Neuroradiologic studies can provide valuable diagnostic information in women who present during pregnancy or the puerperium with apparent eclampsia or similar neurologic manifestations, British investigators have reported.
A host of less common neurologic conditions and manifestations may mimic or resemble eclampsia and, because signs and symptoms are often nonspecific, it can be difficult to differentiate these conditions “on clinical grounds alone,” they said in a recently published pictorial review.
“Neuroimaging in a clearly defined case of eclampsia may not be necessary but, if there is focal neurology or deterioration in neurological status, imaging should be performed,” said Dr. R. Dineen of the department of neuroradiology at Queen's Medical Centre in Nottingham, England, and his associates.
Without it, the diagnosis of various conditions—from intracranial hemorrhage and other cerebrovascular conditions, to intracranial tumors and various pituitary and metabolic conditions—may be delayed as women are mistakenly treated for eclampsia, they said.
In women with true eclampsia, the most frequent abnormality detected on cranial MRI is high-signal change on T2-weighted and FLAIR images. Lesions are commonly seen in both deep and subcortical white matter, often with a posterior circulation distribution, and within the basal ganglia.
Lesions also occur within the pons and brainstem, and correspond to low-attenuation areas on CT scanning. The majority of lesions are reversible but some may progress to infarction, they said.
Several “overlap syndromes”—postpartum cerebral angiopathy, hypertensive encephalopathy, and reversible posterior leukoencephalopathy syndrome—may show neuroimaging features that are similar to or indistinguishable from those of eclampsia, they said (Clin. Radiol. 2005;60:1156-70).
Neuroimaging features are more distinct with other neurologic emergencies, such as the cerebrovascular disorders that can occur in pregnancy or the puerperal period: arterial ischemia and infarction, intracranial hemorrhage, venoocclusive disease, and vasculitis.
The mainstay for investigating ruptured intracranial aneurysms—the most common cause of subarachnoid hemorrhage and a cause of intracerebral hemorrhage—is CT with either CT angiography or conventional angiography. Magnetic resonance angiography, however, can be used to assess aneurysms without the need for ionizing radiation or contrast media.
Just as the risk of ruptured intracranial aneurysms increases for women who are pregnant or in the puerperal period, compared with nonpregnant women, the risk of intracranial venoocclusive disease is particularly increased around the puerperal period. Intracranial venoocclusive disease also can occur in women with preeclampsia.
Women with the condition present with headache, confusion, decreased consciousness level, papilledema, seizures, and often, focal deficits.
CT scanning shows hyperdensity in the venous sinuses, cortical veins, or deep cerebral veins. When venous infarction develops, areas of low attenuation are seen. Patterns of venous infarction on MRI “do not conform to the contours expected from an arterial occlusion,” the investigators note. T2-weighted images show high-signal change involving the white matter with absent flow void in the related cortical vein or dural venous sinus.
Precautions should be taken to limit fetal exposure to ionizing radiation, but “fetal exposure to ionizing radiation from CT of the maternal head is extremely low, and the risk to the fetus is likely to be considerably less than the risk to both the fetus and mother from an acute neurological condition,” the investigators reported.
An internal carotid catheter angiogram shows a giant intracavernous aneurysm at the underside of the C4 segment.
A CT shows high density in the left transverse sinus and hemorrhagic venous infarction in the left temporal lobe. ©Elsevier, Clinical Radiology, Vol. 60, R. Dineen, “Imaging of acute neurological conditions in pregnancy and puerperium,” 1156 - 1170, 2005, Reprinted with permission from The Royal College of Radiologists