Can clinical and MRI findings predict the prognosis of variant and classical type of posterior reversible encephalopathy syndrome (PRES)?

Background: Posterior reversible encephalopathy syndrome (PRES) is characterized by clinical symptoms that are associated with bilateral and symmetric vasogenic edema in the parietal and occipital lobes. However, this is rarely present with predominant involvement of the brain stem and cerebellum (variant).
Purpose: To evaluate which clinical or magnetic resonance imaging (MRI) findings can help to predict the prognosis of variant and classical type of PRES and whether or not there is difference between two types of PRES.
Material and Methods: We retrospectively evaluated MRI and clinical findings from 49 patients with PRES. These patients were divided into two groups. In group I, patients had atypical distribution of lesions. In group II, patients had typical distribution of lesions. Follow-up MRI was performed on 26 patients. We assessed the MRI features, clinical data, and the patients' outcomes.
Results: The mean blood pressure (BP) was significantly higher in group I (195.52/121.09 mmHg and 156.78/99.53 mmHg for groups I and II, respectively). The other factors assessed were not significantly different between the two groups. Lesions in 24 of 26 patients reversed upon follow-up. Sequelae were observed in 11 patients (group I, 7; group II, 4). However, there were no significant differences between the two groups. Except for those patients who died, seven of the nine patients with sequelae upon follow-up imaging had hemorrhage or irreversibility of lesions.
Conclusion: Even though BP influences the involvement of the brain stem, involvement of the brain stem is not influential on the prognosis. It seems that the influential factor to prognosis is the reversibility of lesions and hemorrhage.