The link between arterial blood pressure and vasogenic edema in pediatric PRES.

Abstract

Dear Sir, We welcome the comments made by Dr. Donmez regarding etiologic factors in the development of posterior reversible encephalopathy syndrome (PRES), in particular the potential contribution of Epstein barr virus (EBV) infection. A large number of disorders have been described in association with PRES in the pediatric population including solid organ and bone marrow transplantation, renal dysfunction, autoimmunity, sepsis, and chemotherapy with hypertension being observed in up to 88 % of children at symptoms onset [1]. As Dr. Donmez points out, additional underlying factors may incite or potentiate the development of PRES such as viral infection or medication effects. Such factors, in addition to hypertension, vary from case to case but are known to be present in most PRES cases in adults and children [1, 2]. Whether hypertension directly contributes to the development of PRES or is instead a downstream effect of an underlying systemic toxicity that affects both the cerebral vasculature (manifesting characteristic MRI and MRA findings) and the renal vasculature (resulting in hypertension) is unclear. In our case, the patient did have a brief period of hypertension which may or may not have contributed to the development of PRES [3]. Taking a step back, it seems plausible that this patient’s hypertension could be attributed to GuillainBarre syndrome (GBS) through altered autonomic regulation of the sympathetic nervous system [4, 5]. Such amechanism is supported by the extensive involvement of upper cervical nerve roots observed in this case and their contribution to the cervical ganglia [3]. Further, this patient had no prior history of hypertension nor has he experienced hypertension following the resolution of the GBS/ PRES episode. The presence of viral markers of EBV may explain the development of GBS; however, we posit that any specific correlation between Epstein Barr viremia and the development of PRES in our case is less robust than our proposed correlation between GBS and PRES. Although PRES is well known to occur in the setting of infection including viral illness [6], sepsis represents the most common scenario in which the development of PRES has been attributed to an infectious etiology [2]. Thus, it is our opinion that among the potential contributing factors in the cascade leading to PRES in this individual, GBS remains at the forefront. In this regard, we have recently observed a statistically significant correlation between systolic blood pressure at symptoms onset and normalized ADC values in 25 children with PRES further supporting the association between vasogenic edema and hypertension [1]. Attempts to isolate a single etiologic factor in PRES development have failed given that PRES is likely a multi-factorial entity. A better understanding of PRES pathophysiology may be likely gained by viewing PRES as a downstream result of a cascade of events which may alter the blood brain barrier homeostasis [7]. * Giulio Zuccoli giulio.zuccoli@gmail.com