Infantile spasms are a type of epilepsy with a characteristic age of onset (typical age when seizures start), pattern of seizures and electroencephalogram (EEG). This means that it is an ‘electroclinical epileptic syndrome’. The syndrome is called ‘West syndrome’ after Dr West, who first described the condition in his 4-month-old son in 1841. This type of epilepsy occurs in about one in 2,500-3,000 children. Every year in the UK about 350-400 children will develop West syndrome.
In 9 out of 10 children with the condition, infantile spasms occur in the first year of life, typically between 3 and 8 months old. To begin with, the attacks are usually brief and infrequent and do not occur in clusters. Therefore it is quite common for the diagnosis to be made late. The parents may initially be told their infant has colic because of the pattern of the attacks and the cry that a child gives during or after an attack.
The typical pattern is of a sudden flexion (bending forward) in a tonic (stiffening) fashion of the body, arms and legs. Sometimes, the episodes are different, with the arms and legs being flung outwards (these are called ‘extensor’ spasms). Usually, they affect both sides of the body equally.
Typically, each episode lasts just 1 or 2 seconds, there is then a pause for a few seconds followed by a further spasm. While single spasms may happen, infantile spasms usually happen in ‘runs’ or ‘clusters’ of several in a row. It is common for babies who have infantile spasms to become irritable and for their development to slow up or even to go backwards until the spasms are controlled. These babies can also behave as if they cannot see. These problems can improve if the spasms can be controlled and the EEG improves.
The diagnosis of infantile spasms is made by a combination of the typical features with a typical EEG. The EEG shows a very disorganised pattern called ‘hypsarrhythmia’. The EEG is always abnormal in children with West syndrome but sometimes this abnormality is seen only during sleep. Infantile spasms, like many other ‘electroclinical syndromes’, have lots of different causes. A particular cause will be found in 7 or 8 out of every 10 children with West syndrome. A video of the spasms is also very helpful.
Most children with infantile spasms will need a number of tests apart from the EEG. These include brain scans, blood tests, urine tests and, sometimes, spinal fluid and other tests in order to try to identify the underlying cause. The most important brain scan is the magnetic resonance imaging (MRI) scan.
The main treatments used are corticosteroids or vigabatrin (Sabril). Nitrazepam and sodium valproate (Epilim) may also be used. There are different types of steroid that can be used. These are prednisolone (given by mouth), hydrocortisone (given by mouth or sometimes by injection) or tetracosactide (given by an intramuscular injection). Steroids must be used carefully as this treatment may cause some unpleasant side-effects. Vigabatrin may also be associated with some side-effects. Ketogenic dietary therapy (often called the ketogenic diet) may also be helpful for some infants.
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.
Information about treatments for children can be found on the Medicines for Children website.
In some children, infantile spasms respond easily to treatment, whereas in others they keep on happening. Most children unfortunately go on to have other kinds of seizures in later childhood including an epilepsy syndrome called Lennox-Gastaut syndrome. Most children also have learning difficulties and these may be mild or severe. The long-term outlook for West syndrome, for both the spasms stopping and the child’s development and learning, depends mainly on the cause of the syndrome.
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.
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.