Infantile Spasms/West Syndrome
Infantile spasms may begin up to age 2, but most commonly begin between the 4 and 6 months, with about 90 percent beginning in the first year. The causes are widely variable and in some cases are unknown. However, the most common causes are tuberous sclerosis and perinatal asphyxia (lack of oxygen).
Parents sometimes attribute the cause to pertussis vaccination, a connection that has yet to be proven. Since the peak in onset of spasms occurs at the same age range that the vaccination is given, it is likely that the concurrent timing is the only link.
The characteristic symptoms of infantile spasms are, usually, rapid, though generally not violent , muscular contractions or extensions of limbs or other parts of the body. The spasms last one to two seconds and occur in clusters ranging from a few to more than 100 at a time. Infants may experience up to 60 clusters a day. The episodes rarely occur during sleep but are common in the early morning and just after naps.
The following are behaviors or symptoms that might occur in what is classified as infantile spasms or West syndrome:
Infants may cry and show irritability during or after a flurry of spasms.
Spasms are easily missed, especially if they occur singly or in small or infrequent clusters. Other potential symptoms that parents might notice are a loss of muscle tone, loss of head control or reaching ability, loss of eye contact, inattention to sounds, lack of responsiveness, poor smiling, or decrease in alertness.
Almost any condition that can cause brain damage is a potential cause of infantile spasms. Brain abnormalities are seen in about three-fourths of infants with this syndrome. In tracking down the specific cause, the doctor will likely order a variety of laboratory tests and EEGs, plus a CT or MRI brain imaging scan.
The initial step is a detailed medical history and physical examination. Among the signs the doctor will look for are neurological abnormalities that might have been present before the onset of seizures. Since tuberous sclerosis is often associated with infantile spasms, an examination of the skin for possible lesions (hypopigmentation) typical of tuberous sclerosis may be conducted.
Brain-wave patterns are especially informative in diagnosing infantile spasms. EEG tracings taken during and between seizures, and during both sleep and wakefulness are useful in confirming the diagnosis. A chaotic pattern (hypsarrythmia) between seizures is characteristic of those with infantile spasms. The pattern during sleep is markedly different and, in some infants, the disordered waves may be seen to lessen or disappear.
Neuroimaging by CT or MRI is conducted for possible signs of tuberous sclerosis, brain infection, or structural abnormality. If the cause still remains unknown, the initial battery of laboratory tests ordered by the doctor will likely be expanded to rule out metabolic and other potential causes.
Spasms in some infants may stop spontaneously without any treatment. But most will require some form of therapy, the primary drugs for which are adrenocorticotropic hormone (ACTH) or synthetic corticosteroid drug such as prednisone. These therapies can have a dramatic effect in arresting or slowing seizure activity and the treatment period may be relatively short. The side effects can be significant, however, and long-term use of these drugs requires careful monitoring.
Some infants may respond to conventional anticonvulsant drugs such as felbamate, lamotrigine, topiramate and valproic acid. Infantile spasms associated with tuberous sclerosis responds especially well to vigabatrin. However, vigabatrin, which is available in the United States, is toxic to the eye and can cause loss of peripheral vision.
A medically controlled ketogenic diet, may control or reduce seizures in some infants when medications fail. Brain surgery is another option when the seizures are identified with a lesion or structural abnormality that can be removed without damage to vital tissue. For example, new innovations in surgical procedures have begun to increase the success rate for surgery in infants with tuberous sclerosis.
The prognosis for children with infantile spasms is directly related to the cause. Infants with an known cause for their spasms have a better prognosis than those with an unknown cause for their spasms. Infants with no signs of neurological abnormality or developmental delay before the onset of spasms also have better outcomes. Those whose seizures come under control quickly or cease early tend to fair better as well.
Infantile spasms rarely continue beyond age 5, but are sometimes replaced by other seizure types. A significant number of infants with this syndrome have long-term cognitive and learning impairment. Some may have a behavior disorder accompanied by autistic symptoms. These impairments are likely due to the same brain injury that causes the seizures.
The presence of other seizures types with the spasms may also suggest a poor outcome. In the most severe cases, seizures will continue and the condition may evolve to the Lennox-Gastaut syndrome.