Posterior reversible encephalopathy syndrome (PRES) is a disorder of reversible vasogenic brain edema which mainly involves the parieto-occipital lobes in various clinical settings. The main mechanism is known to be cerebral autoregulation failure and endothelial dysfunction leading to the disruption of the blood-brain barrier. We report the case of a 47-year-old woman with PRES which involved the brain stem and thalami, sparing the cerebral hemispheres. She was admitted to the emergency room because of acute-onset confusion. Her initial blood pressure was 270/220 mm Hg. Routine blood lab tests showed pleocytosis, hyperglycemia, and azotemia. Brain magnetic resonance imaging (MRI) showed a lesion of vasogenic edema involving nearly the whole area of pons, the left side of the midbrain, and the bilateral medial thalami. Cerebrospinal fluid (CSF) examination revealed an increased level of protein with normal white blood cell count. With conservative care, the patient markedly recovered 3 days after symptom onset, and a follow-up MRI confirmed complete resolution of the vasogenic edema. This case suggests that PRES can rarely involve the "central zone" only, sparing the cerebral hemispheres, which may be confused with other neurological diseases. Besides, the CSF albuminocytologic dissociation may suggest the disruption of the blood-brain barrier in patients with PRES.