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 one or at the very most two, children will have gelastic epilepsy.
The most common areas of the brain which give rise to gelastic seizures are the hypothalamus (a small but 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 three or four years of age. The seizures usually start with laughter This 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 is like.
The laughter usually lasts less than one minute, and is then followed by signs that are more usually recognised with 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. This may last for seconds to many minutes and then stops.
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 also 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 in some children with gelastic epilepsy. The MRI scan is more powerful than the computed tomography (CT) brain scan and therefore more likely to show very small tumours.
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), levetiracetam (Keppra), oxcarbazepine (Trileptal) and topiramate (Topamax). Unfortunately no epilepsy medicines are likely to stop all seizures from happening. Surgery, or 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 causing 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.
Epilepsy Action has more information about the treatment of epilepsy.
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 probably seen in those children (and adults) who have a benign tumour in the hypothalamus (the hamartoma or astrocytoma) 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
- Dr Richard Appleton, and Dr Rachel Kneen, consultant paediatric neurologists at Alder Hey Children’s Hospital, Liverpool, UK and
- Dr Stewart Macleod, consultant paediatric neurologist at Royal Hospital for Sick Children, Glasgow, UK.
They have kindly prepared the information on this page. It is based on their own research, experience and expertise.