Distinct imaging patterns and lesion distribution in posterior reversible encephalopathy syndrome

Abstract

Background and purpose: Although the term posterior reversible encephalopathy syndrome (PRES) was popularized because of the typical presence of vasogenic edema in the parietal and occipital lobes, other regions of the brain are also frequently affected. We evaluated lesion distribution with CT and MR in a large cohort of patients who experienced PRES to comprehensively assess the imaging patterns identified.

Materials and methods: The locations of the PRES lesion at toxicity were comprehensively identified and tabulated in 136 patients by CT (22 patients) and MR (114 patients) imaging including the hemispheric, basal ganglial, and infratentorial locations. Clinical associations along with presentation at toxicity including blood pressure were assessed.

Results: Vasogenic edema was consistently present in the parietal or occipital regions (98%), but other locations were common including the frontal lobes (68%), inferior temporal lobes (40%), and cerebellar hemispheres (30%). Involvement of the basal ganglia (14%), brain stem (13%), and deep white matter (18%) including the splenium (10%) was not rare. Three major patterns of PRES were noted: the holohemispheric watershed (23%), superior frontal sulcal (27%), and dominant parietal-occipital (22%), with additional common partial or asymmetric expression of these primary PRES patterns (28%).

Conclusion: Involvement of the frontal lobe, temporal lobe, and cerebellar hemispheres is common in PRES, along with the occasional presence of lesions in the brain stem, basal ganglia, deep white matter, and splenium. Three primary PRES patterns are noted in the cerebral hemispheres, along with frequent partial or asymmetric expression of these PRES patterns. Awareness of these patterns and variations is important to recognize PRES neurotoxicity more accurately when present.

Fig 1.

A 21-year-old woman with SLE, lupus nephritis, and difficult-to-control hypertension presented with headache and change in vision progressing to generalized seizure. Blood pressure at toxicity was 213/167 mm Hg. A–D, Brain MR imaging (FLAIR sequence) obtained the day of the toxic event demonstrates extensive holohemispheric pattern with vasogenic edema at the junction between the medial hemispheric (ACA, PCA) and lateral hemispheric (MCA) branches. The pattern outlines the entire supratentorial watershed or borderzone in the frontal (arrows), parietal (curved arrows), occipital (open arrows), and temporal lobes (arrowheads). Vasogenic edema in the frontal lobes extends to the frontal pole region. Diffusion-weighted sequence demonstrated no restricted diffusion. E, Postcontrast T1-weighted MR image demonstrating prominent cortex and adjacent subcortical white matter edema (arrows) with focal sulcal compression and distortion.

Fig 2.

A 50-year-old woman 6 months post liver transplant experienced a generalized seizure and unresponsiveness. Blood pressure at the time of the toxic event fluctuated markedly with a range between 106 and 200 mm Hg systolic and 54 and 80 mm Hg diastolic. A–E, Brain MR imaging (FLAIR sequence) obtained the day of the toxic event demonstrates moderate vasogenic edema in the subcortical white matter of the frontal (white arrows), parietal (white curved arrows), and occipital regions (white open arrows) with some cortical involvement consistent with a milder expression of the holohemispheric pattern. Thalamic involvement is present (black arrowhead, 2B) along with the upper margin of vasogenic edema present in the pons (black arrow, 2A).

Fig 3.

A 36-year-old man with severe type 1 diabetes and recurrent septic arthritis of the shoulder requiring frequent debridement presented with several days of headache, nausea, and visual changes along with hypertension. Blood pressure at toxicity was 184/111 mm Hg. A–E, Brain MR imaging (FLAIR sequence) demonstrates moderate vasogenic edema in the parietal (white curved arrows) and occipital (white open arrows) cortex and white matter with linear involvement along the superior frontal sulcus (white arrows) in the mid to posterior frontal lobes bilaterally. The extreme frontal poles seem normal (3B). This pattern is consistent with the superior frontal sulcus pattern. Cerebellar involvement (white arrowheads) is also present along with vasogenic edema at the junction of the pons and midbrain on the right (black arrowhead, 3A).

Fig 4.

A 48-year-old woman with acute myelogenous leukemia status post allogenic BMT had a seizure 19 days after transplantation. Baseline blood pressure was 134/84 mm Hg, and blood pressure at toxicity was 132/48 mm Hg. A–B, Vasogenic edema is present in the occipital poles (open arrows) and thalamus (arrowheads) bilaterally along with deep white matter in the subinsular region (small arrow). C–D, Vasogenic edema is present in the parietal region (curved arrows) and corona radiata and subinsular region (small arrows) bilaterally and caudate nucleus on the left (arrowhead). E, Vasogenic edema is present in the parietal region (curved arrows) bilaterally with involvement along the superior frontal sulcus (large arrows) bilaterally. A linear “string-of-pearl” pattern is also present in the adjacent left centrum semiovale (small arrows). MR imaging is consistent with a more diminutive expression of the superior frontal sulcus pattern.

Fig 5.

A 56-year-old diabetic man with a foot infection on antibiotic treatment experienced a headache and visual change. Baseline blood pressure was 191/88 mm Hg, and blood pressure at toxicity was 215/115 mm Hg. A–B, Brain MR imaging (FLAIR sequence) obtained at toxicity demonstrates vasogenic edema in the occipital lobes (open arrows) and parietal region (curved arrows) bilaterally as well as involvement in the cerebellum bilaterally (not shown). This is representative and typical of the dominant parietal-occipital pattern. CSF hyperintensity is noted, likely related to ongoing oxygen administration.

Fig 6.

A 20-year-old woman with a high-risk pregnancy who at 32 weeks of gestation became preeclamptic. At 33 weeks of gestation, she experienced a significant headache, blurred vision, and mild hypertension (156/106 mm Hg) with fetal distress and ultimately had a generalized seizure at delivery. A–C, MR imaging demonstrates patchy vasogenic edema in the parietal region (curved arrows) bilaterally along with linear involvement along the superior frontal sulcus on the left (arrows) consistent with the findings in eclampsia. Involvement in the occipital lobe was not present, and the temporal lobes and cerebellum were normal bilaterally. Absence of occipital lobe involvement placed this in the partial and asymmetric expression group consistent with partial expression of the PRES pattern.