West's Syndrome
AMI PATEL, BSC, MICROBIOLOGY & IMMUNOLOGY, EPILEPSY CANADA, AND DR. LIONEL CARMANT, MD, FRCPC, UNIVERSITÉ DE MONTRÉAL
West's syndrome is a rare form of epilepsy seen predominantly in the first year of life. The incidence of infantile spasms is low in the general population, but this syndrome represents a catastrophic form of epilepsy, because it is associated with developmental regression. A British physician, W.J.West, documented its existence in the first volume of Lancet in 1841, based on observations of his own son.
West's syndrome is commonly classified in two categories: cryptogenic (no known cause) or symptomatic (a known cause). A variety of factors can influence the development of a symptomatic case. Causes range from bacterial infections, tuberous sclerosis (25%), brain abnormalities, trauma or ischemic injury (stroke), febrile seizures and, less often, metabolic disorders.
DIAGNOSIS
This syndrome is first observed during the first few months after birth, at around 4 to 8 months of age. The spasms are usually brief, generalised seizures. The body becomes rigid with large flexion movements with occasional extensor reflexes, which is often seen as a generalised repetitive jerking of muscle groups, similar to myoclonic seizures. In West's syndrome, spasms usually occur in clusters, often on waking or right before sleeping. Infants with West's syndrome may have up to 100 seizures per day. At the end of a cluster of seizures, the infant may cry for a short while, which may lead parents to mistake this syndrome for colic.
The typical pattern of an abnormal, chaotic-appearing EEG, known as hypsarrhythmia, occurs in twothirds of infants with West's syndrome. Sleep patterns show a widespread disruption in neuronal activity. At first, the remaining onethird of infants with West's syndrome may be difficult to distinguish from infants who suffer from myoclonic seizures or non-epileptic disorders. They may be misdiagnosed, because they do not have hypsarrhythmia or other psychomotor problems.
CT and MRI scans should be able to tell if an infant has any prior disposition for West's syndrome. They will indicate the presence of any underlying brain abnormalities, e.g., lesions or atrophy. A PET scan may determine if any changed in metabolism exist in different brain regions.
Hypometabolism (slow metabolism) has been identified in some infants with West's syndrome. If a region of hypometabolism or structural lesion is present, surgery may be an option, if the surgeon believes that removal will help to reduce the frequency of seizures.
TREATMENT
Treatment for infants with West's syndrome presents a problem, because seizure control does not necessarily lead to a better cognitive outcome. In recent years, newer antiepileptic drugs, such as vigabatrin (Sabril), have become the drugs of choice due to their safer side-effect profiles.
If this treatment fails, patients are switched to adrenocorticotropin (ACTH) to suppress the production of corticotrophin-releasing hormone (CRH), which is controlled by the hypothalamus. ACTH has a wide range of side effects, so this therapy is usually administered for only a few months. Prednisone, like ACTH, is a steroid drug that may be used to help to control spasms. However, there is a high incidence of relapse after seizures are controlled and steroids gradually removed.
Valproic acid and nitrazepam have shown some benefit to infants with West's syndrome.
Alternative treatments, such as the ketogenic diet, have proven to be effective in some infants. This diet is often prescribed after all other therapeutic options have failed. Depending on the frequency of seizures, the neurologist and dietician can adjust the diet to help to reduce the seizures.
PROGNOSIS
As the child ages, the frequency and severity of seizures usually decreases. However, in over 75% of infants with West's syndrome, longterm effects include impaired cognitive function and other disorders, such as cerebral palsy. A few infants (<10%) may fully recover, but most subsequently develop other epilepsy syndromes, such as Lennox-Gastaut syndrome and other forms of cognitive and psychomotor impairment.
Printed with permission of Epilepsy Canda.
