Understanding Posterior Reversible Encephalopathy Syndrome

An atypical subacute presentation of posterior reversible encephalopathy syndrome

“…In our patient, the only clinical feature present on admission to our hospital was altered mental status, which has been reported in 13–90% of cases [12]. Seizure is the most common feature of PRES, occurring in up to 92% of cases [12]. Although she had seizure episodes three months prior and three days prior to presentation, there was no seizure demonstrated clinically or by EEG during the third presentation, when MRI findings consistent with PRES were first noted.…”

“…Clinically, PRES is typified by headache, altered mental status, visual abnormalities, and seizure activity, which can occur in various combinations. In our patient, the only clinical feature present on admission to our hospital was altered mental status, which has been reported in 13–90% of cases [12]. Seizure is the most common feature of PRES, occurring in up to 92% of cases [12].…”

“…Although she had seizure episodes three months prior and three days prior to presentation, there was no seizure demonstrated clinically or by EEG during the third presentation, when MRI findings consistent with PRES were first noted. Visual abnormality and headaches were absent during all three presentations, though they are noted to be present in up to 67% and 53% of cases, respectively [12]. …”

“…The posterior circulation was believed to be preferentially affected due to its relatively poorer sympathetic innervation [13]. Cohort studies [6,12] have described four different radiological patterns of PRES and reported that this archetypal pattern, referred to as ‘the dominant parietal-occipital pattern’, occurred in only 22% in their studied cohort of 136 cases. The topographic distribution seen in our case with signal hyperintensities present in the frontal, parietal, and occipital lobes bilaterally as well as the brainstem and pons best fits the description of a ‘holohemispheric watershed pattern’.…”

“…However, Legriel et al describe two hypotheses [12]. Although both theories oppose each other, they both propose that blood–brain barrier (BBB) dysfunction with resultant vasogenic edema is the final end point.…”