This condition is very rare. Most children with this syndrome begin to have epilepsy between the age of 6 and 16 years. It is one of the epilepsies in the group called ‘progressive myoclonic epilepsy’.
One of the main problems in this syndrome seems to be a fault in the part of the brain called the cerebellum. The cerebellum controls motor activity, for example it sends messages to the muscles telling them to move smoothly. Following a period of malfunction, these nerve cells will eventually die. The motor problems are referred to as ataxia.
The condition is inherited genetically (in the genes). The pattern of genetic inheritance is called autosomal recessive. People with the condition receive one faulty gene from each of their parents. There are 2 copies of our genes, therefore the parents themselves are quite healthy because they still have a good gene copy working. But every time they have a child they have a 1 in 4 chance of having another child with the same condition.
The genetic cause of Unverricht-Lundborg syndrome is due to a mutation in a gene called the CSTB gene. The CSTB gene gives instructions for making a protein called cystatin B. This protein is important in brain function and particularly part of the brain called the cerebellum. The abnormal cystatin B protein causes the different symptoms and signs in Unverricht-Lundborg syndrome.
Other names for Unverricht-Lundborg syndrome
• Baltic myoclonus
• A progressive myoclonic epilepsy
• Progressive myoclonic epilepsy Type 1
All children with this syndrome will have myoclonus, which is a brief, rapid, shock-like jerking movement. Myoclonus can happen in one or more limbs, or may be generalised, involving most of the body. The myoclonus stops during sleep or when the child is at rest. Loud noises or sudden movements can trigger the myoclonus, which can be severe enough to cause falls.
Something as simple as starting to move or a simple daily task, such as beginning to dress or eat, may cause a sudden jerk which might then cause the child to fall down. These movements are called ‘action myoclonus’, because the myoclonus is most noticeable when the child tries or ‘acts’ to do something.
Children with this syndrome also have very poor co-ordination which means that they are often not able to walk in a straight line, use a fork and spoon, or dress and undress themselves. This poor co-ordination is called ‘ataxia’.
Tonic-clonic seizures connected to this condition happen either during sleep or on waking from sleep.
The diagnosis is initially made or suspected on clinical grounds – meaning the age at which the seizures start, the type of seizures and the fact that the myoclonus gets worse as the child gets older.
Sometimes the early course of Unverricht-Lundborg syndrome can look a lot like another, far more common and much milder type of epilepsy, called juvenile myoclonic epilepsy (JME).
The results of an electroencephalogram (EEG) may help in making the diagnosis by showing runs of spikes at the vertex (top of the brain) during part of a child’s sleep called ‘rapid eye movement (REM) sleep’. The EEG may also be abnormal during wakefulness and show polyspike discharges and photosensitivity (spike and wave or polyspike and wave activity in response to flashing lights).
Recently, the discovery of a genetic abnormality has been able to confirm a diagnosis of Unverricht-Lundborg syndrome in many, but not all, children. This is very useful as the genetic abnormality can be looked for in a simple blood test.
There is no cure for the condition, but much can be done to help. Epilepsy medicines can be used to control the seizures and the action myoclonus. These medicines include sodium valproate (Epilim), clonazepam (Rivotril), levetiracetam (Keppra) and topiramate (Topamax). Piracetam is a different type of medicine that might be helpful in older children and teenagers who have severe action myoclonus. Piracetam can be safely used with epilepsy medicines. A new medicine, brivaracetam (Briviact) might also be helpful. Finally, the ketogenic diet may also be helpful in this condition, mainly by reducing the numbers of tonic-clonic and myoclonic seizures.
The epilepsy medicines phenytoin (Epanutin), carbamazepine (Tegretol) and vigabatrin (Sabril) should not be used to treat this condition because they usually make the myoclonus and ataxia much worse.
The tendency for arms and legs to jump uncontrollably when the child tries to move can therefore be helped. However, sometimes the myoclonus may be so bad that the children are unable to walk. Piracetam may be helpful in this situation.
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.
Your child is likely to have prolonged but particularly very frequent and repeated seizures as part of Unverricht-Lundborg syndrome. Your child’s hospital doctor (paediatrician or paediatric neurologist) will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures. It is important that your child is given this ‘rescue’ care plan.
The faulty working of the part of the brain called the cerebellum leads to great difficulty with balance and co-ordination, which increases as the condition worsens. This lack of co-ordination makes it very difficult to do all the normal activities of daily living, including washing, dressing and undressing, eating and writing. By the late teenage years or early adulthood, people with this condition need help with these activities and may not be able to walk.
Fortunately, the epileptic seizures happen less frequently as the child gets older and the seizures may in fact stop by the late teenage years or adult life. However, the ‘action myoclonus’ usually continues to worsen.
Children’s vision and hearing are not usually affected by Unverricht-Lundborg syndrome. Their speech can become slurred (called ‘dysarthria’) in the teenage years. Children and young teenagers with this condition do not usually develop any learning difficulties; however, some mild difficulties may occur in older teenagers (aged 18 and 19 years) and young adults. Some teenagers and adults can become frustrated and depressed because of the very frequent myoclonus and co-ordination problems.
With modern medicines and support, the condition is not life-threatening. Occupational therapy and physiotherapy may help in overcoming some of the problems with poor co-ordination and ataxia.
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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 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.
Epilepsy Action would like to thank Dr Richard Appleton, consultant paediatric neurologist at Alder Hey Children’s Hospital, Liverpool, UK for preparing this information.