eMedicine Specialties > Neurology > Seizures and Epilepsy

Preeclampsia and Eclampsia: Differential Diagnoses & Workup

Author: Aashit K Shah, MD, Associate Professor of Neurology, Wayne State University; Program Director, Clinical Neurophysiology Fellowship, Department of Neurology, Detroit Medical Center
Contributor Information and Disclosures

Updated: Jun 18, 2009

Differential Diagnoses

Other Problems to Be Considered

Dural sinus thrombosis
Epilepsy presenting during pregnancy or in the postpartum period
Brainstem syndromes
Hypertension and stroke
Postpartum cerebral angiopathy

Workup

Laboratory Studies

• CBC count
  • CBC count is essential to rule out CNS infection manifesting as seizures.
  • Evaluating thrombocytopenia, a potentially dangerous complication of pregnancy-induced toxemia, is also helpful. Another condition that may be associated and may be a part of the syndrome is hemolytic anemia, elevated liver enzymes, and low platelet, also known as HELLP.
  • Anemia is common in women with eclampsia and is believed to be a contributing factor.
• Peripheral smear: This study is ordered to evaluate for microangiopathic hemolytic anemia with destruction of RBCs.
• Urinalysis
  • Proteinuria is common (usually >2+). In preeclampsia/eclampsia, it should be present in a repeat study at least 6 hours later.
  • On 24-hour urine analysis, most women with eclampsia have significant proteinuria (>300 mg/24 h).
• Serum studies: Several studies are useful.
  • Serum blood urea nitrogen (BUN) and creatinine measurements are necessary to evaluate and monitor kidney function.
  • The liver is another organ affected in eclampsia. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin measurements are helpful. The most common abnormality is elevation of serum AST.

Imaging Studies

• CT scanning of the brain
  • CT scanning of the brain is useful in diagnosing cerebral hemorrhage, a rare complication in eclampsia. However, rarely preeclampsia/eclampsia is associated with primary nonaneurysmal subarachnoid hemorrhage.¹⁰ This is usually localized to a small area over the cerebral convexity, and the amount of blood is small. This is in contrast to the usual finding in aneurysmal bleed, which shows blood basal brain cisterns (see Media file 5).
    
    

    

    CT scan of head without contrast showing small amount of subarachnoid hemorrhage over the surface of the brain and in Sylvian fissure in two separate patients.

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    CT scan of head without contrast showing small amount of subarachnoid hemorrhage over the surface of the brain and in Sylvian fissure in two separate patients.

  • CT scanning is also helpful in diagnosis of other causes of cerebral hemorrhage, such as arteriovenous malformation, cerebral tumor, and calcification representing a brain tumor or old infection, such as tuberculosis, cysticercosis, or other fungal/parasitic infections.
  • Characteristic findings of eclampsia in CT scanning include white matter hypodensities, mainly affecting cerebral white matter of the occipital/parietal lobes or the deep white matter of internal/external capsules.¹⁷ (See Media file 1.) These changes are transient and may resolve over a few days.
    
    

    

    Nonenhanced CT scan of the brain of a woman following an eclamptic seizure showing hypodense areas involving the white matter of occipital lobes and high frontal/parietal lobes.

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    Nonenhanced CT scan of the brain of a woman following an eclamptic seizure showing hypodense areas involving the white matter of occipital lobes and high frontal/parietal lobes.

• MRI of the brain
  • MRI is more sensitive than CT scanning of the brain in identifying changes related to eclampsia.
  • The characteristic findings include hyperintense lesions on T2-weighted, fluid attenuation inversion recovery (FLAIR) or proton-weighted sequences affecting the white matter and adjacent gray matter of the occipital/parietal lobes; however, deep white matter structures, basal ganglia, and white matter of the frontal or temporal lobes and brain stem can also be affected.^18,19 (see Media files 2-4).
    
    

    

    Axial T2-weighted MRI of the brain of a woman with eclampsia showing abnormal areas (hyperintense lesions) affecting the pons, cerebral peduncles, and internal capsules.

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    Axial T2-weighted MRI of the brain of a woman with eclampsia showing abnormal areas (hyperintense lesions) affecting the pons, cerebral peduncles, and internal capsules.

    
    
    

    

    T2-weighted axial image of the brain in a woman with transient Balint syndrome due to eclampsia showing hyperintense lesions affecting gray and white matter of the occipital and posterior temporal lobes bilaterally.

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    T2-weighted axial image of the brain in a woman with transient Balint syndrome due to eclampsia showing hyperintense lesions affecting gray and white matter of the occipital and posterior temporal lobes bilaterally.

    
    

    

    Axial T2-weighted images of the brain of a woman with transient cortical blindness and seizure due to eclampsia. Images show abnormal hyperintense areas involving the occipital white matter bilaterally. In addition, a single lesion affecting the white matter of the right frontal lobe is also observed.

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    Axial T2-weighted images of the brain of a woman with transient cortical blindness and seizure due to eclampsia. Images show abnormal hyperintense areas involving the occipital white matter bilaterally. In addition, a single lesion affecting the white matter of the right frontal lobe is also observed.

  • T1-weighted images are usually unremarkable or may show subtle hypodensities in the same structures.
  • DWI and apparent diffusion coefficient (ADC) mapping are new techniques to evaluate acute cerebral ischemia. In patients with eclampsia, DWI MR images or ADC maps usually show no abnormalities suggestive of ischemia (cytotoxic edema). The changes seen on T2-weighted images representing vasogenic edema are reversible. In cases in which DWI MRI show findings of restricted diffusion suggestive of cytotoxic edema, persistent imaging abnormalities suggesting permanent brain damage may be observed on a follow-up MRI. These changes may affect only small areas compared with the much larger area of involvement with vasogenic edema that is reversible. Thus, MRI combining T2-weighted images and DWI ADC images can be very useful to determine the extent of likely permanent cerebral injury.¹⁸
  • Magnetic resonance (MR) angiography findings may be normal or may show reversible cerebral vasospasm.
  • MR venography findings are usually normal and are helpful in excluding the possibility of dural sinus thrombosis, an important differential diagnosis.
  • Combination of routine MRI with T1- and T2-weighted images, DWI, and MR venography is very helpful in suspected cases of eclampsia.¹⁸ Routine MR imaging with T1- and T2-weighted images helps in confirming the diagnosis of eclampsia by showing characteristic changes. DWI helps to exclude the possibility of acute stroke (ie, absence of abnormal signal on DWI in the same region showing hyperintense lesion on T2-weighted images). Recently, reports have indicated that some of the lesions observed on T2-weighted images are hyperintense on DWI and show restricted diffusion. This, in turn, suggests that some lesions may result from cytotoxic edema and result in irreversible damage and small areas of ischemic infarcts. This has been shown on repeat MRI. In addition, MR venography helps to demonstrate patency of dural sinuses, helping to eliminate the possibility of sinus thrombosis.
  • MRI of the brain should thus be preferred over CT scanning in women with suspected eclampsia.
  • Location of imaging abnormalities on basis of T2-weighted MR imaging in decreasing frequency is as follows: high parietal, high posterior frontal, lateral occipital, occipital pole, medial occipital, basal ganglia, anterior frontal, lateral temporal, internal capsule, cerebellum, external capsule, corona radiata, inferior parietal, brain stem, medial temporal lobe, and thalamus.⁸
• Cerebral angiography: Cerebral angiography should not be performed routinely. It shows focal/segmental cerebral vasoconstriction. The venous phase of the study also helps to show normal flow pattern in dural sinuses, again helping to exclude sinus thrombosis.
• Transcranial Doppler study: This is a research tool used in the evaluation of eclampsia. It shows an increased velocity of blood flow in the middle cerebral artery, which is reversible. The changes tend to parallel the severity of the clinical syndrome.²⁰
• Ultrasonography: Abdominal ultrasonography may be needed to evaluate for hepatic abnormalities or hemorrhage. It should be performed in women with abdominal tenderness.

Procedures

Amniocentesis may be necessary prior to delivery to determine fetal lung maturity.

Histologic Findings

Cerebral hemorrhage or softening was found in 60% of patients with eclampsia who died within 2 days of the onset of convulsions but in only 20% of those who survived longer. The pathologic findings (in order of decreasing frequency) are cortical petechial hemorrhages, multiple focal softening or petechiae in the white matter or midbrain, hemorrhage into basal ganglia, pia-arachnoid hemorrhage, and hemorrhage in the pons.²¹ A schematic representation of some of these findings is shown in Media file 6.

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