AQP4 and obstructive hydrocephalus: ELISA also, showed (Figure 2 A and Table 1) that AQP4 was also greater in communicating hydrocephalus when compared to the control (χ 22 = 7.14 p < 0,05) and when compared to obstructive hydrocephalus (χ 22 = 4.32 p < 0.05).