(also known as baltic myoclonus)
This condition is very rare. Most children with this syndrome begin to have epilepsy between the age of six and 16 years. Half will have tonic-clonic seizures which often start in the night, during sleep, and the other half will have myoclonic seizures (jerks).
The child also experiences myoclonus, which is a brief, rapid, shock-like jerking movement. Myoclonus can happen in one or more limbs, or may be generalised, involving much of the body. The myoclonus stops during sleep or when the child is resting. Things including loud noises, or sudden movements can trigger the myoclonus.
Something as simple as starting to move or a simple daily task 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 to do something.
Children 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, 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.
One of the main problems in the condition 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. The gene is important for producing a protein which scientists have not yet been able to identify, which is needed for the normal activity of the cerebellum. There are two 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 one in four chance of having another child with the same condition.
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 be seem to be very like another, far more common and much milder type of epilepsy, called juvenile myoclonic epilepsy.
The electroencephalogram (EEG) tracing 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.
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. Anti-epileptic drugs can be used to control the seizures and the action myoclonus. These medications include sodium valproate (Epilim), clonazepam (Rivotril) and levetiracetam (Keppra).
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.
The faulty working of 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, eating and writing.
Fortunately, the epileptic seizures occur less frequently as the child gets older and the seizures may in fact stop by the late teenage years or adult life.
Children’s intelligence, vision and hearing are also not usually affected by Unverricht-Lundborg syndrome. However, some teenagers and adults can become frustrated and depressed because of the very frequent myoclonus and co-ordination problems.
With modern drugs and support, the condition is not life-threatening. Occupational therapy and physiotherapy may be help in overcoming some of the problems with poor co-ordination and ataxia.
Contact a Family, 209-211 City Road, London, EC1V 1JN, telephone 0808 808 3555, http://www.cafamily.org.uk/
Because this page is written by an epilepsy healthcare professional and not by Epilepsy Action, it falls outside the requirements of the Information Standard.
Epilepsy Action is indebted to Dr Richard Appleton, a Consultant Paediatric Neurologist who specialises in children’s epilepsy, and to Dr Rachel Kneen, Consultant Paediatric Neurologist and Dr Stewart Macleod, Specialist Registrar in paediatric neurology, at Alder Hey at Alder Hey Children’s Hospital, Liverpool, who have kindly prepared this information.