Expanding the spectrum of subacute diencephalic angioencephalopathy

• We report the seventh and most thoroughly investigated case of subacute diencephalic angioencephalopathy (SDAE).
• We present a review of the literature on SDAE and related disorders, including subacute brainstem angioencephalopathy (SBAE).
• This is the first evidence of a potential sentinel syndrome, which may empowering earlier diagnosis and treatment.
• We present new evidence suggesting a possible pathophysiologic relationship between SDAE/SBAE and posterior reversible encephalopathy syndrome (PRES).

We present a patient with subacute diencephalic angioencephalopathy (SDAE), a poorly understood syndrome of progressive confusion, disorientation, and dementia that rapidly deteriorates to severe encephalopathy and death. This is the seventh and most thoroughly investigated report of this exceedingly rare diagnosis to date, and we present the first evidence of a potential sentinel syndrome that may allow for earlier diagnosis and therapeutic intervention. We also review the relevant literature, and highlight new evidence that suggests that SDAE and the related disorder, subacute brainstem angioencephalopathy (SBAE), represent severe and terminal variants of posterior reversible encephalopathy syndrome (PRES). Taken together, we suggest a new understanding of SDAE/SBAE and PRES as a spectrum of hypertension-associated non-inflammatory vascular encephalopathies that are mediated by a loss of venous autoregulation, marked by cytotoxic edema, and that ultimately produce subacute-to-acute diencephalic, brainstem, and posterior fossa injuries with devastating neurologic consequences.