Posterior reversible encephalopathy in eclampsia: diffusion-weighted imaging and apparent diffusion coefficient-mapping as prognostic tools?

Posterior reversible encephalopathy syndrome in eclampsia

Posterior reversible encephalopathy syndrome is characterized by acute headache, visual impairment, seizures, and altered mental status; neuroimaging may show cerebral edema affecting the parietal and occipital lobes of the brain. The objective of this article is to review the current understanding of posterior reversible encephalopathy syndrome in eclampsia. Literature was searched from PubMed, Scopus, and Google Scholar databases. The search terms included "eclampsia", "eclampsia and posterior reversible encephalopathy syndrome", and "pregnancy and posterior reversible encephalopathy syndrome". We reviewed all published original articles with the search term "posterior reversible encephalopathy syndrome". Up to 100% of eclamptic patients may have reversible posterior leukoencephalopathy syndrome. Two putative mechanisms - "vasogenic" and "vasospasm" - are considered to be responsible. Cerebral edema and petechial cortical hemorrhages are common autopsy findings. Clinical and neuroimaging manifestations are reversible in the majority of patients. Prompt correction of increased blood pressure and treatment of seizures are the cornerstones of treatment. Magnesium sulfate is the drug of choice for seizures. Some survivors may have permanent vision loss and other disabling sequelae. In conclusion, posterior reversible encephalopathy is a devastating complication of eclampsia. Early recognition helps in preventing some of its devastating sequelae.

Posterior Reversible Encephalopathy Syndrome (PRES): Restricted Diffusion does not Necessarily Mean Irreversibility

Background

Restricted diffusion is the second most common atypical presentation of PRES. This has a very important implication, as lesions with cytotoxic edema may progress to infarction. Several studies suggested the role of DWI in the prediction of development of infarctions in these cases. Other studies, however, suggested that PRES is reversible even with cytotoxic patterns. Our aim was to evaluate whether every restricted diffusion in PRES is reversible and what factors affect this reversibility.

Material/Methods

Thirty-six patients with acute neurological symptoms suggestive of PRES were included in our study. Inclusion criteria comprised imaging features of atypical PRES where DWI images and ADC maps show restricted diffusion. Patients were imaged with 0.2-T and 1.5-T machines. FLAIR images were evaluated for the severity of the disease and a FLAIR/DWI score was used. ADC values were selectively recorded from the areas of diffusion restriction. A follow-up MRI study was carried out in all patients after 2 weeks. Patients were classified according to reversibility into: Group 1 (reversible PRES; 32 patients) and Group 2 (irreversible changes; 4 patients). The study was approved by the University’s research ethics committee, which conforms to the declaration of Helsinki.

Results

The age and blood pressure did not vary significantly between both groups. The total number of regions involved and the FLAIR/DWI score did not vary significantly between both groups. Individual regions did not reveal any tendency for the development of irreversible lesions. Similarly, ADC values did not reveal any significant difference between both groups.

Conclusions

PRES is completely reversible in the majority of patients, even with restricted diffusion. None of the variables under study could predict the reversibility of PRES lesions. It seems that this process is individual-dependent.

Reversibility of cytotoxic edema in tacrolimus leukoencephalopathy

Posterior reversible encephalopathy syndrome, a serious neurotoxicity, may develop rarely in patients receiving tacrolimus. Because the underlying etiology of posterior reversible encephalopathy syndrome is vasogenic edema, it is generally accepted to be a reversible neurologic condition. Cranial magnetic resonance imaging techniques enable detection of the type of edema, and they are widely used in the differential diagnosis and prognostic prediction of posterior reversible encephalopathy syndrome. Presented here is a case of posterior reversible encephalopathy syndrome in which the patient recovered completely, despite radiologic findings indicating the coexistence of vasogenic and cytotoxic edema secondary to tacrolimus therapy after liver transplantation.