Posterior reversible encephalopathy syndrome with thalamic involvement during vasopressor treatment of vertebrobasilar vasospasm after subarachnoid hemorrhage.

Hemodynamic augmentation is the primary medical intervention employed to reverse neurological deficits associated with vasospasm and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage. Failure to improve despite induced hypertension (IH) may raise concern for persistent hypoperfusion and prompt even more aggressive blood pressure augmentation. However, posterior reversible encephalopathy syndrome (PRES) is a hyperperfusion syndrome reported as a rare complication of IH that may confound this picture. We report a case of PRES with prominent thalamic involvement and impaired level of consciousness secondary to blood pressure augmentation for the treatment of symptomatic vertebrobasilar vasospasm. Recognition of this syndrome in distinction to worsening ischemia is particularly critical, as normalization of blood pressure should lead to rapid clinical improvement.