Brain AVMs during pregnancy

An AVM (arteriovenous malformation) of the brain is an abnormal tangle of blood vessels in the brain connecting the arteries to the veins. The tangle of abnormal blood vessels is called a 'nidus'. If the arteries and veins are connected one-to-one without the intervening tangle of blood vessels, it is called a fistula. Because these blood vessels are abnormal, they have a tendency to rupture leading to bleeding within the brain. AVMs are not unique to the brain and can occur in other parts of the body. However, brain AVMs are unique in that they cause severe devastating effects if they rupture.

Brain AVMs diagnosed during pregnancy present a challenge to the neurosurgeon as well as to the obstetrician. The normal changes in the mother during pregnancy may predispose to rupture of the AVM, thus causing brain bleed. If untreated, the AVM runs the risk of bleeding and at the same time, treatment of the AVM may itself pose significant risk to the mother and the fetus. The overall risk of AVM rupture during pregnancy is about 1 in 100,000 deliveries.

What precautions should be taken in a pregnant mother diagnosed with brain AVM

• The highest risk of rupture of an AVM is in the second trimester due to the normal pregnancy related changes in the mother.
• The risk of AVM rupture does not increase during labor and delivery and hence, normal delivery should be encouraged
• As the changes occurring in the mother do not immediately revert following delivery, the risk of AVM rupture remains high immediately following delivery
• If the mother presents with seizures, due consideration should be given to the anti-seizure drug as it may harm the fetus
• The symptoms of AVM rupture mimic other common symptoms such as pregnancy induced hypertension and hence a high index of suspicion is required to diagnose a brain AVM
• when a mother presents with severe headache, seizures, speech difficulty or weakness of arm or leg, brain imaging is warranted
• MRI is the preferred method of choice to diagnose brain AVM in pregnancy as it avoids the radiation risk
• Surgery or endovascular therapy for an AVM in a pregnant mother should be carefully thought and undertaken with the understanding all the associated risks such as that of anesthesia, blood loss and radiation. There are no guidelines for the management of brain AVMs during pregnancy
• Stresses associated with normal delivery should be minimized. Primarily, the straining involved in the second stage of labor should be addressed. A combination of an outlet forceps delivery and the use of epidural anesthesia is recommended as means to reduce the duration of labor.
• There is no clear evidence to recommend that women with unruptured AVMs not have children.
• On the other hand, if a woman presents with a history of an AVM rupture in the recent past (within a year), there is evidence to support the recommendation that the patient undergo treatment for the AVM