Strokes in Pregnancy

Generally speaking, pregnant women are young and healthy, and so neurologic complications of pregnancy are rare.  That said, pregnancy does fundamentally change a woman’s physiology in some ways that increase the risk of certain neurological problems.  Stroke is the most common seriously disabling complication of being pregnant.  Even so, it only occurs in about 4-7/ 100,000 pregnancies.   

Stroke is generally to be considered when there is a sudden loss of ability, especially on one side of the body or the other.

 A neurological examination and neuroimaging can quickly confirm most strokes.  A thorough work-up for ischemic stroke should include searching for stroke risk factors such as hyperlipidemia or diabetes.  Genetic tests for hypercoaguable states should also be considered.   For some of these tests, however, it’s best to wait at least 6 weeks to allow the body to return to something closer to its normal state.

Types of Stroke in Pregnancy

Strokes can occur in two ways-- ischemic and hemorrhagic.  Ischemic means that too little blood is reaching part of the brain. Hemorrhagic means that blood has spilled from the vessels into the brain tissue.  There are two main ways in which strokes occur in pregnancy: cardioembolic (clots traveling from the heart) and venous sinus thrombosis.  It is important to also consider other mechanisms by which stroke can occur in the young, such as arterial dissection or moyamoya syndrome.

 

Intraarterial tissue plasminogen activator (tPA) is the best approved treatment for ischemic stroke, though there may also be a role for intraarterial procedures as well.   There is very little data on the use of this drug in pregnancy, but most clinicians feel it is indicated if the expectant mother is suffering potentially serious symptoms from the stroke.

 

 Stroke Risk Factors in Pregnancy

Several changes in the body in pregnancy may increase the risk of stroke, though all  For example of these changes are complex and poorly understood.   For example, pregnancy is thought to be a “hypercoagulable state” in which clots form more easily.  This is likely the body’s way of preventing significant blood loss with child birth, but can also increase the risk of clots forming when and where they are not needed, or may even be dangerous.  The risk is greatest shortly before and after giving birth.

Pre-eclampsia is a condition involving high blood pressure, leg swelling, and loss of protein in the urine (proteinuria).  The condition is called pre-eclampsia because it sometimes precedes the onset of seizures in pregnancy (eclampsia), which can be very dangerous unless treated.  The cause is uncertain, though abnormal immune responses are a likely culprit.  Pre-eclampsia may predispose towards stroke by altering blood vessel responses to normal hormonal and signals, as well a increased activation of clotting agents in the blood.

The result is smaller vessels which are more prone to catch clots, as well as a greater tendency for such clots to form. There is an entity called postpartum angiopathy, which involves severe headaches and reversible narrowing of arteries inside the brain.  This can lead to seizures, bleeding, and brain swelling in addition to strokes.   Findings include characteristic changes on an MRI.  Treatment is with close blood pressure control, manage any seizures that arise.  Intravenous magnesium is generally recommended.  

Venous Thrombosis

Cerebral venous thrombosis involves clots in the veins that drain blood from the head.  This can lead to local swelling or bleeding in addition to ischemic stroke due to decreased blood flow. Neuroimaging can be very helpful in confirming the presence of this disorder.  Treatment is with anticoagulants.

Brain Bleeding in Pregnancy

Hemorrhagic stroke is also rare in pregnancy, ranging from between 5=35 cases per 100,000 in reported literature.  Despite this low risk, pregnancy increases the risk for hrmorrhaghic more than ischemic stroke.  It is greatest during the early post-partum period.  Hemorrhagic stroke is more often lethal than ischmic stroke, so is an important cause of pregnancy-related deaths.   Eclampsia and preeclampsia are common causes, as are arteriovenous malformations (AVM) or aneurysms.  As pregnancy increases blood volume and pressure, as well as increasing elasticity of blood vessel walls, blood may be more likely to rupture through vessels as the due date approaches.  If an aneurysm or AVM is found, surgical treatment should proceed as it would anyone else. 

Source: 

Steven K. Feske, MD; Aneesh B. Singhal, MD. Cerebrovascular Disorders Complicating Pregnancy. Continuum 2014, 20(1) 80-99 

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