Infant Seizures and Their Causes and Symptoms
The human brain is like the central command and control center for the entire body. All movements of the body are generated and controlled by electrical impulse signals transmitted from the brain. Infant or neonatal seizures are a relatively common but potentially serious medical event that occurs when the brain is suddenly flooded by abnormal electrical transmissions that momentarily disrupts the functioning of the brain.Types of Infant Seizures
Infant seizures are classified into different subtypes based on the particular area of the brain that is involved, how severe the brain interruption is, and the physical response triggered by the seizure.
Focal Seizures: a focal seizure (also referred to as a "partial seizure) occurs when the abnormal brain functioning is focused on one or more specific areas of side of the brain. Infants and children will often experience some sort of pre-cursor symptom (called an "aura") just before the seizure occurs. Common pre-cursor signs include mental confusion, fear/anxiety, vision or hearing changes, and strange smells. Focal seizures are further divided into 2 subtypes: (1) simple; and (2) complex. Simple focal seizures involved various symptoms and characteristics depending on the particular part of the brain that is affected. Most simple focal seizures involve the occipital lob and trigger muscle spasms in an isolated group of muscles such as the arms or legs. Complex focal seizures involve the temporal lobe of the brain and the infant or child typically passes out or temporarily loses mental awareness.
The types of seizures described below are considered "generalized seizures" involving both sides and more than one specific area within the brain. With these types of seizures, there is almost always a brief loss of consciousness.
- Absence Seizures: also known as "petit mal" seizures, absence seizures typically involve a sudden altered state of consciousness while the child or baby's eyes remain open in an abnormal fixed gaze. This type of seizure rarely lasts longer than 20-30 seconds and can happen several times a day. Infants rarely experience absence seizures as they almost always begin after a child is 4-5 years old.
- Atonic Seizures: this type of seizure causes a very sudden and dramatic loss of muscle tone causing babies to go limp (like a rag doll) or older children to fall from a standing position or drop their head and arms and become unresponsive.
- General Tonic-Clonic Seizures: also referred to as "grand mal" seizures, these normally involve a series of phases: the arms, legs and/or body will first contract; then straighten out; followed by tremors or shakes; and end with a clonic phase where the muscles gradually relax and return to normal.
- Infantile Spasms: this is a particularly rare type of seizure occurring in infants under 6 months old. This type of seizure is characterized by sudden spasms of the neck, legs and/or body which often occur just as the baby is waking up or falling asleep. These seizures can occur over a hundred times in a single day and can have very serious, long-term health consequences.
- Febrile Seizures: febrile seizures are somewhat different in that they are generally only triggered by high fevers (usually caused by infections) and not necessarily related to underlying neurologic issues - although infants with brain damage are generally more prone to febrile seizures when they get fevers.
When infants experience any of the various types of seizures described above the most likely potential causes are trauma during birth causing damage to the baby's brain, congenital birth defects, or infection.
- Brain Injury During Birth: all types of seizures are the result of some type of electrical abnormality involving the brain. Infant seizures are often an indication of underlying neurologic problems that may be the result of oxygen deprivation during labor and delivery. Infant seizures can be a proximate result of a number of different types of head and brain related injuries that frequently occur during a difficult childbirth. External trauma to the baby's head is a common problem. Head trauma during birth is often related to the use of vacuum extractors or obstetrical forceps by doctors to facilitate vaginal delivery of a baby. When these instruments are not used with the necessary level of care and skill they are notorious for causing injuries to a baby's head and neck. External head trauma from forceps or vacuum extractors can lead to injuries such as hematomas (brain bleeds), skull fractures, hydrocephalus and other potentially serious injuries that can affect the brain and cause different types of seizures. The primary cause of brain injury to babies during childbirth is oxygen deprivation. When the baby is deprived of oxygen or its oxygen supply is restricted for any length of time during delivery it can cause cells in the brain to decay and die. Oxygen deprivation is probably the leading cause of major birth injuries involving the brain and infant seizures are a key early indicator of brain damage.
- Infection: another frequent cause of seizures in infants (particularly certain types of seizures) is infection. Although seizures can be caused by a number of different types of infection, there are certain infections, namely Group B strep, passed from mother to baby during pregnancy, that are strongly linked with infant seizures. Group B strep is an exceedingly common type of infection that affects 1 out of every 4 pregnancies. This is why careful 37th week screening for group B strep (and other types of infection) is a critical part of prenatal care. If the infection is diagnosed it can be easily treated to prevent it from being passed onto the baby. If left untreated, however, infections can cause fever and trigger seizures in infants.
- Cerebral Palsy: certain types of infant seizures (particularly the generalized seizures such as "petit mal" or "grand mal" seizures) are often one of the earliest and most definitive symptoms that a newborn baby may have cerebral palsy. Cerebral palsy is a movement disorder caused by injury to the developing brain of a fetus (usually from oxygen deprivation) during pregnancy or childbirth. The damage disrupts the full, normal development of the baby's brain leaving it unable to properly control the movement of certain muscles in the body.