Infantile spasms are brief contractions of the neck, trunk, and arm muscles, followed by a phase of sustained muscle contraction lasting less than 2 seconds. Spasms occur most frequentlywhen the child is awakening from or going to sleep. Each jerkis followed by a brief period of relaxation with repeated spasmsin clusters of variable duration. Many clusters occur each day.West syndrome is the triad of infantile spasms, developmentalregression, and a dramatically abnormal EEG pattern (hypsarrhythmia). Hypsarrhythmia consists of chaotic high-voltageslow waves, spikes, and polyspikes. The peak age at onset is 3to 8 months. When flexion of the thighs and crying are prominent, the syndrome may be mistaken for colic or gastroesophageal reflux. The underlying etiology of the spasms dictates theprognosis. More than 200 different etiologies have been identified, including tuberous sclerosis, malformations of cortical development (lissencephaly), genetic syndromes (trisomy 21),acquired brain injury (stroke, perinatal hypoxic-ischemicencephalopathy), and metabolic disorders (phenylketonuria).Infants for whom an etiology is determined are classified as having symptomatic infantile spasms and are at very high risk for long-term neurodevelopmental difficulties. The etiology is notdetermined for a small subset of children. These patients withcryptogenic spasms have a somewhat better long-term prognosis but remain at high risk for adverse outcomes. First-line treatment options for infantile spasms include adrenocorticotropichormone, high-dose oral corticosteroids, and vigabatrin. Forinfants with underlying tuberous sclerosis, vigabatrin is considered the treatment of choice. For other patients, treatmentdeterminations are made on a case-by-case basis.
Lennox-Gastaut syndrome is a severe epilepsy syndrome with variable age of onset. Most children present before age 5 years. Frequent, multiple seizure types, including atonic, focal, atypical absence, and generalized tonic, clonic, or tonic-clonic varieties, characterize the disorder. Many children have underlying brain injury or malformations. The seizures usually respond poorly to treatment, and most patients have significant intellectual disability.
Benign neonatal convulsions are an autosomal dominant genetic disorder linked to abnormal neuronal potassium channels. Otherwise well newborns present with focal seizures toward the end of the first week of life, leading to the colloquial term fifth-day fits. Response to treatment is generally excellent, and the long-term outcome is typically favorable.
Acquired epileptic aphasia (Landau-Kleffner syndrome)is characterized by the abrupt loss of previously acquired language in young children. The language disability is an acquired cortical auditory deficit (auditory agnosia). The EEG is highly epileptiform in sleep, the peak area of abnormality often being in the dominant perisylvian region (language areas). This diagnosis should be considered for young patients with clear autistic regression, as it is a potentially treatable entity.
Status epilepticus is a neurologic emergency and is defined as ongoing seizure activity or repetitive seizures without return of consciousness for greater than 30 minutes. Status epilepticus carries an approximately 14% risk of new neurologic deficits, most secondary to the underlying pathology. Similarly, the mortality rate of status epilepticus (4% to 5%) is related to the underlying etiology. Etiologies include new-onset epilepsy of any type, drug intoxication, drug withdrawal (especially missed anticonvulsant doses among children with preexisting epilepsy), hypoglycemia, electrolyte imbalance, acute head trauma, infection, ischemic stroke, intracranial hemorrhage, metabolic disorders, and hypoxia.