Neonatal Seizures

Neonatal seizures, or convulsions, are one of the common indications of a birth injury. The neonatal period is the time period in which a baby is most vulnerable to developing seizure activity. In fact, 80% of neonatal seizures happen in the first seven days of a baby’s life, as outlined in Neurology of the Newborn. Approximately 1.5% of all infants will experience some type of seizure activity in the neonatal period.

Perinatal or neonatal events such as fetal distress, maternal bleeding, placental abruption, or cord prolapse, as well as negligent or failed resuscitation of a distressed newborn, can cause neonatal seizures. Other factors include brain hemorrhage, bleeding in the brain from actual trauma during delivery, hemorrhage into different areas of the brain, or cerebral arterial or venous infarction (stroke). Metabolic disorders such as elevated bilirubin (liver enzyme) or hypoglycemia (low sugar levels) are also commonly associated with neonatal seizures.

The most common cause of infantile seizures is hypoxic–ischemic encephalopathy or HIE. HIE is caused by lack of oxygenation and blood flow to the brain during labor and delivery, and is also a leading cause of cerebral palsy. Statistics show that HIE is responsible for 80% of all neonatal seizures in the first 2 days of life and that it contributes to poor neurological outcome.

There are 5 recognized types of seizure activity: subtle seizures, tonic seizures, clonic seizures, myoclonic seizures, and non-paroxysmal repetitive behaviors.

Subtle seizures may include seizure activity in the infant’s brain, as well as non-seizure activity indicative of severely abnormal brain function. Symptoms of subtle seizures include horizontal deviation of the eyes with or without jerking (also known as nystagmus), abnormal posturing of the body (with arms and legs straight out, or other increased muscle tone), excessive eye blinking or fluttering, making sucking motions when not feeding, smacking of the lips, excessive drooling, bicycling movements in the lower extremities, swimming or rowing movements in the upper extremities, and apnea.

Symptoms of tonic seizures include increased muscle tone and sudden stiffening of the body, arms, or legs. These seizures usually occur during sleep, but may happen when an infant is awake, and often the infant will maintain consciousness throughout the seizure activity. Infants with tonic seizures have a poor prognosis since these are often a sign of underlying bleeding in the brain.

Clonic seizures are characterized by rhythmic, repetitive shuddering or shaking of the extremities. They often begin in one area and spread throughout the body. Infants who experience clonic seizures may also be sluggish, underactive, and display complex non-purposeful movements. A symptom of this kind of seizure can be noticed in a baby “staring into space” with the caregiver not able to get the baby’s attention.

Symptoms of myocolonic seizures include sudden jerking movements that appear as if the infant has been struck with a jolt of electricity. This type of seizure may occur as an isolated incident or as a series of events. Myocolonic seizures are also often resistant to treatment, and in particular have poor prognoses, as they can lead to early progressive brain tissue injury and death.

The infant can exhibit any of the above symptoms without signs of seizures when examined via electroencephalogram.