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 Epilepsy Action.
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 1 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. Astrocytomas 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. The laughter occurs suddenly, comes on for no obvious reason, and is usually completely out of place. Sometimes older children may complain of a warning beforehand, although they are not always able to 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 eye and head moving to one or the other side, automatisms (such as lip-smacking, mumbling or fidgeting of the hands) and altered awareness. These signs may last for seconds to many minutes and then stop.
Children may also have other types of seizures, either immediately after these gelastic seizures or at other times. These include tonic-clonic and atonic seizures.
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 and this may delay the diagnosis. This is particularly likely to happen in young children. Sometimes a video 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 be done to look for the tumours that might be found in the hypothalamus. A computed tomography (CT) brain scan may not show very small tumours – so any brain scans must be with done with MRI.
Epilepsy Action has more information about diagnosing epilepsy.
The epilepsy medicines used to treat focal (partial) 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.
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.
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 this syndrome 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 are often very difficult to control. It is rare for anyone 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.
Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.