It is still unknown which bio-chemical mechanisms lead to the occurrence of West syndrome. It is conjectured that it is a malfunction of neurotransmitter function, or more precisely, a malfunction in the regulation of the GABA transmission process.
Another possibility being researched is a hyper-production of the Corticotropin-releasing hormone (CRH). It is possible that more than one factor is involved.
Both hypotheses are supported by the effect of certain medications used to treat West syndrome.
If a cause presents itself, the syndrome is referred to as ''symptomatic'' West syndrome, as the attacks manifest as a symptom of another problem. Almost any cause of brain damage could be associated, and these are divided into prenatal, perinatal, and post-natal. The following is a partial list:
- In around one third of the children, there is evidence of a profound organic disorder of the brain. This includes:
- Furthermore, other causes increasingly being named in the literature are:
- Incontinentia pigmenti
- Foix-Chavany-Marie syndrome
- Patau syndrome (trisomy 13)
- Sturge-Weber syndrome
- neurometabolic diseases
- congential infections (e.g. Cytomegalovirus)
- brain damage due to asphyxiation or hypoxia (lack of oxygen, e.g. during birth), periventricular leukomalacia, cephalhematoma, cerebrovascular accident or brain damage of various types as well as that caused by premature birth.
- There are known cases in which the spasms occurred for the first time after vaccination against Measles, Mumps and Rubella or Tetanus, Pertussis, Diphtheria, Polio, Hepatitis B and Haemophilus influenzae Type B. However, there is no causal relationship between immunization and West syndrome, since stress of any kind is a common trigger for seizures, and the immunization occurs during the time-frame in which many typical cases become conspicuous.
West syndrome in babies with Down's syndrome
West syndrome appears in 1% to 5% of infants with Down's syndrome. This form of epilepsy is relatively difficult to treat in children who do not have the chromosomal abnormalities involved in Down's syndrome. However, in children with Down's syndrome, the syndrome is often far more mild, and the children often react better to medication. The German Down Syndrom InfoCenter noted in 2003 that what was normally a serious epilepsy was in such cases often a relatively benign one.
EEG records for children with Down's syndrome are often more symmetrical with fewer unusual findings. Although not all children can become entirely free from attacks with medication, children with Down's syndrome are less likely to go on to develop Lennox-Gastaut syndrome or other forms of epilepsy than those without additional hereditary material on the 21st chromosome. The reason why it is easier to treat children with Down's syndrome is not known.
If, however, a child with Down's syndrome has seizures that are difficult to control, the child is at risk to develop an autistic spectrum disorder.
When a direct cause cannot be determined but the children has other neurological disorder, the case is referred to as ''cryptogenic'' West syndrome, where an underlying cause is most likely but even with our modern means cannot be detected. Currently the cryptogenic group is often combined with idiopathic while referred to as "cryptogenic".
Sometimes multiple children within the same family develop West syndrome. In this case it is also referred to as ''cryptogenic'', in which genetic and sometimes hereditary influences play a role. There are known cases in which West syndrome appears in successive generations in boys; this has to do with X-chromosomal heredity.
Occasionally the syndrome is referred to as ''idiopathic'' West syndrome, when a cause cannot be determined. Important diagnostic criteria are:
- Regular development until the onset of the attacks or before the beginning of the therapy
- no pathological findings in neurological or neuroradiological studies
- no evidence of a trigger for the spasms
Those are becoming rare due to modern medicine.
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Last Updated: Jul 9, 2013