Infantile Spasms (West Syndrome)
Syndrome describes a collection of signs and symptoms that indicate a person has a particular condition. Patients with West syndrome experience spasms, abnormal brain patterns called ‘hypsarrhthmia’ and a general learning disability. Diagnosis of West syndrome still can be made in absence of one the symptoms listed. In general, the seizure begins with a sudden jerk followed by stiffening of the affected body part. The seizure lasts about 2 seconds and occurs in series.
About 350 to 400 children will develop West syndrome each year in the UK. In 9 out of 10 children, infantile spasms usually begin 3 to 7 months post delivery. Normally, these spasms stop when the children reach 5 years old but they may be replaced by another seizure disorder. 1 out of 4 children will continue on to develop Lennox-Gastaut syndrome, another type of seizure disorder. Some parents may have mistaken the seizure attacks as colic, but the cramps of colic do not occur in series.
Types of West Syndrome
Generally, West syndrome is classified into symptomatic and cryptogenic. The cause can be identified in symptomatic West syndrome whereas the cause cannot be identified in cryptogenic West syndrome.
There is also a subdivision of West Syndrome known as X-linked infantile spasms. X-linked infantile spasms develop in infants due to a mutated gene on the X chromosome. Males are more affected compared to females because they do not have a back up for a healthy copy of this gene, unlike females.
Causes of West Syndrome
A specific cause often related to some form of brain disorder or brain injury before the infantile spasms can be identified in about 70 - 75% of affected infants. However, there are infants who have West syndrome with no apparent injury and the baby had previously been developing normally.
Some of the causes that can lead to West syndrome include:
- lack of the oxygen to the brain during delivery
- meningitis, which is inflammation of the protective membranes surrounding the brain and spinal cord
- encephalitis, which is the inflammation of the brain itself
- genetic predisposition, such as Down’s syndrome
- brain malformations
- metabolic diseases, such as phenylketonuria
- neurocutaneous disorders, such as tuberous sclerosis complex (TSC)
Signs and Symptoms
Normally, the episodes are short and frequent. They happen most frequently after the baby has just woken up and are less frequent during sleep. Sometimes, they may occur in clusters that can last up to 10 – 20 minutes.
The spasms are typically characterized by a sudden involuntary contraction of the head, trunk and limbs. At other times, the baby may have a different episode with uncontrolled extension of the legs and arms. These are called ‘extensor’ spasms. The severity of the symptoms can vary widely among infants. It can range from slight twitching of the shoulder to jackknife or “salaam” movements where the baby fully bends forward.
Besides the spasms, infants with West syndrome have erratic EEG (electroencephalogram) patterns when the seizures are not happening. This means that their brain activity is abnormal. It is common for babies who have infantile spasms to experience some degree of delayed development until the spasms are corrected. This is because they are left behind in acquiring skills that require voluntary movements and coordination of the muscles.
Diagnosis The diagnosis of West syndrome often depends on the electroencephalogram (EEG). Electrodes are placed on the scalp to help pick up brain signals and record them as electrical waves during periods of activity and during sleep. The process should be painless and non – intrusive. A child with infantile spasms will experience a disorganized pattern of the brain known as ‘hypsarrhythmia’ which are large, chaotic spikes in the graph recorded. Children with West syndrome have abnormal EEG but sometimes it is only manifested while they are asleep.
Brains scans are used to identify any tissue or structural abnormality in the brain. The brain scans the doctor may ask your child to take include a computed tomography (CT) scan, which uses multiple X rays to generate a single picture of the brain, or a magnetic resonance imaging (MRI), which uses electromagnetic waves to identify any brain abnormalities.
The majority of children will need further testing to identify the underlying cause of West syndrome. This includes blood tests, cerebrospinal fluid analysis via lumbar puncture and urine tests.
The first line of treatment doctors opt for are steroids. Adrenocorticotrophic hormone (ACTH) is given in the form of daily intramuscular injection whereas prednisolone is taken orally. However, steroids usage comes with some serious side effects, for example changes in behavior, weight gain and irritation of the stomach lining.
The other popular first line treatment is vigabatrin (Sabril). Vigabatrin is the best choice of treatment for infants suffering from tuberous sclerosis (a disorder associated with the development of benign tumours in the brain, kidneys, eyes, hearts, lungs and skin). However, parents of the children concerned need to know that Sabril can potentially lead to damage of the retina in children, especially when it is continually used for many months. Anticonvulsants such as nitrazepam and sodium valproate (Epilim) may also be used. Some possible side effects of nitrazepam include fatigue, dizziness and dry mouth. One of the major setbacks of sodium valproate is the children may eventually get serious liver disease. If the infant gets jaundice (where the skin or eyes look yellow), has stomach pain and has more seizures than normal, take them to the hospital immediately.
Unfortunately, most children with infantile spasms will be developmentally delayed in life. This tends to be more severe in children whose spasms are caused by a developmental brain disorder. Children who initially developed normally before having the spasms have better prospects: 10% to 20% will have normal mental function. A fraction of the children with West syndrome will continue on to develop autism.
Early recognition and management of West syndrome has been shown to improve the outcomes especially for the children whose causes of spasms could not be identified.