Perihematomal edema: Implications for intracerebral hemorrhage research and therapeutic advances

In humans, perihematomal edema (PHE) is considered to be a radiological marker of secondary injury following intracerebral hemorrhage (ICH). There is also evidence that PHE might contribute to poor outcome in ICH patients. Given the rising interest in secondary injury after ICH as a therapeutic target, PHE is becoming increasingly used as a proof-of-concept surrogate measure to assess the potential efficacy of various therapeutic interventions in clinical trials. We review the pathophysiology of PHE and its evolution, its prognostic significance and relationship to clinical outcomes, and variabilities in its detection and measurement methodologies to determine the advantages versus shortcomings of using PHE as a translational target or radiological marker to examine the efficacy of interventions aiming to mitigate secondary injury in ICH.