsy is a chronic neurological disease marked by recurrent, unpredictable seizures. These seizures are caused by abnormal electrical discharges in the brain, leading to behavior, sensation, or consciousness alterations. They can also cause transient impairment of awareness, interfering with daily activities.
Various factors can trigger epilepsy, including genetic factors, brain damage, metabolic causes, and unknown etiology. Diagnosis of epilepsy involves electroencephalography (EEG), which...

Epilepsy ll: Types

Epilepsy ll: Types

Recurrent seizures, stemming from abnormal electrical activity in the brain, are the defining characteristic of epilepsy, a chronic neurological condition. Because seizure features vary greatly, epilepsy is classified using two systems: by seizure type and by epilepsy syndromes. These classifications enable clinicians to describe seizure patterns and select suitable treatment strategies.I. Classification by Seizure Type1. Focal EpilepsyFocal epilepsy begins in one hemisphere of the brain.

Seizures: Classification

Seizures: Classification

Epilepsy is primarily characterized by unpredictable seizures, either provoked by an identifiable factor, such as injury or illness, or unprovoked, occurring spontaneously without apparent cause.
Seizures are typically classified into two main categories: focal and generalized seizures.
Focal Seizures
Focal seizures originate from specific regions of the brain. These seizures are further sub-classified into two types:

Seizures ll: Types

Seizures ll: Types

Seizures are sudden bursts of abnormal electrical discharge in the brain that interfere with normal function. They are commonly divided into three groups: focal seizures, generalized seizures, and other types that do not fit neatly into either category.Focal SeizuresFocal seizures begin in a single brain region. When awareness is preserved, they are called focal aware seizures and may cause sensations such as tingling, unusual smells, or flashing lights. When awareness is impaired, they are...

Seizures l: Introduction

Seizures l: Introduction

Understanding seizures and epilepsy relies on key definitions that help in recognizing, classifying, and managing these disorders. These definitions provide a framework for recognizing, classifying, and managing seizure disorders.DefinitionsA seizure is a sudden, abnormal burst of electrical activity in the brain that can cause changes in awareness, movement, sensation, or behavior, depending on the area involved. Epilepsy is a chronic condition characterized by recurrent, unprovoked seizures,...

Antiepileptic Drugs: Glutamate Antagonists

Antiepileptic Drugs: Glutamate Antagonists

Glutamate is a fundamental neurotransmitter in the central nervous system, playing a vital role in neuronal communication and various cognitive processes. Glutamate stands as the principal excitatory neurotransmitter in the brain. Its presence is crucial for the communication between neurons, underpinning essential processes such as synaptic transmission, neuronal excitability, and plasticity. These functions are vital for higher-order cognitive processes, including learning and memory. The...

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Related Experiment Video

Updated: May 11, 2026

Electromagnetic Source Imaging in Presurgical Evaluation of Children with Drug-Resistant Epilepsy

Electromagnetic Source Imaging in Presurgical Evaluation of Children with Drug-Resistant Epilepsy

Published on: September 20, 2024

Progressive myoclonus epilepsy.

Jean-Marie Girard¹, Julie Turnbull, Nivetha Ramachandran

¹Division of Neurology, Department of Paediatrics, Hospital for Sick Children and University of Toronto, Toronto, Canada.

Handbook of Clinical Neurology

|April 30, 2013

Summary

This summary is machine-generated.

Progressive myoclonus epilepsies (PMEs) involve myoclonic seizures and neurodegeneration. Understanding the genetic and cellular defects in conditions like Lafora disease and Unverricht-Lundborg disease is crucial for diagnosis and treatment.

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Last Updated: May 11, 2026

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Published on: July 8, 2025

Area of Science:

Neuroscience
Genetics
Biochemistry

Background:

Progressive myoclonus epilepsies (PMEs) are a group of debilitating neurological disorders characterized by myoclonic seizures and progressive neurodegeneration, typically with onset during childhood or adolescence.
Lafora disease, a type of neuronal glycogenosis, involves the accumulation of abnormal starch-like polyglucosans in neurons due to mutations in laforin or malin genes.
Unverricht-Lundborg disease is linked to the absence of cystatin B, leading to neuronal damage from lysosomal cathepsins and reactive oxygen species.

Purpose of the Study:

To elucidate the underlying mechanisms of progressive myoclonus epilepsies (PMEs).
To identify key diagnostic features for differentiating between various PME subtypes.
To explore the genetic and molecular basis of neuronal dysfunction in PMEs.

Main Methods:

Review of existing literature on PME genetics and pathophysiology.
Analysis of clinical presentations and diagnostic criteria for Lafora disease and Unverricht-Lundborg disease.
Comparison of lysosomal storage disorders associated with PME phenotypes.

Main Results:

Lafora disease is characterized by polyglucosan accumulation and presents with early cognitive decline, visual seizures, and EEG slowing.
Unverricht-Lundborg disease shows preserved cognition and background EEG, with specific myoclonus and EEG patterns.
Other lysosomal diseases like sialidosis and Gaucher disease can also manifest as PMEs, though the link between lysosomal defects and epilepsy remains unclear.

Conclusions:

Distinct genetic defects and molecular pathways underlie different PMEs, impacting neuronal function and leading to progressive neurodegeneration.
Early identification of diagnostic clues such as cognitive deterioration, seizure types, and EEG findings is vital for PME diagnosis.
Further research is needed to understand how lysosomal dysfunction culminates in myoclonus and epilepsy in specific PME subtypes.