Gelastic epilepsy is a type of epilepsy in which the seizures are 'gelastic'. Gelastikos is the Greek word for laughter. Gelastic epilepsy is slightly more common in boys than in girls. It is, however, very rare and of every 1,000 children with epilepsy, only one, or at the very most 2, children will have gelastic epilepsy.
The most common areas of the brain which give rise to gelastic seizures are the hypothalamus (a small and extremely important structure deep in the centre of the brain), the temporal lobes and the frontal lobes.
A common cause of gelastic epilepsy is a small tumour in the hypothalamus. This tumour may be either a hamartoma or an astrocytoma. A hamartoma is a benign (non-cancerous) growth made up of an abnormal mixture of cells and tissues normally found in the area of the body where the growth occurs. An astrocytoma is a nervous system tumour that grows from astrocytes. Astrocytes are a type of glial cell. Glial cells are the supporting cells of the nervous system.
The majority of these tumours are benign. This means that they may grow only very slowly, and do not spread to other parts of the brain or body.
If a child has gelastic seizures and precocious puberty (which means that they go into puberty very early, usually under 10 years of age), then it is likely that they will be found to have a hypothalamic hamartoma (a hamartoma in the hypothalamus part of the brain).
It is common for older children who have gelastic epilepsy caused by a hypothalamic hamartoma to also have learning and behavioural problems. These usually get worse in the mid to late teenage years.
Seizures may begin at any age, but usually before 3 or 4 years of age. The seizures usually start with laughter. The laughter is often described as being 'hollow' or 'empty' and not very pleasant. However, sometimes the laughter may sound like a child’s normal laughter except that it is out of place. The laughter occurs suddenly, comes on for no obvious reason, and is usually completely out of place, meaning that nothing funny will have happened to make the child laugh. Sometimes older children may complain of a warning beforehand. The warning may be feeling scared, an abnormal smell or taste, although sometimes they cannot describe exactly what this warning feels like.
The laughter usually lasts less than 30 to 45 seconds and stops suddenly. It may then be followed by signs that are more usually seen in focal seizures. These signs can include eyes and head moving to one or the other side, automatisms (such as lip-smacking, mumbling or fidgeting of the hands), altered awareness and lack of response to people around them. These signs may last for seconds to many minutes and then stop. The child may seem confused and want to sleep.
A detailed history or description of the child's episodes must be taken from someone who has actually seen them. The episodes of laughter can be confused with behavioural or emotional disorders, including in children with attention difficulties or features of autism. This may therefore delay the diagnosis. This is particularly likely to happen in young children. Sometimes a video, with sound, of the child's episodes may be very helpful. The electroencephalogram (EEG) can show focal and generalised abnormalities (sharp waves, spikes or spike and slow waves). A magnetic resonance imaging (MRI) brain scan should always be done. This is to look for the tumours that might be found in the hypothalamus or for tumours or abnormal areas in the temporal or frontal lobes, called ‘focal cortical dysplasia’. A computed tomography (CT) brain scan may not show very small tumours – so any scans of the brain must be done with MRI.
The epilepsy medicines used to treat focal seizures may also be effective in treating gelastic epilepsy. These include carbamazepine (Tegretol), clobazam (Frisium), lamotrigine (Lamictal), lacosamide (Vimpat), levetiracetam (Keppra), oxcarbazepine (Trileptal) and topiramate (Topamax). Unfortunately none of the epilepsy medicines is likely to stop all seizures from happening. Surgery, or, less likely, a special form of radiotherapy, may be possible if a tumour in the hypothalamus (or, less commonly in the temporal or frontal lobes) is found to be the cause of the gelastic epilepsy. These treatments are only available in very few specialist centres in the UK. These centres are called the ‘Children’s Epilepsy Surgery Service’ (CESS).
If a child also has precocious puberty, then this can be treated with hormones or hormone-like medicines. Unfortunately, the learning and behavioural problems rarely respond to medical treatment. They may, however, improve after a surgical or radiotherapy treatment, if the cause is due to a hamartoma. Children will usually need additional input in school and some psychological support to help with their learning and behavioural problems.
Information about treatments for children can be found on the Medicines for Children website.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
If your child has gelastic seizures caused by a hypothalamic hamartoma, they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.
The gelastic and other types of seizures that often accompany them are often very difficult to control. It is rare for anyone with this type of epilepsy to have their seizures controlled for more than a few weeks or months at a time. The best outcome is usually seen in those children (and adults) who have a benign tumour in the hypothalamus (the hamartoma or astrocytoma) or in a temporal or frontal lobe causing their epilepsy. Successful surgery in these children and adults may improve not just their seizure control but also improve their behavioural and even learning problems.
What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact the Epilepsy Action Helpline.
Epilepsy Action would like to thank Dr Richard Appleton, consultant paediatric neurologist and honorary professor in paediatric neurology at Alder Hey Children’s Hospital, Liverpool, UK for preparing this information.