Catheter angiography, MR angiography, and MR perfusion in posterior reversible encephalopathy syndrome

Abstract

Background and purpose: The cause of posterior reversible encephalopathy syndrome (PRES) is unknown. Two primary hypotheses exist: 1) hypertension exceeding auto-regulatory limits leading to forced hyper-perfusion and 2) vasoconstriction and hypo-perfusion leading to ischemia with resultant edema. The purpose of this study was to evaluate the catheter angiography (CA), MR angiography (MRA), and MR perfusion (MRP) features in PRES in order to render further insight into its mechanism of origin.

Materials and methods: In 47 patients with PRES, 9 CAs and 43 MRAs were evaluated for evidence of vasculopathy (vasoconstriction and vasodilation), and 15 MRP studies were evaluated for altered relative cerebral blood volume (rCBV) in PRES lesions and regions. Visualization of vessels on MRA and toxicity blood pressures were compared with the extent of hemispheric vasogenic edema.

Results: Vasculopathy was present in 8 of 9 patients on CA (direct correlation to MRA in 3/6 patients). At MRA, moderate to severe vessel irregularity consistent with vasoconstriction and vasodilation was present in 30 of 43 patients and vessel pruning or irregularity in 7 patients, with follow-up MRA demonstrating reversal of vasoconstriction or vasodilation in 9 of 11 patients. Vasogenic edema was less in patients with hypertension compared with patients who were normotensive. Preserved normal length of the posterior cerebral artery (PCA) was commonly seen in patients with severe hypertension despite diffuse or focal vasoconstriction or vasodilation. In these patients, lengthier visualization of the distal PCA correlated with a lower grade of hemispheric edema (P = .002). Cortical rCBV was significantly reduced in 51 of 59 PRES lesions and regions compared with a healthy reference cortex (average 61% of reference cortex) with mild decrease in the remainder.

Conclusion: Vasculopathy was a common finding on CA and MRA in our patients with PRES, and MRP demonstrated reduced cortical rCBV in PRES lesions. Vasogenic edema was reduced in patients with hypertension, and superior distal PCA visualization correlated with reduced hemispheric edema in patients with PRES and severe hypertension.

Fig 1.

Patient 43 is a 53-year-old woman with a baseline blood pressure of 131/74 mm Hg who was receiving oral and skin patch narcotic pain control for a recently sustained pelvic fracture in a motor vehicle crash. She developed nausea, vomiting, and altered mentation then progressed to generalized seizure with a blood pressure at toxicity of 149/105 mm Hg. A, Axial MR imaging (FLAIR sequence) obtained 1 day after acute toxicity demonstrates vasogenic edema in the occipital region (open arrows) consistent with PRES. Similar areas of vasogenic edema consistent with PRES was present in the frontal and parietal regions (not shown). B, MR angiogram obtained on the same day demonstrates areas of focal vasodilation in the branches of MCA bilaterally with focal vasoconstriction also noted on the left (arrows). C, Frontal view from the left common carotid catheter angiogram obtained the same day demonstrates an identical area of focal vasodilation and vasoconstriction in the branch of the left MCA (arrow). An identical finding was present at angiography in the right MCA consistent with the MRA observation on the right. Similar findings were present on both MRA and CA in the PCA bilaterally (not shown).

Fig 2.

Patient 10 is a 27-year-old man with a history of drug and alcohol abuse with a necrotic pneumonia and empyema growing Pseudomonas and Klebsiella. He developed altered mentation and an asymmetric neurologic examination with blood pressures ranging between 130/77 and 130/100 mm Hg. A, Axial MR imaging (FLAIR sequence) demonstrates extensive vasogenic edema in the occipital lobes (open arrows) and temporooccipital junction (arrowheads) consistent with PRES. Additional extensive areas of vasogenic edema consistent with PRES judged vasogenic edema grade 4 were present in the frontal and parietal lobes (not shown). B, Vertebral catheter angiogram obtained after development of occipital hemorrhage (5 days after initial toxicity) demonstrates areas of vessel narrowing and dilation along with a string-of-bead appearance and areas of focal spasm in parietal and occipital branches of the PCA. Right common carotid catheter angiogram (not shown) also demonstrated extensive vasospasm in branches of the ACA and MCA. C, MR angiogram obtained 5 days after catheter angiogram (10 days after initial toxicity) demonstrates persistent vessel irregularity in the posterior cerebral branches (arrows) with a pattern nearly identical to the appearance of the catheter angiogram. Follow-up MR imaging demonstrated improvement of the extensive vasogenic edema.

Fig 3.

Patient 16 is a 39-year-old woman status post bowel resection and appendectomy for Crohn disease being maintained on antibiotics and steroids with baseline blood pressure of 100/60 mm Hg. Brain imaging was obtained when she developed headache, vertigo, and moderate elevation in blood pressure (145/95 mm Hg). A, Axial MR imaging (FLAIR sequence) results demonstrate vasogenic edema in occipital lobes (open arrows) consistent with PRES. Additional areas of vasogenic edema consistent with PRES were present in the frontal and parietal regions, and abnormality of signal intensity with restricted diffusion was also present in the medial right cerebellar hemisphere (not shown). B, MR angiogram obtained 1 day after toxicity demonstrates marked vessel irregularity in the PCAs bilaterally (arrows), greater on the right than on the left. C, Left vertebral catheter angiogram (selected posterior magnified lateral view) demonstrates a beaded appearance (arrow) and focal vasoconstriction and vasodilation (arrowhead) of right third- and fourth-order branches of the PCA along with a beaded appearance of the branches of the distal medial posterior inferior cerebellar artery on the left (open arrow). D Results of follow-up MR angiogram obtained 3 days after initial study demonstrate normalization of the vessel irregularity and marked improvement in vessel caliber (arrows) consistent with reversal of the vasospasm/arteritis confirmed on conventional angiography. Follow-up MR imaging demonstrated reversal of the PRES pattern.

Fig 4.

Patient 34 is a 56-year-old woman with long-standing sickle cell disease and a baseline blood pressure of 140/60 mm Hg in a sickle cell crisis with new-onset pneumonia. She developed altered mental status and a seizure with blood pressure at toxicity of 170/110 mm Hg. A, Axial MR imaging (FLAIR sequence) demonstrates typical vasogenic edema in the occipital pole regions bilaterally (open arrows) consistent with PRES and judged edema, grade 3. Occipital lobe rCBV relative to a healthy reference cortex was 63% on the right and 54% on the left. B, Collapsed view of the 3D TOF MRA sequence demonstrates both focal vasospasm (arrows) and pruning of the PCAs bilaterally. Foreshortening of the PCAs and only partial visualization to the midportion of the calcarine arteries are noted bilaterally (arrowheads) and were judged PCA pruning, grade 2. Follow-up MR imaging and MRA (not shown) obtained 1 month after toxicity demonstrated complete resolution of the vasogenic edema in the occipital poles with marked improvement in distal PCA flow bilaterally along with reversal of the pruning and vasospasm.

Fig 5.

Patient 33 is a 23-year-old pregnant woman with baseline blood pressure of 125/75 mm Hg who developed eclampsia. Blood pressure at toxicity was 200/103 mm Hg. A, Axial MR imaging (FLAIR sequence) demonstrates vasogenic edema consistent with PRES in the parietal lobes bilaterally (curved arrows) and was judged edema, grade 1. Vasogenic edema consistent with PRES was also present in the frontal lobes, occipital region, and cerebellum (not shown). B, Collapsed view of the 3D TOF MRA sequence demonstrates PCA spasms bilaterally without PCA foreshortening (arrows) and was judged PCA pruning, grade 1. The ACA spasm present is also partially visible on this collapsed view (arrowheads).

Fig 6.

Patient 41 is a 34-year-old woman with baseline blood pressure of 104/60 mm Hg who at 33 weeks of pregnancy developed preeclampsia (toxicity blood pressure of 153/102 mm Hg) followed by seizures and status epilepticus. She ultimately required cesarean delivery for seizure control. A, Axial MR imaging (FLAIR sequence) demonstrates typical PRES vasogenic edema in the parietal regions (curved arrows) bilaterally and was judged edema, grade 2. Frontal and occipital involvement was also present bilaterally (not shown). B, rCBV color map demonstrates decreased perfusion in the region of the right parietal lesion (curved arrow). Lesion rCBV was 65% relative to a reference healthy cortex.