Although uncommon in young women, cerebrovascular strokes due to ischemia or hemorrhage are a prominent cause of maternal deaths in the United States. From 1991 to 1999, stroke caused 5 percent of 4200 pregnancy related deaths in the United States. By far the most common risk factor for pregnancy associated stroke is some form of hypertension—chronic, gestational, or preeclamptic (preeclampsia). Ninety percent of them occur in the intrapartum period. Types of strokes during pregnancy are summarized in Table 77-1.
TABLE 77-1. Types of Strokes during Pregnancy or Puerperium
Ischemic strokes are usually due to preeclampsia–eclampsia or arterial thrombosis, but may also occur in venous thrombosis, vasculopathy, embolism, or malignancy. Some women with eclampsia suffer from areas of cerebral infarction and residual cognitive disruption. The evaluation and treatment of women suspected of having a stroke should not be delayed because they are pregnant.
Cerebral Artery Thromboses
Most thrombotic strokes occur in older individuals and are caused by atherosclerosis. Most cases are preceded by transient ischemic attacks. The woman usually presents with sudden onset of severe headache, seizures, hemiplegia, or other neurological deficits. Evaluation should include serum lipid profiles, echocardiogram, and cranial CT, MR imaging or angiography. Because antiphospholipid antibodies cause up to a third of ischemic strokes in healthy young women, this testing should also be undertaken. Therapy includes rest, analgesia, and aspirin. Prompt treatment with low-molecular-weight heparin or tissue plasminogen activator (t-PA) may improve outcomes though this is associated with bleeding due to impaired coagulation.
Cerebral embolism may complicate the latter half of pregnancy or early postpartum period and most commonly involves the middle cerebral artery. Common causes include cardiac arrhythmia, especially atrial fibrillation due to rheumatic valvular disease, mitral valve prolapse, and infective endocarditis. Management of embolic stroke consists of supportive measures and antiplatelet therapy. Anticoagulation is controversial.
Cerebral Venous Thrombosis
Venous thromboses occur in approximately 1 in 11,000 to 45,000 deliveries. Lateral or superior sagittal venous sinus thromboses usually occur in the puerperium, often associated with preeclampsia, sepsis, or thrombophilias (see Chapter 52). Symptoms include severe headache, drowsiness, confusion, convulsions, and focal neurological deficits, along with hypertension and papilledema. Magnetic resonance is the imaging procedure of choice. Management includes anticonvulsants to control seizures. Heparin anticoagulation is controversial because bleeding may develop. The prognosis is guarded and survivors have a recurrence risk of 1 to 2 percent.
The two distinct categories of spontaneous intracranial bleeding are intracerebral and subarachnoid hemorrhage. Trauma associated subdural and epidural hemorrhage is not considered.
Bleeding into the substance of the brain most commonly is caused by spontaneous rupture of small vessels damaged by chronic hypertension, chronic hypertension with superimposed preeclampsia, or preeclampsia alone. Intracerebral hemorrhage has a much higher morbidity and mortality rate than subarachnoid hemorrhage. The importance to proper management for gestational hypertension—especially systolic hypertension to prevent cerebrovascular pathology is underscored.
These bleeds are usually caused by an underlying cerebrovascular malformation. Ruptured aneurysms cause 80 percent of all subarachnoid hemorrhages; ruptured arteriovenous malformations, coagulopathies, angiopathies, venous thromboses, infections, drug abuse, tumors, and trauma cause the remainder.
A ruptured aneurysm is most common during the second half of pregnancy. Prompt diagnosis is important because rebleeding can be fatal and early neurosurgical clip ligation can prevent this. MR imaging has been shown to be superior to CT scanning for all varieties of stroke. If the imaging is normal, but there is a strong clinical suspicion of a ruptured aneurysm, cerebrospinal fluid should be examined to confirm the presence of blood. If found, angiography should be done to locate the lesion. If the woman requires neurosurgery near term, cesarean delivery followed by craniotomy is a consideration. If remote from term, there is no advantage to pregnancy termination. Vaginal delivery is not contraindicated following surgical resection. If the aneurysm has not been repaired, however, cesarean delivery is recommended.
Bleeding secondary to cerebral arteriovenous malformations (AVMs) is uncommon and is not increased by pregnancy. Management decisions should be based on neurosurgical considerations. Because of the high risk of recurrent hemorrhage in women with uncorrected arteriovenous malformations, cesarean delivery is usually recommended.
For further reading in Williams Obstetrics, 23rd ed.,
see Chapter 55, “Neurological and Psychiatric Disorders.”.