What is Epilepsy?By definition epilepsy is a disease of the brain in which a person suffers from infrequent and unpredictable but recurrent seizures (convulsions). Most people who are not familiar with epilepsy think of it as causing the whole body to shake. Although some seizures fit that description, seizures can vary from mere moments of staring into space without body shaking to transient shaking of a single body part without loss of consciousness. Epilepsy can be "cryptogenic" (i.e., due to an unknown cause), but commonly it is caused by an abnormality in the structure of the brain (e.g., the presence of an arteriovenous malformation).
How Perinatal Strokes and Epilepsy Are Linked
A permanent injury to the brain caused by a stroke can become a cause of recurrent seizures (i.e., epilepsy). In fact, perinatal strokes are thought to be the second most common cause of perinatal seizures. Perinatal strokes occur with a frequency of 1 in 4,000 live births. About 17% of full-term babies who suffer perinatal seizures have suffered strokes.
Causes of Stroke Before Birth?Causes of stroke before birth include:
- Porencephalic cysts: These are rare fluid filled cavities found inside the brain of some babies, which can impair blood flow to a given part of the brain, causing strokes.
- Blood clots: When two or more babies share the same womb, and one of them dies before birth, blood clots are formed. This becomes dead tissue, which can be reabsorbed and migrate inside the placenta and lead to a stroke in the living unborn baby.
- Spasms of the blood vessels that bring blood to the babyâs brain: These can occur when cocaine or amphetamines are used by the mother during pregnancy.
- Profuse bleeding during delivery: When a large volume of blood is lost during a difficult delivery, the mother's blood pressure can drop so low that not enough blood is pumped to the unborn babyâs brain, causing an ischemic stroke.
Causes of Strokes After BirthCommon causes of stroke after birth include:
- Abnormalities in the anatomy of the heart: Abnormalities in the anatomy and the function of the heart can lead to the formation of blood clots which can travel to the brain and cause stroke.
- Infections of the heart valves (infective endocarditis): When the valves of the heart are infected by bacteria, small pellets made of these bacteria can migrate to the brain and cause strokes. Infection of the heart can also induce arrhythmias which lead to stroke by increasing the likelihood of blood clot formation.
- Maternal Antiphospholipid, and other abnormal antibodies that can induce blood clot formation.
- Maternal diabetes.
- Trauma during birth.
- Surgery to correct a birth defect in the heart of a baby.
How Common Is Stroke-Induced Epilepsy?Approximately 70% of babies who suffer perinatal strokes go on to develop childhood epilepsy. Nonetheless, with appropriate treatment and follow-up by a pediatric neurologist, more that 60% of these infants become seizure-free over the years.
Rod Hunt and Terry Inder, Perinatal and neonatal ischaemic stroke: A review Thrombosis Research; Volume 118, Issue 1, 2006, Pages 39-48