Imaging pattern of intracranial hemorrhage in the setting of posterior reversible encephalopathy syndrome

Intracranial hemorrhage (ICH) has been rarely described in the setting of posterior reversible encephalopathy syndrome (PRES). However, existing studies have even more rarely addressed the imaging pattern of PRES-related intracranial hemorrhage. The primary purpose of this study was to define the imaging characteristics of subarachnoid and intraparenchymal hemorrhage in the setting of PRES, including the location of hemorrhage with respect to the regions of parenchymal edema. We also reviewed PRES-related clinical features. We conducted a retrospective review of 263 patients with PRES seen at our institution between 2001 and 2008, and identified patients with PRES-related hemorrhage. We reviewed clinical charts and imaging studies of these patients in detail. The clinical data studied included factors predisposing to PRES (such as hypertension, eclampsia, immunosuppressant toxicity, etc.), mean arterial pressure, and coagulation parameters. Imaging characteristics we analyzed included the amount of hemorrhage, its location, multiplicity, and spatial relationship with parenchymal edema. We identified a total of 51 patients with PRES-related hemorrhage. The blood pressure was elevated in 80% of these patients, while 47% patients showed coagulopathy. Intraparenchymal hemorrhage (IPH) was present in 46 patients and subarachnoid hemorrhage (SAH) in 14. SAH spared basal cisterns in all patients, and was usually small in amount. IPH was often multifocal, and associated mass effect was rare. In most of the 51 patients, hemorrhage occurred near the parenchymal edema. The prevalence of ICH in PRES was 19.4% in our series. Both SAH and IPH can occur in association with PRES, typically in a location approximating that of parenchymal edema.