2017 Revised Classification of Seizures

The International League against Epilepsy (ILAE) is the world's main scientific body devoted to the study of epilepsy, and it has recently revised its classification of seizures. The changes will help make diagnosing and classifying seizures more accurate and easier. In this article, you'll find the new general outline and basic seizure classification. In the coming weeks, epilepsy.com will be updated to reflect the new classification to help users searching for both the older and newer terms.

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Gelastic and dacrystic seizures are most commonly found in people with hypothalamic hamartomas (HH). For many individuals with HH, the first seizure to occur is the gelastic seizure. Gelastic seizures are called the “laughing seizure” because they may look like bouts of uncontrolled laughter or giggling. However, the laughter-like sounds are often forced and combined with a facial contraction similar to a smile or smirk. In some children, the vocalization has a crying quality and the facial contraction resembles a grimace. These crying seizures are called dacrystic seizures.

The gelastic seizures are not associated with any sense of well-being or delight for the individual, but instead can result in a feeling of fear or loss of control. It is not uncommon for gelastic and dacrystic seizures to go undetected for years because of their unusual presentation. Often the seizures go unrecognized until some other seizure type appears. Gelastics often occur as a child is falling off to sleep but can occur throughout the day and night. Infants and children will often be aroused out of sleep by a gelastic seizure, then settle down and go right back to sleep.

Gelastics may present differently with each child; however, some commonalities are evident. There is often an aura, which may appear as a startle, or even a look of panic or fear. The eyes may seem vacant, dilate, or move up and to the left or right. There often is a slight smile that seems somewhat forced and laughter or grunting that seems unusual or not appropriate at that time. In infants, there may be grunting and unusual squirming as well. Some children respond by seeking comfort from a parent or favorite toy for no apparent reason, others will run to a location where they feel safe. Parents have reported gelastics occurring with their children that appear to be triggered by loud noises or fearful responses to sudden actions. Gelastic can also be triggered by excitement and anxiety. 

Gelastic seizures are rarely diagnosed at onset yet they begin in infancy in over one-third of documented patients. Gelastic seizures can occur with very high frequency and amazing regularity. Diagnosis is further complicated by the fact that electroencephalographic studies (EEGs) are often normal or only nonspecifically abnormal in children when only gelastic seizures are present. For many parents, when they hear a description of a gelastic seizure, they realize the activity was indeed there before, yet unrecognized as a seizure.

In many children, it is only with the development of the more devastating absence, complex partial, or generalized seizures that the diagnosis of HH is eventually made. The most dramatic and disabling seizures associated with HH are more generalized seizures – specifically generalized tonic-clonic seizures and atonic seizures (drop attacks). Generalized seizures often appear after the onset of gelastic and complex partial seizures. When they do occur, they are often preceded by an initial gelastic or complex partial seizure. It is usually when other seizure types begin, that behavior and cognitive issues become more obvious. Other seizures common to HH patients include:

For more information, a dedicated HH community Forum, support, and research, visit www.hopeforhh.org

Hope for Hypothalamic Hamartomas © 2009 – Adapted with permission.

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