Molecular, Pathological, Clinical, and Therapeutic Aspects of Perihematomal Edema in Different Stages of Intracerebral Hemorrhage

Table 2

The features of ionic and vasogenic edema in the perihematomal area after ICH.

Classifications	Ionic edema	Vasogenic edema	References
Time phase	Undefined. It may appear in the hyperacute phase or in the late phase of ICH	Undefined. It always appears in the acute and subacute phases of ICH	[25, 77]
Mechanisms	Various ion channels and transporters in the BBB, including Sur1-Trpm4, NKCC1, AQP4, Na^+-H^+ exchanger, and Na^+-Ca^2+ exchanger, drive this process	Cytotoxic substances such as inflammatory factors and free radical metalloprotease-induced transendothelial permeability pore formation	[79, 98]
Cellular components in the BBB involved	Endothelial cells	Mainly endothelial cells	[79, 98]
BBB integrity	Intact	Partially destroyed (capillaries still maintain BBB structural integrity)	[79, 98]
Reversibility	Reversible	Partially reversible	[79, 98]
Substances transported	Na^+, Cl^-, and water	Na^+, Cl^-, water, plasma proteins, and other macromolecules (without RBCs)	[14, 22]
Destination of substances transported	From blood vessels to the extracellular space of the brain parenchyma	From blood vessels to the extracellular space of the brain parenchyma	[12, 78, 79, 98]
Imaging characteristics (CT, T1WI, T2WI, and FLAIR images)	It should present as a perihematomal hypodensity seen on CT. Shows an increase in the T2WI and FLAIR image and a decrease in the T1WI	Similar to ionic edema	[82, 84–88]
Imaging characteristics (DWI and ADC images)	The imaging characteristics of ionic edema in DWI and ADC images have not been well defined. If it is similar to cytotoxic edema, it will appear as a reduction in signal on ADC maps but an increase in DWI. However, the chances are high that the imaging features of ionic edema will resemble those of interstitial edema that present as a normal to low signal on DWI and a mild high signal on ADC maps	It shows a normal to low signal on the DWI and a mild high signal on the ADC maps in perihematomal tissue. If the imaging features of ionic edema are finally verified to be similar to those of interstitial edema in perihematomal tissue, it will be challenging to distinguish it from vasogenic edema	[12, 14, 27, 78, 87–89]

Abbreviations: ICH: intracerebral hemorrhage; BBB: blood-brain barrier; Sur1-Trpm4: sulfonylurea receptor 1-transient receptor potential melastatin 4; NKCC1: Na⁺-K⁺-2Cl⁻ cotransporter protein-1; AQP4: aquaporin 4; RBCs: red blood cells; CT: computerized axial tomography; T1WI: T1-weighted MRI; T2WI: T2-weighted MRI; FLAIR: fluid-attenuated inversion recovery image; DWI: diffusion-weighted magnetic resonance imaging; ADC: apparent diffusion coefficient maps.