Gelastic seizures are the most specific symptom associated with hypothalamic hamartomas (HH). These are also referred to as laughing seizures although not all individuals with gelastic seizures present with a true laughing sound. They are usually brief, often lasting less than 30 seconds, however they can go longer – sometimes up to a few minutes in duration. They can be occasional or very frequent, with hundreds of seizures per day in more severely affected individuals.
Gelastic seizures can be associated with little or no change in consciousness, although making this determination in infants and young children can be challenging. Although gelastics may sound like laughter, individuals generally do not experience happy feelings, and most family members can readily distinguish the gelastic seizure from true laughter. Some individuals may also experience seizures that more closely resemble crying rather than laughing. These crying seizures are called dacrystic seizures and may occur with or without the presence of gelastic seizures.
Gelastic seizures can also be quite subtle. They are commonly mistaken for other conditions, particularly during early infancy, including colic and gastroesophageal reflux disease (GERD).