2. Shattering Myths: Myoclonic Epilepsy is Not a Single Disorder
In the realm of epilepsy, many laypersons tend to view it as a single, all-encompassing condition. However, in truth, epilepsy is not one disease but a family of disorders sharing common features, among which myoclonic epilepsy is one member. This fact is fundamental in understanding the nature of myoclonic epilepsy.
Myoclonic epilepsy, as a term, encompasses a range of different disorders. Each subtype has its own unique features, including the age of onset, type of seizures, potential triggers, and associated symptoms. These subtypes illustrate the complexity and diversity of myoclonic epilepsy.
Juvenile Myoclonic Epilepsy (JME), for instance, often begins in adolescence. It is marked by myoclonic jerks that often occur in the early morning hours. A characteristic feature of JME is that seizures are often triggered by sleep deprivation or sudden arousal from sleep. Other seizure types, like generalized tonic-clonic seizures and absence seizures, can also be part of the clinical picture in JME.
Progressive Myoclonus Epilepsies (PME), on the other hand, are a group of disorders characterized by myoclonus, seizures, and progressive neurological decline. This category includes diseases like Lafora disease and Unverricht-Lundborg disease. In these conditions, the myoclonus and seizures are often accompanied by a gradual loss of cognitive and motor skills.
Another subtype, Myoclonic Astatic Epilepsy (MAE) or Doose syndrome, is characterized by multiple seizure types including myoclonic-astatic seizures, where the individual has a sudden jerk followed by a loss of muscle tone. This typically begins in early childhood and can affect cognitive development.
Myoclonic Absence Epilepsy is another distinctive subtype, characterized by absence seizures with a myoclonic component. These are seizures where the individual seems to ‘zone out’ for a few seconds, but with the addition of myoclonic jerks.
Finally, there is Infantile Spasms (West syndrome), a severe epilepsy syndrome that begins in infancy. Here, the seizures are characterized by sudden jerks or “spasms,” and are often associated with a specific pattern on EEG called “hypsarrhythmia“. The condition can have a significant impact on the child’s cognitive development. (2)
