Pregnancy and Stroke Risk in Women

Jessica Tate; Cheryl Bushnell

Disclosures

Women's Health. 2011;7(3):363-374. 

In This Article

Diagnosis of Pregnancy-related Stroke & CVT

Diagnosis of stroke in pregnancy may be hindered by fear of adverse fetal outcomes from specific diagnostic tests. For example, physicians may be hesitant to obtain an MRI because of the effects of the magnetic field on the fetus, especially in the first trimester. However, the American College of Radiology guidelines state that pregnant patients can undergo MRI if warranted by the risk–benefit ratio, although administration of gadolinium contrast should probably be avoided in most cases because it does cross the placenta and its effects on the fetus have not been studied.[24] In most cases, a complete stroke work-up, including brain CT scan and/or MRI, transthoracic echocardiogram and vascular ultrasound, should be completed in pregnant women. Echocardiography is a standard test in stroke patients to evaluate for sources of cardiac emboli, but this may be especially important in Asian populations. Two studies in Taiwan identified cardioembolism as the most common etiology of pregnancy-related stroke, possibly due to the persistent presence of rheumatic heart disease in some Asian countries.[12,20]

In the past, prior to the advent of modern imaging techniques such as magnetic resonance venogram, the majority of pregnancy-related strokes were attributed to 'cerebral thrombophlebitis'.[25] Cross et al. challenged this idea in 1968 by demonstrating with carotid angiography that 70% of women with strokes (n = 31) were due to arterial occlusion.[25] Today, it is well documented that the majority of cerebral infarcts in pregnancy are related to arterial causes. However, CVT is an important diagnosis because it can lead to infarction or hemorrhage or both. The diagnosis of CVT can still be challenging, despite modern imaging capabilities, since it may present primarily as a severe headache with other signs of increased intracranial pressure, such as vomiting or papilledema, with or without subtle focal neurologic deficits due to venous infarction.[26] The best imaging modality for diagnosis is most likely MRI, with magnetic resonance venogram if possible, to evaluate for both thrombosis and acute stroke. The risk factors for CVT are classically related to dehydration, postpartum infection and thrombophilia, but also include those that overlap those for arterial stroke, including hypertension, older age and excessive vomiting.[4,5] One review of 67 cases of CVT suggested that morbidity and mortality is reduced in pregnancy-related CVT compared with those that occur outside pregnancy.[16]

Postpartum angiopathy is a unique condition associated with pregnancy, and it falls within the spectrum of disorders known as reversible cerebral vasoconstriction syndromes.[10] Although the pathophysiology may be similar, postpartum angiopathy is not confined to patients with history of preeclampsia or eclampsia and frequently occurs in patients who had uncomplicated pregnancies and deliveries. Patients classically present within days of delivery with thunderclap headache, vomiting, altered mental status and/or focal neurologic deficits. Such deficits may be transient or may be a result of ischemic stroke or cerebral hemorrhage.[10] Diagnosis is made with angiography, which demonstrates multifocal segmental narrowing in the large and medium-sized cerebral arteries, with a similar appearance to vasculitis. The cerebrospinal fluid is typically normal. By definition, the process is generally self-limited, with resolution of angiographic abnormalities within 4–6 weeks and typically complete resolution of symptoms.[10] However, owing to its association with both infarction and hemorrhage, postpartum angiopathy does carry a risk of morbidity and mortality. Some studies have also suggested an association between postpartum angiopathy and cervical arterial dissection.[27,28]

Subarachnoid hemorrhage should be considered in pregnant patients with sudden onset of severe headache, particularly in the setting of neck stiffness, altered mental status, nausea and vomiting, seizure, focal neurologic signs and/or hypertension. It is important to note that these symptoms may be mistaken for preeclampsia/eclampsia, especially when proteinuria is present.[19] If subarachnoid hemorrhage is suspected, emergent uninfused CT scan should be performed. If this test is carried out within 24 h, it will detect subarachnoid blood in approximately 90–95% of cases, although the sensitivity decreases with time.[29] If angiography is indicated, special modifications, such as shielding of the fetus, fetal monitoring, and maternal hydration to avoid fetal dehydration due to contrast, should be made.[30]

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