Infantile Spasms

Usually, infantile spasms occur in infants with serious brain disorders and developmental abnormalities that often have already been recognized. These disorders may include

• Injuries to the brain during the perinatal period

• Metabolic disorders

• Brain malformations

Tuberous sclerosis complex is a common cause; prognosis is sometimes better when seizures are caused by this disorder than when seizures have other identifiable causes.

Sometimes the cause of infantile spasms cannot be identified.

Spasms begin with a sudden, rapid, tonic contraction of the trunk and limbs, sometimes for several seconds. Spasms range from subtle head nodding to contraction of the whole body. They involve flexion, extension, or, more often, both (mixed). The spasms usually occur in clusters, often several dozen, in close succession and occur typically after children wake up and occasionally when falling asleep. Sometimes, at first, they are mistaken for startles.

Developmental delays (see Childhood Development) may be present before the onset of infantile spasm. In infants with normal development, developmental regression can occur (eg, children may stop smiling or lose the ability to sit up or roll over).

Rate of premature death ranges from 5 to 31% (1) and is related to the etiology of the infantile spasms.

• Electroencephalography (EEG) with awake and asleep stages

• Neuroimaging, preferably MRI

• Testing to identify the cause unless an underlying significant neurologic disorder has already been identified

Previous history (eg, neonatal hypoxic-ischemic encephalopathy) and/or symptoms and signs suggest the diagnosis of infantile spasms in some children. Physical and neurologic examinations are done, but often no pathognomonic findings are identified except in tuberous sclerosis complex.

EEG is done to confirm the diagnosis and check for specific abnormalities. Typically, the interictal pattern is hypsarrhythmia (chaotic, high-voltage polymorphic delta and theta waves with superimposed multifocal spike discharges). Multiple variations (eg, focal or asymmetric hypsarrhythmia) are possible. The ictal pattern is usually a sudden, marked and diffuse attenuation of electrical activity.

Neuroimaging, preferably MRI, is done if it has not already recently been done.

• Intramuscular adrenocorticotropic hormone (ACTH)

• Oral corticosteroids

• Vigabatrin (especially for tuberous sclerosis complex)

Infantile spasms are not responsive to typical antiseizure medications.

The standard therapies for infantile spasms can be any one of the following.

ACTH can be given daily IM as either high-dose (150 units/m²) ACTH or low-dose (20 units/m²) ACTH. The Pediatric Epilepsy Research Consortium (PERC) recommends the higher dose, given for 2 weeks and then tapered down every 3 days until 29 days of treatment are completed. If low-dose therapy is tried and has not stopped spasms within 2 weeks, the higher dose is used.

Corticosteroids

• Days 1 to 14: 10 mg 4 times a day

• Days 15 to 19: 10 mg 3 times a day

• Days 20 to 24: 10 mg 2 times a day

• Days 25 to 29: 10 mg once a day

Vigabatrin is the drug of choice when the spasms are caused by tuberous sclerosis complex

In some patients with resistant spasms or with focal cortical malformation, epilepsy surgery can eliminate seizures.

There is evidence that the more quickly effective therapy is initiated, the better the neurodevelopmental outcome, particularly when no cause is identified.

• Infantile spasms last a few seconds and can recur many times a day; they may resolve spontaneously by about 5 years of age but are often replaced by other types of seizures.

• Usually, infantile spasms occur in infants with serious brain disorders and developmental abnormalities that often have already been recognized; tuberous sclerosis complex is a common cause.

• Do electroencephalography to confirm the diagnosis, and other tests (eg, brain MRI and metabolic and genetic testing) to evaluate the cause of infantile spasm.