Medical Explanations

Causes of Foetal Stroke and HIE

Foetal stroke is one of the most common known causes of cerebral palsy in term and near-term infants.  In addition, foetal stroke and hypoxic ischemic encephalopathy (HIE) often occur together.  The following list includes common risk factors for and causes of a foetal stroke:

  • Birth asphyxia or hypoxic ischemic encephalopathy (HIE). This is when the foetus is deprived of an adequate supply of oxygen, which can lead to a stroke.
  • Trauma.  Trauma can be caused by a number of forces being exerted on the baby. These forces may be generated by the process of labor itself, and sometimes they are forces caused by those attempting to deliver the baby. Inappropriate use of vacuum extractors and forceps can cause severe brain damage from brain bleeds, contusions in the brain, stretching and tearing of blood vessels and brain tissue, and compression of the brain with changes in blood flow.  Trauma also may occur from the cumulative effect of prolonged periods of contractions and pushing, forcing the baby’s head and brain repeatedly against the mother’s pelvis.  All of these traumatic events can cause a stroke.  In addition, trauma can cause the formation of blood clots inside blood vessels (thrombosis), which can lead to a stroke.
  • Preeclampsia.  This is when a pregnant woman develops high blood pressure and protein in the urine after the 20th week of pregnancy. Preeclampsia can cause a decrease in blood flow from the placenta to the baby, which can cause a stroke.
  • Premature rupture of the membranes.  This is when there is rupture of the membrane of the amniotic sac and chorion more than one hour before the onset of labor. A prolonged rupture of the membranes is when the amniotic sac is ruptured or leaking for more than 18 hours before the onset of labor. The longer the membranes are ruptured, the higher the chances that the unborn baby will become infected and the placenta will develop an infection called chorioamnionitis.  Prenatal infections can lead to foetal stroke.
  • Chorioamnionitis.  This is an inflammation of the fetal membranes (amnion and chorion) due to a bacterial infection.  When this infection occurs, treatment needs to begin immediately because the baby is at risk for meningitis and brain bleeds, which can cause a stroke. Typically, antibiotics are administered and the baby is delivered immediately by C-section.
  • Gestational diabetes.  Women with gestational diabetes are at a higher risk for having a macrosomic baby (baby’s weight is >4000 grams, about 8.8 pounds), which occurs because of the increased blood glucose and insulin levels, which stimulate foetal growth.  When a baby is large, it may make vaginal delivery more difficult.  This may prompt the physician to utilize a vacuum extractor or forceps for assistance in the delivery, which can increase the likelihood of trauma to the baby.  Gestational diabetes also may cause reduced uteroplacental perfusion (RUPP).  RUPP is a serious condition that affects blood flow between the mother and baby. RUPP is a reduction in the flow of fluids, including blood, to and from the placenta.  This leads to a condition called endothelial dysfunction, in which the flat cells that line the blood vessels are damaged, causing hardening and thickening of the arteries.  The result is hypertension (abnormally high blood pressure), which is a life-threatening condition for both the mother and baby.  Furthermore, RUPP can cause preeclampsia, another very serious condition.  Both hypertension and preeclampsia can cause the baby to have a stroke.
  • Placental abruption.  Placental abruption occurs when the placenta separates from the uterus before the foetus is delivered. The placenta delivers oxygen and nutrients to the baby prior to birth. A placental abruption can induce extreme bleeding, which can cause a severe reduction of blood flow to the baby’s brain, thereby causing a stroke.
  • Fetomaternal hemorrhaging.  This is profuse bleeding that causes the baby to be deprived of blood and oxygen, which can cause a stroke.  Placental abruption and neonatal alloimmune thrombocytopenia (NAITP) are conditions that can cause fetomaternal hemorrhaging.
  • Placental thrombosis. This is when there is intravascular coagulation (blood clotting) that occurs in the placenta and veins of the uterus.  This can cause a stroke because it obstructs blood flow.
  • Twin to twin transfusion syndrome.  This occurs when blood moves from one twin to the other, which may cause both twins to have problems that can cause a stroke.

Risk Factors for Foetal Stroke

Other disorders that may increase the risk of foetal stroke include the following:

  • Cardiac disorders, including congenital heart disease, patent ductus arteriosus and pulmonary valve atresia.
  • Blood disorders due to deficiencies or mutations in coagulation factors and hyperviscocity syndromes which make an infant’s blood more likely to clot or hemorrhage.  Blood, homocysteine, and lipid disorders include polycythaemia, disseminated intravascular coagulopathy, Factor-V Leiden mutation, Protein-S deficiency, Protein-C deficiency, Prothrombin mutation, Homocysteine, Lipoprotein (a), and Factor VIII.
  • Infection leads to a hypercoagulable state and has been found to be a risk factor for cerebrovascular disease.  Central nervous system infection and systemic infection are perinatal risk factors.
  • The mother used cocaine while pregnant.
  • The mother has congenital heart disease, an autoimmune disorder, a coagulation disorder or anticardiolipin antibodies.
  • The mother has high blood pressure (hypertension) or low blood pressure (hypotension).

Signs and Symptoms of Foetal Stroke

Symptoms of a foetal stroke may not show up until months or years after the stroke occurred.  In some cases, the child develops normally, but at a much slower pace, and the child exhibits developmental delays.  A baby who suffered a more serious stroke with more brain damage may experience seizures.  Signs and symptoms of foetal stroke include the following:

  • Seizures
  • Problems feeding
  • Trouble breathing or pauses in breathing (apnea)
  • Early preference for use of one hand over the other
  • Developmental delays, such as rolling over and crawling later than what is normal

Diagnosing a Foetal Stroke

Early diagnosis and treatment of a foetal stroke is crucial to recovery.  Below are some of the tests that may be utilized to diagnose a stroke:

  • Blood tests
  • MRI (magnetic resonance imaging).  This is a test that uses magnets, radio waves, and computer technology to produce images of the brain.
  • MRA (magnetic resonance angiography).  This is an MRI of specific arteries in the brain.
  • MRV (magnetic resonance venography).  This is an MRI of specific veins in the brain.
  • CT scan (computed tomography).  This is a test that produces images of the brain using X-rays and a computer.
  • CTA (computed tomography angiography).  This is an X-ray of specific arteries in the brain.
  • Cranial ultrasound.  This utilizes high-frequency sound waves that bounce off organs and create an image of the brain.
  • Lumbar puncture.  This is a procedure that is performed to collect cerebrospinal fluid for diagnostic purposes.

Treating Fetal Strokes and HIE

Treatment of a foetal stroke must be administered immediately, followed by rehabilitation to help ensure that further damage and complications will not arise. Doctors must act to ensure the infant has adequate oxygen and circulation. The medical team may supply intravenous fluids or give blood-thinning medications to reduce the risk of a recurrent stroke. Should the medical staff on duty fail to recognize stroke, a subsequent stroke is more likely to occur and cause greater damage to the baby’s brain.

Hypothermia treatment induced by head cooling or body cooling administered within 6 hours of birth for 72 hours has proven beneficial in reducing death and neurological impairments at 18 months of age.  Combined therapies of hypothermia and pharmacological agents or growth factors to improve neurological outcomes can be used for damaged neonatal brains, such as after a stroke.

Sometimes signs of a stroke do not show up for months or years after the stroke occurred.  Treatment for a stroke is determined by how old the child is, what signs and symptoms he or she experiences, which area of the brain is affected, how much brain tissue was damaged, and whether another ongoing condition was the cause of the stroke.

Many different treatments are possible. For example, a child who is having seizures may require anti-seizure medications, whereas a child with a heart defect might need medication to thin the blood. For most children, treatment also involves age-appropriate rehabilitation and therapy.

The brain damage that occurs during a stroke can cause a number of other problems that could affect a child throughout life, including:

  • Cerebral palsy
  • Intellectual disabilities
  • Developmental delays
  • Paralysis or weakness on one side
  • Communication problems
  • Vision deficits
  • Psychological difficulties

Children who have had a stroke will see physicians that specialise in helping people cope with these problems. These specialists might include occupational, physical, and speech therapists. A child’s care may be overseen by a neurorehabilitation specialist, which is a physician who uses many different types of therapy to help children recover from stroke.

The Relationship Between Fetal Stroke and HIE

Foetal stroke  increases the likelihood of the occurrence of hypoxic ischemic encephalopathy.  In fact, research that examines radiological studies (such as an MRI) shows that HIE and fetal stroke often occur together.  HIE, or birth asphyxia, is a condition whereby a lack of oxygen to a baby’s brain causes cell death and damage to the central nervous system, which includes the brain and spinal cord. This deprivation of oxygen typically is due to a lack of oxygen in the baby’s blood (hypoxemia / hypoxia) and restricted blood supply (ischemia) to the brain tissue.

Many of the complications that cause HIE can also cause foetal stroke.  Furthermore, HIE and stroke both can cause long-term complications such as cerebral palsy, epilepsy / seizure disorder, developmental problems and intellectual impairments.  Hypothermia / brain cooling treatment is used for babies that suffer from HIE, as well as those that have had a stroke, and can reduce the severity of neurological injury that results from both illnesses.

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