Reversible posterior leukoencephalopathy syndrome

We read with interest the retrospective study of 36 patients with reversible posterior leukoencephalopathy syndrome (RPLS), a transient and symmetrically patchy neurological illness characterized by its clinical and neuroimaging manifestations. Few laboratory data from body fluids were given in this study and no pathological examination results were presented. The discussion of mechanism focused on subcortical vasogenic edema somewhat characteristic of hypertensive encephalopathy with disruption of local vasomotor autoregulatory mechanisms; this was consistent with the observation of hypertension in many patients. Additionally, a large percentage of patients had a malignancy, an infectious disease, or another potential alteration of immune physiology caused by pregnancy, transplantation, or a specific illness, such as Sjögren syndrome or glomerulonephritis. One patient had neuromyelitis optica. Schiff and Lopes reported that a single biopsied case of RPLS revealed mild vacuolation, a mild inflammatory reaction, abundant reactive astrocytes, and no evidence of myelinopathy. Other recent reports have described paraneoplastic and parainfectious leukoencephalopathies, which were shown pathologically to be associated with both focal and multifocal demyelination in the brain. An immune mechanism for these has been postulated, but only some cases of paraneoplastic neuromyelitis optica have been associated with a specific antibody, collapsin response-mediator protein-5 immunoglobulin.3 Still other reports have postulated that focal cerebral edema can be caused by cytokines, chemokines, and dysfunctional astrocytes4 responding to immunogenic stimuli that are not yet well understood. In this study of RPLS, most patients had an associated illness that was capable of altering immune physiology. Although the findings do not suggest that RPLS is a demyelinating illness, we speculate that RPLS is predominantly an immune-mediated condition and that hypertension may be secondary to nonneurological manifestations in some cases. The study describes the “clinical spectrum of RPLS.” We speculate that RPLS is part of a larger spectrum of clinical and pathological phenomena joined together by a common immune-mediated mechanism occurring in white matter in the brain. We further speculate that RPLS is mechanistically related to paraneoplastic and parainfectious demyelination in the brain and that they are different phenomena in a single immunemediated disease spectrum occurring within similar patient populations.