NGF and edema: Our previous study showed that 100 Hz EA at GV20 and GV26 can increase the level of nerve growth factor (NGF) in the cerebral tissues of middle cerebral artery occlusion/reperfusion rats during the recovery period [3 weeks after the operation when the integrity of BBB was ensured (Abulrob et al., 2008)], favor the regeneration and repair of nerves, and did not cause cerebral edema or secondary brain injury (Zhang et al., 2018).