Posterior reversible encephalopathy syndrome in liver transplant patients: clinical presentation, risk factors and initial management.

Posterior reversible encephalopathy syndrome (PRES) is an uncommon but well-known complication after transplantation diagnosed by characteristic radiological features. As limited data on this complex syndrome exist we sought to better define the incidence, clinical presentation and risk factors for PRES in liver transplant (LTx) patients. We conducted a retrospective analysis of 1923 adult LTx recipients transplanted between 2000 and 2010. PRES was diagnosed radiologically in 19 patients (1%), with 84% of cases occurring within 3 months post-LTX. We compared this cohort of PRES patients to 316 other LTx recipients also requiring radiographic imaging within 3 months after LTx for neurological symptoms. Seizure was the most common clinical manifestation in the PRES group (88% vs. 16%, p< 0.001) and 31% had an intracranial hemorrhage. Those with hemorrhage on imaging were more likely to be coagulopathic. PRES patients were significantly more likely to have had alcoholic liver disease and infection/sepsis. These factors may be related to a common pathway of vascular dysregulation/damage that appears to characterize this complex syndrome. Intracranial bleeding and seizures may be the end result of these phenomena. The relationship of these associated factors to the hypothesized pathophysiology of PRES is discussed.

Initial experience in using continuous arterial spin-labeled MR imaging for early detection of Alzheimer disease.

BACKGROUND AND PURPOSE: MR imaging of the brain has significant potential in the early detection of neurodegenerative disorders such as AD. The purpose of this work was to determine if perfusion MR imaging can be used to separate AD from normal cognition in individual subjects. We investigated the diagnostic utility of perfusion MR imaging for early detection of AD compared with structural imaging. MATERIALS AND METHODS: Data were analyzed from 32 participants in the institutional review board-approved CHS-CS: 19 cognitively healthy individuals and 13 with clinically adjudicated AD. All subjects underwent structural T1-weighted SGPR and CASL MR imaging. Four readers with varying experience separately rated each CASL and SPGR scan finding as normal or abnormal on the basis of standardized qualitative diagnostic criteria for observed perfusion abnormalities on CASL or volume loss on SPGR and rated the confidence in their evaluation. RESULTS: Inter-rater reliability was superior in CASL (kappa = 0.7 in experienced readers) compared with SPGR (kappa = 0.17). CASL MR imaging had the highest sensitivity (85%) and accuracy (70%). Frontal lobe CASL findings increased sensitivity to 88% and accuracy to 79%. Fifty-seven percent of false-positive readings with CASL were in controls with cognitive decline or instability within 5 years. Three of the 4 readers revealed a statistically significant relationship between confidence and correct classification when using CASL. CONCLUSIONS: Readers were able to separate individuals with mild AD from those with normal cognition with high sensitivity by using CASL but not volumetric MR imaging. This initial experience suggests that CASL MR imaging may be a useful technique for detecting AD.

Influenza A encephalopathy, cerebral vasculopathy, and posterior reversible encephalopathy syndrome: combined occurrence in a 3-year-old child.

Encephalopathy is an uncommon complication of childhood influenza infection, typically recognized during influenza epidemics. Imaging hallmarks include characteristic thalamic lesions, thalamic necrosis and hemispheric edema. We describe a child with acute influenza A associated necrotizing encephalopathy with MR angiographic evidence of significant cerebral vasculopathy and a hemispheric edema pattern consistent with PRES. This case reinforces that significant cerebral vasculopathy can accompany influenza infection and that influenza is a likely trigger for PRES.

Hemorrhage in posterior reversible encephalopathy syndrome: imaging and clinical features.

BACKGROUND AND PURPOSE: Hemorrhage is known to occur in posterior reversible encephalopathy syndrome (PRES), but the characteristics have not been analyzed in detail. The purpose of this study was to evaluate the imaging and clinical features of hemorrhage in PRES. MATERIALS AND METHODS: Retrospective assessment of 151 patients with PRES was performed, and 23 patients were identified who had intracranial hemorrhage at toxicity. Hemorrhage types were identified and tabulated, including minute focal hemorrhages (<5 mm), sulcal subarachnoid hemorrhage, and focal hematoma. Clinical features of hemorrhage and nonhemorrhage PRES groups were evaluated, including toxicity blood pressure, coagulation profile/platelet counts, coagulation-altering medication, and clinical conditions associated with PRES. Toxicity mean arterial pressure (MAP) groups were defined as normal (<106 mm Hg), mildly hypertensive (106-116 mm Hg), or severely hypertensive (>116 mm Hg). RESULTS: The overall incidence of hemorrhage was 15.2%, with borderline statistical significance noted between the observed clinical associations (P = .07). Hemorrhage was significantly more common (P = .02) after allogeneic bone marrow transplantation (allo-BMT) than after solid-organ transplantation. The 3 hemorrhage types were noted with equal frequency. A single hemorrhage type was found in 16 patients, with multiple types noted in 7. Patients undergoing therapeutic anticoagulation were statistically more likely to develop hemorrhage (P = .04). No difference in hemorrhage incidence was found among the 3 blood pressure subgroups (range, 14.9%-15.9%). CONCLUSIONS: Three distinct types of hemorrhage (minute hemorrhage, sulcal subarachnoid hemorrhage, hematoma) were identified in PRES with equal frequency. The greatest hemorrhage frequency was seen after allo-BMT and in patients undergoing therapeutic anticoagulation. Hemorrhage rate was independent of the toxicity blood pressure.

Posterior reversible encephalopathy syndrome after solid organ transplantation.

BACKGROUND AND PURPOSE: Posterior reversible encephalopathy syndrome (PRES) is known to occur after solid organ transplantation (SOT), potentially associated with cyclosporine and tacrolimus. In this study, we assess the frequency and clinical and imaging characteristics of PRES after SOT. MATERIALS AND METHODS: We identified 27 patients (13 men and 14 women; age range, 22-72 years) who developed PRES after SOT. Features noted included SOT subtype, incidence and timing of PRES, infection and rejection, mean arterial pressure (MAP), and toxicity brain edema. RESULTS: PRES developed in 21 (0.49%) of 4222 patients who underwent transplantation within the study period (no significant difference among SOT subtypes). Transplantation was performed in 5 patients before the study period, and 1 patient underwent transplantation elsewhere. In consideration of all 27 patients, PRES typically developed in the first 2 months in patients who had SOT of the liver (9 of 10 patients) and was associated with cytomegalovirus (CMV), mild rejection, or systemic bacterial infection. PRES also typically developed after 1 year in patients who had SOT of the kidney (8 of 9 patients) and was associated with moderate rejection or bacterial infection. Toxicity MAP was significantly lower (P < .001) in liver transplants (average MAP, 104.8 +/- 16 mm Hg) compared with that in kidney transplants (average MAP, 143 +/- 20 mm Hg). Toxicity brain edema was significantly greater (P < .001) in patients who had liver transplants and developed PRES compared with patients who had undergone kidney transplants despite severe hypertension in those who had the kidney transplants. CONCLUSION: Patients who had undergone SOTs have a similar low incidence of developing PRES. Differences between those who have had liver and kidney transplants included time after transplant, toxicity MAP, and PRES vasogenic edema noted at presentation. In patients who have undergone kidney transplants, severely elevated MAP was associated with reduced, not greater, brain edema.

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

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.

Distinct imaging patterns and lesion distribution in posterior reversible encephalopathy syndrome.

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.

Posterior reversible encephalopathy syndrome in infection, sepsis, and shock.

BACKGROUND AND PURPOSE: The cause of "posterior reversible encephalopathy syndrome" (PRES) is not established. We recently encountered several patients who developed PRES in the setting of severe infection. In this study, we comprehensively reviewed the clinical and imaging features in a large cohort of patients who developed PRES, with particular attention to those with isolated infection, sepsis, or shock (I/S/S). METHODS: The clinical/imaging features of 106 patients who developed PRES were comprehensively evaluated. In 25 of these patients, PRES occurred in association with severe I/S/S separate from transplantation. The clinical/imaging features (computer tomography, MR imaging, and MR angiography [MRA]) of the patients with I/S/S were further evaluated, including organ/tissue/blood culture results, mean arterial blood pressure (MAP) at toxicity, extent of cerebral edema, and presence of vasospasm. RESULTS: PRES occurred in association with I/S/S in 25 of 106 patients (23.6%), in addition to 4 other major clinical settings, including cyclosporine/FK-506 (post-transplant) neurotoxicity (46.2%), autoimmune disease (10.4%), postchemotherapy (3.7%), and eclampsia (10.4%). In the 25 patients with I/S/S, available cultures demonstrated a predominance of gram-positive organisms (84%). Blood pressure was "normal" at toxicity in 10 patients (MAP, 95 mm Hg); "severe" hypertension was present in 15 patients (MAP, 137 mm Hg). Extent of brain edema graded on imaging studies was greater in the normal MAP group compared with the severe hypertension group (P < .05). MRA demonstrated vasospasm in patients with severe hypertension and vessel "pruning" in the normal MAP group. CONCLUSION: Infection/sepsis/shock may be an important cause of PRES, particularly in relation to infection with gram-positive organisms.