Features of infratentorial-predominant posterior reversible encephalopathy syndrome

Abstract

Introduction PRES is a neurotoxic process that typically occurs in the setting of immune dysregulation. In contrast to the characteristic pattern involving parieto-occipital and posterior frontal regions, predominant involvement of the infratentorial brain occurs in a minority of PRES patients. We examined six patients with IPPRES relative to those with typical PRES in terms of clinical factors of toxicity and outcomes. We review the current understanding of PRES pathophysiology. Methods An institutional database of PRES patients was created through an IRB-approved search of the electronic record from 2007-2012. MR images were reviewed and classified by two neuroradiologists. Clinical data including laboratory data, blood pressure, and discharge outcome were collected through review of existing electronic medical records. Characteristics of the two groups were compared. Results Six cases among 80 PRES patients displayed an atypical distribution of signal abnormality predominantly involving the infratentorial brain. In IPPRES patients, signal abnormalities within the supratentorial brain, when present, showed a predominantly central distribution rather than the typical peripheral distribution. IPPRES patients showed higher rates of extreme hypertension, renal dysfunction, abnormal serum calcium, and abnormal serum magnesium relative to typical PRES patients. Outcomes were similar between the two groups. Discussion In our small series, IPPRES differs from typical PRES patients not only in the distribution of imaging abnormalities but also in rates of extreme hypertension and several laboratory indices. Despite these differences, clinical outcome in the IPPRES group was similar to that of typical PRES.

Diffuse leukoencephalopathy in a 29-year-old male with hypertensive emergency

“… 5 Not surprisingly, the association between these features and extreme hypertension has been described previously. 6 Our report supports this association, where the recorded blood pressure of the patient was 250/150 mmHg, which is much higher than the mean blood pressure of 191/104 mmHg seen in PRES. 4 Symmetry is not a significant finding, being present in one-half of the cases in most reports.…”

“…According to this theory, vasoconstriction is caused by endothelial dysfunction, which is, in turn, the result of the immunotoxic effects of vasoactive agents released in response to increased intracranial pressure from hypertension. 6 …”

Posterior Reversible Encephalopathy Syndrome With Isolated Involving Infratentorial Structures

“…PRES with atypical radiology involving the frontal and temporal lobes, basal ganglia, brainstem, cerebellum, and other cerebral areas has been reported in recent years ( 3 , 4 , 6 , 7 , 27 ). These atypical distributions have a higher rate than we thought ( 21 ).…”

“…Several articles pointed out that the lower density of sympathetic innervations in the vertebrobasilar system, an essential factor for the control of cerebrovascular autoregulation (presumably protecting the brain from marked increases in intravascular pressure, such as with severe hypertension), might be attributed to the high incidence of reversible vasogenic edema in posterior zone ( 1 , 7 , 9 , 27 ). There is no clear explanation for isolated involvement of infretentorial territories thus far.…”

Isolated pons involvement in Posterior Reversible Encephalopathy Syndrome: Case report and review of the literature

“…Overall, they show a dissociation between the mild clinical features, mostly not referable to the brainstem, and the severity of the MRI images [11] , [12] , [13] , [14] . This pattern of clinico - radiological dissociation may be considered a key feature of brainstem PRES, and represents a clue for diagnosis and differentiation from typical PRES, the latter being associated to encephalopathy, seizures, status epilepticus, headache, visual disturbances and focal findings [1] , usually with typical MRI imaging pattern [2] .…”